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Sample records for aerogenes enterobacter cloacae

  1. [Application of gas chromatography in the identification of Enterobacter cloacae, Enterobacter aerogenes, and Enterobacter agglomerans].

    PubMed

    Robles Valderrama, E; Ramírez García, P; González Arreaga, M E; Sáinz Morales, M G; Martínez Rodríguez, B; Durán Díaz, A; Chávez Ramírez, D

    1999-01-01

    Enterobacter cloacae, Enterobacter aerogenes and Enterobacter agglomerans were identified using gas chromatography as a substitution of the traditional techniques. Their acid methyl esters profiles were determined using a gas chromatograph Hewlett Packard 5890A and a RSL-150 heliflex capillary column. A total of 120 samples were analyzed from reference strains (ATCC 13047, 13048, 27155) and environmental isolations, eleven fatty acids were included in the profiles from which cis-9, 10-methyleneoctadecanoic acid (peak 24), cis-9-hexadecenoic acid (peak 14), octadecanoic acid (peak 23) and dodecanoic acid (peak 3), were the most important for the differentiation of the three species analyzed.

  2. Comparison of the clinical and microbiologic characteristics of patients with Enterobacter cloacae and Enterobacter aerogenes bacteremia: a prospective observation study.

    PubMed

    Song, Eun Hee; Park, Ki-Ho; Jang, Eun-Young; Lee, Eun Jung; Chong, Yong Pil; Cho, Oh-Hyun; Kim, Sung-Han; Lee, Sang-Oh; Sung, Heungsup; Kim, Mi-Na; Jeong, Jin-Yong; Kim, Yang Soo; Woo, Jun Hee; Choi, Sang-Ho

    2010-04-01

    We compared the characteristics and outcomes of 172 Enterobacter cloacae bacteremia and 67 Enterobacter aerogenes bacteremia (EAB) cases. Antimicrobial resistance rates to E. cloacae were higher than those to E. aerogenes. However, EAB more frequently presented as septic shock and was associated with poorer outcomes.

  3. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment

    PubMed Central

    Davin-Regli, Anne; Pagès, Jean-Marie

    2015-01-01

    Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution. PMID:26042091

  4. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment.

    PubMed

    Davin-Regli, Anne; Pagès, Jean-Marie

    2015-01-01

    Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution.

  5. Irreproducible and uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes.

    PubMed

    Landman, David; Salamera, Julius; Quale, John

    2013-12-01

    Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of ≤2 μg/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution.

  6. Detection of extended-spectrum beta-lactamases in clinical isolates of Enterobacter cloacae and Enterobacter aerogenes.

    PubMed

    Tzelepi, E; Giakkoupi, P; Sofianou, D; Loukova, V; Kemeroglou, A; Tsakris, A

    2000-02-01

    The aim of the present study was to investigate the frequency of extended-spectrum beta-lactamases (ESBLs) in a consecutive collection of clinical isolates of Enterobacter spp. The abilities of various screening methods to detect ESBLs in enterobacters were simultaneously tested. Among the 68 consecutive isolates (56 Enterobacter cloacae and 12 Enterobacter aerogenes isolates) that were analyzed for beta-lactamase content, 21 (25 and 58%, respectively) possessed transferable ESBLs with pIs of 8.2 and phenotypic characteristics of SHV-type enzymes, 8 (14.3%) of the E. cloacae isolates produced a previously nondescribed, clavulanate-susceptible ESBL that exhibited a pI of 6.9 and that conferred a ceftazidime resistance phenotype on Escherichia coli transconjugants, and 2 E. cloacae isolates produced both of these enzymes. Among the total of 31 isolates that were considered ESBL producers, the Vitek ESBL detection test was positive for 2 (6.5%) strains, and the conventional double-disk synergy test (DDST) with amoxicillin-clavulanate and with expanded-spectrum cephalosporins and aztreonam was positive for 5 (16%) strains. Modifications of the DDST consisting of closer application of the disks (at 20 instead of 30 mm), the use of cefepime, and the use of both modifications increased the sensitivity of this test to 71, 61, and 90%, respectively. Of the 37 isolates for which isoelectric focusing failed to determine ESBLs, the Vitek test was false positive for 1 isolate and the various forms of DDSTs were false-positive for 3 isolates.

  7. Draft Genome Assemblies of Enterobacter aerogenes CDC 6003-71, Enterobacter cloacae CDC 442-68, and Pantoea agglomerans UA 0804-01.

    PubMed

    Minogue, T D; Daligault, H E; Davenport, K W; Bishop-Lilly, K A; Bruce, D C; Chain, P S; Coyne, S R; Chertkov, O; Freitas, T; Frey, K G; Jaissle, J; Koroleva, G I; Ladner, J T; Palacios, G F; Redden, C L; Xu, Y; Johnson, S L

    2014-10-23

    The Enterobacteriaceae are environmental and enteric microbes. We sequenced the genomes of two Enterobacter reference strains, E. aerogenes CDC 6003-71 and E. cloacae CDC 442-68, as well as one near neighbor used as an exclusionary reference for diagnostics, Pantoea agglomerans CDC UA0804-01. The genome sizes range from 4.72 to 5.55 Mbp and have G+C contents from 54.6 to 55.1%.

  8. Characterization of KPC-2-producing Escherichia coli, Citrobacter freundii, Enterobacter cloacae, Enterobacter aerogenes, and Klebsiella oxytoca isolates from a Chinese Hospital.

    PubMed

    Luo, Yanping; Yang, Jiyong; Ye, Liyan; Guo, Lin; Zhao, Qiang; Chen, Rong; Chen, Yong; Han, Xuelin; Zhao, Jingya; Tian, Shuguang; Han, Li

    2014-08-01

    Twelve nonduplicated KPC-2-producing enterobacterial isolates, including three Escherichia coli, two Citrobacter freundii, two Enterobacter cloacae, four Enterobacter aerogenes, and one Klebsiella oxytoca, were collected from various clinical samples within 18 months (March 2011 to September 2012). Two of the 12 patients died from infections caused by KPC-2-producing pathogens, while the rest of the patients with KPC-2-producing pathogens improved or were cured. The majority of the clinical isolates exhibited a high-level of resistance to oxyimino-cephalosporins and carbapenems, and possessed self-transferable bla(KPC-2)-carrying plasmids with sizes ranging from 20 to 120 kb. Most isolates carried bla(CTX-M) and plasmid-mediated quinolone resistance genes, while some isolates produced 16S rRNA methylases (ArmA or RmtB). The genetic environment of bla(KPC-2) of most clinical strains was consistent with the genetic structure surrounding bla(KPC-2) on the plasmid pKP048, which contains an integration structure of a Tn3-based transposon and partial Tn4401 segment. Inserted fragments (truncated bla(TEM)) were detected upstream of the bla(KPC-2) gene for two E. aerogenes strains. In conclusion, the enterobacterial isolates exhibited sporadic emergence and did not arise by clonal spread at our hospital. The outcome of infections caused by KPC-producing enterobacterial isolates and their mortality were closely associated with the baseline condition of patients. The spread of bla(KPC-2) gene between different enterobacterial species in China was mainly mediated by horizontal transfer of the Tn3-based transposons and not the bla(KPC-2)-carrying plasmids.

  9. Evaluation of Phoenix Automated Microbiology System for detecting extended-spectrum beta-lactamases among chromosomal AmpC-producing Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, and Serratia marcescens.

    PubMed

    Park, Yeon-Joon; Yu, Jin Kyung; Lee, Seungok; Park, Jung-Jun; Oh, Eun-Jee

    2007-01-01

    We evaluated the BD Phoenix Extended-Spectrum beta-Lactamase (ESBL) detection test among chromosomal AmpC-producing Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, and Serratia marcescens. The study was conducted on 72 non-repetitive ESBL producers (33 E. cloacae, 13 E. aerogenes, 14 C. freundii, and 12 S. marcescens) and 77 ESBL non-producers (33 E. cloacae, 9 E. aerogenes, 6 C. freundii, and 29 S. marcescens). The organisms were selected as suspected ESBL-producers based on the double disk synergy test and confirmed by PCR amplification of blaTEM-1, blaSHV-1, blaCTX-M-1, blaCTX-M-2, and blaCTX-M-9. The Phoenix ESBL test, using a 5-well confirmatory test and the BDXpert system, was evaluated. Of the 72 isolates identified as ESBL-producers based on the DDST, 46 isolates harbored CTX-M-type enzymes, 21 harbored TEM type enzymes, and 31 harbored SHV enzymes. The Phoenix system identified ESBL only in 15 isolates. Of the 77 ESBL non-producers, ths Phoenix system identified ESBL in 4 isolates, 3 of which were confirmed to be ESBL-producers. In this study, the Phoenix system was highly specific (76/77, 98.7%), and it identified 3 additional ESBL-producers that were not detected by DDST. However, the Phoenix system's sensitivity was very low (15/72, 20.8%). Considering the increasing prevalence of ESBL production among AmpC-producers, the BD Phoenix system could not be considered a reliable stand-alone ESBL detection method for the strains tested in our study.

  10. Infectious discitis caused by Enterobacter cloacae.

    PubMed Central

    Solans, R; Simeon, P; Cuenca, R; Fonollosa, V; Bago, J; Vilardell, M

    1992-01-01

    The case is reported of a patient who developed a vertebral osteomyelitis caused by Enterobacter cloacae. The organism was isolated in cultures of blood and vertebral puncture biopsy samples. The patient was satisfactorily treated with trimethroprim and sulphamethoxazole. Enterobacter cloacae, a Gram negative organism, has been confirmed as the cause of bacteremia in patients with burns, urinary infections, in adults with pneumonia, and in children with joint infections. Spondylodiscitis caused by Enterobacter cloacae has not previously been described. Images PMID:1632668

  11. Comparative Genome Analysis of Enterobacter cloacae

    PubMed Central

    Liu, Wing-Yee; Wong, Chi-Fat; Chung, Karl Ming-Kar; Jiang, Jing-Wei; Leung, Frederick Chi-Ching

    2013-01-01

    The Enterobacter cloacae species includes an extremely diverse group of bacteria that are associated with plants, soil and humans. Publication of the complete genome sequence of the plant growth-promoting endophytic E. cloacae subsp. cloacae ENHKU01 provided an opportunity to perform the first comparative genome analysis between strains of this dynamic species. Examination of the pan-genome of E. cloacae showed that the conserved core genome retains the general physiological and survival genes of the species, while genomic factors in plasmids and variable regions determine the virulence of the human pathogenic E. cloacae strain; additionally, the diversity of fimbriae contributes to variation in colonization and host determination of different E. cloacae strains. Comparative genome analysis further illustrated that E. cloacae strains possess multiple mechanisms for antagonistic action against other microorganisms, which involve the production of siderophores and various antimicrobial compounds, such as bacteriocins, chitinases and antibiotic resistance proteins. The presence of Type VI secretion systems is expected to provide further fitness advantages for E. cloacae in microbial competition, thus allowing it to survive in different environments. Competition assays were performed to support our observations in genomic analysis, where E. cloacae subsp. cloacae ENHKU01 demonstrated antagonistic activities against a wide range of plant pathogenic fungal and bacterial species. PMID:24069314

  12. Enterobacter cloacae causing pneumatocele in a neonate.

    PubMed

    Glustein, J Z; Kaplan, M

    1994-09-01

    Pneumatocele formation, a cyst-like rarefaction that develops within the lung parenchyma, is an unusual complication of pneumonia in the neonate. It has been reported to occur with Staphlococcus aureus, Escherichia coli, Klebsiella pneumoniae, Streptococcus pneumoniae, and Pseudomonas aeruginosa infections. We describe a case of a premature neonate with pneumonia and subsequent pneumatocele formation caused by Enterobacter cloacae.

  13. Bioengineering of the Enterobacter aerogenes strain for biohydrogen production.

    PubMed

    Zhang, Chong; Lv, Feng-Xiang; Xing, Xin-Hui

    2011-09-01

    Enterobacter aerogenes is one of the most widely-studied model strains for fermentative hydrogen production. To improve the hydrogen yield of E. aerogenes, the bioengineering on a biomolecular level and metabolic network level is of importance. In this review, the fermentative technology of E. aerogenes for hydrogen production will be first briefly summarized. And then the bioengineering of E. aerogenes for the improvement of hydrogen yield will be thoroughly reviewed, including the anaerobic metabolic networks for hydrogen evolution in E. aerogenes, metabolic engineering for improving hydrogen production in E. aerogenes and mixed culture of E. aerogenes with other hydrogen-producing bacteria to enhance the overall yield in anaerobic cultivation. Finally, a perspective on E. aerogenes as a hydrogen producer including systems bioengineering approach for improving the hydrogen yield and application of the engineered E. aerogenes in mixed culture will be presented.

  14. Complete genome sequence of Enterobacter aerogenes KCTC 2190.

    PubMed

    Shin, Sang Heum; Kim, Sewhan; Kim, Jae Young; Lee, Soojin; Um, Youngsoon; Oh, Min-Kyu; Kim, Young-Rok; Lee, Jinwon; Yang, Kap-Seok

    2012-05-01

    This is the first complete genome sequence of the Enterobacter aerogenes species. Here we present the genome sequence of E. aerogenes KCTC 2190, which contains 5,280,350 bp with a G + C content of 54.8 mol%, 4,912 protein-coding genes, and 109 structural RNAs.

  15. Complete Genome Sequence of Enterobacter aerogenes KCTC 2190

    PubMed Central

    Shin, Sang Heum; Kim, Sewhan; Kim, Jae Young; Lee, Soojin; Um, Youngsoon; Oh, Min-Kyu; Kim, Young-Rok; Lee, Jinwon

    2012-01-01

    This is the first complete genome sequence of the Enterobacter aerogenes species. Here we present the genome sequence of E. aerogenes KCTC 2190, which contains 5,280,350 bp with a G + C content of 54.8 mol%, 4,912 protein-coding genes, and 109 structural RNAs. PMID:22493190

  16. Enterobacter cloacae complex: clinical impact and emerging antibiotic resistance.

    PubMed

    Mezzatesta, Maria Lina; Gona, Floriana; Stefani, Stefania

    2012-07-01

    Species of the Enterobacter cloacae complex are widely encountered in nature, but they can act as pathogens. The biochemical and molecular studies on E. cloacae have shown genomic heterogeneity, comprising six species: Enterobacter cloacae, Enterobacter asburiae, Enterobacter hormaechei, Enterobacter kobei, Enterobacter ludwigii and Enterobacter nimipressuralis, E. cloacae and E. hormaechei are the most frequently isolated in human clinical specimens. Phenotypic identification of all species belonging to this taxon is usually difficult and not always reliable; therefore, molecular methods are often used. Although the E. cloacae complex strains are among the most common Enterobacter spp. causing nosocomial bloodstream infections in the last decade, little is known about their virulence-associated properties. By contrast, much has been published on the antibiotic-resistance features of these microorganisms. In fact, they are capable of overproducing AmpC β-lactamases by derepression of a chromosomal gene or by the acquisition of a transferable ampC gene on plasmids conferring the antibiotic resistance. Many other resistance determinants that are able to render ineffective almost all antibiotic families have been recently acquired. Most studies on antimicrobial susceptibility are focused on E. cloacae, E. hormaechei and E. asburiae; these studies reported small variations between the species, and the only significant differences had no discriminating features.

  17. Emergence of VIM-1-carbapenemase-producing Enterobacter cloacae in Tyrol, Austria.

    PubMed

    Heller, Ingrid; Grif, Katharina; Orth, Dorothea

    2012-04-01

    The rapid emergence and dissemination of carbapenemase-producing Enterobacter species and other members of the Enterobacteriaceae poses a considerable threat to the care of hospitalized patients and to public health. In this study, Enterobacter isolates demonstrating decreased susceptibility to carbapenems detected at the Division of Hygiene and Medical Microbiology, Innsbruck Medical University, between January 2006 and December 2010 were tested for bla(VIM-1), bla(NDM-1), bla(IMP), bla(KPC) and bla(OXA-48) using a multiplex PCR with published primers. PFGE was performed to determine the genetic relatedness. In total, 33 isolates (28 Enterobacter cloacae and 5 Enterobacter aerogenes) were collected during the study period. From 2006 to 2009, between two and seven isolates were found per year. In 2010, a significant increase of carbapenem-resistant strains was observed (n = 12). The bla(VIM-1) gene was detected in all 28 isolates of E. cloacae. Typing of E. cloacae by PFGE revealed three distinct clusters, the biggest of which contained 18 isolates. These findings demonstrate the emergence of VIM-1-producing Enterobacter in Tyrol, western Austria. The clonal relationship confirms the risk of spread of these organisms and their possible persistence over time.

  18. Transmission of Enterobacter aerogenes septicemia in healthcare workers.

    PubMed

    Jha, Piyush; Kim, Choon-Mee; Kim, Dong-Min; Chung, Jong-Hoon; Yoon, Na-Ra; Jha, Babita; Kim, Seok Won; Jang, Sook Jin; Ahn, Young-Joon; Chung, Jae Keun; Jeon, Doo Young

    2016-01-01

    Enterobacter aerogenes is recognized as an important bacterial pathogen in hospital-acquired infections. This report describes two unusual cases of septicemia caused by E. aerogenes in immunocompetent healthcare workers. E. aerogenes was isolated from blood cultures of the two patients experiencing septicemia. The clinical isolates were initially identified as E. aerogenes using a VITEK II automated system and 16S rRNA sequence analysis, and; both isolates involved in the outbreak shared a common pulse-field gel electrophoresis pattern. The similarities between the two cases included the simultaneous development of gastroenteritis symptoms, severe sepsis and thrombocytopenia after taking intravenous injections of ketorolac tromethamine. A common source of normal saline, a 100 mL bottle, was used for diluting the analgesic in both cases. In addition to the general population, healthcare workers, especially those who are also intravenous drug abusers, should be considered subjects that could cause a transmission of Enterobacter infection.

  19. Transmission of Enterobacter aerogenes septicemia in healthcare workers.

    PubMed

    Jha, Piyush; Kim, Choon-Mee; Kim, Dong-Min; Chung, Jong-Hoon; Yoon, Na-Ra; Jha, Babita; Kim, Seok Won; Jang, Sook Jin; Ahn, Young-Joon; Chung, Jae Keun; Jeon, Doo Young

    2016-01-01

    Enterobacter aerogenes is recognized as an important bacterial pathogen in hospital-acquired infections. This report describes two unusual cases of septicemia caused by E. aerogenes in immunocompetent healthcare workers. E. aerogenes was isolated from blood cultures of the two patients experiencing septicemia. The clinical isolates were initially identified as E. aerogenes using a VITEK II automated system and 16S rRNA sequence analysis, and; both isolates involved in the outbreak shared a common pulse-field gel electrophoresis pattern. The similarities between the two cases included the simultaneous development of gastroenteritis symptoms, severe sepsis and thrombocytopenia after taking intravenous injections of ketorolac tromethamine. A common source of normal saline, a 100 mL bottle, was used for diluting the analgesic in both cases. In addition to the general population, healthcare workers, especially those who are also intravenous drug abusers, should be considered subjects that could cause a transmission of Enterobacter infection. PMID:27610316

  20. Draft genome sequence of Enterobacter cloacae subsp. cloacae strain 08XA1, a fecal bacterium of giant pandas.

    PubMed

    Yan, Yue; Zhao, Chuan-Wu; Zhang, Yi-Zheng; Zhang, Zhi-He; Pan, Guang-Lin; Liu, Wen-Wang; Ma, Qing-Yi; Hou, Rong; Tan, Xue-Mei

    2012-12-01

    Enterobacter cloacae, a common pathogenic bacterium, is a Gram-negative bacillus. We analyzed the draft genome of Enterobacter cloacae subsp. cloacae strain 08XA1 from the feces of a giant panda in China. Genes encoding a β-lactamase and efflux pumps, as well as other factors, have been found in the genome. PMID:23209197

  1. Draft genome sequence of Enterobacter cloacae subsp. cloacae strain 08XA1, a fecal bacterium of giant pandas.

    PubMed

    Yan, Yue; Zhao, Chuan-Wu; Zhang, Yi-Zheng; Zhang, Zhi-He; Pan, Guang-Lin; Liu, Wen-Wang; Ma, Qing-Yi; Hou, Rong; Tan, Xue-Mei

    2012-12-01

    Enterobacter cloacae, a common pathogenic bacterium, is a Gram-negative bacillus. We analyzed the draft genome of Enterobacter cloacae subsp. cloacae strain 08XA1 from the feces of a giant panda in China. Genes encoding a β-lactamase and efflux pumps, as well as other factors, have been found in the genome.

  2. Single-cell protein from methanol with Enterobacter aerogenes

    SciTech Connect

    Gnan, S.O.; Abodreheba, A.O.

    1987-02-20

    An identified Enterobacter aerogenes utilizing methanol as a sole carbon source was studied for the optimization of biomass production and the reduction of its nucleic acid content. Results indicated that the highest yield and conversion were obtained at 0.5% methanol. The addition of seawater as a source of trace elements has an adverse effect. However, the addition of urea as source of nitrogen enhanced the growth of E. aerogenes. Heat shock at 60 degrees C for one minute followed by incubation at 50 degrees C for 2 hours caused 72.6% reduction in the nucleic acid. 12 references.

  3. Enterobacter cloacae inhibits human norovirus infectivity in gnotobiotic pigs

    PubMed Central

    Lei, Shaohua; Samuel, Helen; Twitchell, Erica; Bui, Tammy; Ramesh, Ashwin; Wen, Ke; Weiss, Mariah; Li, Guohua; Yang, Xingdong; Jiang, Xi; Yuan, Lijuan

    2016-01-01

    Human noroviruses (HuNoVs) are the leading cause of epidemic gastroenteritis worldwide. Study of HuNoV biology has been hampered by the lack of an efficient cell culture system. Recently, enteric commensal bacteria Enterobacter cloacae has been recognized as a helper in HuNoV infection of B cells in vitro. To test the influences of E. cloacae on HuNoV infectivity and to determine whether HuNoV infects B cells in vivo, we colonized gnotobiotic pigs with E. cloacae and inoculated pigs with 2.74 × 104 genome copies of HuNoV. Compared to control pigs, reduced HuNoV shedding was observed in E. cloacae colonized pigs, characterized by significantly shorter duration of shedding in post-inoculation day 10 subgroup and lower cumulative shedding and peak shedding in individual pigs. Colonization of E. cloacae also reduced HuNoV titers in intestinal tissues and in blood. In both control and E. cloacae colonized pigs, HuNoV infection of enterocytes was confirmed, however infection of B cells was not observed in ileum, and the entire lamina propria in sections of duodenum, jejunum, and ileum were HuNoV-negative. In summary, E. cloacae inhibited HuNoV infectivity, and B cells were not a target cell type for HuNoV in gnotobiotic pigs, with or without E. cloacae colonization. PMID:27113278

  4. Sublethal effects of ultraviolet A radiation on Enterobacter cloacae.

    PubMed

    Oppezzo, O J; Pizarro, R A

    2001-09-15

    We report the sublethal effects of ultraviolet A (UVA) on Enterobacter cloacae in comparison with those produced in Escherichia coli. UVA-induced sublethal effects were investigated in either bacterial membrane and at tRNA level. Limited dependence on oxygen concentration for photoinduced inhibition of biochemical membrane functions and low levels of oxidative damage during the irradiation period were found in En. cloacae. On the other hand, ultraviolet spectroscopy and reversed-phase HPLC analysis of hydrolysed tRNA showed that radio induced damage to tRNA is similar in En. cloacae and E. coli. Nevertheless, growth delay induced by UVA in En. cloacae was shorter than that found in E. coli submitted to the same experimental conditions. A limited post-irradiation ppGpp accumulation and the absence of any influence of the membrane damage on the growth delay extent seem to be responsible for the shortness of this effect in En. cloacae. Most of the differences between En. cloacae and E. coli could be attributed to an increased ability of En. cloacae to overcome oxidative stress during UVA exposure.

  5. Enterobacter cloacae outbreak in the NICU related to disinfected thermometers.

    PubMed

    van den Berg, R W; Claahsen, H L; Niessen, M; Muytjens, H L; Liem, K; Voss, A

    2000-05-01

    In the first week ot December 1997, an increasing incidence of neonates colonized with multi-drug resistant Enterobacter cloacae (MR-E. cloacae) was observed in the neonatal Intensive care unit of our 950-bed university hospital. Initially, re-enforcement of infection control practices including hand disinfection and cohort isolation seemed to be sufficient to control the outbreak. Nevertheless, an increasing number of newly admitted patients was paralleled by another rise in the incidence of colonized neonates. Since E. cloacae was initially found in urine specimens of the patients, surveillance and environmental cultures were aimed at procedures and instruments that might colonize the gastro-intestinal and/or urinary tract. E, cloacae was isolated from a single cap of an electronic digital thermometer. Despite banning of this possible source, newly admitted neonates still became colonized. The unit was closed for further admissions and a second round of extensive screening was started; this time including all available thermometers and continuous rectal temperature probes. Ready-to-use 'disinfected thermometers and probes were found to be colonized with MR-E. cloacae. Observation of disinfection procedures and a laboratory investigation revealed that 'rushed disinfection with alcohol 80% led to a 1 in 10 chance of thermometers still being contaminated. Furthermore, alcoholic hand rub used for convenience disinfection failed to disinfect thermometers in 40% and 20% of the cases when done in a 'rushed' or 'careful' fashion, respectively. Adequate disinfection of the thermometers led to the control of the outbreak, with no new occurrence of MR-E. cloacae in the following months.

  6. Purification and Genetic Determination of Bacteriocin Production in Enterobacter cloacae

    PubMed Central

    de Graaf, F. K.; Tieze, G. A.; Bonga, Sj. Wendelaar; Stouthamer, A. H.

    1968-01-01

    Enterobacter cloacae (strain DF13) was found to produce a bacteriocin which could be induced by mitomycin C. In the supernatant fluid of the induced culture phagelike particles were found. The bacteriocin was partially purified from induced cultures by ammonium sulfate precipitation and gel-filtration on Sephadex G-150. Ultraviolet-absorbing material was eluted from the Sephadex column in three fractions. The biological activity was mainly present in the second fraction and is associated with a protein with a molecular weight of about 61,000. The phagelike particles were found in the first fraction and show no biological activity. Upon conjugation of E. cloacae strain DF13 with another strain of the same species and with Escherichia coli K-12S, the ability to produce bacteriocin was transferred. The new bacteriocinogenic strain produced bacteriocin, which could not be distinguished from that produced by E. cloacae strain DF13. Although transfer of the bacteriocinogenic factor often occurred together with transfer of the ability to produce phagelike particles, it was shown that these two factors are two separate genetic entities. In addition to a bacteriocinogenic factor, E. cloacae strain DF13 was found to carry two other transferable plasmids: one determining resistance against streptomycin and sulfanilamide and another determining resistance against penicillin. Images PMID:4867749

  7. Properties of Silver Sulfadiazine-Resistant Enterobacter cloacae

    PubMed Central

    Rosenkranz, Herbert S.; Coward, Joe E.; Wlodkowski, Theodore J.; Carr, Howard S.

    1974-01-01

    Two silver sulfadiazine-resistant isolates of Enterobacter cloacae obtained in a burns unit where the drug was in use were studied. These strains were resistant to elevated levels of the drug, and they were cross-resistant to silver benzoate, but not to silver nitrate. Growth of the strains in nutritionally poor defined media sensitized them to the inhibitory action of the drug. Exposure of the bacteria to penicillins rendered them susceptible to silver sulfadiazine. The resistant bacteria harbored episomes for resistance to carbenicillin and kanamycin; however, resistance to silver sulfadiazine could not be transferred by these episomes. Twenty-three strains of E. cloacae isolated in a general hospital were sensitive to much lower levels of the drug (≤50 μg/ml). PMID:4840432

  8. Biological Conversion of Glycerol to Ethanol by Enterobacter aerogenes

    NASA Astrophysics Data System (ADS)

    Nwachukwu, Raymond E. S.

    In a search to turn the economically and environmentally non-valuable "waste" streams of biodiesel production into a profitable byproduct, a mutant strain of Enterobacter aerogenes ATCC 13048 was developed by six-tube subculturing technique. This technique is based on the principle of adaptive evolution, and involved subculturing the bacterium in a tryptic soy broth without dextrose (TSB) containing specific glycerol and ethanol concentration for six consecutive times. Then, the six consecutive subculturing was repeated in a fresh TSB of higher glycerol and ethanol concentrations. A new mutant strain, E. aerogenes S012, which could withstand a combination of 200 g/l glycerol and 30 g/l ethanol concentrations, was developed. The wild and mutant strains were used for the fermentation of pure (P-) and recovered (R-) glycerol. Taguchi and full factorial methods of design of experiments were used to screen and optimize the important process factors that influence the microbial production of ethanol. A statistically sound regression model was used to establish the mathematical relationship between the process variables and ethanol production. Temperature of 38°C, agitation speed of 200 rpm, pH of 6.3-6.6, and microaerobic condition were the optimum process conditions. Different pretreatment methods to recover glycerol from the crude glycerol and the subsequent fermentation method showed that direct acidification using 85% H3PO4 was the best. The R-glycerol contained 51% pure glycerol and 21% methanol. The wild strain, E. aerogenes ATCC 13048, produced only 12 g/l and 12.8 g/l ethanol from 20 g/l P- and R-glycerol respectively, and could not utilize higher glycerol concentrations. The mutant, E. aerogenes S012, produced ethanol amount and yield of 43 g/l and 1.12 mol/mol-glycerol from P-glycerol, respectively within 96 h. It also produced ethanol amount and yield of 26.8 g/l and 1.07 mol/mol-glycerol, respectively, from R-glycerol within the same duration. In a

  9. Hydrogen production from biodiesel byproduct by immobilized Enterobacter aerogenes.

    PubMed

    Han, Jinmi; Lee, Dohoon; Cho, Jinku; Lee, Jeewon; Kim, Sangyong

    2012-01-01

    The recent rapid growth of the biodiesel industry has generated a significant amount of glycerol as a byproduct. As a result, the price of glycerol is currently relatively low, making it an attractive starting material for the production of chemicals with higher values. Crude glycerol can be directly converted through microbial fermentation into various chemicals such as hydrogen. In this study, we optimized immobilization of a facultative hydrogen producing microorganism, Enterobacter aerogenes, with the goal of developing biocatalysts that was appropriate for the continuous hydrogen production from glycerol. Several carriers were tested and agar was found to be the most effective. In addition, it was clearly shown that variables such as the carrier content and cell loading should be controlled for the immobilization of biocatalysts with high hydrogen productivity, stability, and reusability. After optimization of these variables, we were able to obtain reusable biocatalysts that could directly convert the byproduct stream from biodiesel processes into hydrogen in continuous processes.

  10. Antibiotic failure mediated by a resistant subpopulation in Enterobacter cloacae.

    PubMed

    Band, Victor I; Crispell, Emily K; Napier, Brooke A; Herrera, Carmen M; Tharp, Greg K; Vavikolanu, Kranthi; Pohl, Jan; Read, Timothy D; Bosinger, Steven E; Trent, M Stephen; Burd, Eileen M; Weiss, David S

    2016-01-01

    Antibiotic resistance is a major public health threat, further complicated by unexplained treatment failures caused by bacteria that appear antibiotic susceptible. We describe an Enterobacter cloacae isolate harbouring a minor subpopulation that is highly resistant to the last-line antibiotic colistin. This subpopulation was distinct from persisters, became predominant in colistin, returned to baseline after colistin removal and was dependent on the histidine kinase PhoQ. During murine infection, but in the absence of colistin, innate immune defences led to an increased frequency of the resistant subpopulation, leading to inefficacy of subsequent colistin therapy. An isolate with a lower-frequency colistin-resistant subpopulation similarly caused treatment failure but was misclassified as susceptible by current diagnostics once cultured outside the host. These data demonstrate the ability of low-frequency bacterial subpopulations to contribute to clinically relevant antibiotic resistance, elucidating an enigmatic cause of antibiotic treatment failure and highlighting the critical need for more sensitive diagnostics. PMID:27572838

  11. An efficient ribitol-specific dehydrogenase from Enterobacter aerogenes.

    PubMed

    Singh, Ranjitha; Singh, Raushan; Kim, In-Won; Sigdel, Sujan; Kalia, Vipin C; Kang, Yun Chan; Lee, Jung-Kul

    2015-05-01

    An NAD(+)-dependent ribitol dehydrogenase from Enterobacter aerogenes KCTC 2190 (EaRDH) was cloned and successfully expressed in Escherichia coli. The complete 729-bp gene was amplified, cloned, expressed, and subsequently purified in an active soluble form using nickel affinity chromatography. The enzyme had an optimal pH and temperature of 11.0 and 45°C, respectively. Among various polyols, EaRDH exhibited activity only toward ribitol, with Km, Vmax, and kcat/Km values of 10.3mM, 185Umg(-1), and 30.9s(-1)mM(-1), respectively. The enzyme showed strong preference for NAD(+) and displayed no detectable activity with NADP(+). Homology modeling and sequence analysis of EaRDH, along with its biochemical properties, confirmed that EaRDH belongs to the family of NAD(+)-dependent ribitol dehydrogenases, a member of short-chain dehydrogenase/reductase (SCOR) family. EaRDH showed the highest activity and unique substrate specificity among all known RDHs. Homology modeling and docking analysis shed light on the molecular basis of its unusually high activity and substrate specificity.

  12. Eight-Year Surveillance of Antimicrobial Resistance among Enterobacter Cloacae Isolated in the First Bethune Hospital

    NASA Astrophysics Data System (ADS)

    Zhou, Qi; Zhang, Man; Wang, Ailin; Xu, Jiancheng; Yuan, Ye

    This study was to investigate the antimicrobial resistance of Enterobacter cloacae isolated in 8 consecutive years in the First Bethune Hospital. Disk diffusion test was used to study the antimicrobial resistance. The data were analyzed by WHONET 5 software according to Clinical and Laboratory Standards Institute (CLSI). Most of 683 strains of Enterobacter cloacae were collected from sputum 410 (60.0%), secretions and pus 105 (15.4%), urine 69 (10.1%) during the past 8 years. No Enterobacter cloacae was resistant to imipenem and meropenem in the First Bethune Hospital. The antimicrobial resistance of Enterobacter cloacae had increased in recent 8 years. The change of the antimicrobial resistance should be investigated in order to direct rational drug usage in the clinic and prevent bacterial strain of drug resistance from b eing transmitted.

  13. Complete Genome Sequence of Enterobacter cloacae B2-DHA, a Chromium-Resistant Bacterium

    PubMed Central

    Rahman, Aminur; Nahar, Noor; Olsson, Björn

    2016-01-01

    Previously, we reported a chromium-resistant bacterium, Enterobacter cloacae B2-DHA, isolated from the landfills of tannery industries in Bangladesh. Here, we investigated its genetic composition using massively parallel sequencing and comparative analysis with other known Enterobacter genomes. Assembly of the sequencing reads revealed a genome of ~4.21 Mb in size. PMID:27257201

  14. Complete genome sequence of Enterobacter cloacae GGT036: a furfural tolerant soil bacterium.

    PubMed

    Gong, Gyeongtaek; Um, Youngsoon; Park, Tai Hyun; Woo, Han Min

    2015-01-10

    Enterobacter cloacae is a facultative anaerobic bacterium to be an important cause of nosocomial infection. However, the isolated E. cloacae GGT036 showed higher furfural-tolerant cellular growth, compared to industrial relevant strains such as Escherichia coli and Corynebacterium glutamicum. Here, we report the complete genome sequence of E. cloacae GGT036 isolated from Mt. Gwanak, Seoul, Republic of Korea. The genomic DNA sequence of E. cloacae GGT036 will provide valuable genetic resources for engineering of industrially relevant strains being tolerant to cellular inhibitors present in lignocellulosic hydrolysates. PMID:25444880

  15. Complete genome sequence of Enterobacter cloacae GGT036: a furfural tolerant soil bacterium.

    PubMed

    Gong, Gyeongtaek; Um, Youngsoon; Park, Tai Hyun; Woo, Han Min

    2015-01-10

    Enterobacter cloacae is a facultative anaerobic bacterium to be an important cause of nosocomial infection. However, the isolated E. cloacae GGT036 showed higher furfural-tolerant cellular growth, compared to industrial relevant strains such as Escherichia coli and Corynebacterium glutamicum. Here, we report the complete genome sequence of E. cloacae GGT036 isolated from Mt. Gwanak, Seoul, Republic of Korea. The genomic DNA sequence of E. cloacae GGT036 will provide valuable genetic resources for engineering of industrially relevant strains being tolerant to cellular inhibitors present in lignocellulosic hydrolysates.

  16. Resistance emerging after pefloxacin therapy of experimental Enterobacter cloacae peritonitis.

    PubMed Central

    Lucain, C; Regamey, P; Bellido, F; Pechére, J C

    1989-01-01

    Resistance emerging after pefloxacin therapy was investigated in an experimental Enterobacter cloacae infection. Mice were inoculated intraperitoneally (mean inoculum, 0.9 X 10(8) CFU) with one of four strains initially susceptible to quinolones and treated with a single 25-mg/kg dose of pefloxacin. This therapy produced a net decrease of bacterial counts in the peritoneal fluid, but with the of the isolates, posttherapy (PT1) strains emerged with decreased susceptibilities to quinolones (4- to 1,024-fold), to the structurally unrelated antibiotics (4- to 16-fold) chloramphenicol and trimethoprim, and sometimes to tetracycline and beta-lactam compounds. In a second set of experiments, new mice were similarly infected with PT1 strains and treated with up to five 25-mg/kg doses of pefloxacin. Compared with parent isolates, PT1 strains produced similar disease and peritoneal bacterial count in the control animals. In treated mice posttherapy (PT2) strains emerged that showed 8- to 64-fold increases in quinolone MICs compared with the PT1 strains inoculated. All PT1 and PT2 strains showed altered outer membrane protein patterns, principally marked by a decreased 37,000-molecular-weight band generally accompanied by an increased 42,000-molecular-weight band. Whole cells from all PT1 and PT2 strains, exposed to [14C]pefloxacin for 15 to 60 s, bound significantly less radioactivity than the corresponding parent strains. After partial purification, DNA gyrase extracted from the most resistant isolates (one PT1 and the PT2 strains) showed a 100- to 450-fold 50% inhibitory concentration increase for pefloxacin. Altogether, pefloxacin can select in vivo two types of resistant strain, one with only decreased permeability and another with decreased permeability combined with altered DNA gyrase. Images PMID:2548441

  17. Isolation and characterization of a bacteriophage phiEap-2 infecting multidrug resistant Enterobacter aerogenes.

    PubMed

    Li, Erna; Wei, Xiao; Ma, Yanyan; Yin, Zhe; Li, Huan; Lin, Weishi; Wang, Xuesong; Li, Chao; Shen, Zhiqiang; Zhao, Ruixiang; Yang, Huiying; Jiang, Aimin; Yang, Wenhui; Yuan, Jing; Zhao, Xiangna

    2016-01-01

    Enterobacter aerogenes (Enterobacteriaceae) is an important opportunistic pathogen that causes hospital-acquired pneumonia, bacteremia, and urinary tract infections. Recently, multidrug-resistant E. aerogenes have been a public health problem. To develop an effective antimicrobial agent, bacteriophage phiEap-2 was isolated from sewage and its genome was sequenced because of its ability to lyse the multidrug-resistant clinical E. aerogenes strain 3-SP. Morphological observations suggested that the phage belongs to the Siphoviridae family. Comparative genome analysis revealed that phage phiEap-2 is related to the Salmonella phage FSL SP-031 (KC139518). All of the structural gene products (except capsid protein) encoded by phiEap-2 had orthologous gene products in FSL SP-031 and Serratia phage Eta (KC460990). Here, we report the complete genome sequence of phiEap-2 and major findings from the genomic analysis. Knowledge of this phage might be helpful for developing therapeutic strategies against E. aerogenes. PMID:27320081

  18. Isolation and characterization of a bacteriophage phiEap-2 infecting multidrug resistant Enterobacter aerogenes.

    PubMed

    Li, Erna; Wei, Xiao; Ma, Yanyan; Yin, Zhe; Li, Huan; Lin, Weishi; Wang, Xuesong; Li, Chao; Shen, Zhiqiang; Zhao, Ruixiang; Yang, Huiying; Jiang, Aimin; Yang, Wenhui; Yuan, Jing; Zhao, Xiangna

    2016-06-20

    Enterobacter aerogenes (Enterobacteriaceae) is an important opportunistic pathogen that causes hospital-acquired pneumonia, bacteremia, and urinary tract infections. Recently, multidrug-resistant E. aerogenes have been a public health problem. To develop an effective antimicrobial agent, bacteriophage phiEap-2 was isolated from sewage and its genome was sequenced because of its ability to lyse the multidrug-resistant clinical E. aerogenes strain 3-SP. Morphological observations suggested that the phage belongs to the Siphoviridae family. Comparative genome analysis revealed that phage phiEap-2 is related to the Salmonella phage FSL SP-031 (KC139518). All of the structural gene products (except capsid protein) encoded by phiEap-2 had orthologous gene products in FSL SP-031 and Serratia phage Eta (KC460990). Here, we report the complete genome sequence of phiEap-2 and major findings from the genomic analysis. Knowledge of this phage might be helpful for developing therapeutic strategies against E. aerogenes.

  19. TEM Derivative-Producing Enterobacter aerogenes Strains: Dissemination of a Prevalent Clone

    PubMed Central

    Dumarche, P.; De Champs, C.; Sirot, D.; Chanal, C.; Bonnet, R.; Sirot, J.

    2002-01-01

    TEM-24 (CAZ-6) extended-spectrum β-lactamase (ESBL) was detected in 1988 in Clermont-Ferrand, France, in Klebsiella pneumoniae (blaTEM-24) and Enterobacter aerogenes (blaTEM-24b), and since 1994, a TEM-24-producing E. aerogenes clonal strain has been observed elsewhere in the country. To determine if the spread of this clonal strain was restricted to TEM-24-producing E. aerogenes strains, 84 E. aerogenes strains (non-TEM/SHV-producing strains, TEM-1- or -2-producing strains, and different ESBL-producing strains), isolated from 1988 to 1999 in Clermont-Ferrand (n = 59) and in 11 other French hospitals in 1998 (n = 25), were studied. A clonal strain was found for TEM-24- but also for TEM-3- and TEM-1- or 2-producing isolates. This study shows that there is a clonal strain dependent on acquisition of the TEM-type enzyme (TEM-24 and other TEM types). PMID:11897606

  20. Isolation and characterization of a bacteriophage phiEap-2 infecting multidrug resistant Enterobacter aerogenes

    PubMed Central

    Li, Erna; Wei, Xiao; Ma, Yanyan; Yin, Zhe; Li, Huan; Lin, Weishi; Wang, Xuesong; Li, Chao; Shen, Zhiqiang; Zhao, Ruixiang; Yang, Huiying; Jiang, Aimin; Yang, Wenhui; Yuan, Jing; Zhao, Xiangna

    2016-01-01

    Enterobacter aerogenes (Enterobacteriaceae) is an important opportunistic pathogen that causes hospital-acquired pneumonia, bacteremia, and urinary tract infections. Recently, multidrug-resistant E. aerogenes have been a public health problem. To develop an effective antimicrobial agent, bacteriophage phiEap-2 was isolated from sewage and its genome was sequenced because of its ability to lyse the multidrug-resistant clinical E. aerogenes strain 3-SP. Morphological observations suggested that the phage belongs to the Siphoviridae family. Comparative genome analysis revealed that phage phiEap-2 is related to the Salmonella phage FSL SP-031 (KC139518). All of the structural gene products (except capsid protein) encoded by phiEap-2 had orthologous gene products in FSL SP-031 and Serratia phage Eta (KC460990). Here, we report the complete genome sequence of phiEap-2 and major findings from the genomic analysis. Knowledge of this phage might be helpful for developing therapeutic strategies against E. aerogenes. PMID:27320081

  1. Enterobacter aerogenes Needle Stick Leads to Improved Biological Management System

    SciTech Connect

    Johanson, Richard E.

    2004-08-01

    A laboratory worker who received a needle stick from a contaminated needle while working with a culture containing Enterobactor aerogenes developed a laboratory acquired infection. Although this organism has been shown to cause community and nosocomial infections, there have been no documented cases of a laboratory acquired infections. Lessons learned from the event led to corrective actions which included modification of lab procedures, development of a biological inventory tracking and risk identification system and the establishment of an effective biological safety program.

  2. Evaluating Hawaii-Grown Papaya for Resistance to Internal Yellowing Disease Caused by Enterobacter cloacae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Papaya (Carica papaya L.) cultivars and breeding lines were evaluated for resistance to Enterobacter cloacae (Jordan) Hormaeche & Edwards, the bacterial causal agent of internal yellowing disease (IY), using a range of concentrations of the bacterium. Linear regression analysis was performed and IY ...

  3. Association of antibiotic resistance with SHV-12 extended-spectrum β-lactamase in Enterobacter cloacae

    PubMed Central

    LIU, JUN; LI, GUO-MING; LIN, LI-YAO; WU, XIA-LEI; HUANG, SHAO-LONG; ZHOU, YONG; ZHAO, ZU-GUO

    2016-01-01

    The association between antibiotic resistance and SHV-12 extended-spectrum β-lactamase (ESBL) in Enterobacter cloacae remains unknown. The aim of the present study was to investigate the prevalence of both chromosome- and plasmid-borne SHV-12 ESBL genes in Enterobacter cloacae. Transmission of the SHV-12 ESBL gene was explored, and the risk factors for antibiotic resistance in E. cloacae were analyzed. Polymerase chain reaction (PCR) results showed that 58 out of the 100 isolates carried the SHV-12 ESBL gene: 34.48% of them occurred in the chromosome, 48.28% were plasmid-borne and 17.24% appeared in both. Enterobacterial repetitive intergenic consensus-PCR tests detected 82 chromosomal genotypes. Conjugation assays showed that 70.00% of plasmid-borne SHV-12 ESBL genes were successfully transconjugated into E. coli C600 and that the antibiotic resistance phenotype of E. cloacae was partially (84%) or completely (10%) transferred. A significantly higher SHV-12 ESBL detection rate was found in patients with underlying conditions and/or complications compared with those without (P<0.05). The detection of SHV-12 ESBL-producing E. cloacae from vertical transmission varied significantly across clinical departments and age groups (P<0.05), with the highest rates in the intensive care unit and the group of patients aged ≥60 years. The present results indicate that the location and transmission efficiency of SHV-12 ESBL are closely correlated with the antibiotic resistance of E. cloacae. PMID:26889253

  4. The melatonin-sensitive circadian clock of the enteric bacterium Enterobacter aerogenes.

    PubMed

    Paulose, Jiffin K; Cassone, Vincent M

    2016-09-01

    Circadian clocks are fundamental properties of all eukaryotic organisms and at least some prokaryotic organisms. Recent studies in our laboratory have shown that the gastrointestinal system contains a circadian clock that controls many, if not all, aspects of gastrointestinal function. We now report that at least one species of intestinal bacteria, Enterobacter aerogenes, responds to the pineal and gastrointestinal hormone melatonin by an increase in swarming activity. This swarming behavior is expressed rhythmically, with a period of approximately 24 hrs. Transformation of E. aerogenes to express luciferase with a MotA promoter reveals circadian patterns of bioluminescence that are synchronized by melatonin and whose periods are temperature compensated from 26°C to 40°C. Bioinformatics suggest similarities between the E. aerogenes and cyanobacterial clocks, suggesting the circadian clock may have evolved very early in the evolution of life. They also point to a coordination of host circadian clocks with those residing in the microbiota themselves. PMID:27387841

  5. The melatonin-sensitive circadian clock of the enteric bacterium Enterobacter aerogenes.

    PubMed

    Paulose, Jiffin K; Cassone, Vincent M

    2016-09-01

    Circadian clocks are fundamental properties of all eukaryotic organisms and at least some prokaryotic organisms. Recent studies in our laboratory have shown that the gastrointestinal system contains a circadian clock that controls many, if not all, aspects of gastrointestinal function. We now report that at least one species of intestinal bacteria, Enterobacter aerogenes, responds to the pineal and gastrointestinal hormone melatonin by an increase in swarming activity. This swarming behavior is expressed rhythmically, with a period of approximately 24 hrs. Transformation of E. aerogenes to express luciferase with a MotA promoter reveals circadian patterns of bioluminescence that are synchronized by melatonin and whose periods are temperature compensated from 26°C to 40°C. Bioinformatics suggest similarities between the E. aerogenes and cyanobacterial clocks, suggesting the circadian clock may have evolved very early in the evolution of life. They also point to a coordination of host circadian clocks with those residing in the microbiota themselves.

  6. A multiple antibiotic-resistant enterobacter cloacae strain isolated from a bioethanol fermentation facility.

    PubMed

    Murphree, Colin A; Li, Qing; Heist, E Patrick; Moe, Luke A

    2014-09-17

    An Enterobacter cloacae strain (E. cloacae F3S3) that was collected as part of a project to assess antibiotic resistance among bacteria isolated from bioethanol fermentation facilities demonstrated high levels of resistance to antibiotics added prophylactically to bioethanol fermentors. PCR assays revealed the presence of canonical genes encoding resistance to penicillin (ampC) and erythromycin (ermG). Assays measuring biofilm formation under antibiotic stress indicated that erythromycin induced biofilm formation in E. cloacae F3S3. Planktonic growth and biofilm formation were observed at a high ethanol content, indicating E. cloacae F3S3 can persist in a bioethanol fermentor under the highly variable environmental conditions found in fermentors. PMID:24941895

  7. Cloning and Characterization of Aerobactin Biosynthesis Genes of the Biological Control Agent Enterobacter cloacae

    PubMed Central

    Loper, Joyce E.; Ishimaru, Carol A.; Carnegie, Susan R.; Vanavichit, Apichart

    1993-01-01

    Five strains of Enterobacter cloacae that are biological control agents of Pythium damping-off diseases produced the hydroxamate siderophore aerobactin under iron-limiting conditions. Genes determining aerobactin biosynthesis of the biocontrol strain E. cloacae EcCT-501 were localized to a 12.3-kb region, which conferred aerobactin production to Escherichia coli DH5α. The aerobactin biosynthesis genes of E. cloacae hybridized to those of the pColV-K30 plasmid of E. coli, but restriction patterns of the aerobactin regions of pColV-K30 and E. cloacae differed. A derivative strain with a deletion in the aerobactin biosynthesis locus was as effective as strain EcCT-501 in biological control of Pythium damping-off of cucumber. Thus, aerobactin production did not contribute significantly to the biological control activity of EcCT-501 under the conditions of this study. PMID:16349118

  8. Resistant Enterobacter cloacae in a burn center: the ineffectiveness of silver sulfadiazine.

    PubMed

    Gayle, W E; Mayhall, C G; Lamb, V A; Apollo, E; Haynes, B W

    1978-05-01

    Enterobacter cloacae sepsis was found in 15 burn center patients in 1976, of whom 13 died. Nine of the deaths occurred in the first 60 days. The Burn Center isolates were resistant to silver sulfadiazine (AgSD) in agar cup-plate tests and confirmed by tube dilution tests. Hospital, non-burn isolates of E. cloacae were sensitive to AgSD. All E. cloacae isolates were sensitive to mafenide acetate (MA) in the agar cup-plate tests, but this was not confirmed by the tube dilution tests. The agar cup-plate susceptibility test is a simple, rapid and effective technique for determining resistant and sensitive isolates of E. cloacae. Patients who were changed from AgSD to MA because of resistant E. cloacae infection did not have improved survival. An animal study showed that AgSD was ineffective against this strain of E. cloacae and that MA was more effective than AgSD when applied 24 hr postburn but neither were effective at 48 hr postburn. MA was bacteriostatic but not bactericidal with this E. cloacae strain.

  9. Infective endocarditis due to Enterobacter cloacae resistant to third- and fourth-generation cephalosporins.

    PubMed

    Yoshino, Yusuke; Okugawa, Shu; Kimura, Satoshi; Makita, Eiko; Seo, Kazunori; Koga, Ichiro; Matsunaga, Naohisa; Kitazawa, Takatoshi; Ota, Yasuo

    2015-04-01

    We report the case of using a long-term combination of meropenem and amikacin to treat infective endocarditis caused by Enterobacter cloacae resistant to third- and fourth-generation cephalosporins. Multi-drug resistant Gram-negative bacilli, such as the E. cloacae in our study, may become possible pathogens of infective endocarditis. Our experience with this case indicates that long-term use of a combination of β-lactam and aminoglycosides might represent a suitable management option for future infective endocarditis cases due to non-Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella spp. (HACEK group) Gram-negative bacilli such as ours.

  10. Partial purification and characterization of a novel histidine decarboxylase from Enterobacter aerogenes DL-1.

    PubMed

    Zou, Yu; Hu, Wenzhong; Jiang, Aili; Tian, Mixia

    2015-08-18

    Histidine decarboxylase (HDC) from Enterobacter aerogenes DL-1 was purified in a three-step procedure involving ammonium sulfate precipitation, Sephadex G-100, and DEAE-Sepharose column chromatography. The partially purified enzyme showed a single protein band of 52.4 kD on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH for HDC activity was 6.5, and the enzyme was stable between pH 4 and 8. Enterobacter aerogenes HDC had optimal activity at 40°C and retained most of its activity between 4 and 50°C. HDC activity was reduced in the presence of numerous tested compounds. Particularly with SDS, it significantly (p < 0.01) inhibited enzyme activity. Conversely, Ca(2+) and Mn(2+) showed prominent activation effects (p < 0.01) with activity increasing to 117.20% and 123.42%, respectively. The Lineweaver-Burk plot showed that K m and V max values of the enzyme for L-histidine were 0.21 mM and 71.39 µmol/min, respectively. In comparison with most HDCs from other microorganisms and animals, HDC from E. aerogenes DL-1 displayed higher affinity and greater reaction velocity toward L-histidine.

  11. Use of flow cytometry for analysis of phage-mediated killing of Enterobacter aerogenes.

    PubMed

    Verthé, Kristof; Verstraete, Willy

    2006-09-01

    In this study, the use of flow cytometry to analyze phage-mediated killing of Enterobacter aerogenes under varying conditions of temperature and nutrient availability was assessed. Bacteriophage UZ1, specific for an E. aerogenes strain, was applied at a multiplicity of infection (MOI) of 1 and 1000 to a Teflon surface, artificially infected with its host at a level of 4.5 log cells. After incubation for 20 h, bacteriophages were quantified using the soft agar layer method. For the quantification of bacterial cells, plate counting and flow cytometric analysis of live/dead stained cells were performed in parallel. At an MOI of 1, phage treatment was successful only after incubation under nutrient-rich conditions at 37 degrees C: E. aerogenes cells were not detected and a tenfold increase in phage UZ1 was observed. At a MOI of 1000, no E. aerogenes cells could be cultured after incubation at 37 and 4 degrees C. However, flow cytometric analysis revealed that lysis did not occur at 4 degrees C but was achieved during subsequent plate culture. In conclusion, the use of flow cytometry enabled identification of culture-based bias during plate culture. The flow cytometric assay used in this study proved to be rapid, as this culture-independent method does not require lengthy incubation periods post-sampling. The bacteriophage-mediated killing of E. aerogenes cells on Teflon surfaces indicated that disinfection of E. aerogenes with bacteriophage UZ1 can be successful when high MOIs are achieved, while at low multiplicities of infection conditions favorable for phage replication are required.

  12. Extreme furfural tolerance of a soil bacterium Enterobacter cloacae GGT036.

    PubMed

    Choi, Sun Young; Gong, Gyeongtaek; Park, Hong-Sil; Um, Youngsoon; Sim, Sang Jun; Woo, Han Min

    2015-01-10

    Detoxification process of cellular inhibitors including furfural is essential for production of bio-based chemicals from lignocellulosic biomass. Here we isolated an extreme furfural-tolerant bacterium Enterobacter cloacae GGT036 from soil sample collected in Mt. Gwanak, Republic of Korea. Among isolated bacteria, only E. cloacae GGT036 showed cell growth with 35 mM furfural under aerobic culture. Compared to the maximal half inhibitory concentration (IC50) of well-known industrial strains Escherichia coli (24.9 mM furfural) and Corynebacterium glutamicum (10 mM furfural) based on the cell density, IC50 of E. cloacae GGT036 (47.7 mM) was significantly higher after 24 h, compared to E. coli and C. glutamicum. Since bacterial cell growth was exponentially inhibited depending on linearly increased furfural concentrations in the medium, we concluded that E. cloacae GGT036 is an extreme furfural-tolerant bacterium. Recently, the complete genome sequence of E. cloacae GGT036 was announced and this could provide an insight for engineering of E. cloacae GGT036 itself or other industrially relevant bacteria.

  13. Production of Internal Yellowing Symptoms on Resistant and Susceptible Papaya Cultivars by Enterobacter cloacae at Varying Inoculum Concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Internal yellowing (IY) is a bacterial disease of ripening papaya flesh caused by Enterobacter cloacae and characterized by yellow softening tissue. IY restricts food safety of value-added products like fresh or frozen papaya cubes. The incidence of E. cloacae presumably differs in resistant (R) a...

  14. Development of Enterobacter aerogenes fuel cells: from in situ biohydrogen oxidization to direct electroactive biofilm.

    PubMed

    Zhuang, Li; Zhou, Shungui; Yuan, Yong; Liu, Tinglin; Wu, Zhifeng; Cheng, Jiong

    2011-01-01

    This study described an Enterobacter aerogenes-catalyzed microbial fuel cell (MFC) with a carbon-based anode that exhibited a maximum power density of 2.51 W/m(3) in the absence of artificial electron mediators. The MFC was started up rapidly, within hours, and the current generation in the early stage was demonstrated to result from in situ oxidation of biohydrogen produced by E. aerogenes during glucose fermentation. Over periodic replacement of substrate, both planktonic biomass in the culture liquid and hydrogen productivity decreased, while increased power density and coulombic efficiency and decreased internal resistance were unexpectedly observed. Using scanning electron microscopy and cyclic voltammetry, it was found that the enhanced MFC performance was associated with the development of electroactive biofilm on the anodic surface, proposed to involve an acclimation and selection process of E. aerogenes cells under electrochemical tension. The significant advantage of rapid start-up and the ability to develop an electroactive biofilm identifies E. aerogenes as a suitable biocatalyst for MFC applications.

  15. An adaptive response of Enterobacter aerogenes to imipenem: regulation of porin balance in clinical isolates.

    PubMed

    Lavigne, Jean-Philippe; Sotto, Albert; Nicolas-Chanoine, Marie-Hélène; Bouziges, Nicole; Pagès, Jean-Marie; Davin-Regli, Anne

    2013-02-01

    Imipenem (IPM) is a carbapenem antibiotic frequently used in severe hospital infections. Several reports have mentioned the emergence of resistant isolates exhibiting membrane modifications. A study was conducted between September 2005 and August 2007 to survey infections due to Enterobacter aerogenes in patients hospitalised in a French university hospital. Resistant E. aerogenes clinical isolates obtained from patients treated with IPM and collected during the 3 months following initiation of treatment were phenotypically and molecularly characterised for β-lactamases, efflux pumps activity and outer membrane proteins. Among the 339 patients infected with E. aerogenes during the study period, 41 isolates (12.1%) were resistant to extended-spectrum cephalosporins and 17 patients (5.0%) were treated with IPM. The isolates from these 17 patients presented TEM-24 and basal efflux expression. Following IPM treatment, an IPM-intermediate-susceptible (IPM-I) isolate emerged in 11 patients and an IPM-resistant (IPM-R) isolate in 6 patients. A change in the porin balance (Omp35/Omp36) was observed in IPM-I isolates exhibiting ertapenem resistance. Finally, a porin deficiency (Omp35 and Omp36 absence) was detected in IPM-R isolates associated with efflux pump expression. This study indicates that the alteration in porin expression, including the shift of porin expression and lack of porins, contribute to the E. aerogenes adaptive response to IPM treatment.

  16. Colistin heteroresistance in Enterobacter cloacae is associated with cross-resistance to the host antimicrobial lysozyme.

    PubMed

    Napier, Brooke A; Band, Victor; Burd, Eileen M; Weiss, David S

    2014-09-01

    Here, we describe the first identification of colistin-heteroresistant Enterobacter cloacae in the United States. Treatment of this isolate with colistin increased the frequency of the resistant subpopulation and induced cross-resistance to the host antimicrobial lysozyme. This is the first description of heteroresistance conferring cross-resistance to a host antimicrobial and suggests that clinical treatment with colistin may inadvertently select for bacteria that are resistant to components of the host innate immune system.

  17. Effect of Some nitrosative agents on the growth of vgb-bearing Enterobacter aerogenes strains.

    PubMed

    Khleifat, Khaled M; Al-Mustafa, Ahmed H

    2007-07-01

    The effect of transnitrosation intermediate between S-nitroso-N-acetylcysteine (NACysNO) and cysteine on the growth of vgb-bearing Enterobacter aerogenes was investigated using three parameters: the ratio of the specific growth rates, the inhibition zone, and alpha-amylase synthesis for the culture exposed to stressors to that of the same stressor-free cultures. The effect of NACysNO/cysteine on the growth of Enterobacter strains was distinctive as compared with the CysNO, NACysNO, and their combination. At a higher concentration (2 mM), the extents of inhibition based on the mu(NACysNO/cysteine)/mu(no stress) ratio for these cultures were 57%, 62%, and 68% for VHb-expressing, parental, and pUC9-harboring cells, respectively. The inhibition caused by 2 mM: NACysNO in the presence of 1 mM cysteine in all bacterial strains was almost twofold that achieved by NACysNO alone. Based on the diameter of the inhibition zone and alpha-amylase productivity, the four compounds (NACysNO/Cysteine, CysNO, NACysNO, and their combinations) affected the E. aerogenes strains in a concentration-dependent and negative manner. This negative effect was lower in vgb-bearing than vgb-lacking strains. Thus, sulfur-to-sulfur transnitrosation was an efficient NO release and significantly (P < 0.05) affects the growth of Enterobacter strains, to a lesser extent in vgb-bearing strains.

  18. Reduction of selenite to elemental selenium by Enterobacter cloacae SLD1a-1

    SciTech Connect

    Dungan, R.S.; Frankenberger, W.T. Jr.

    1998-11-01

    The facultative anaerobic bacterium Enterobacter cloacae strain SLD1a-1 was studied in washed cell suspensions to assess optimal conditions required for the reduction of selenite (SeO{sub 3}{sup 2{minus}}) to elemental selenium (Se{sup 0}). Enterobacter cloacae using glucose (1.4 mM) as an electron donor removed 79% of the added SeO{sub 3}{sup 2{minus}} from solution in 2.5 h. Optimal SeO{sub 3}{sup 2{minus}} reduction occurred at a pH of 6.5 and a temperature of 40 C. Carbohydrate sources arabinose, xylose, and sorbose were found to significantly enhance SeO{sub 3}{sup 2{minus}} reduction over that of glucose. The reduction of SeO{sub 3}{sup 2{minus}} at 7.9 {micro}M was inhibited by nitrate of levels 1 to 100 times greater, nitrite at levels 5 and 10 times greater, while sulfite at levels of two to four times greater was found to stimulate the reduction of SeO{sub 3}{sup 2{minus}}. Enterobacter cloacae grows on anaerobically incubated plates containing NO{sub 3}{sup {minus}} as the sole terminal electron acceptor and acetate as the electron donor. Use of SeO{sub 3}{sup 2{minus}} as the terminal electron acceptor during anaerobic respiration did not support growth and could only be reduced to Se{sup 0} when NO{sub 3}{sup {minus}} was present.

  19. Studies on nutritional and oxygen requirements for production of L-asparaginase by Enterobacter aerogenes.

    PubMed

    Mukherjee, J; Majumdar, S; Scheper, T

    2000-02-01

    The carbon and nitrogen sources most suitable for L-asparaginase production by Enterobacter aerogenes were selected and their concentrations optimized in shake-flask cultures. Sodium citrate (1.0%) and diammonium hydrogen phosphate (0.16%) proved to be the best sources of carbon and nitrogen, respectively. Nitrogen catabolite repression of enzyme formation was absent in this bacterium. Cultivation in a reactor showed that the dissolved oxygen level is the limiting factor for L-asparaginase production by E. aerogenes. Glucose was found to be a repressor of enzyme synthesis. Asparagine was absent intracellularly when the L-asparaginase level was high. An increase in the extracellular alanine level when the dissolved oxygen remained low indicated a shift from aerobic to fermentative metabolism. PMID:10709980

  20. Enhanced dark hydrogen fermentation by addition of ferric oxide nanoparticles using Enterobacter aerogenes.

    PubMed

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Liu, Min; Zhou, Junhu; Cen, Kefa

    2016-05-01

    Ferric oxide nanoparticles (FONPs) were used to facilitate dark hydrogen fermentation using Enterobacter aerogenes. The hydrogen yield of glucose increased from 164.5±2.29 to 192.4±1.14mL/g when FONPs concentration increased from 0 to 200mg/L. SEM images of E. aerogenes demonstrated the existence of bacterial nanowire among cells, suggesting FONPs served as electron conduits to enhance electron transfer. TEM showed cellular internalization of FONPs, indicating hydrogenase synthesis and activity was potentially promoted due to the released iron element. When further increasing FONPs concentration to 400mg/L, the hydrogen yield of glucose decreased to 147.2±2.54mL/g. Soluble metabolic products revealed FONPs enhanced acetate pathway of hydrogen production, but weakened ethanol pathway. This shift of metabolic pathways allowed more nicotinamide adenine dinucleotide for reducing proton to hydrogen.

  1. Enhanced dark hydrogen fermentation by addition of ferric oxide nanoparticles using Enterobacter aerogenes.

    PubMed

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Liu, Min; Zhou, Junhu; Cen, Kefa

    2016-05-01

    Ferric oxide nanoparticles (FONPs) were used to facilitate dark hydrogen fermentation using Enterobacter aerogenes. The hydrogen yield of glucose increased from 164.5±2.29 to 192.4±1.14mL/g when FONPs concentration increased from 0 to 200mg/L. SEM images of E. aerogenes demonstrated the existence of bacterial nanowire among cells, suggesting FONPs served as electron conduits to enhance electron transfer. TEM showed cellular internalization of FONPs, indicating hydrogenase synthesis and activity was potentially promoted due to the released iron element. When further increasing FONPs concentration to 400mg/L, the hydrogen yield of glucose decreased to 147.2±2.54mL/g. Soluble metabolic products revealed FONPs enhanced acetate pathway of hydrogen production, but weakened ethanol pathway. This shift of metabolic pathways allowed more nicotinamide adenine dinucleotide for reducing proton to hydrogen. PMID:26890796

  2. Engineered Enterobacter aerogenes for efficient utilization of sugarcane molasses in 2,3-butanediol production.

    PubMed

    Jung, Moo-Young; Park, Bu-Soo; Lee, Jinwon; Oh, Min-Kyu

    2013-07-01

    Sugarcane molasses is considered to be a good carbon source for biorefinery due to its high sugar content and low price. Sucrose occupies more than half of the sugar in the molasses. Enterobacter aerogenes is a good host strain for 2,3-butanediol production, but its utilization of sucrose is not very efficient. To improve sucrose utilization in E. aerogenes, a sucrose regulator (ScrR) was disrupted from the genomic DNA. The deletion mutation increased the sucrose consumption rate significantly when sucrose or sugarcane molasses was used as a carbon source. The 2,3-butanediol production from sugarcane molasses by the mutant was enhanced by 60% in batch fermentation compared to that by the wild type strain. In fed-batch fermentation, 98.69 g/L of 2,3-butanediol production was achieved at 36 h.

  3. Purification and antibiofilm activity of AHL-lactonase from endophytic Enterobacter aerogenes VT66.

    PubMed

    Rajesh, P S; Rai, V Ravishankar

    2015-11-01

    The opportunistic pathogen Pseudomonas aeruginosa uses biofilm lifestyle to resist antibiotic treatment. In our study, endophytic bacterium Enterobacter aerogenes VT66 quenched the N-acyl homoserine lactone (AHL) molecules produced by P. aeruginosa PAO1. The quorum quenching activity was attributed to the presence of AHL-lactonase. The AHL-lactonase was purified using column chromatography and purified AHL-lactonase was applied for the control of biofilm formation in P. aeruginosa PAO1. The results showed that purified AHL-lactonase obtained with a molecular weight about 30kDa was able to inhibit more than 70% of biofilm in P. aeruginosa PAO1 (P<0.001). Antibiofilm activity of AHL-lactonase was correlated well with results from staining technique used to determine inhibition of biomass and viable cell activity. Therefore, results unambiguously confirm that the AHL-lactonase from E. aerogenes VT66 could be used as antibiofilm therapeutics in P. aeruginosa associated biomedical applications.

  4. Biotransformation of ferulic acid to 4-vinylguaiacol by Enterobacter soli and E. aerogenes.

    PubMed

    Hunter, William J; Manter, Daniel K; van der Lelie, Daniel

    2012-12-01

    We investigated the conversion of ferulic acid to 4-vinylguaiacol (4-VG), vanillin, vanillyl alcohol, and vanillic acid by five Enterobacter strains. These high-value chemicals are usually synthesized by chemical methods but biological synthesis adds market value. Ferulic acid, a relatively inexpensive component of agricultural crops, is plentiful in corn hulls, cereal bran, and sugar-beet pulp. Two Enterobacter strains, E. soli, and E. aerogenes, accumulated 550-600 ppm amounts of 4-VG when grown in media containing 1,000 ppm ferulic acid; no accumulations were observed with the other strains. Decreasing the amount of ferulic acid present in the media increased the conversion efficiency. When ferulic acid was supplied in 500, 250, or 125 ppm amounts E. aerogenes converted ~72 % of the ferulic acid present to 4-VG while E. soli converted ~100 % of the ferulic acid to 4-VG when supplied with 250 or 125 ppm amounts of ferulic acid. Also, lowering the pH improved the conversion efficiency. At pH 5.0 E. aerogenes converted ~84 % and E. soli converted ~100 % of 1,000 ppm ferulic acid to 4-VG. Only small, 1-5 ppm, accumulations of vanillin, vanillyl alcohol, and vanillic acid were observed. E. soli has a putative phenolic acid decarboxylase (PAD) that is 168 amino acids long and is similar to PADs in other enterobacteriales; this protein is likely involved in the bioconversion of ferulic acid to 4-VG. E. soli or E. aerogenes might be useful as a means of biotransforming ferulic acid to 4-VG.

  5. Isolation and Characterization of an Enterobacter cloacae Strain That Reduces Hexavalent Chromium under Anaerobic Conditions

    PubMed Central

    Wang, Pi-Chao; Mori, Tsukasa; Komori, Kohya; Sasatsu, Masanori; Toda, Kiyoshi; Ohtake, Hisao

    1989-01-01

    An Enterobacter cloacae strain (HO1) capable of reducing hexavalent chromium (chromate) was isolated from activated sludge. This bacterium was resistant to chromate under both aerobic and anaerobic conditions. Only the anaerobic culture of the E. cloacae isolate showed chromate reduction. In the anaerobic culture, yellow turned white with chromate and the turbidity increased as the reduction proceeded, suggesting that insoluble chromium hydroxide was formed. E. cloacae is likely to utilize toxic chromate as an electron acceptor anaerobically because (i) the anaerobic growth of E. cloacae HO1 accompanied the decrease of toxic chromate in culture medium, (ii) the chromate-reducing activity was rapidly inhibited by oxygen, and (iii) the reduction occurred more rapidly in glycerol- or acetate-grown cells than in glucose-grown cells. The chromate reduction in E. cloacae HO1 was observed at pH 6.0 to 8.5 (optimum pH, 7.0) and at 10 to 40°C (optimum, 30°C). PMID:16347962

  6. Plant growth promoting bacteria Enterobacter asburiae JAS5 and Enterobacter cloacae JAS7 in mineralization of endosulfan.

    PubMed

    Abraham, Jayanthi; Silambarasan, Sivagnanam

    2015-04-01

    Endosulfan and their metabolites can be detected in soils with a history of endosulfan application. Microbial degradation offers an effective approach to remove toxicants, and in this study, Enterobacter asburiae JAS5 and Enterobacter cloacae JAS7 were isolated through enrichment technique. The biodegradation of endosulfan and its metabolites rate constant (k) and DT50 were determined through first-order kinetic models. E. asburiae JAS5 degraded the endosulfan, and its metabolites in liquid medium was characterized by the k which was 0.382 day(-1) (α-endosulfan), 0.284 day(-1) (β-endosulfan) and 0.228 day(-1) (endosulfan sulphate), and DT50 was 1.8 day (α-endosulfan), 2.4 days (β-endosulfan) and 3.0 days (endosulfan sulphate). The α-endosulfan, β-endosulfan and endosulfan sulphate metabolites were present in the liquid medium that was degraded by E. cloacae JAS7 which was characterized by the k of 0.391, 0.297 day(-1) and 0.273 day(-1), and DT50 was 1.7, 2.3 and 2.5 days, respectively. The infrared spectrum of endosulfan degraded sample in the aqueous medium by E. asburiae JAS5 and E. cloacae JAS7 showed a band at 1402 cm(-1) which is the characteristics of COOH group. E. asburiae JAS5 and E. cloacae JAS7 strains also showed the ability of plant growth promoting traits such as indole-3-acetic acid (IAA) production, organic acids production and solubilization of various inorganic phosphates. E. asburiae JAS5 solubilized 324 ± 2 μg ml(-1) of tricalcium phosphate, 296 ± 6 μg ml(-1) of dicalcium phosphate and 248 ± 5 μg ml(-1) of zinc phosphate, whereas E. cloacae JAS7 solubilized 338 ± 5, 306 ± 4 and 268 ± 3 μg ml(-1) of tricalcium phosphate, dicalcium phosphate and zinc phosphate, respectively. The IAA production by JAS5 and JAS7 strains were estimated to be 38.6 ± 0.3 and 46.6 ± 0.5 μg ml(-1), respectively. These bacterial strains form a potential candidate for bioremediation of pesticide-contaminated agricultural

  7. Most Enterobacter aerogenes Strains in France Belong to a Prevalent Clone

    PubMed Central

    Bosi, Claude; Davin-Regli, Anne; Bornet, Charleric; Mallea, Monique; Pages, Jean-Marie; Bollet, Claude

    1999-01-01

    The aim of this study was to determine the distribution in France of the Enterobacter aerogenes prevalent clone isolated in the hospitals of the Marseille area (A. Davin-Regli, D. Monnet, P. Saux, C. Bosi, R. Charrel, A. Barthelemy, and C. Bollet, J. Clin. Microbiol. 34:1474–1480, 1996). A total of 123 E. aerogenes isolates were collected from 23 hospital laboratories and analyzed by random amplification of polymorphic DNA and enterobacterial repetitive intergenic consensus-PCR to determine their epidemiological relatedness. Molecular typing revealed that 21 of the 23 laboratories had isolated this prevalent clone harboring the plasmid encoding for extended-spectrum β-lactamase of the TEM-24 type. Most isolates were susceptible only to imipenem and gentamicin. Their dissemination seems to be clonal and was probably the result of the general use of broad-spectrum cephalosporins and quinolones. Four isolates showed an alteration of their outer membrane proteins, causing decrease of susceptibility to third-generation cephalosporins and imipenem and leading to the critical situation of having no alternative therapeutic. The large dissemination of the E. aerogenes prevalent clone probably results from its good adaptation to the antibiotics administered in France and the hospital environment, particularly in intensive care units. PMID:10364580

  8. Deletion of lactate dehydrogenase in Enterobacter aerogenes to enhance 2,3-butanediol production.

    PubMed

    Jung, Moo-Young; Ng, Chiam Yu; Song, Hyohak; Lee, Jinwon; Oh, Min-Kyu

    2012-07-01

    2,3-Butanediol is an important bio-based chemical product, because it can be converted into several C4 industrial chemicals. In this study, a lactate dehydrogenase-deleted mutant was constructed to improve 2,3-butanediol productivity in Enterobacter aerogenes. To delete the gene encoding lactate dehydrogenase, λ Red recombination method was successfully adapted for E. aerogenes. The resulting strain produced a very small amount of lactate and 16.7% more 2,3-butanediol than that of the wild-type strain in batch fermentation. The mutant and its parental strain were then cultured with six different carbon sources, and the mutant showed higher carbon source consumption and microbial growth rates in all media. The 2,3-butanediol titer reached 69.5 g/l in 54 h during fed-batch fermentation with the mutant,which was 27.4% higher than that with the parental strain.With further optimization of the medium and aeration conditions,118.05 g/l 2,3-butanediol was produced in 54 h during fed-batch fermentation with the mutant. This is by far the highest titer of 2,3-butanediol with E. aerogenes achieved by metabolic pathway engineering.

  9. Inactivation of Enterobacter aerogenes in reconstituted skim milk by high- and low-frequency ultrasound.

    PubMed

    Gao, Shengpu; Hemar, Yacine; Lewis, Gillian D; Ashokkumar, Muthupandian

    2014-11-01

    The inactivation of Enterobacter aerogenes in skim milk using low-frequency (20kHz) and high-frequency (850kHz) ultrasonication was investigated. It was found that low-frequency acoustic cavitation resulted in lethal damage to E. aerogenes. The bacteria were more sensitive to ultrasound in water than in reconstituted skim milk having different protein concentrations. However, high-frequency ultrasound was not able to inactivate E. aerogenes in milk even when powers as high as 50W for 60min were used. This study also showed that high-frequency ultrasonication had no influence on the viscosity and particle size of skim milk, whereas low-frequency ultrasonication resulted in the decrease in viscosity and particle size of milk. The decrease in particle size is believed to be due to the breakup of the fat globules, and possibly to the cleavage of the κ-casein present at the surface of the casein micelles. Whey proteins were also found to be slightly affected by low-frequency ultrasound, with the amounts of α-lactalbumin and β-lactoglobulin slightly decreasing.

  10. Regulation of glycerol metabolism in Enterobacter aerogenes NBRC12010 under electrochemical conditions.

    PubMed

    Hatayama, Kouta; Yagishita, Tatsuo

    2009-06-01

    Enterobacter aerogenes NBRC12010 was able to ferment glycerol to ethanol and hydrogen gas. Fermentation of glycerol ceased in the stationary phase of growth, and it was activated by electrochemical reactions using thionine as an electron transfer mediator from bacterial cells to an electrode. Using resting cells of E. aerogenes NBRC12010 in only citrate buffer solution, the cells did not consume glycerol at all, but they could metabolize glucose. These results suggest that the regulation of glycerol metabolism occurred at enzymatic steps before glycolysis. In E. aerogenes NBRC12010, glycerol was metabolized via glycerol dehydrogenase (GDH) and then dehydroxyacetone kinase. The GDH-catalyzed reaction mainly depended on the ratio of NAD(+)/NADH. At a NAD(+)/NADH ratio of nearly 1 or less, it was substantially suppressed and glycerol metabolism stopped. When the ratio was higher than 1, GDH was activated and glycerol was metabolized. Thus, the reaction of glycerol metabolism depended on the balance of cellular NAD(+)/NADH. Exogenous NADH was oxidized to NAD(+) by electrochemical reactions with thionine. We proposed the activation mechanism of glycerol metabolism under electrochemical conditions.

  11. Characteristics of the melibiose transporter and its primary structure in Enterobacter aerogenes.

    PubMed

    Okazaki, N; Kuroda, M; Shimamoto, T; Shimamoto, T; Tsuchiya, T

    1997-05-22

    Cells of Enterobacter aerogenes can grow on melibiose as a sole source of carbon. This suggests the presence of melibiose operon in this organism. We found that E. aerogenes cells possess both alpha-galactosidase activity and melibiose transport activity, which were induced by melibiose. Neither Na+ nor Li+ stimulated the melibiose transport. However, transport of methyl-beta-thiogalactoside (TMG) was stimulated by Li+ but not by Na+. These findings suggest that the major coupling cation for the melibiose transporter in E. aerogenes is H+. In fact, we observed H+ entry into cells caused by an influx of melibiose and some of its analogs. We cloned the melB gene which encodes the melibiose transporter, and sequenced it. Deduced amino acid sequence of the transporter revealed that the melibiose transporter consists of 471 amino acid residues and the molecular weight was calculated to be 52214 Da. The sequence showed high homology with the sequences of the melibiose transporters of Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae. Higher homology was found with the melibiose transporter of K. pneumoniae than with that of E. coli and S. typhimurium.

  12. [Isolation and identification of degradation bacteria Enterobacter aerogenes for pyrethriods pesticide residues and its degradation characteristics].

    PubMed

    Liao, Min; Zhang, Hai-jun; Xie, Xiao-mei

    2009-08-15

    By incubation experiment, the bacterial strain labeled as M6R9 was isolated from the tame sludge in water course of Pesticide Factory of Hangzhou, and was identified as Enterobacter aerogenes, which had highly efficient degradation for Bifenthrin, Fenpropathrin and Cypermethrin. By investigating the physiological characteristics of the strain, the results show that the bacterium is a gram-negative aerobe bacilli, size is (0.8-1.9) microm x (0.5-1.0) microm, and is capable of utilizing Bifenthrin, Fenpropathrin and Cypermethrin as sole carbon source. Under the condition of ventilation, (25-30) degrees C, inoculated amount at D(415 nm) 0.2, pH 7.0, pesticide concentration 100 mg x L(-1) and vibrational speed 180 r x min(-1), the degradation efficiencies to Bifenthrin, Fenpropathrin and Cypermethrin are the highest by strain M6R9. Under such condition, in the mixture culture medium with 100 mg x L(-1) Bifenthrin, Fenpropathrin and Cypermethrin, the degradation ratios are 55.74%, 55.11% and 55.96% after culturing 3 d, respectively, the degradation processes are fitted for first-order kinetic equation and the half lives (t(1/2)) are 65.4,70.7 and 68.6 h respectively. The degradation ability of Enterobacter aerogenes M6R9 on Bifenthrin, Fenpropathrin and Cypermethrin is positively correlated to inoculated amount,vibrational speed and ventilation.

  13. Stability and activity of an Enterobacter aerogenes-specific bacteriophage under simulated gastro-intestinal conditions.

    PubMed

    Verthé, K; Possemiers, S; Boon, N; Vaneechoutte, M; Verstraete, W

    2004-09-01

    A bacteriophage, designated UZ1 and showing lytic activity against a clinically important strain (BE1) of Enterobacter aerogenes was isolated from hospital sewage. The stability and lytic activity against this strain under simulated gastro-intestinal conditions was evaluated. After addition of bacteriophage UZ1 to a liquid feed at gastric pH 2, the phage was immediately inactivated and could not be recovered. However, by use of an antacid to neutralize stomach acidity, no significant changes in phage titer were observed after 2 h incubation at 37 degrees C. After supplementing pancreatic juice and further incubation for 4 h, the phage titer remained stable. The persistence of UZ1 in a mixed microbial ecosystem that was representative for the large intestine was monitored using an in vitro simulation of the human intestinal microbial ecosystem. A pulse administration of bacteriophage UZ1 at a concentration of 10(5) plaque-forming units (PFU)/ml to reactor 3 (which simulates the ascending colon) showed that, in the absence of the host, bacteriophage UZ1 persisted for 13 days in the simulated colon, while the theoretical washout was calculated at 16 days. To assess its lytic activity in an intestinal microbial ecosystem, a green fluorescent protein (gfp)-labeled E. aerogenes BE1 strain was constructed and gfp-specific primers were designed in order to quantify the host strain using real-time PCR. It was observed that bacteriophage UZ1 was able to replicate and showed lytic activity against E. aerogenes BE1/ gfp in an intestinal microbial ecosystem. Indeed, after 17 h a 2 log unit reduction of E. aerogenes BE1/ gfp was measured as compared with the assay without bacteriophage UZ1, while the phage titer increased by 2 log units at an initial multiplicity of infection of 0.07 PFU/colony-forming unit. This is the first report of an in vitro model to study bacteriophage activity in the complex intestinal microbial community.

  14. Biodegradation of 2-methylquinoline by Enterobacter aerogenes TJ-D isolated from activated sludge.

    PubMed

    Wang, Lin; Li, Yongmei; Duan, Jingyuan

    2013-07-01

    Bacterial strain Enterobacter aerogenes TJ-D capable of utilizing 2-methylquinoline as the sole carbon and energy source was isolated from acclimated activated sludge under denitrifying conditions. The ability to degrade 2-methylquinoline by E. aerogenes TJ-D was investigated under denitrifying conditions. Under optimal conditions of temperature (35 degrees C) and initial pH 7, 2-methylquinoline of 100 mg/L was degraded within 176 hr. The degradation of 2-methylquinoline by E. aerogenes TJ-D could be well described by the Haldane model (R2 > 0.91). During the degradation period of 2-methylquinoline (initial concentration 100 mg/L), nitrate was almost completely consumed (the removal efficiency was 98.5%), while nitrite remained at low concentration (< 0.62 mg/L) during the whole denitrification period. 1,2,3,4-Tetrahydro-2-methylquinoline, 4-ethyl-benzenamine, N-butyl-benzenamine, N-ethyl-benzenamine and 2,6-diethyl-benzenamine were metabolites produced during the degradation. The degradation pathway of 2-methylquinoline by E. aerogenes TJ-D was proposed. 2-Methylquinoline is initially hydroxylated at C-4 to form 2-methyl-4-hydroxy-quinoline, and then forms 2-methyl-4-quinolinol as a result of tautomerism. Hydrogenation of the heterocyclic ring at positions 2 and 3 produces 2,3-dihydro-2-methyl-4-quinolinol. The carbon-carbon bond at position 2 and 3 in the heterocyclic ring may cleave and form 2-ethyl-N-ethyl-benzenamine. Tautomerism may result in the formation of 2,6-diethyl-benzenamine and N-butyl-benzenamine. 4-Ethyl-benzenamine and N-ethyl-benzenamine were produced as a result of losing one ethyl group from the above molecules.

  15. Bacteriophage lytic patterns for identification of salmonellae, shigellae, Escherichia coli, Citrobacter freundii, and Enterobacter cloacae.

    PubMed

    He, X Q; Pan, R N

    1992-03-01

    A series of bacteriophages specific for Escherichia coli (E-1, E-2, E-3, and E-4), Citrobacter freundii (phi I, phi II, and phi III), Enterobacter cloacae (Ent), and Shigella spp. (Sh) have been isolated from hospital sewage. These bacteriophages, in combination with Felix Salmonella phage O-I, were used as a diagnostic phage typing set which included seven phage preparations: O-I, C (phi I and phi III), Sh, E (E-1 and E-2), CE (phi II and E-3), E-4, and Ent. After 20,280 cultures of 27 species and 9 biogroups of 15 genera of the family Enterobacteriaceae and 276 cultures of 8 species of 6 genera outside the Enterobacteriaceae were tested, it was shown that most strains of salmonellae, E. coli, C. freundii, and E. cloacae can be identified accurately. The sensitivities of identification were 83.6% for E. cloacae, 88.8% for C. freundii, 90.3% for E. coli, and 95.76% for salmonellae. The specificities were 99.78% for salmonellae, 99.84% for E. cloacae, 99.89% for E. coli, and 99.97% for C. freundii. The results of bacteriophage lytic patterns were highly correlated with Shigella serotypes. Therefore, such a phage typing set may be used routinely in public hygiene and clinical laboratories.

  16. Anti-biofilm effects of honey against wound pathogens Proteus mirabilis and Enterobacter cloacae.

    PubMed

    Majtan, Juraj; Bohova, Jana; Horniackova, Miroslava; Klaudiny, Jaroslav; Majtan, Viktor

    2014-01-01

    Biofilm growth and its persistence within wounds have recently been suggested as contributing factors to impaired healing. The goal of this study was to investigate the anti-biofilm effects of several honey samples of different botanical origin, including manuka honey against Proteus mirabilis and Enterobacter cloacae wound isolates. Quantification of biofilm formation was carried out using a microtiter plate assay. All honeys at a sub-inhibitory concentration of 10% (w/v) significantly reduced the biofilm development of both isolates. Similarly, at a concentration of 50% (w/v), each of the honeys caused significant partial detachment of Pr. mirabilis biofilm after 24 h. On the other hand, no honey was able to significantly detach Ent. cloacae biofilm. In addition, treatment of Ent. cloacae and Pr. mirabilis biofilms with all honeys resulted in a significant decrease in colony-forming units per well values in a range of 0.35-1.16 and 1.2-7.5 log units, respectively. Of the tested honeys, manuka honey possessed the most potent anti-biofilm properties. Furthermore, methylglyoxal, an antibacterial compound of manuka honey, was shown to be responsible for killing biofilm-embedded wound bacteria. These findings suggest that manuka honey could be used as a potential therapy for the treatment of wounds containing Pr. mirabilis or Ent. cloacae.

  17. KPC and VIM producing Enterobacter cloacae strain from a hospital in northeastern Venezuela.

    PubMed

    Martínez, Dianny; Marcano, Daniel; Rodulfo, Hectorina; Salgado, Nurys; Cuaical, Nirvia; Rodriguez, Lucy; Caña, Luisa; Medina, Belkis; Guzman, Militza; De Donato, Marcos

    2015-06-01

    An 83-year-old male patient is admitted to the central hospital in Cumana, Venezuela with severe urinary infection, history of hospitalizaions and prolonged antimicrobial treatments. A strain of Enterobacter cloacae was isolated showing resistance to multiple types of antibiotics (only sensitive to gentamicin), with phenotype of serine- and metallo-carbapenemases. Both, bla(VIM-2) and bla(KPC) genes were detected in the isolate. This is the first report of an Enterobacteriaceae species producing both KPC carbapenemase and VIM metallo carbapenemase in Venezuela. This finding has a great clinical and epidemiological impact in the region, because of the feasibility of transferring these genes, through mobile elements to other strains of Enterobacter and to other infection-causing species of bacteria.

  18. Polygalacturonase production by calcium alginate immobilized Enterobacter aerogenes NBO2 cells.

    PubMed

    Darah, I; Nisha, M; Lim, Sheh-Hong

    2015-03-01

    Bacterial cells of Enterobacter aerogenes NBO2 were entrapped in calcium alginate beads in order to enhance polygalacturonase production compared to free cells. The optimized condition of 5 % (w/v) sodium alginate concentration, agitation speed of 250 rpm, and 15 beads of calcium alginate with inoculum size of 4 % (v/v; 5.4 × 10(7) cells/ml) produced 23.48 U/mL of polygalacturonase compared to free cells of 18.54 U/ml. There was about 26.6 % increment in polygalaturonase production. However, in this study, there was 296.6 % of increment in polygalacturonase production after improvement parameters compared to before improvement parameters of calcium alginate bead immobilization cells (5.92 U/ml). This research has indicated that optimized physical parameters of calcium alginate bead immobilization cells have significantly enhanced the production of polygalacturonase.

  19. Blood infection with Enterobacter aerogenes--an unusual cause of portal vein gas.

    PubMed

    Fayyaz, Afshan

    2011-01-01

    Portal vein gas was once thought of as an invariably fatal condition. Now, with the availability of better equipment and expertise, the condition is more frequently diagnosed. A case of fever with rigors is presented and on ultrasound and CT examination was found to have portal venous gas which resolved with adequate antibiotic treatment. Blood culture revealed growth of gram negative bacillus; Enterobacter aerogenes. Patient was investigated further for portal vein gas, and although no other cause for the development of portal vein gas was found, she was treated with antibiotics and showed an immediate response. The aim of this case report is to highlight the benign causes of portal vein gas as well as to discuss the causes which warrant immediate surgery. Portal vein gas may herald a more ominous condition, which if intercepted in its course may result in complete cure.

  20. Identification of sdiA-regulated genes in a mouse commensal strain of Enterobacter cloacae

    PubMed Central

    Sabag-Daigle, Anice; Dyszel, Jessica L.; Gonzalez, Juan F.; Ali, Mohamed M.; Ahmer, Brian M. M.

    2015-01-01

    Many bacteria determine their population density using quorum sensing. The most intensively studied mechanism of quorum sensing utilizes proteins of the LuxI family to synthesize a signaling molecule of the acylhomoserine lactone (AHL) type, and a protein of the LuxR family to bind AHL and regulate transcription. Genes regulated by quorum sensing often encode functions that are most effective when a group of bacteria are working cooperatively (e.g., luminescence, biofilm formation, host interactions). Bacteria in the Escherichia, Salmonella, Klebsiella, and Enterobacter genera do not encode an AHL synthase but they do encode an AHL receptor of the LuxR family, SdiA. Instead of detecting their own AHL synthesis, these organisms use SdiA to detect the AHLs synthesized by other bacterial species. In this study, we used a genetic screen to identify AHL-responsive genes in a commensal Enterobacter cloacae strain that was isolated from a laboratory mouse. The genes include a putative type VI secretion system, copA (a copper transporter), and fepE (extends O-antigen chain length). A new transposon mutagenesis strategy and suicide vectors were used to construct an sdiA mutant of E. cloacae. The AHL-responsiveness of all fusions was entirely sdiA-dependent, although some genes were regulated by sdiA in the absence of AHL. PMID:26075189

  1. Enhancing hydrogen production of Enterobacter aerogenes by heterologous expression of hydrogenase genes originated from Synechocystis sp.

    PubMed

    Song, Wenlu; Cheng, Jun; Zhao, Jinfang; Zhang, Chuanxi; Zhou, Junhu; Cen, Kefa

    2016-09-01

    The hydrogenase genes (hoxEFUYH) of Synechocystis sp. PCC 6803 were cloned and heterologously expressed in Enterobacter aerogenes ATCC13408 for the first time in this study, and the hydrogen yield was significantly enhanced using the recombinant strain. A recombinant plasmid containing the gene in-frame with Glutathione-S-Transferase (GST) gene was transformed into E. aerogenes ATCC13408 to produce a GST-fusion protein. SDS-PAGE and western blot analysis confirm the successful expression of the hox genes. The hydrogenase activity of the recombinant strain is 237.6±9.3ml/(g-DW·h), which is 152% higher than the wild strain. The hydrogen yield of the recombinant strain is 298.3ml/g-glucose, which is 88% higher than the wild strain. During hydrogen fermentation, the recombinant strain produces more acetate and butyrate, but less ethanol. This is corresponding to the NADH metabolism in the cell due to the higher hydrogenase activity with the heterologous expression of hox genes. PMID:27343449

  2. Isolation and characterization of a bacteriophage F20 virulent to Enterobacter aerogenes.

    PubMed

    Mishra, Charitra Kumar; Choi, Tae Jin; Kang, Sun Chul

    2012-10-01

    An aquatic phage, designated F20, was characterized and its physico-chemical characteristics studied. F20 was specifically virulent to only two strains of Enterobacter aerogenes (ATCC 13048 and the multi-drug-resistant strain K113) among other species tested (n = 15). It was classified in the family Siphoviridae of T1-like viruses and contained a linear dsDNA genome estimated to be 51.5 kbp enclosed by an isometric capsid of 50±2 nm in diameter and a tail of 150±3 nm in length. F20 was able to survive in a broad pH range between 4 and 11, showed potential for future animal trials using oral solution and resisted chloroform and ethanol. It exhibited remarkable stability between room temperature and 70 °C for up to 150 min, and even up to 6 months at room temperature. Knowledge of this phage belonging to the widespread T1-like viruses might be helpful for adopting therapeutic strategies against E. aerogenes.

  3. Hospital clonal dissemination of Enterobacter aerogenes producing carbapenemase KPC-2 in a Chinese teaching hospital.

    PubMed

    Qin, Xiaohua; Yang, Yang; Hu, Fupin; Zhu, Demei

    2014-02-01

    Carbapenems are first-line agents for the treatment of serious nosocomial infections caused by multidrug-resistant Enterobacteriaceae. However, resistance to carbapenems has increased dramatically among Enterobacteriaceae in our hospital. In this study, we report clonal dissemination caused by carbapenem-resistant Enterobacter aerogenes (CREA). In 2011, CREA was identified from 12 patients admitted to the neurosurgical ward. All 12 clinical isolates were non-susceptible to cefotaxime, ceftazidime, cefoxitin, ertapenem, imipenem or meropenem. All isolates carried the gene encoding Klebsiella pneumoniae carbapenemase-2 (KPC-2), except for the isolate E4. However, a remarkably lower expression level of the porin OmpF was detected in the non-KPC-2-producing isolate E4 on SDS-PAGE compared with the carbapenem-susceptible isolate. Epidemiological and molecular investigations showed that a single E. aerogenes strain (PFGE type A), including seven KPC-2-producing clinical isolates, was primarily responsible for the first isolation and subsequent dissemination. In a case-control study, we identified risk factors for infection/colonization with CREA. Mechanical ventilation, the changing of sickbeds and previous use of broad-spectrum antibiotics were identified as potential risk factors. Our findings suggest that further studies should focus on judicious use of available antibiotics, implementation of active antibiotic resistance surveillance and strict implementation of infection-control measures to avoid the rapid spread or clonal dissemination caused by carbapenem-resistant Enterobacteriaceae in healthcare facilities.

  4. Enhancing hydrogen production of Enterobacter aerogenes by heterologous expression of hydrogenase genes originated from Synechocystis sp.

    PubMed

    Song, Wenlu; Cheng, Jun; Zhao, Jinfang; Zhang, Chuanxi; Zhou, Junhu; Cen, Kefa

    2016-09-01

    The hydrogenase genes (hoxEFUYH) of Synechocystis sp. PCC 6803 were cloned and heterologously expressed in Enterobacter aerogenes ATCC13408 for the first time in this study, and the hydrogen yield was significantly enhanced using the recombinant strain. A recombinant plasmid containing the gene in-frame with Glutathione-S-Transferase (GST) gene was transformed into E. aerogenes ATCC13408 to produce a GST-fusion protein. SDS-PAGE and western blot analysis confirm the successful expression of the hox genes. The hydrogenase activity of the recombinant strain is 237.6±9.3ml/(g-DW·h), which is 152% higher than the wild strain. The hydrogen yield of the recombinant strain is 298.3ml/g-glucose, which is 88% higher than the wild strain. During hydrogen fermentation, the recombinant strain produces more acetate and butyrate, but less ethanol. This is corresponding to the NADH metabolism in the cell due to the higher hydrogenase activity with the heterologous expression of hox genes.

  5. Effect of nanocomposite packaging containing ZnO on growth of Bacillus subtilis and Enterobacter aerogenes.

    PubMed

    Esmailzadeh, Hakimeh; Sangpour, Parvaneh; Shahraz, Farzaneh; Hejazi, Jalal; Khaksar, Ramin

    2016-01-01

    Recent advances in nanotechnology have opened new windows in active food packaging. Nano-sized ZnO is an inexpensive material with potential antimicrobial properties. The aim of the present study is to evaluate the antibacterial effect of low density Polyethylene (LDPE) containing ZnO nanoparticles on Bacillus subtilis and Enterobacter aerogenes. ZnO nanoparticles have been synthesized by facil molten salt method and have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). Nanocomposite films containing 2 and 4 wt.% ZnO nanoparticles were prepared by melt mixing in a twin-screw extruder. The growth of both microorganisms has decreased in the presence of ZnO containing nanocomposites compared with controls. Nanocomposites with 4 wt.% ZnO nanoparticles had stronger antibacterial effect against both bacteria in comparison with the 2 wt.% ZnO containing nanocomposites. B. subtilis as Gram-positive bacteria were more sensitive to ZnO containing nanocomposite films compared with E. aerogenes as Gram-negative bacteria. There were no significant differences between the migration of Zn ions from 2 and 4 wt.% ZnO containing nanocomposites and the released Zn ions were not significantly increased in both groups after 14 days compared with the first. Regarding the considerable antibacterial effects of ZnO nanoparticles, their application in active food packaging can be a suitable solution for extending the shelf life of food.

  6. The purification, crystallization and preliminary diffraction of a glycerophosphodiesterase from Enterobacter aerogenes

    SciTech Connect

    Jackson, Colin J.; Carr, Paul D.; Kim, Hye-Kyung; Liu, Jian-Wei; Ollis, David L.

    2006-07-01

    The metallo-glycerophosphodiesterase from E. aerogenes (GpdQ) has been cloned, expressed in E. coli and purified. Initial screening of crystallization conditions for this enzyme resulted in the identification of needles from one condition in a sodium malonate grid screen. Removal of the metals from the enzyme and subsequent optimization of these conditions led to crystals. The metallo-glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) has been cloned, expressed in Escherichia coli and purified. Initial screening of crystallization conditions for this enzyme resulted in the identification of needles from one condition in a sodium malonate grid screen. Removal of the metals from the enzyme and subsequent optimization of these conditions led to crystals that diffracted to 2.9 Å and belonged to space group P2{sub 1}3, with unit-cell parameter a = 164.1 Å. Self-rotation function analysis and V{sub M} calculations indicated that the asymmetric unit contains two copies of the monomeric enzyme, corresponding to a solvent content of 79%. It is intended to determine the structure of this protein utilizing SAD phasing from transition metals or molecular replacement.

  7. Study of the role of anaerobic metabolism in succinate production by Enterobacter aerogenes.

    PubMed

    Tajima, Yoshinori; Kaida, Kenichi; Hayakawa, Atsushi; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Fudou, Ryosuke; Matsui, Kazuhiko; Usuda, Yoshihiro; Sode, Koji

    2014-09-01

    Succinate is a core biochemical building block; optimizing succinate production from biomass by microbial fermentation is a focus of basic and applied biotechnology research. Lowering pH in anaerobic succinate fermentation culture is a cost-effective and environmentally friendly approach to reducing the use of sub-raw materials such as alkali, which are needed for neutralization. To evaluate the potential of bacteria-based succinate fermentation under weak acidic (pH <6.2) and anaerobic conditions, we characterized the anaerobic metabolism of Enterobacter aerogenes AJ110637, which rapidly assimilates glucose at pH 5.0. Based on the profile of anaerobic products, we constructed single-gene knockout mutants to eliminate the main anaerobic metabolic pathways involved in NADH re-oxidation. These single-gene knockout studies showed that the ethanol synthesis pathway serves as the dominant NADH re-oxidation pathway in this organism. To generate a metabolically engineered strain for succinate production, we eliminated ethanol formation and introduced a heterogeneous carboxylation enzyme, yielding E. aerogenes strain ΔadhE/PCK. The strain produced succinate from glucose with a 60.5% yield (grams of succinate produced per gram of glucose consumed) at pH <6.2 and anaerobic conditions. Thus, we showed the potential of bacteria-based succinate fermentation under weak acidic conditions.

  8. Purification and antibiofilm activity of AHL-lactonase from endophytic Enterobacter aerogenes VT66.

    PubMed

    Rajesh, P S; Rai, V Ravishankar

    2015-11-01

    The opportunistic pathogen Pseudomonas aeruginosa uses biofilm lifestyle to resist antibiotic treatment. In our study, endophytic bacterium Enterobacter aerogenes VT66 quenched the N-acyl homoserine lactone (AHL) molecules produced by P. aeruginosa PAO1. The quorum quenching activity was attributed to the presence of AHL-lactonase. The AHL-lactonase was purified using column chromatography and purified AHL-lactonase was applied for the control of biofilm formation in P. aeruginosa PAO1. The results showed that purified AHL-lactonase obtained with a molecular weight about 30kDa was able to inhibit more than 70% of biofilm in P. aeruginosa PAO1 (P<0.001). Antibiofilm activity of AHL-lactonase was correlated well with results from staining technique used to determine inhibition of biomass and viable cell activity. Therefore, results unambiguously confirm that the AHL-lactonase from E. aerogenes VT66 could be used as antibiofilm therapeutics in P. aeruginosa associated biomedical applications. PMID:26432367

  9. Multidrug efflux systems in Escherichia coli and Enterobacter cloacae obtained from wholesome broiler carcasses

    PubMed Central

    Moreira, Maria Aparecida S.; Rodrigues, Patrícia P.C.F.; Tomaz, Rafael S.; de Moraes, Célia A.

    2009-01-01

    Members of the Enterobacteriaceae family are present in the intestines of man and animals as commensals or are important disease causing agents. Bacteria bearing multidrug efflux systems (MDR) are able to survive adverse ecological niches. Multiresistant Escherichia coli and Enterobacter cloacae isolates from wholesome broiler carcasses were investigated for the presence of MDR. Lowering of Minimal Inhibitory Concentration for antimicrobials in the presence of a proton-motive force (PMF) uncoupler was tested as a potential display of the MDR phenotype. PCR amplification of the genes encoding AcrA and AcrB, components of a MDR system was performed. Diversity of each species was ascertained by Pulsed-Field Gel Electrophoresis (PFGE) of DNA digested with endonuclease XbaI. For all the isolates, except E. coli 1 and E. cloacae 9, lowering of MIC or of the growth rate in the presence of antimicrobials was observed, indicating a PMF dependent resistance mechanism. Expected products of DNA amplification with acrAB derived primers was obtained with all E. coli strains and with two of the five E. cloacae strains. Dendrogram generated shows diverse pulsetypes, confirming the genetic diversity among the strains. An important issue and related public health is the fact that different models and mechanisms of antimicrobial resistance are present in a small number of non-pathogenic strains and isolated from the same origin. These may be sources of resistance genes to others microorganisms, among them, pathogenic strains. PMID:24031352

  10. Clonal Dissemination of Enterobacter cloacae Harboring blaKPC-3 in the Upper Midwestern United States

    PubMed Central

    Hargreaves, Melissa L.; Shaw, Kristin M.; Dobbins, Ginette; Snippes Vagnone, Paula M.; Harper, Jane E.; Boxrud, Dave; Lynfield, Ruth; Aziz, Maliha; Price, Lance B.; Silverstein, Kevin A. T.; Danzeisen, Jessica L.; Youmans, Bonnie; Case, Kyle; Sreevatsan, Srinand

    2015-01-01

    Carbapenemase-producing, carbapenem-resistant Enterobacteriaceae, or CP-CRE, are an emerging threat to human and animal health, because they are resistant to many of the last-line antimicrobials available for disease treatment. Carbapenemase-producing Enterobacter cloacae harboring blaKPC-3 recently was reported in the upper midwestern United States and implicated in a hospital outbreak in Fargo, North Dakota (L. M. Kiedrowski, D. M. Guerrero, F. Perez, R. A. Viau, L. J. Rojas, M. F. Mojica, S. D. Rudin, A. M. Hujer, S. H. Marshall, and R. A. Bonomo, Emerg Infect Dis 20:1583–1585, 2014, http://dx.doi.org/10.3201/eid2009.140344). In early 2009, the Minnesota Department of Health began collecting and screening CP-CRE from patients throughout Minnesota. Here, we analyzed a retrospective group of CP-E. cloacae isolates (n = 34) collected between 2009 and 2013. Whole-genome sequencing and analysis revealed that 32 of the strains were clonal, belonging to the ST171 clonal complex and differing collectively by 211 single-nucleotide polymorphisms, and it revealed a dynamic clone under positive selection. The phylogeography of these strains suggests that this clone existed in eastern North Dakota and western Minnesota prior to 2009 and subsequently was identified in the Minneapolis and St. Paul metropolitan area. All strains harbored identical IncFIA-like plasmids conferring a CP-CRE phenotype and an additional IncX3 plasmid. In a single patient with multiple isolates submitted over several months, we found evidence that these plasmids had transferred from the E. cloacae clone to an Escherichia coli ST131 bacterium, rendering it as a CP-CRE. The spread of this clone throughout the upper midwestern United States is unprecedented for E. cloacae and highlights the importance of continued surveillance to identify such threats to human health. PMID:26438492

  11. Isolation and characterization of a glyphosate-degrading rhizosphere strain, Enterobacter cloacae K7.

    PubMed

    Kryuchkova, Yelena V; Burygin, Gennady L; Gogoleva, Natalia E; Gogolev, Yuri V; Chernyshova, Marina P; Makarov, Oleg E; Fedorov, Evgenii E; Turkovskaya, Olga V

    2014-01-20

    Plant-growth-promoting rhizobacteria exert beneficial effects on plants through their capacity for nitrogen fixation, phytohormone production, phosphate solubilization, and improvement of the water and mineral status of plants. We suggested that these bacteria may also have the potential to express degradative activity toward glyphosate, a commonly used organophosphorus herbicide. In this study, 10 strains resistant to a 10 mM concentration of glyphosate were isolated from the rhizoplane of various plants. Five of these strains--Alcaligenes sp. K1, Comamonas sp. K4, Azomonas sp. K5, Pseudomonas sp. K3, and Enterobacter cloacae K7--possessed a number of associative traits, including fixation of atmospheric nitrogen, solubilization of phosphates, and synthesis of the phytohormone indole-3-acetic acid. One strain, E. cloacae K7, could utilize glyphosate as a source of P. Gas-liquid chromatography showed that E. cloacae growth correlated with a decline in herbicide content in the culture medium (40% of the initial 5mM content), with no glyphosate accumulating inside the cells. Thin-layer chromatography analysis of the intermediate metabolites of glyphosate degradation found that E. cloacae K7 had a C-P lyase activity and degraded glyphosate to give sarcosine, which was then oxidized to glycine. In addition, strain K7 colonized the roots of common sunflower (Helianthus annuus L.) and sugar sorghum (Sorghum saccharatum Pers.), promoting the growth and development of sunflower seedlings. Our findings extend current knowledge of glyphosate-degrading rhizosphere bacteria and may be useful for developing a biotechnology for the cleanup and restoration of glyphosate-polluted soils. PMID:23545355

  12. KPC-2 carbapenemase and DHA-1 AmpC determinants carried on the same plasmid in Enterobacter aerogenes.

    PubMed

    Kuai, Shougang; Shao, Haifeng; Huang, Lihua; Pei, Hao; Lu, Zhonghua; Wang, Weiping; Liu, Jun

    2014-03-01

    This study was conducted to analyse the presence of a plasmid-mediated carbapenem resistance mechanism in a clinical Enterobacter aerogenes isolate from a patient from Jiangsu province, People's Republic of China. PCR and sequencing confirmed that the isolate harboured Klebsiella pneumoniae carbapenemase (KPC)-2, DHA-1 and TEM-1 β-lactamase genes. Both the KPC-2 and DHA-1 genes were transferred to Escherichia coli C600 by transconjugation, and Southern blotting confirmed that these two genes were located on the same plasmid, which was of approximately 56 kb in size. The Enterobacter aerogenes isolate was resistant to carbapenems and other tested antimicrobial agents. The Escherichia coli transconjugant showed reduced susceptibility but not resistance to carbapenems and other β-lactams, indicating the presence of another, possibly permeability-related, resistance mechanism in the clinical isolate.

  13. Structure characterization of a fucose-containing exopolysaccharide produced by Enterobacter cloacae Z0206.

    PubMed

    Wang, Fengqin; Yang, Hangxian; Wang, Yizhen

    2013-01-30

    A novel high molecular weight (1.1 × 10(6)Da) exopolysaccharide (EPS) produced by Enterobacter cloacae Z0206 strain was isolated by column chromatography. Complete hydrolysis of the EPS followed by gas chromatography mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC) analyses showed that the EPS is composed of L-fucose, D-glucose, D-galactose, D-glucuronic acid and pyruvic acid in the approximate molar ratio of 2:1:3:1:1. Partial acid hydrolysis of the purified EPS followed by gel permeation chromatography (GPC) yielded a hexasaccharide. A combination of chemical analysis coupled with mass spectrometry and 1D and 2D NMR spectroscopy applied to the oligosaccharide showed that the EPS comprises a heptasaccharide repeating unit.

  14. Biosensing and bioremediation of Cr(VI) by cell free extract of Enterobacter aerogenes T2.

    PubMed

    Panda, Jigisha; Sarkar, Priyabrata

    2014-01-01

    Hexavalent chromium or Cr(VI) enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Hence it is required to be detected and remediated from the environment. In this study, low-cost and environment-friendly methods of biosensing and bioremediation of Cr(VI) have been proposed. Crude cell free extract (CFE) of previously isolated Enterobacter aerogenes T2 (GU265554; NII 1111) was prepared and exploited to develop a stable biosensor for direct estimation of Cr(VI) in waste water, by using three electrodes via cyclic voltammetry. For bioremediation studies, a homogeneous solution of commercially available sodium alginate and CFE was added dropwise in a continuously stirred calcium chloride solution. Biologically modified calcium alginate beads were produced and these were further utilized for bioremediation studies. The proposed sensor showed linear response in the range of 10-40 μg L(-1) Cr(VI) and the limit of detection was found to be 6.6 μg L(-1) Cr(VI). No interference was observed in presence of metal ions, e.g., lead, cadmium, arsenic, tin etc., except for insignificant interference with molybdenum and manganese. In bioremediation studies, modified calcium alginate beads showed encouraging removal rate 900 mg Cr(VI)/m(3) water per day with a removal efficiency of 90%, much above than reported in literature. The proposed sensing system could be a viable alternative to costly measurement procedures. Calcium alginate beads, modified with CFE of E. aerogenes, could be used in bioremediation of Cr(VI) since it could work in real conditions with extraordinarily high capacity.

  15. Characteristics of a Novel Aerobic Denitrifying Bacterium, Enterobacter cloacae Strain HNR.

    PubMed

    Guo, Long-Jie; Zhao, Bin; An, Qiang; Tian, Meng

    2016-03-01

    A novel aerobic denitrifier strain HNR, isolated from activated sludge, was identified as Enterobacter cloacae by16S rRNA sequencing analysis. Glucose was considered as the most favorable C-source for strain HNR. The logistic equation well described the bacterial growth, yielding a maximum growth rate (μmax) of 0.283 h(-1) with an initial NO3 (-)-N concentration of 110 mg/L. Almost all NO3 (-)-N was removed aerobically within 30 h with an average removal rate of 4.58 mg N L(-1) h(-1). Nitrogen balance analysis revealed that proximately 70.8 % of NO3 (-)-N was removed as gas products and only 20.7 % was transformed into biomass. GC-MS result indicates that N2 was the end product of aerobic denitrification. The enzyme activities of nitrate reductase and nitrite reductase, which are related to the process of aerobic denitrification, were 0.0688 and 0.0054 U/mg protein, respectively. Thus, the aerobic denitrification of reducing NO3 (-) to N2 by strain HNR was demonstrated. The optimal conditions for nitrate removal were C/N ratio 13, pH value 8, shaking speed 127 rpm and temperature 30 °C. These findings show that E. cloacae strain HNR has a potential application on wastewater treatment to achieve nitrate removal under aerobic conditions.

  16. Imipenem- and meropenem-resistant mutants of Enterobacter cloacae and Proteus rettgeri lack porins.

    PubMed Central

    Raimondi, A; Traverso, A; Nikaido, H

    1991-01-01

    Carbapenems such as imipenem and meropenem are not rapidly hydrolyzed by commonly occurring beta-lactamases. Nevertheless, it was possible, by mutagenesis and selection, to isolate mutant strains of Enterobacter cloacae and Proteus rettgeri that are highly resistant to meropenem and imipenem. Two alterations were noted in the E. cloacae mutants. First, the mutant strains appeared to be strongly derepressed in the production of beta-lactamases, which reached a very high level when the strains were grown in the presence of imipenem. Second, these mutants were deficient in the production of nonspecific porins, as judged by the pattern of outer membrane proteins as well as by reconstitution assays of permeability. As with most porin-deficient mutants, their cultures were unstable, and their cultivation in the absence of carbapenems rapidly led to an overgrowth of porin-producing revertants. Analysis of the data suggests that the synergism between the lowered outer membrane permeability and the slow but significant hydrolysis of carbapenems by the overproduced enzymes can explain the resistance phenotypes quantitatively, although the possibility of alteration of the target cannot be excluded at present. With P. rettgeri mutants, there was no indication of further derepression of beta-lactamase, but the enzyme hydrolyzed imipenem much more efficiently than the E. cloacae enzyme did. In addition, the major porin was absent in one mutant strain. These results suggest that a major factor for the carbapenem resistance of these enteric bacteria is the porin deficiency, and this conclusion forms a contrast to the situation in Pseudomonas aeruginosa, in which the most prevalent class of imipenem-resistant mutants appears to lack the specific channel protein D2 yet retains the major nonspecific porin F. Images PMID:1656855

  17. Occurrence of efflux mechanism and cephalosporinase variant in a population of Enterobacter aerogenes and Klebsiella pneumoniae isolates producing extended-spectrum beta-lactamases.

    PubMed

    Tran, Que-Tien; Dupont, Myrielle; Lavigne, Jean-Philippe; Chevalier, Jacqueline; Pagès, Jean-Marie; Sotto, Albert; Davin-Regli, Anne

    2009-04-01

    We investigated the occurrence of multidrug resistance in 44 Enterobacter aerogenes and Klebsiella pneumoniae clinical isolates. Efflux was involved in resistance in E. aerogenes isolates more frequently than in K. pneumoniae isolates (100 versus 38% of isolates) and was associated with the expression of phenylalanine arginine beta-naphthylamide-susceptible active efflux. AcrA-TolC overproduction in E. aerogenes isolates was noted. An analysis of four E. aerogenes isolates for which cefepime MICs were high revealed no modification in porin expression but a new specific mutation in the AmpC beta-lactamase.

  18. Growth of Enterobacter aerogenes in a chemostat with double nutrient limitations.

    PubMed Central

    Cooney, C L; Wang, D I; Mateles, R I

    1976-01-01

    The behavior of Enterobacter aerogenes during growth in chemostats limited by single and double nutrient restrictions was examined. On the assumption that different essential nutrients act to limit growth in different ways, we selected pairs of nutrients likely to affect different aspects of metabolism. Results show that macromolecular cell composition can be controlled by using more than one nutrient restriction. The polysaccharide content of the cells is readily manipulated by the ratio of carbon to nitrogen in the inlet nutrients. Also, at low dilution rates, ratios of protein to ribonucleic acid are dependent on the ratio of phosphate to nitrogen in the input nutrients. An examination of both acetic acid and metabolite production (as measured by ultraviolet absorbance of culture filtrates) showed that accumulation of these products was dependent on both dilution rate and type of nutrient limitation(s). These results were examined in terms of the problems of translation of batch to continuous culture processes and the use of selected nutrient limitations to control noncellular product formation. PMID:942212

  19. Optimization of cultural conditions for conversion of glycerol to ethanol by Enterobacter aerogenes S012

    PubMed Central

    2013-01-01

    The aim of this research is to optimize the cultural conditions for the conversion of glycerol to ethanol by Enterobacter aerogenes S012. Taguchi method was used to screen the cultural conditions based on their signal to noise ratio (SN). Temperature (°C), agitation speed (rpm) and time (h) were found to have the highest influence on both glycerol utilization and ethanol production by the organism while pH had the lowest. Full factorial design, statistical analysis, and regression model equation were used to optimize the selected cultural parameters for maximum ethanol production. The result showed that fermentation at 38°C and 200 rpm for 48 h would be ideal for the bacteria to produce maximum amount of ethanol from glycerol. At these optimum conditions, ethanol production, yield and productivity were 25.4 g/l, 0.53 g/l/h, and 1.12 mol/mol-glycerol, repectively. Ethanol production increased to 26.5 g/l while yield and productivity decreased to 1.04 mol/mol-glycerol and 0.37 g/l/h, respectively, after 72 h. Analysis of the fermentation products was performed using HPLC, while anaerobic condition was created by purging the fermentation vessel with nitrogen gas. PMID:23388539

  20. Effect of crude glycerol-derived inhibitors on ethanol production by Enterobacter aerogenes.

    PubMed

    Lee, Sang Jun; Kim, Sung Bong; Kang, Seong Woo; Han, Sung Ok; Park, Chulhwan; Kim, Seung Wook

    2012-01-01

    In this study, ethanol production from pure and crude glycerol using Enterobacter aerogenes ATCC 29007 was evaluated under anaerobic culture conditions. Inhibitory effects of substrate concentrations, pH, and salt concentrations were investigated based on crude glycerol components. Ethanol production was performed with pure glycerol concentrations ranging from 5 to 30 g/L to evaluate the effects of substrate concentration and osmotic pressure. The consumed glycerol was 5-14.33 g/L, and the yield of ethanol was higher than 0.75 mol ethanol/mol glycerol after 24 h of cultivation. To evaluate the inhibitory effects of salts (NaCl and KCl), experiments were performed with 0-20 g/L of each salt. Inhibitory effects of salts were strongest at high salt concentrations. The inhibitory effect of pH was performed in the pH range 4-10, and cell growth and ethanol production were highest at pH 5-6. Also, ethanol production was slightly inhibited at low concentration of crude glycerol comparison with pure glycerol. However, significant inhibitory effects were not observed at 1.5 and 2% crude glycerol which showed higher ethanol production compared to pure glycerol.

  1. Biodegradation of acrylamide by Enterobacter aerogenes isolated from wastewater in Thailand.

    PubMed

    Buranasilp, Kanokhathai; Charoenpanich, Jittima

    2011-01-01

    A widespread use of acrylamide, probably a neurotoxicant and carcinogen, in various industrial processes has led to environmental contamination. Fortunately, some microorganisms are able to derive energy from acrylamide. In the present work, we reported the isolation and characterization of a novel acrylamide-degrading bacterium from domestic wastewater in Chonburi, Thailand. The strain grew well in the presence of acrylamide as 0.5% (W/V), at pH 6.0 to 9.0 and 25 degrees C. Identification based on biochemical characteristics and 16S rRNA gene sequence identified the strain as Enterobacter aerogenes. Degradation of acrylamide to acrylic acid started in the late logarithmic growth phase as a biomass-dependent pattern. Specificity of cell-free supernatant towards amides completely degraded butyramide and urea and 86% of lactamide. Moderate degradation took place in other amides with that by formamide > benzamide > acetamide > cyanoacetamide > propionamide. No degradation was detected in the reactions of N,N-methylene bisacrylamide, sodium azide, thioacetamide, and iodoacetamide. These results highlighted the potential of this bacterium in the cleanup of acrylamide/amide in the environment.

  2. Improved hydrogen production under microaerophilic conditions by overexpression of polyphosphate kinase in Enterobacter aerogenes.

    PubMed

    Lu, Yuan; Zhang, Chong; Lai, Qiheng; Zhao, Hongxin; Xing, Xin-Hui

    2011-02-01

    Effects of different microaerophilic conditions on cell growth, glucose consumption, hydrogen production and cellular metabolism of wild Enterobacter aerogenes strain and polyphosphate kinase (PPK) overexpressing strain were systematically studied in this paper, using NaH(2)PO(4) as the phosphate sources. Under different microaerophilic conditions, PPK-overexpressing strain showed better cell growth, glucose consumption and hydrogen production than the wild strain. In the presence of limited oxygen (2.1%) and by PPK overexpression, the hydrogen production per liter of culture, the hydrogen production per cell and the hydrogen yield per mol of glucose increased by 20.1%, 12.3% and 10.8%, respectively, compared with the wild strain under strict anaerobic conditions. Metabolic analysis showed that the increase of the total hydrogen yield was attributed to the improvement of NADH pathway. The result of more reductive cellular oxidation state balance also further demonstrated that, under proper initial microaerophilic conditions and by PPK overexpression, the cell could adjust the cellular redox states and make more energy flow into hydrogen production pathways.

  3. [Mechanisms of bioelectricity generation in Enterobacter aerogenes-based microbial fuel cells].

    PubMed

    Zhang, Jin-Tao; Zhou, Shun-Gui; Zhang, Li-Xia; Lu, Na; Deng, Li-Fang; Ni, Jin-Ren

    2009-04-15

    Microbial fuel cells (MFCs) using hydrogen-producing bacteria (HPB) could utilize a large number of substrates to generate power. However, the coulombic efficiency is limited by the fact that only suspended cells are used as biocatalyst in anodic medium. MFCs using Fe (III)-reducing bacteria have high energy recovery efficiency, but can only utilize some simple organic matters. In this study, Enterobacter aerogenes XM02, a hydrogen-producing strain with Fe(III)-reducing activity, was selected as biocatalyst for MFCs, which could produce electricity by digesting lots of carbohydrates even starch. Graphite felt, a material with high specific surface area and hydrogen catalysis, instead of carbon paper supported platinum, was used as anode material. The coulombic efficiency had been substantially improved from 1.68% to 42.49%, higher than other HPB-based MFCs previously reported. The SEM image proved the ability of XM02 strain to colonize on the anode surface. Power generation of MFCs could restore quickly when anodic medium was completely replaced with non-growth medium containing glucose. This suggested that the attached cells contributed to electricity production because planktonic cells had been removed during the medium replacement. This study proposed the mechanism of power generated from in situ oxidation of hydrogen produced by the XM02 strain biofilm.

  4. Dominance of IMP-4-Producing Enterobacter cloacae among Carbapenemase-Producing Enterobacteriaceae in Australia

    PubMed Central

    Townell, Nicola; Nimmo, Graeme R.; George, Narelle M.; Robson, Jennifer; Vohra, Renu; Davis, Louise; Heney, Claire; Paterson, David L.

    2015-01-01

    The prevalence of carbapenemase-producing Enterobacteriaceae (CPE) has been increasing worldwide. blaIMP has been reported to be the predominant carbapenemase-encoding gene within Enterobacteriaceae in Australia. However, there are limited data currently available on CPE from Queensland, Australia. A total of 58 CPE isolates were isolated between July 2009 and March 2014 from Queensland hospitals. The clonality of isolates was determined by Diversilab repetitive sequence-based PCR. The isolates were investigated for the resistance mechanisms carbapenemase, extended-spectrum β-lactamase, and AmpC β-lactamase and for aminoglycoside resistance and plasmid-mediated quinolone resistance genes by PCR. The plasmid types associated with carbapenemase-encoding genes were characterized. The majority of the CPE were Enterobacter cloacae (n = 29). The majority of Queensland CPE isolates were IMP producers and comprised 11 species (n = 48). Nine NDM-producing Enterobacteriaceae were identified. One NDM-producing Klebsiella pneumoniae isolate coproduced OXA-48. One K. pneumoniae isolate was an OXA-181 producer. The incidence of IMP producers increased significantly in 2013. blaIMP-4 was found in all IMP-producing isolates. blaTEM, qnrB, and aacA4 were common among IMP-4 producers. The HI2 (67%) and L/M (21%) replicons were associated with blaIMP-4. All HI2 plasmids were of sequence type 1 (ST1). All but one of the NDM producers possessed blaCTX-M-15. The 16S rRNA methylase genes found among NDM producers were armA, rmtB, rmtC, and rmtF. The substantial increase in the prevalence of CPE in Queensland has been associated mainly with the emergence E. cloacae strains possessing HI2 plasmids carrying blaIMP-4 over the past 2 years. The importation of NDM producers and/or OXA-48-like producers in patients also contributed to the increased emergence of CPE. PMID:25918153

  5. Detecting the form of selection in the outer membrane protein C of Enterobacter aerogenes strains and Salmonella species.

    PubMed

    Padhi, Abinash; Verghese, Bindhu; Otta, Subhendu K

    2009-01-01

    The types of selective pressure operating on the outer membrane protein C (ompC) of Enterobacter aerogenes strains, the causative agent for nosocomial infections, and Salmonella sp., the hazardous pathogen are investigated using the maximum likelihood-based codon substitution models. Although the rate of amino acid replacement to the silent substitution (omega) across the entire codon sites of ompC of E. aerogenes (omega=0.3194) and Salmonella sp. (omega=0.2047) indicate that the gene is subjected to purifying selection (i.e. omega<1), approximately 3.7% of ompC codon sites in E. aerogenes (omega=21.52) are under the influence of positive Darwinian selection (i.e. omega>1). Such contrast in the intensity of selective pressures in both pathogens could be associated with the differential response to the adverse environmental changes. In E. aerogenes, majority of the positively selected sites are located in the hypervariable cell-surface-exposed domains whereas the trans-membrane domains are functionally highly constrained.

  6. Metal accumulation and vanadium-induced multidrug resistance by environmental isolates of Escherichia hermannii and Enterobacter cloacae.

    PubMed

    Hernández, A; Mellado, R P; Martínez, J L

    1998-11-01

    Contaminated soils from an oil refinery were screened for the presence of microorganisms capable of accumulating either nickel, vanadium, or both metals. Three strains of bacteria that belonged to the family Enterobacteriaceae were selected. Two of them were Escherichia hermannii strains, and outer membrane profile (OMP) analysis showed that they were similar to a strain of clinical origin; the other one was an Enterobacter cloacae strain that differed from clinical isolates. The selected bacteria accumulated both nickel and vanadium. Growth in the presence of vanadium induced multidrug resistance phenotypes in E. hermannii and E. cloacae. Incubation with this metal changed the OMP profile of E. hermannii but did not produce variations in the expression of the major OMPs of E. cloacae. PMID:9797283

  7. Metal Accumulation and Vanadium-Induced Multidrug Resistance by Environmental Isolates of Escherichia hermannii and Enterobacter cloacae

    PubMed Central

    Hernández, Alicia; Mellado, Rafael P.; Martínez, José L.

    1998-01-01

    Contaminated soils from an oil refinery were screened for the presence of microorganisms capable of accumulating either nickel, vanadium, or both metals. Three strains of bacteria that belonged to the family Enterobacteriaceae were selected. Two of them were Escherichia hermannii strains, and outer membrane profile (OMP) analysis showed that they were similar to a strain of clinical origin; the other one was an Enterobacter cloacae strain that differed from clinical isolates. The selected bacteria accumulated both nickel and vanadium. Growth in the presence of vanadium induced multidrug resistance phenotypes in E. hermannii and E. cloacae. Incubation with this metal changed the OMP profile of E. hermannii but did not produce variations in the expression of the major OMPs of E. cloacae. PMID:9797283

  8. Genome Sequence of Enterobacter cloacae Strain SENG-6, a Bacterium Producing Histo-Blood Group Antigen-Like Substances That Can Bind with Human Noroviruses

    PubMed Central

    Amarasiri, Mohan; Hashiba, Satoshi; Yang, Peiyi; Okabe, Satoshi

    2016-01-01

    Enterobacter sp. strain SENG-6, isolated from healthy human feces, produces histo-blood group antigen (HBGA)-like substances that can bind with human noroviruses. Based on the genome sequence analysis, strain SENG-6 belongs to the species Enterobacter cloacae. The genome sequence of this strain should help identify genes associated with the production of HBGA-like substances. PMID:27563051

  9. Genome Sequence of Enterobacter cloacae Strain SENG-6, a Bacterium Producing Histo-Blood Group Antigen-Like Substances That Can Bind with Human Noroviruses.

    PubMed

    Ishii, Satoshi; Amarasiri, Mohan; Hashiba, Satoshi; Yang, Peiyi; Okabe, Satoshi; Sano, Daisuke

    2016-01-01

    Enterobacter sp. strain SENG-6, isolated from healthy human feces, produces histo-blood group antigen (HBGA)-like substances that can bind with human noroviruses. Based on the genome sequence analysis, strain SENG-6 belongs to the species Enterobacter cloacae The genome sequence of this strain should help identify genes associated with the production of HBGA-like substances. PMID:27563051

  10. Genome Sequence of Enterobacter cloacae Strain SENG-6, a Bacterium Producing Histo-Blood Group Antigen-Like Substances That Can Bind with Human Noroviruses.

    PubMed

    Ishii, Satoshi; Amarasiri, Mohan; Hashiba, Satoshi; Yang, Peiyi; Okabe, Satoshi; Sano, Daisuke

    2016-01-01

    Enterobacter sp. strain SENG-6, isolated from healthy human feces, produces histo-blood group antigen (HBGA)-like substances that can bind with human noroviruses. Based on the genome sequence analysis, strain SENG-6 belongs to the species Enterobacter cloacae The genome sequence of this strain should help identify genes associated with the production of HBGA-like substances.

  11. Bioremediation of hexavalent chromium (VI) by a soil-borne bacterium, Enterobacter cloacae B2-DHA.

    PubMed

    Rahman, Aminur; Nahar, Noor; Nawani, Neelu N; Jass, Jana; Hossain, Khaled; Saud, Zahangir Alam; Saha, Ananda K; Ghosh, Sibdas; Olsson, Björn; Mandal, Abul

    2015-01-01

    Chromium and chromium containing compounds are discharged into the nature as waste from anthropogenic activities, such as industries, agriculture, forest farming, mining and metallurgy. Continued disposal of these compounds to the environment leads to development of various lethal diseases in both humans and animals. In this paper, we report a soil borne bacterium, B2-DHA that can be used as a vehicle to effectively remove chromium from the contaminated sources. B2-DHA is resistant to chromium with a MIC value of 1000 µg mL(-1) potassium chromate. The bacterium has been identified as a Gram negative, Enterobacter cloacae based on biochemical characteristics and 16S rRNA gene analysis. TOF-SIMS and ICP-MS analyses confirmed intracellular accumulation of chromium and thus its removal from the contaminated liquid medium. Chromium accumulation in cells was 320 µg/g of cells dry biomass after 120-h exposure, and thus it reduced the chromium concentration in the liquid medium by as much as 81%. Environmental scanning electron micrograph revealed the effect of metals on cellular morphology of the isolates. Altogether, our results indicate that B2-DHA has the potential to reduce chromium significantly to safe levels from the contaminated environments and suggest the potential use of this bacterium in reducing human exposure to chromium, hence avoiding poisoning.

  12. Long-term arsenic monitoring with an Enterobacter cloacae microbial fuel cell.

    PubMed

    Rasmussen, Michelle; Minteer, Shelley D

    2015-12-01

    A microbial fuel cell was constructed with biofilms of Enterobacter cloacae grown on the anode. Bioelectrocatalysis was observed when the biofilm was grown in media containing sucrose as the carbon source and methylene blue as the mediator. The presence of arsenic caused a decrease in bioelectrocatalytic current. Biofilm growth in the presence of arsenic resulted in lower power outputs whereas addition of arsenic showed no immediate result in power output due to the short term arsenic resistance of the bacteria and slow transport of arsenic across cellular membranes to metabolic enzymes. Calibration curves plotted from the maximum current and maximum power of power curves after growth show that this system is able to quantify both arsenate and arsenate with low detection limits (46 μM for arsenate and 4.4 μM for arsenite). This system could be implemented as a method for long-term monitoring of arsenic concentration in environments where arsenic contamination could occur and alter the metabolism of the organisms resulting in a decrease in power output of the self-powered sensor.

  13. Infections with VIM-1 Metallo-β-Lactamase-Producing Enterobacter cloacae and Their Correlation with Clinical Outcome▿

    PubMed Central

    Falcone, Marco; Mezzatesta, Maria Lina; Perilli, Mariagrazia; Forcella, Chiara; Giordano, Alessandra; Cafiso, Viviana; Amicosante, Gianfranco; Stefani, Stefania; Venditti, Mario

    2009-01-01

    The aim of this study was to ascertain the incidence and clinical significance of metallo-β-lactamases among Enterobacter strains isolated from patients with nosocomial infections. We prospectively collected data on patients with Enterobacter infection during a 13-month period. All of the strains were investigated for antibiotic susceptibility, the presence and expression of metallo-β-lactamases, and clonality. Of 29 infections (11 involving the urinary tract, 7 pneumonias, 3 skin/soft tissue infections, 3 intra-abdominal infections, 3 bacteremias, and 2 other infections), 7 (24%) were caused by Enterobacter cloacae strains harboring a blaVIM-1 gene associated or not with a blaSHV12 gene. Infections caused by VIM-1-producing strains were more frequently associated with a recent prior hospitalization (P = 0.006), cirrhosis (P = 0.03), relapse of infection (P < 0.001), and more prolonged duration of antibiotic therapy (P = 0.01) than were other infections. All of the isolates were susceptible to imipenem and meropenem and had blaVIM-1 preceded by a weak P1 promoter and inactivated P2 promoters. Most VIM-1-producing Enterobacter isolates belonged to a main clone, but four different clones were found. Multiclonal VIM-1-producing E. cloacae infections are difficult to diagnose due to an apparent susceptibility to various beta-lactams, including carbapenems, and are associated with a high relapse rate and a more prolonged duration of antibiotic therapy. PMID:19741074

  14. Bioproduction of D-psicose from allitol with Enterobacter aerogenes IK7: a new frontier in rare ketose production.

    PubMed

    Gullapalli, Pushpakiran; Takata, Goro; Poonperm, Wayoon; Rao, Devendar; Morimoto, Kenji; Akimitsu, Kazuya; Tajima, Shigeyuki; Izumori, Ken

    2007-12-01

    D-psicose, a new alternative sweetener, was produced from allitol by microbial oxidation of the newly isolated strain Enterobacter aerogenes IK7. Cells grown in tryptic soy broth medium (TSB) supplemented with D-mannitol at 37 degrees C were found to have the best oxidation potential. The cells, owing to broad substrate specificity, oxidized various polyols (tetritol, pentitol, and hexitol) to corresponding rare ketoses. By a resting cell reaction, 10% of allitol was completely transformed to the product D-psicose, which thus becomes economically feasible for the mass production of D-psicose. Finally, the product was crystallized and confirmed to be D-psicose by analytical methods.

  15. Expression of NAD+-dependent formate dehydrogenase in Enterobacter aerogenes and its involvement in anaerobic metabolism and H2 production.

    PubMed

    Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Wu, Xi; Xing, Xin-Hui

    2009-10-01

    An expression system for NAD(+)-dependent formate dehydrogenase gene (fdh1), from Candida boidinii, was constructed and cloned into Enterobacter aerogenes IAM1183. With the fdh1 expression, the total H(2) yield was attributed to a decrease in activity of the lactate pathway and an increase of the formate pathway flux due to the NADH regeneration. Analysis of the redox state balance and ethanol-to-acetate ratio in the fdhl-expressed strain showed that increased reducing power arose from the reconstruction of NADH regeneration pathway from formate thereby contributing to the improved H(2) production.

  16. Fluoroquinolone Resistance Mechanisms and population structure of Enterobacter cloacae non-susceptible to Ertapenem in North-Eastern France

    PubMed Central

    Guillard, Thomas; Cholley, Pascal; Limelette, Anne; Hocquet, Didier; Matton, Lucie; Guyeux, Christophe; Lebreil, Anne-Laure; Bajolet, Odile; Brasme, Lucien; Madoux, Janick; Vernet-Garnier, Véronique; Barbe, Coralie; Bertrand, Xavier; de Champs on behalf of CarbaFrEst Group, Christophe

    2015-01-01

    Fluoroquinolone (FQ) agents are a potential resort to treat infection due to Enterobacteriaceae producing extended spectrum β-lactamase and susceptible to FQ. In a context of increase of non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 75 Enterobacter cloacae isolates non-susceptible to ertapenem in North-Eastern France in 2012 and describe the population structure by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Among them, 14.7% (12/75) carried a carbapenemase-encoding gene. Except one isolate producing VIM-1, the carbapenemase-producing isolates carried the well-known IncL/M pOXA48a plasmid. Most of the isolates (59/75) harbored at least a FQ-R determinant. qnr genes were predominant (40%, 30/75). The MLST study revealed that E. cloacae isolates’ clonality was wide [24 different sequence types (STs)]. The more widespread STs were ST74, ST101, ST110, ST114, and ST133. Carbapenem MICs were higher for E. cloacae ST74 than for other E. cloacae isolates. Plasmid-mediated quinolone resistance determinants were more often observed in E. cloacae ST74 isolates. These findings showed that (i) pOXA-48a is spreading in North-Eastern France, (ii) qnr is preponderant in E. cloacae, (iii) E. cloacae comprised a large amount of lineages spreading in North-Eastern France, and (iv) FQ as an alternative to β-lactams to treat ertapenem non-susceptible Enterobacteriaceae are compromised. PMID:26557115

  17. Acanthamoeba castellanii of the T4 genotype is a potential environmental host for Enterobacter aerogenes and Aeromonas hydrophila

    PubMed Central

    2013-01-01

    Background Acanthamoeba can interact with a wide range of microorganisms such as viruses, algae, yeasts, protists and bacteria including Legionella pneumophila, Pseudomonas aeruginosa, Vibrio cholerae, Helicobacter pylori, Listeria monocytogenes, Mycobacterium spp., and Escherichia coli. In this capacity, Acanthamoeba has been suggested as a vector in the transmission of bacterial pathogens to the susceptible hosts. Methods Here, we used a keratitis isolate of A. castellanii of the T4 genotype and studied its interactions with two bacterial genera which have not been tested before, Enterobacter aerogenes, and Aeromonas hydrophila, as well as E. coli. Assays were performed to determine bacterial association with and invasion of A. castellanii. Additionally, bacterial survival intracellular of A. castellanii trophozoites as well as cysts was determined. Results All three bacterial isolates tested, associated, invaded, and survived inside A. castellanii trophozoites as well as A. castellanii cysts. However, E. aerogenes and E. coli exhibited significantly reduced association with and invasion of A. castellanii as compared with A. hydrophila (P < 0.01 using paired T-test, one tail distribution). In the long term survival assays, all three bacterial isolates tested remained viable inside A. castellanii trophozoites, while amoeba remained intact; however A. hydrophila exhibited higher survival inside amoebae (14.54 ± 3.3 bacteria:amoeba ratio) compared with E. aerogenes (3.96 ± 0.7 bacteria:amoeba ratio) and E. coli (5.85 ± 1.1 bacteria:amoeba ratio). A. hydrophila, E. coli, and E. aerogenes remained viable during the encystment process and exhibited higher levels of recovery from mature cysts (14.13 ± 0.89 A. hydrophila:amoeba ratio, 10.13 ± 1.17 E. aerogenes:amoeba ratio, and 11.95 ± 0.7 E. coli:amoeba ratio). Conclusions A. hydrophila and E. aerogenes also joined the ranks of other bacteria that could benefit from A. castellanii

  18. Effects of carbon source and Vitreoscilla hemoglobin (VHb) on the production of beta-galactosidase in Enterobacter aerogenes.

    PubMed

    Khleifat, Khaled M; Abboud, Muayad M; Al-Mustafa, Ahmed H; Al-Sharafa, Khalid Y

    2006-10-01

    At fixed concentration (0.5%), lactose and galactose acted as inducers while glucose and other tested carbon sugars showed repression effects on beta-galactosidase production in Enterobacter aerogenes strain. The expression of Vitreoscilla hemoglobin gene (vgb) in this bacterial strain managed to overcome the repression effects as well as improving the induction of beta-galactosidase formation by carbon sources. In parallel, the bacterial O(2) consumption was increased correspondingly to the vgb induction of beta-galactosidase synthesis. When Enterobacter aerogenes strains were grown at the incubation temperature 42 degrees C, about 5-fold higher enzyme productivity was obtained than with a similar incubation at 37 degrees C. The bacterial growth expressed as biomass yield had a different optimum temperature and was not influenced to the same extent by variations in the carbon sources. These data are discussed in terms of proposed enhancement in beta-galactosidase productivity by vgb expression as well as its significance to improve the technology of whey processing.

  19. Complex Regulation Pathways of AmpC-Mediated β-Lactam Resistance in Enterobacter cloacae Complex.

    PubMed

    Guérin, François; Isnard, Christophe; Cattoir, Vincent; Giard, Jean Christophe

    2015-12-01

    Enterobacter cloacae complex (ECC), an opportunistic pathogen causing numerous infections in hospitalized patients worldwide, is able to resist β-lactams mainly by producing the AmpC β-lactamase enzyme. AmpC expression is highly inducible in the presence of some β-lactams, but the underlying genetic regulation, which is intricately linked to peptidoglycan recycling, is still poorly understood. In this study, we constructed different mutant strains that were affected in genes encoding enzymes suspected to be involved in this pathway. As expected, the inactivation of ampC, ampR (which encodes the regulator protein of ampC), and ampG (encoding a permease) abolished β-lactam resistance. Reverse transcription-quantitative PCR (qRT-PCR) experiments combined with phenotypic studies showed that cefotaxime (at high concentrations) and cefoxitin induced the expression of ampC in different ways: one involving NagZ (a N-acetyl-β-D-glucosaminidase) and another independent of NagZ. Unlike the model established for Pseudomonas aeruginosa, inactivation of DacB (also known as PBP4) was not responsible for a constitutive ampC overexpression in ECC, whereas it caused AmpC-mediated high-level β-lactam resistance, suggesting a post-transcriptional regulation mechanism. Global transcriptomic analysis by transcriptome sequencing (RNA-seq) of a dacB deletion mutant confirmed these results. Lastly, analysis of 37 ECC clinical isolates showed that amino acid changes in the AmpD sequence were likely the most crucial event involved in the development of high-level β-lactam resistance in vivo as opposed to P. aeruginosa where dacB mutations have been commonly found. These findings bring new elements for a better understanding of β-lactam resistance in ECC, which is essential for the identification of novel potential drug targets. PMID:26438498

  20. Complex Regulation Pathways of AmpC-Mediated β-Lactam Resistance in Enterobacter cloacae Complex

    PubMed Central

    Guérin, François; Isnard, Christophe; Giard, Jean Christophe

    2015-01-01

    Enterobacter cloacae complex (ECC), an opportunistic pathogen causing numerous infections in hospitalized patients worldwide, is able to resist β-lactams mainly by producing the AmpC β-lactamase enzyme. AmpC expression is highly inducible in the presence of some β-lactams, but the underlying genetic regulation, which is intricately linked to peptidoglycan recycling, is still poorly understood. In this study, we constructed different mutant strains that were affected in genes encoding enzymes suspected to be involved in this pathway. As expected, the inactivation of ampC, ampR (which encodes the regulator protein of ampC), and ampG (encoding a permease) abolished β-lactam resistance. Reverse transcription-quantitative PCR (qRT-PCR) experiments combined with phenotypic studies showed that cefotaxime (at high concentrations) and cefoxitin induced the expression of ampC in different ways: one involving NagZ (a N-acetyl-β-d-glucosaminidase) and another independent of NagZ. Unlike the model established for Pseudomonas aeruginosa, inactivation of DacB (also known as PBP4) was not responsible for a constitutive ampC overexpression in ECC, whereas it caused AmpC-mediated high-level β-lactam resistance, suggesting a post-transcriptional regulation mechanism. Global transcriptomic analysis by transcriptome sequencing (RNA-seq) of a dacB deletion mutant confirmed these results. Lastly, analysis of 37 ECC clinical isolates showed that amino acid changes in the AmpD sequence were likely the most crucial event involved in the development of high-level β-lactam resistance in vivo as opposed to P. aeruginosa where dacB mutations have been commonly found. These findings bring new elements for a better understanding of β-lactam resistance in ECC, which is essential for the identification of novel potential drug targets. PMID:26438498

  1. Characterization of the plant growth promoting bacterium, Enterobacter cloacae MSR1, isolated from roots of non-nodulating Medicago sativa

    PubMed Central

    Khalifa, Ashraf Y.Z.; Alsyeeh, Abdel-Moneium; Almalki, Mohammed A.; Saleh, Farag A.

    2015-01-01

    The aim of the present study was to characterize the endophytic bacterial strain designated MSR1 that was isolated from inside the non-nodulating roots of Medicago sativa after surface-sterilization. MSR1 was identified as Enterobacter cloacae using both 16S rDNA gene sequence analysis and API20E biochemical identification system (Biomerieux, France). Furthermore, this bacterium was characterized using API50CH kit (Biomerieux, France) and tested for antibacterial activities against some food borne pathogens. The results showed that E. cloacae consumed certain carbohydrates such as glycerol, d-xylose, d-maltose and esculin melibiose as a sole carbon source and certain amino acids such as arginine, tryptophan ornithine as nitrogen source. Furthermore, MSR1 possessed multiple plant-growth promoting characteristics; phosphate solubility, production of phytohormones acetoin and bioactive compounds. Inoculation of Pisum sativum with MSR1 significantly improved the growth parameters (the length and dry weight) of this economically important grain legume compared to the non-treated plants. To our knowledge, this is the first report addressing E. cloacae which exist in roots of alfalfa growing in Al-Ahsaa region. The results confirmed that E. cloacae exhibited traits for plant growth promoting and could be developed as an eco-friendly biofertilizer for P. sativum and probably for other important plant species in future. PMID:26858542

  2. Characterization of the plant growth promoting bacterium, Enterobacter cloacae MSR1, isolated from roots of non-nodulating Medicago sativa.

    PubMed

    Khalifa, Ashraf Y Z; Alsyeeh, Abdel-Moneium; Almalki, Mohammed A; Saleh, Farag A

    2016-01-01

    The aim of the present study was to characterize the endophytic bacterial strain designated MSR1 that was isolated from inside the non-nodulating roots of Medicago sativa after surface-sterilization. MSR1 was identified as Enterobacter cloacae using both 16S rDNA gene sequence analysis and API20E biochemical identification system (Biomerieux, France). Furthermore, this bacterium was characterized using API50CH kit (Biomerieux, France) and tested for antibacterial activities against some food borne pathogens. The results showed that E. cloacae consumed certain carbohydrates such as glycerol, d-xylose, d-maltose and esculin melibiose as a sole carbon source and certain amino acids such as arginine, tryptophan ornithine as nitrogen source. Furthermore, MSR1 possessed multiple plant-growth promoting characteristics; phosphate solubility, production of phytohormones acetoin and bioactive compounds. Inoculation of Pisum sativum with MSR1 significantly improved the growth parameters (the length and dry weight) of this economically important grain legume compared to the non-treated plants. To our knowledge, this is the first report addressing E. cloacae which exist in roots of alfalfa growing in Al-Ahsaa region. The results confirmed that E. cloacae exhibited traits for plant growth promoting and could be developed as an eco-friendly biofertilizer for P. sativum and probably for other important plant species in future. PMID:26858542

  3. Co-fermentation of carbon sources by Enterobacter aerogenes ATCC 29007 to enhance the production of bioethanol.

    PubMed

    Thapa, Laxmi Prasad; Lee, Sang Jun; Yang, Xiao Guang; Yoo, Hah Young; Kim, Sung Bong; Park, Chulhwan; Kim, Seung Wook

    2014-06-01

    We investigated the enhancement of bioethanol production in Enterobacter aerogenes ATCC 29007 by co-fermentation of carbon sources such as glycerol, glucose, galactose, sucrose, fructose, xylose, starch, mannitol and citric acid. Biofuel production increases with increasing growth rate of microorganisms; that is why we investigated the optimal growth rate of E. aerogenes ATCC 29007, using mixtures of different carbon sources with glycerol. E. aerogenes ATCC 29007 was incubated in media containing each carbon source and glycerol; growth rate and bioethanol production improved in all cases compared to those in medium containing glycerol alone. The growth rate and bioethanol production were highest with mannitol. Fermentation was carried out at 37 °C for 18 h, pH 7, using 50 mL defined production medium in 100 mL serum bottles at 200 rpm. Bioethanol production under optimized conditions in medium containing 16 g/L mannitol and 20 g/L glycerol increased sixfold (32.10 g/L) than that containing glycerol alone (5.23 g/L) as the carbon source in anaerobic conditions. Similarly, bioethanol production using free cells in continuous co-fermentation also improved (27.28 g/L) when 90.37 % of 16 g/L mannitol and 67.15 % of 20 g/L glycerol were used. Although naturally existing or engineered microorganisms can ferment mixed sugars sequentially, the preferential utilization of glucose to non-glucose sugars often results in lower overall yield and productivity of ethanol. Here, we present new findings in E. aerogenes ATCC 29007 that can be used to improve bioethanol production by simultaneous co-fermentation of glycerol and mannitol.

  4. Aerobic degradation of 2,4,6-trinitrotoluene by Enterobacter cloacae PB2 and by pentaerythritol tetranitrate reductase

    SciTech Connect

    French, C.E.; Bruce, N.C.; Nicklin, S.

    1998-08-01

    Enterobacter cloacae PB2 was originally isolated on the basis of its ability to utilize nitrate esters, such as pentaerythritol tetranitrate (PETN) and glycerol trinitrate, as the sole nitrogen source for growth. The enzyme responsible is an NADPH-dependent reductase designated PETN reductase. E. cloacae PB2 was found to be capable of slow aerobic growth with 2,4,6-trinitrotoluene (TNT) as the sole nitrogen source. Dinitrotoluenes were not produced and could not be used as nitrogen sources. Purified PETN reductase was found to reduce TNT to its hydride-Meisenheimer complex, which was further reduced to the dihydride-Meisenheimer complex. Purified PETN reductase and recombinant Escherichia coli expressing PETN reductase were able to liberate nitrogen as nitrite from TNT. The ability to remove nitrogen from TNT suggests that PB2 or recombinant organisms expressing PETN reductase may be useful for bioremediation of TNT-contaminated soil and water.

  5. Failure of the MicroScan WalkAway system to detect heteroresistance to carbapenems in a patient with Enterobacter aerogenes bacteremia.

    PubMed

    Gordon, N C; Wareham, D W

    2009-09-01

    We report the failure of the automated MicroScan WalkAway system to detect carbapenem heteroresistance in Enterobacter aerogenes. Carbapenem resistance has become an increasing concern in recent years, and robust surveillance is required to prevent dissemination of resistant strains. Reliance on automated systems may delay the detection of emerging resistance.

  6. Characterization of an Enterobacter cloacae Strain Producing both KPC and NDM Carbapenemases by Whole-Genome Sequencing

    PubMed Central

    Wu, Wenjing; Feng, Yu; Carattoli, Alessandra

    2015-01-01

    A carbapenem-resistant Enterobacter cloacae strain, WCHECl-14653, causing a fatal bloodstream infection, was characterized by genome sequencing and conjugation experiments. The strain carried two carbapenemase genes, blaNDM-1 and blaKPC-2, on separate IncF plasmids. The coexistence of blaNDM-1 and blaKPC-2 conferred slightly higher-level carbapenem resistance compared with that of blaNDM-1 or blaKPC-2 alone, and the coexistence of two IncF plasmids may generate new platforms for spreading carbapenemase genes. PMID:26248381

  7. Reduction of vanadium(V) by Enterobacter cloacae EV-SA01 isolated from a South African deep gold mine.

    PubMed

    van Marwijk, Jacqueline; Opperman, Diederik J; Piater, Lizelle A; van Heerden, Esta

    2009-06-01

    Dissimilatory reduction of vanadium(V) by Enterobacter cloacae EV-SA01, isolated from a gold mine at 1.6 km below surface, is shown to occur anaerobically as well as aerobically. Growth rates were unaffected by up to 2 mM V(2)O(5). Reduction of vanadium(V) was growth phase-dependent and resulted in cell deformities and precipitation of the vanadium in its lower oxidation states. The vanadate reductase activity was membrane-associated and coupled the oxidation of NADH to the reduction of vanadate.

  8. Biological control of an insect pest by gut-colonizing Enterobacter cloacae transformed with ice nucleation gene.

    PubMed

    Watanabe, K; Abe, K; Sato, M

    2000-01-01

    The ice nucleation (IN) gene inaA of epiphytic Erwinia (Pantoea) ananas IN10 was transformed into Enterobacter cloacae WBMH-3-CMr originated from the faeces of silkworms. The transformant designated as Ent. cloacae WBMH-3-CMr(pICE6S13) exhibited IN activity, unlike the parent strain. The transgenic strain was ingested by mulberry pyralid larvae, fed on detached mulberry leaves, and the supercooling capacity and cold hardiness of these larvae were examined. The mean supercooling point (SCP) of the larvae ingesting the transgenic strain was - 3.3 degrees C, 8 degrees C higher than that of larvae treated with distilled water (control) and 1.5 C higher than an ice nucleation active (INA) strain of Erw. ananas. The SCPs of the larvae were stably maintained over the 9 d after ingestion. The maintenance of these high SCPs was due to transgenic Ent. cloacae having a more stable and efficient gut colonization than Erw. ananas, which is identified by the distribution of a narrower range of SCPs (-2 to -5 degrees C) in larvae treated with the transgenic stain. Furthermore, most of the larvae ingesting the transgenic strain froze and died when they were exposed to cold conditions of -5 degrees C for 18 h, 3 or 7 d after ingestion. In contrast, most of the larvae ingesting no bacterium did not die under similar conditions. On the other hand, the growth ability of Ent. cloacae WBMH-3-CMr on mulberry leaves tended to be lower than that of epiphytic Erw. ananas, as assayed by pot tests. These findings would expand the possibility of biological control using INA bacteria since Ent. cloacae would harbour a broader host (insect) range for gut colonization and a smaller affinity to plants to benefit from prevention of plant frost injury. PMID:10735247

  9. Prevalence of decreased susceptibility to carbapenems among Serratia marcescens, Enterobacter cloacae, and Citrobacter freundii and investigation of carbapenemases.

    PubMed

    Lee, Hae Kyung; Park, Yeon-Joon; Kim, Ja-Young; Chang, Eundeok; Cho, Seok Goo; Chae, Hiun Suk; Kang, Chang Suk

    2005-08-01

    Between March and July 2002, total of 612 clinical isolates of Serratia marcescens, Enterobacter cloacae, and Citrobacter freundii (201 S. marcescens, 228 E. cloacae, and 183 C. freundii) were collected from 13 clinical laboratories in a nationwide distribution. Imipenem and meropenem minimum inhibitory concentrations (MICs) were determined using the agar dilution method according to the National Committee for Clinical Laboratory Standards guidelines. For the isolates with a decreased susceptibility to carbapenems (MICs of >or=2 microg/mL), isoelectric focusing, polymerase chain reaction (PCR) amplification of the carbapenemase genes (bla(IMP-1), bla(VIM-2), bla(SME-1), bla(OXA-23), bla(OXA-25), bla(KPC-1)), and sequencing were performed. The prevalence of S. marcescens, E. cloacae, and C. freundii with a decreased susceptibility to imipenem was 17.9% (36/201), 0.4% (1/228), and 0.5% (1/183), respectively, and to meropenem, it was 11.4% (23/201), 0% (0/228), and 0.5% (1/183), respectively. The bla(VIM-2) was the only carbapenemase detected, and was found in 0.5% (1/201) of S. marcescens and 0.5% (1/183) of C. freundii isolate.

  10. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor.

    PubMed

    Jitrwung, Rujira; Yargeau, Viviane

    2015-01-01

    Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol. PMID:25970750

  11. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor

    PubMed Central

    Jitrwung, Rujira; Yargeau, Viviane

    2015-01-01

    Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol. PMID:25970750

  12. Physiological characterisation of the efflux pump system of antibiotic-susceptible and multidrug-resistant Enterobacter aerogenes.

    PubMed

    Martins, A; Spengler, G; Martins, M; Rodrigues, L; Viveiros, M; Davin-Regli, A; Chevalier, J; Couto, I; Pagès, J M; Amaral, L

    2010-10-01

    Enterobacter aerogenes predominates amongst Enterobacteriaceae species that are increasingly reported as producers of extended-spectrum beta-lactamases. Although this mechanism of resistance to beta-lactams is important, other mechanisms bestowing a multidrug-resistant (MDR) phenotype in this species are now well documented. Amongst these mechanisms is the overexpression of efflux pumps that extrude structurally unrelated antibiotics prior to their reaching their targets. Interestingly, although knowledge of the genetic background behind efflux pumps is rapidly advancing, few studies assess the physiological nature of the overall efflux pump system of this, or for that matter any other, bacterium. The study reported here evaluates physiologically the efflux pump system of an E. aerogenes ATCC reference as well as two strains whose MDR phenotypes are mediated by overexpressed efflux pumps. The activities of the efflux pumps in these strains are modulated by pH and glucose, although the effects of the latter are essentially restricted to pH 8, suggesting the presence of two general efflux pump systems, i.e. proton-motive force-dependent and ABC transporter types, respectively.

  13. Biohydrogen and polyhydroxyalkanoate co-production by Enterobacter aerogenes and Rhodobacter sphaeroides from Calophyllum inophyllum oil cake.

    PubMed

    Arumugam, A; Sandhya, M; Ponnusami, V

    2014-07-01

    The feasibility of coupled biohydrogen and polyhydroxyalkanoate production by Enterobacter aerogenes and Rhodobacter sphaeroides using Calophyllum inophyllum oil cake was studied under dark and photo fermentation conditions. The utilization of a non-edible acidic oil cake (C. inophyllum), and exploitation of a modified minimal salt media led to reduction in the cost of media. Cost of fermentation is reduced by implementation of alternate dark-photo fermentative periods and through the use of a co-culture consisting of a dark fermentative (E. aerogenes) and a photo fermentative (R. sphaeroides) bacterium. The biohydrogen and polyhydroxyalkanoate produced were 7.95 L H2/L media and 10.73 g/L media, respectively, under alternate dark and photo fermentation and were 3.23 L H2/L media and 5.6g/L media, respectively under complete dark fermentation. The characteristics of the oil cake and alternate dark (16 h) and photo (8h) fermentative conditions were found to be supportive in producing high biohydrogen and polyhydroxyalkanoate (PHA) yield.

  14. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor.

    PubMed

    Jitrwung, Rujira; Yargeau, Viviane

    2015-05-11

    Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol.

  15. Membrane permeability, a pivotal function involved in antibiotic resistance and virulence in Enterobacter aerogenes clinical isolates.

    PubMed

    Lavigne, J-P; Sotto, A; Nicolas-Chanoine, M-H; Bouziges, N; Bourg, G; Davin-Regli, A; Pagès, J-M

    2012-06-01

    Imipenem-susceptible E. aerogenes isolates exhibiting extended spectrum β-lactamases, target mutations and a basal efflux expression, were identified in five patients. After imipenem treatment, imipenem-intermediate susceptible (IMI-I) or resistant (IMI-R) isolates emerged in these patients. Alteration in porin synthesis and increase in efflux expression were observed in the IMI-I isolates whereas complete loss of the porins, LPS alteration and efflux overexpression were observed in the IMI-R isolates. Bacterial virulence of the strains was investigated by the Caenorhabditis elegans model. The IMI-R isolates were shown to be significantly less virulent than the IMI-susceptible or IMI-I isolates. The pleiotropic membrane alteration and its associated fitness burden exhibited by E. aerogenes isolates influence their antibiotic resistance and their virulence behaviour. These findings highlight the balance between the low permeability-related resistance and virulence and their relationships with the treatment of resistant pathogens.

  16. Physicochemical, nutritional, and microbial quality of fresh-cut and frozen papaya prepared from cultivars with varying resistance to internal yellowing disease (Enterobacter cloacae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quality, nutritional, and microbial analyses were completed for fresh-cut and frozen papaya cubes prepared from cultivars with varying resistance to internal yellowing disease, caused by the bacterium Enterobacter cloacae. In general, fresh-cut and frozen papaya retained nutritional and microbial qu...

  17. Regulation of indole-3-acetic acid biosynthesis by branched-chain amino acids in Enterobacter cloacae UW5.

    PubMed

    Parsons, Cassandra V; Harris, Danielle M M; Patten, Cheryl L

    2015-09-01

    The soil bacterium Enterobacter cloacae UW5 produces the rhizosphere signaling molecule indole-3-acetic acid (IAA) via the indolepyruvate pathway. Expression of indolepyruvate decarboxylase, a key pathway enzyme encoded by ipdC, is upregulated by the transcription factor TyrR in response to aromatic amino acids. Some members of the TyrR regulon may also be controlled by branched-chain amino acids and here we show that expression from the ipdC promoter and production of IAA are downregulated by valine, leucine and isoleucine. Regulation of the IAA synthesis pathway by both aromatic and branched-chain amino acids suggests a broader role for this pathway in bacterial physiology, beyond plant interactions.

  18. Biotransformation of Ferulic acid to 4-Vinylguaiacol by Enterobacter soli and E. aerogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the conversion of ferulic acid to 4-vinylguaiacol (4-VG), vanillin, vanillyl alcohol and vanillic acid by five Enterobacter strains. These high-value chemicals are usually synthesized using chemical methods but biological synthesis adds value. Ferulic acid, a relatively inexpensive...

  19. Changes in ciprofloxacin resistance levels in Enterobacter aerogenes isolates associated with variable expression of the aac(6')-Ib-cr gene.

    PubMed

    Ruiz, Elena; Ocampo-Sosa, Alain A; Alcoba-Flórez, Julia; Román, Elena; Arlet, Guillaume; Torres, Carmen; Martínez-Martínez, Luis

    2012-02-01

    Two closely related Enterobacter aerogenes isolates presented a new identical aac(6')-Ib-cr genetic environment, including IS26. One isolate showed lower MICs of ciprofloxacin, norfloxacin, tobramycin, and amikacin and decreased expression of aac(6')-Ib-cr, which might be related to a 12-bp deletion causing a displacement of the -10 box upstream of the aac(6')-Ib-cr gene.

  20. Epidemiological study of an outbreak due to multidrug-resistant Enterobacter aerogenes in a medical intensive care unit.

    PubMed Central

    Arpin, C; Coze, C; Rogues, A M; Gachie, J P; Bebear, C; Quentin, C

    1996-01-01

    In 1993, 63 isolates of Enterobacter aerogenes were collected from 41 patients in a medical intensive care unit (ICU). During the same period, only 46 isolates from 32 patients were collected in the rest of the hospital. All isolates were analyzed by antibiotic resistance phenotype, and 77 representative isolates were differentiated by plasmid restriction analysis, ribotyping, and arbitrarily primed (AP)-PCR. The extended-spectrum beta-lactamases produced by 22 strains were characterized by determination of their isoelectric points and by hybridization of plasmid DNA with specific probes. The isolates were divided into 25 antibiotic resistance phenotypes, either susceptible (group I) or resistant (group II) to aminoglycosides, and exhibited three phenotypes of resistance to beta-lactams: chromosomally derepressed cephalosporinase alone or associated with either extended-spectrum beta-lactamases (mainly of the SHV-4 type) or imipenem resistance. The results of the tests divided the 77 representative isolates (group I, n = 21; group II, n = 56) into 15 plasmid profiles, 14 ribotypes, and 15 AP-PCR patterns. Although the resistant isolates (group II) exhibited different plasmid profiles, ribotyping and AP-PCR analysis demonstrated an identical chromosomal pattern, indicating an epidemiological relatedness. They were mainly found in the medical ICU and occasionally in other units. The susceptible strains (group I) had various and distinct markers and were mainly isolated in units other than the medical ICU. In conclusion, the presence of a nosocomial outbreak in an ICU and the spread of a multidrug-resistant epidemic strain throughout the hospital was confirmed. Ribotyping and AP-PCR represent discriminatory tools for the investigation of nosocomial outbreaks caused by E. aerogenes. PMID:8862578

  1. Outbreak of infection caused by Enterobacter cloacae producing the novel VEB-3 beta-lactamase in China.

    PubMed

    Jiang, Xiaofei; Ni, Yuxing; Jiang, Yanqun; Yuan, Feiyi; Han, Lizhong; Li, Ming; Liu, Hong; Yang, Li; Lu, Yuan

    2005-02-01

    Over a 4-month period from November 2002 to February 2003, 27 ceftazidime-resistant or cefotaxime-resistant nonrepetitive Enterobacter cloacae isolates were collected from 27 patients hospitalized at HuaShan Hospital, Shanghai, People's Republic of China. The Etest did not detect extended-spectrum beta-lactamases (ESBLs) in those 27 isolates; however, screening by the NCCLS ESBL disk test and confirmatory tests detected ESBLs in 4 of 27 isolates and PCR detected ESBLs in 23 of 27 isolates. The majority of ESBL producers exhibited the same repetitive extragenic palindromic PCR pattern but harbored different ESBL genes. CTX-M-3 was the most prevalent ESBL in our study. Interestingly, 12 clonally related E. cloacae isolates possessed a novel bla(VEB)-type beta-lactamase, bla(VEB-3). Bla(VEB-3) was encoded by the chromosome and was located in an integron. Nine of the 12 isolates harbored both the bla(VEB-3) and the bla(CTX-M-3)-like ESBLs. This is the first report of a VEB-1-like ESBL in China and the first report of the simultaneous presence of VEB-1 and CTX-M-3-like ESBLs in an isolate.

  2. Isolation and Identification of an Enterobacter cloacae Strain Producing a Novel Subtype of Shiga Toxin Type 1

    PubMed Central

    McQuaid, Cassandra; Schrader, Kimmi

    2014-01-01

    We describe here the isolation and identification of a Shiga toxin 1 (Stx1)-producing Enterobacter cloacae strain, M12X01451, from a human clinical specimen. The bacterial isolate was identified as E. cloacae using a polyphasic approach that included phenotypic, genetic, and proteomic analyses. The M12X01451 stx1 was sequenced, and the holotoxin was found to share only 87% amino acid sequence identity with the nearest Stx1 subtype reference sequence. Sequence analysis of the regions immediately flanking stx1 displayed similarities with bacteriophage-related sequences, suggesting a prophage origin. The stx1 gene was a stable element within the M12X01451 genome, as demonstrated by real-time PCR detection following successive subculturing of the bacterial isolate. Culture supernatant from M12X01451 was cytotoxic to Vero cells but was not neutralized by an anti-Stx1 monoclonal antibody. In addition, Stx1 from M12X01451 demonstrated limited antigenicity with two commercially available lateral flow immunoassays. The M12X01451 Stx represents a new Stx1 subtype based on the degree of sequence dissimilarity with Stx1 subtype reference sequences and its limited reactivity with anti-Stx1 antibodies. PMID:24759708

  3. Transgenic ice nucleation-active Enterobacter cloacae reduces cold hardiness of corn borer and cotton bollworm larvae.

    PubMed

    Tang, Chaorong; Sun, Fuzai; Zhang, Xinjian; Zhao, Tingchang; Qi, Jiyan

    2004-12-27

    The ice nucleation (IN) gene iceA of Erwinia ananas 110 was integrated into the chromosomes of two Enterobacter cloacae strains (Enc1.2022 and Enc1.181). These two newly derived transgenic strains, designated Enc2022-I and Enc181-I, respectively, possessed ice nucleation activity at -2.5 degrees C, significantly higher than their parent strains (active at approx -10 degrees C or lower). After ingesting these transgenic bacteria, the mean supercooling points (SCPs) of corn borer and cotton bollworm larvae were -3 to -4 degrees C, significantly higher than those of untreated controls. The SCPs remained significantly elevated over the 9-day period after ingestion, which matched well with the efficient gut colonization of the bacteria during this period. All treated larvae froze and eventually died after exposure for 6 h to a temperature of -7 degrees C, and more than 95% died after 12 h at -5 degrees C. In contrast, few or none of the untreated control larvae froze and died under the same conditions. Furthermore, the growth ability of these transgenic ice nucleation-active (INA) En. cloacae strains on corn leaves was reduced, compared to that of wild-type epiphytic E. ananas, as revealed by pot tests conducted in both greenhouse and outdoor conditions. The stable colonization in insect guts and their lower affinity to plants would make these transgenic INA bacteria useful as a novel tool for biological control of insect pests in agricultural fields. PMID:16329857

  4. Enzymatic synthesis of L-tryptophan by Enterobacter aerogenes tryptophanase highly expressed in Escherichia coli, and some properties of the purified enzyme.

    PubMed

    Kawasaki, K; Yokota, A; Tomita, F

    1995-10-01

    We constructed two plasmids that have a strong tac promoter and a structural gene for tryptophanase of Enterobacter aerogenes SM-18 (pKT901EA) or Escherichia coli K-12 (pKT951EC). The tryptophanase activity of E. coli JM109 transformed with pKT901EA (JM109/pKT901EA) was inducible with isopropyl-beta-D-thiogalactopyranoside, and 3.6 times higher than that of E. aerogenes SM-18. Cells of JM109/pKT901EA induced for tryptophanase synthesized L-tryptophan from indole, ammonia, and pyruvate more efficiently than E. aerogenes SM-18. Although JM109/pKT951EC expressed a similar level of tryptophanase activity to that of JM109/pKT901EA, the synthesis of L-tryptophan by the cells of JM109/pKT951EC did not proceed well compared with JM109/pKT901EA. Tryptophanases from E. aerogenes and E. coli K-12 were purified, and their properties were investigated. The purified E. aerogenes tryptophanase showed higher stability against heat inactivation than E. coli tryptophanase.

  5. Tuberculose de l’épaule masquée par une infection concomitante à enterobacter cloacae: à propos d'un cas

    PubMed Central

    Gbané-Koné, Mariam; Koné, Samba; Ouali, Boubacar; Djaha, Kouassi Jean-Mermoz; Diomandé, Mohamed; Eti, Edmond; Touré, Stanislas André; Kouakou, N'zué Marcel

    2015-01-01

    La tuberculose de l’épaule est une localisation rare de même que l'arthrite septique à Enterobacter cloacae, les auteurs rapportent un cas d'ostéoarthrite de l’épaule à Bacille de Koch et à E. Cloacae chez une patiente de 36 ans avec un terrain particulier (drépanocytose SC et infection à VIH). Le diagnostic a été possible grâce aux prélèvements chirurgicaux effectués lors de l'arthrotomie PMID:26401203

  6. Phenolic compounds: Strong inhibitors derived from lignocellulosic hydrolysate for 2,3-butanediol production by Enterobacter aerogenes.

    PubMed

    Lee, Sang Jun; Lee, Ju Hun; Yang, Xiaoguang; Kim, Sung Bong; Lee, Ja Hyun; Yoo, Hah Young; Park, Chulhwan; Kim, Seung Wook

    2015-12-01

    Lignocellulosic biomass are attractive feedstocks for 2,3-butanediol production due to their abundant supply and low price. During the hydrolysis of lignocellulosic biomass, various byproducts are formed and their effects on 2,3-butanediol production were not sufficiently studied compared to ethanol production. Therefore, the effects of compounds derived from lignocellulosic biomass (weak acids, furan derivatives and phenolics) on the cell growth, the 2,3-butanediol production and the enzymes activity involved in 2,3-butanediol production were evaluated using Enterobacter aerogenes ATCC 29007. The phenolic compounds showed the most toxic effects on cell growth, 2,3-butanediol production and enzyme activity, followed by furan derivatives and weak acids. The significant effects were not observed in the presence of acetic acid and formic acid. Also, feasibility of 2,3-butanediol production from lignocellulosic biomass was evaluated using Miscanthus as a feedstock. In the fermentation of Miscanthus hydrolysate, 11.00 g/L of 2,3-butanediol was obtained from 34.62 g/L of reducing sugar. However, 2,3-butanediol was not produced when the concentration of total phenolic compounds in the hydrolysate increased to more than 1.5 g/L. The present study provides useful information to develop strategies for biological production of 2,3-butanediol and to establish biorefinery for biochemicals from lignocellulosic biomass. PMID:26479290

  7. Alteration of hydrogen metabolism of ldh-deleted Enterobacter aerogenes by overexpression of NAD+-dependent formate dehydrogenase.

    PubMed

    Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Wu, Xi; Xing, Xin-Hui

    2010-03-01

    The NAD+-dependent formate dehydrogenase FDH1 gene (fdh1), cloned from Candida boidinii, was expressed in the ldh-deleted mutant of Enterobacter aerogenes IAM1183 strain. The plasmid of pCom10 driven by the PalkB promoter was used to construct the fdh1 expression system and thus introduce a new dihydronicotinamide adenine dinucleotide (NADH) regeneration pathway from formate in the ldh-deleted mutant. The knockout of NADH-consuming lactate pathway affected the whole cellular metabolism, and the hydrogen yield increased by 11.4% compared with the wild strain. Expression of fdh1 in the ldh-deleted mutant caused lower final cell concentration and final pH after 16 h cultivation, and finally resulted in 86.8% of increase in hydrogen yield per mole consumed glucose. The analysis of cellular metabolites and estimated redox state balance in the fdhl-expressed strain showed that more excess of reducing power was formed by the rewired NADH regeneration pathway, changing the metabolic distribution and promoting the hydrogen production.

  8. Mutational analysis of the hyc-operon determining the relationship between hydrogenase-3 and NADH pathway in Enterobacter aerogenes.

    PubMed

    Pi, Jian; Jawed, Muhammad; Wang, Jun; Xu, Li; Yan, Yunjun

    2016-01-01

    In this study, the hydrogenase-3 gene cluster (hycDEFGH) was isolated and identified from Enterobacter aerogenes CCTCC AB91102. All gene products were highly homologous to the reported bacterial hydrogenase-3 (Hyd-3) proteins. The genes hycE, hycF, hycG encoding the subunits of hydrogenase-3 were targeted for genetic knockout to inhibit the FHL hydrogen production pathway via the Red recombination system, generating three mutant strains AB91102-E (ΔhycE), AB91102-F (ΔhycF) and AB91102-G (ΔhycG). Deletion of the three genes affected the integrity of hydrogenase-3. The hydrogen production experiments with the mutant strains showed that no hydrogen was detected compared with the wild type (0.886 mol/mol glucose), demonstrating that knocking out any of the three genes could inhibit NADH hydrogen production pathway. Meanwhile, the metabolites of the mutant strains were significantly changed in comparison with the wild type, indicating corresponding changes in metabolic flux by mutation. Additionally, the activity of NADH-mediated hydrogenase was found to be nil in the mutant strains. The chemostat experiments showed that the NADH/NAD(+) ratio of the mutant strains increased nearly 1.4-fold compared with the wild type. The NADH-mediated hydrogenase activity and NADH/NAD(+) ratio analysis both suggested that NADH pathway required the involvement of the electron transport chain of hydrogenase-3.

  9. Disruption of lactate dehydrogenase and alcohol dehydrogenase for increased hydrogen production and its effect on metabolic flux in Enterobacter aerogenes.

    PubMed

    Zhao, Hongxin; Lu, Yuan; Wang, Liyan; Zhang, Chong; Yang, Cheng; Xing, Xinhui

    2015-10-01

    Hydrogen production by Enterobacter aerogenes from glucose was enhanced by deleting the targeted ldhA and adh genes responsible for two NADH-consuming pathways which consume most NADH generated from glycolysis. Compared with the wild-type, the hydrogen yield of IAM1183-ΔldhA increased 1.5 fold. Metabolic flux analysis showed both IAM1183-ΔldhA and IAM1183-Δadh exhibited significant changes in flux, including enhanced flux towards the hydrogen generation. The lactate production of IAM1183-ΔldhA significantly decreased by 91.42%, while the alcohol yield of IAM1183-Δadh decreased to 30%. The mutant IAM1183-ΔldhA with better hydrogen-producing performance was selected for further investigation in a 5-L fermentor. The hydrogen production of IAM1183-ΔldhA was 2.3 times higher than the wild-type. Further results from the fermentation process showed that the pH decreased to 5.39 levels, then gradually increased to 5.96, indicating that some acidic metabolites might be degraded or uptaken by cells.

  10. Phenolic compounds: Strong inhibitors derived from lignocellulosic hydrolysate for 2,3-butanediol production by Enterobacter aerogenes.

    PubMed

    Lee, Sang Jun; Lee, Ju Hun; Yang, Xiaoguang; Kim, Sung Bong; Lee, Ja Hyun; Yoo, Hah Young; Park, Chulhwan; Kim, Seung Wook

    2015-12-01

    Lignocellulosic biomass are attractive feedstocks for 2,3-butanediol production due to their abundant supply and low price. During the hydrolysis of lignocellulosic biomass, various byproducts are formed and their effects on 2,3-butanediol production were not sufficiently studied compared to ethanol production. Therefore, the effects of compounds derived from lignocellulosic biomass (weak acids, furan derivatives and phenolics) on the cell growth, the 2,3-butanediol production and the enzymes activity involved in 2,3-butanediol production were evaluated using Enterobacter aerogenes ATCC 29007. The phenolic compounds showed the most toxic effects on cell growth, 2,3-butanediol production and enzyme activity, followed by furan derivatives and weak acids. The significant effects were not observed in the presence of acetic acid and formic acid. Also, feasibility of 2,3-butanediol production from lignocellulosic biomass was evaluated using Miscanthus as a feedstock. In the fermentation of Miscanthus hydrolysate, 11.00 g/L of 2,3-butanediol was obtained from 34.62 g/L of reducing sugar. However, 2,3-butanediol was not produced when the concentration of total phenolic compounds in the hydrolysate increased to more than 1.5 g/L. The present study provides useful information to develop strategies for biological production of 2,3-butanediol and to establish biorefinery for biochemicals from lignocellulosic biomass.

  11. Bacillus subtilis and Enterobacter cloacae endophytes from healthy Theobroma cacao L. trees can systemically colonize seedlings and promote growth.

    PubMed

    Leite, Hianna Almeida Câmara; Silva, Anderson Barbosa; Gomes, Fábio Pinto; Gramacho, Karina Peres; Faria, José Cláudio; de Souza, Jorge Teodoro; Loguercio, Leandro Lopes

    2013-03-01

    Clonal genotypes resistant to fungal diseases are an important component of the cocoa production system in southeastern Bahia state (Brazil), so that technologies for faster production of stronger and healthier plantlets are highly desirable. In this study, the effects of inoculated bacterial endophytes isolated from healthy adult cacao plants on seedlings, and aspects related to inoculation methods, colonization patterns, and photosynthesis were investigated. Sequencing of 16S rRNA, hsp-60, and rpo-B genes placed the wild-type isolates within the species Enterobacter cloacae (isolates 341 and 344) and Bacillus subtilis (isolate 629). Spontaneous rifampicin-resistant (rif(R)) variants for 344 were also produced and tested. Endophytic application was either by immersion of surface sterilized seeds in bacterial suspensions or direct inoculation into soil, 20 days after planting non-inoculated seeds into pots. Results from in vitro recovery of inoculated isolates showed that the wild-type endophytes and rif(R) variants systemically colonized the entire cacao seedlings in 15-20 days, regardless of the inoculation method. Some endophytic treatments showed significant increases in seedlings' height, number of leaves, and dry matter. Inoculation methods affected the combined application of endophytes, which maintained the growth-promotion effects, but not in the same manner as in single applications. Interestingly, the 344-3.2 rif(R) variant showed improved performance in relation to both the wild type and another related variant. Photosynthetic rates and stomatal conductance increased significantly for some endophytic treatments, being partially associated with effects on growth and affected by the inoculation method. The results suggest that E. cloacae and B. subtilis endophytes from healthy adult plants (not transmitted by seeds) were able to promote vegetative growth on cacao seedlings. The development of products for large-scale use in seedlings

  12. Genome Sequence of Enterobacter cloacae subsp. dissolvens SDM, an Efficient Biomass-Utilizing Producer of Platform Chemical 2,3-Butanediol

    PubMed Central

    Xu, Youqiang; Wang, Ailong; Tao, Fei; Su, Fei; Tang, Hongzhi

    2012-01-01

    Enterobacter cloacae subsp. dissolvens SDM has an extraordinary characteristic of biomass utilization for 2,3-butanediol production. Here we present a 4.9-Mb assembly of its genome. The key genes for regulation and metabolism of 2,3-butanediol production were annotated, which could provide further insights into the molecular mechanism of high-yield production of 2,3-butanediol. PMID:22275097

  13. Isolation of Enterobacter aerogenes carrying blaTEM-1 and blaKPC-3 genes recovered from a hospital Intensive Care Unit.

    PubMed

    Pulcrano, Giovanna; Pignanelli, Salvatore; Vollaro, Adriana; Esposito, Matilde; Iula, Vita Dora; Roscetto, Emanuela; Soriano, Amata Amy; Catania, Maria Rosaria

    2016-06-01

    Enterobacter aerogenes has recently emerged as an important hospital pathogen. In this study, we showed the emergence of E. aerogenes isolates carrying the blaKPC gene in patients colonized by carbapenem-resistant Klebsiella pneumoniae strains. Two multiresistant E. aerogenes isolates were recovered from bronchial aspirates of two patients hospitalized in the Intensive Care Unit at the "Santa Maria della Scaletta" Hospital, Imola. The antimicrobial susceptibility test showed the high resistance to carbapenems and double-disk synergy test confirmed the phenotype of KPC and AmpC production. Other investigation revealed that ESBL and blaKPC genes were carried on the conjugative pKpQIL plasmid. This is a relevant report in Italy that describes a nosocomial infection due to the production of KPC beta-lactamases by an E. aerogenes isolate in patients previously colonized by K. pneumoniae carbapenem-resistant. In conclusion, it's necessary a continuous monitoring of multidrug-resistant strains for the detection of any KPC-producing bacteria that could expand the circulation of carbapenem-resistant pathogens.

  14. Effects of eliminating pyruvate node pathways and of coexpression of heterogeneous carboxylation enzymes on succinate production by Enterobacter aerogenes.

    PubMed

    Tajima, Yoshinori; Yamamoto, Yoko; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Usuda, Yoshihiro; Sode, Koji

    2015-02-01

    Lowering the pH in bacterium-based succinate fermentation is considered a feasible approach to reduce total production costs. Newly isolated Enterobacter aerogenes strain AJ110637, a rapid carbon source assimilator under weakly acidic (pH 5.0) conditions, was selected as a platform for succinate production. Our previous work showed that the ΔadhE/PCK strain, developed from AJ110637 with inactivated ethanol dehydrogenase and introduced Actinobacillus succinogenes phosphoenolpyruvate carboxykinase (PCK), generated succinate as a major product of anaerobic mixed-acid fermentation from glucose under weakly acidic conditions (pH <6.2). To further improve the production of succinate by the ΔadhE/PCK strain, metabolically engineered strains were designed based on the elimination of pathways that produced undesirable products and the introduction of two carboxylation pathways from phosphoenolpyruvate and pyruvate to oxaloacetate. The highest production of succinate was observed with strain ES04/PCK+PYC, which had inactivated ethanol, lactate, acetate, and 2,3-butanediol pathways and coexpressed PCK and Corynebacterium glutamicum pyruvate carboxylase (PYC). This strain produced succinate from glucose with over 70% yield (gram per gram) without any measurable formation of ethanol, lactate, or 2,3-butanediol under weakly acidic conditions. The impact of lowering the pH from 7.0 to 5.5 on succinate production in this strain was evaluated under pH-controlled batch culture conditions and showed that the lower pH decreased the succinate titer but increased its yield. These findings can be applied to identify additional engineering targets to increase succinate production. PMID:25416770

  15. In vivo development of carbapenem resistance in clinical isolates of Enterobacter aerogenes producing multiple beta-lactamases.

    PubMed

    Chen, Ya-Gang; Zhang, Ying; Yu, Yun-Song; Qu, Ting-Ting; Wei, Ze-Qing; Shen, Ping; Li, Lan-Juan

    2008-10-01

    Four clinical strains of extended-spectrum beta-lactamase- and AmpC-producing Enterobacter aerogenes were isolated successively from a liver transplantation patient. Isolates C(1) and C(2) were isolated prior to carbapenem therapy, whilst isolates C(3) and C(4) were recovered after 40 days of carbapenem therapy. The homology of these strains was analysed by pulsed-field gel electrophoresis (PFGE). beta-Lactamases were analysed by isoelectric focusing, polymerase chain reaction (PCR) and sequencing. Outer membrane proteins were analysed by PCR, sequencing, sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blot. Disruption of OmpE36 in C(1) in vitro was also performed by homologous gene recombination. The isolates demonstrated an indistinguishable PFGE pattern. Molecular characterisation revealed that, in addition to the pre-existing multiple beta-lactamases (DHA-1, TEM-1, SHV-5, CTX-M-3 and CTX-M-14) found in C(1) and C(2), isolates C(3) and C(4) failed to express OmpE36 owing to insertional inactivation by an IS903-like insertion sequence. Other resistance mechanisms, such as production of carbapenem-hydrolysing enzymes or expression of chromosomal efflux, were apparently not involved. Completely replacing OmpE36 by the kanamycin resistance gene (kan) resulted in a significant increase in carbapenem minimum inhibitory concentrations of an ompE36 mutant. Thus, C(3) and C(4) were apparently derived from the previously imipenem-susceptible isolates C(1) and C(2). Following carbapenem exposure, depletion of OmpE36 expression resulted in the collateral effect of carbapenem resistance.

  16. In Vivo Evolution of Bacterial Resistance in Two Cases of Enterobacter aerogenes Infections during Treatment with Imipenem.

    PubMed

    Philippe, Nadège; Maigre, Laure; Santini, Sébastien; Pinet, Elizabeth; Claverie, Jean-Michel; Davin-Régli, Anne-Véronique; Pagès, Jean-Marie; Masi, Muriel

    2015-01-01

    Infections caused by multidrug resistant (MDR) bacteria are a major concern worldwide. Changes in membrane permeability, including decreased influx and/or increased efflux of antibiotics, are known as key contributors of bacterial MDR. Therefore, it is of critical importance to understand molecular mechanisms that link membrane permeability to MDR in order to design new antimicrobial strategies. In this work, we describe genotype-phenotype correlations in Enterobacter aerogenes, a clinically problematic and antibiotic resistant bacterium. To do this, series of clinical isolates have been periodically collected from two patients during chemotherapy with imipenem. The isolates exhibited different levels of resistance towards multiple classes of antibiotics, consistently with the presence or the absence of porins and efflux pumps. Transport assays were used to characterize membrane permeability defects. Simultaneous genome-wide analysis allowed the identification of putative mutations responsible for MDR. The genome of the imipenem-susceptible isolate G7 was sequenced to closure and used as a reference for comparative genomics. This approach uncovered several loci that were specifically mutated in MDR isolates and whose products are known to control membrane permeability. These were omp35 and omp36, encoding the two major porins; rob, encoding a global AraC-type transcriptional activator; cpxA, phoQ and pmrB, encoding sensor kinases of the CpxRA, PhoPQ and PmrAB two-component regulatory systems, respectively. This report provides a comprehensive analysis of membrane alterations relative to mutational steps in the evolution of MDR of a recognized nosocomial pathogen.

  17. Electronic structure analysis of the dinuclear metal center in the bioremediator glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes.

    PubMed

    Hadler, Kieran S; Mitić, Natasa; Yip, Sylvia Hsu-Chen; Gahan, Lawrence R; Ollis, David L; Schenk, Gerhard; Larrabee, James A

    2010-03-15

    The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous, dinuclear metallohydrolase that has potential application in the remediation of organophosphate nerve agents and pesticides. GpdQ employs an unusual reaction mechanism in which the enzyme is predominantly mononuclear in the resting state, and substrate binding induces the formation of the catalytically competent dinuclear center (Hadler et al. J. Am. Chem. Soc. 2008, 130, 14129). Reactivity is further modulated by the coordination flexibility of Asn80, a ligand that binds to the second, loosely bound metal ion (Hadler et al. J. Am. Chem. Soc. 2009, 131, 11900). It is proposed that hydrolysis is initiated by a terminal, metal-bound hydroxide molecule which is activated at unusually low pH by electrostatic/hydrogen bonding interactions with a bridging hydroxide species. In this study, electronic structure analysis of the dinuclear center is employed to study the coordination environment of the dinuclear center at the resting and product-bound stage of catalysis. This is achieved through the use of variable temperature, variable field magnetic circular dichroism experiments involving the Co(II)-substituted wild type enzyme and its Asn80Asp variant. The data support the above model for the catalytic mechanism whereby the metal ion-bridging hydroxide molecule activates a terminally bound hydroxide nucleophile. Replacement of Asn80 by an aspartate residue does prevent coordination flexibility but also leads to cleavage of the mu-hydroxide bridge and reduced reactivity. This is the first study to investigate the electronic structure of an enzyme with a mu-1,1-carboxylate bridged dicobalt(II) center.

  18. Effects of eliminating pyruvate node pathways and of coexpression of heterogeneous carboxylation enzymes on succinate production by Enterobacter aerogenes.

    PubMed

    Tajima, Yoshinori; Yamamoto, Yoko; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Usuda, Yoshihiro; Sode, Koji

    2015-02-01

    Lowering the pH in bacterium-based succinate fermentation is considered a feasible approach to reduce total production costs. Newly isolated Enterobacter aerogenes strain AJ110637, a rapid carbon source assimilator under weakly acidic (pH 5.0) conditions, was selected as a platform for succinate production. Our previous work showed that the ΔadhE/PCK strain, developed from AJ110637 with inactivated ethanol dehydrogenase and introduced Actinobacillus succinogenes phosphoenolpyruvate carboxykinase (PCK), generated succinate as a major product of anaerobic mixed-acid fermentation from glucose under weakly acidic conditions (pH <6.2). To further improve the production of succinate by the ΔadhE/PCK strain, metabolically engineered strains were designed based on the elimination of pathways that produced undesirable products and the introduction of two carboxylation pathways from phosphoenolpyruvate and pyruvate to oxaloacetate. The highest production of succinate was observed with strain ES04/PCK+PYC, which had inactivated ethanol, lactate, acetate, and 2,3-butanediol pathways and coexpressed PCK and Corynebacterium glutamicum pyruvate carboxylase (PYC). This strain produced succinate from glucose with over 70% yield (gram per gram) without any measurable formation of ethanol, lactate, or 2,3-butanediol under weakly acidic conditions. The impact of lowering the pH from 7.0 to 5.5 on succinate production in this strain was evaluated under pH-controlled batch culture conditions and showed that the lower pH decreased the succinate titer but increased its yield. These findings can be applied to identify additional engineering targets to increase succinate production.

  19. Effects of Eliminating Pyruvate Node Pathways and of Coexpression of Heterogeneous Carboxylation Enzymes on Succinate Production by Enterobacter aerogenes

    PubMed Central

    Yamamoto, Yoko; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Usuda, Yoshihiro; Sode, Koji

    2014-01-01

    Lowering the pH in bacterium-based succinate fermentation is considered a feasible approach to reduce total production costs. Newly isolated Enterobacter aerogenes strain AJ110637, a rapid carbon source assimilator under weakly acidic (pH 5.0) conditions, was selected as a platform for succinate production. Our previous work showed that the ΔadhE/PCK strain, developed from AJ110637 with inactivated ethanol dehydrogenase and introduced Actinobacillus succinogenes phosphoenolpyruvate carboxykinase (PCK), generated succinate as a major product of anaerobic mixed-acid fermentation from glucose under weakly acidic conditions (pH <6.2). To further improve the production of succinate by the ΔadhE/PCK strain, metabolically engineered strains were designed based on the elimination of pathways that produced undesirable products and the introduction of two carboxylation pathways from phosphoenolpyruvate and pyruvate to oxaloacetate. The highest production of succinate was observed with strain ES04/PCK+PYC, which had inactivated ethanol, lactate, acetate, and 2,3-butanediol pathways and coexpressed PCK and Corynebacterium glutamicum pyruvate carboxylase (PYC). This strain produced succinate from glucose with over 70% yield (gram per gram) without any measurable formation of ethanol, lactate, or 2,3-butanediol under weakly acidic conditions. The impact of lowering the pH from 7.0 to 5.5 on succinate production in this strain was evaluated under pH-controlled batch culture conditions and showed that the lower pH decreased the succinate titer but increased its yield. These findings can be applied to identify additional engineering targets to increase succinate production. PMID:25416770

  20. In Vivo Evolution of Bacterial Resistance in Two Cases of Enterobacter aerogenes Infections during Treatment with Imipenem

    PubMed Central

    Santini, Sébastien; Pinet, Elizabeth; Claverie, Jean-Michel; Davin-Régli, Anne-Véronique; Pagès, Jean-Marie; Masi, Muriel

    2015-01-01

    Infections caused by multidrug resistant (MDR) bacteria are a major concern worldwide. Changes in membrane permeability, including decreased influx and/or increased efflux of antibiotics, are known as key contributors of bacterial MDR. Therefore, it is of critical importance to understand molecular mechanisms that link membrane permeability to MDR in order to design new antimicrobial strategies. In this work, we describe genotype-phenotype correlations in Enterobacter aerogenes, a clinically problematic and antibiotic resistant bacterium. To do this, series of clinical isolates have been periodically collected from two patients during chemotherapy with imipenem. The isolates exhibited different levels of resistance towards multiple classes of antibiotics, consistently with the presence or the absence of porins and efflux pumps. Transport assays were used to characterize membrane permeability defects. Simultaneous genome-wide analysis allowed the identification of putative mutations responsible for MDR. The genome of the imipenem-susceptible isolate G7 was sequenced to closure and used as a reference for comparative genomics. This approach uncovered several loci that were specifically mutated in MDR isolates and whose products are known to control membrane permeability. These were omp35 and omp36, encoding the two major porins; rob, encoding a global AraC-type transcriptional activator; cpxA, phoQ and pmrB, encoding sensor kinases of the CpxRA, PhoPQ and PmrAB two-component regulatory systems, respectively. This report provides a comprehensive analysis of membrane alterations relative to mutational steps in the evolution of MDR of a recognized nosocomial pathogen. PMID:26398358

  1. Genetic and Biochemical Characterization of FRI-1, a Carbapenem-Hydrolyzing Class A β-Lactamase from Enterobacter cloacae

    PubMed Central

    Dortet, Laurent; Poirel, Laurent; Abbas, Samia; Oueslati, Saoussen

    2015-01-01

    An Enterobacter cloacae isolate was recovered from a rectal swab from a patient hospitalized in France with previous travel to Switzerland. It was resistant to penicillins, narrow- and broad-spectrum cephalosporins, aztreonam, and carbapenems but remained susceptible to expanded-spectrum cephalosporins. Whereas PCR-based identification of the most common carbapenemase genes failed, the biochemical Carba NP test II identified an Ambler class A carbapenemase. Cloning experiments followed by sequencing identified a gene encoding a totally novel class A carbapenemase, FRI-1, sharing 51 to 55% amino acid sequence identity with the closest carbapenemase sequences. However, it shared conserved residues as a source of carbapenemase activity. Purified β-lactamase FRI-1 hydrolyzed penicillins, aztreonam, and carbapenems but spared expanded-spectrum cephalosporins. The 50% inhibitory concentrations (IC50s) of clavulanic acid and tazobactam were 10-fold higher than those found for Klebsiella pneumoniae carbapenemase (KPC), IMI, and SME, leading to lower sensitivity of FRI-1 activity to β-lactamase inhibitors. The blaFRI-1 gene was located on a ca. 110-kb untypeable, transferable, and non-self-conjugative plasmid. A putative LysR family regulator-encoding gene at the 5′ end of the β-lactamase gene was identified, leading to inducible expression of the blaFRI-1 gene. PMID:26392482

  2. Study on biodegradation of Mazut by newly isolated strain Enterobacter cloacae BBRC10061: improving and kinetic investigation

    PubMed Central

    2013-01-01

    Mazut as a source content of various hydrocarbons is hard to be degraded and its cracking could turn mazut into useful materials. Nevertheless degradation of mazut by routine methods is too expensive but application of indigenous microorganisms as biocatalysts could be effective and important to lower the costs and expand its consumption. Mazut biodegradation can be improved using various strategies; Therefore in this study newly isolated strain Enterobacter cloacae BBRC 10061 was used in a method of gradual addition of mazut into medium and its results were compared with simple addition method. To investigate degradation of mazut by BBRC 10061, influence of increase of mazut concentration was assayed based on gradual addition method. Also different kinetic models were used to evaluate kinetics of the process. Results showed that gradual addition method has been a beneficial technique for improvement of mazut degradation because bacterial induction to produce biosurfactant and essential enzymes for cracking mazut was higher during process. Although addition of more mazut increased the rate of biodegradation but percentage of degradation decreased. pH of medium decreased during biodegradation period while electric potential increased. Also the biodegradation kinetics was not fitted with the biokinetic models; therefore kinetics of biodegradation of mazut has to be studied by new models. PMID:23369455

  3. Plasmid-mediated gene transfer between insect-resident bacteria, Enterobacter cloacae, and plant-epiphytic bacteria, Erwinia herbicola, in guts of silkworm larvae.

    PubMed

    Watanabe, K; Sato, M

    1998-11-01

    Five strains of Enterobacter cloacae isolated from several species of plants and insects were able to grow in the guts of silkworm larvae. A much larger population of Ent. cloacae strains was detected in the insect guts and feces collected 3 and 6 days than in samples collected 1 day after feeding artificial diets contaminating these bacteria. Furthermore, insect-origin strains of Ent. cloacae were mated with a donor strain, epiphytic Erwinia herbicola, harboring RSF1010 and pBPW1::Tn7 plasmids in the insect guts by introducing these bacteria through separate artificial diets administered at different times. A number of transconjugants, Ent. cloacae strains which had acquired RSF1010 plasmid, were detected from guts and fecal samples at transfer frequencies of 10(-2) to 10(-3) per recipient. Thus, gene transfer between epiphytic Er. herbicola and insect-resident Ent. cloacae strains in the insect guts was confirmed. These findings may provide significant information about the role of "in insecta mating" in the evolution of these bacteria.

  4. Characterization of carbapenemases, extended spectrum β-lactamases and molecular epidemiology of carbapenem-non-susceptible Enterobacter cloacae in a Chinese hospital in Chongqing.

    PubMed

    Dai, Wei; Sun, Shan; Yang, Ping; Huang, Shifeng; Zhang, Xiaojiao; Zhang, Liping

    2013-03-01

    Carbapenem-resistant Enterobacteriaceae, including strains from multiple species harboring metallo-β-lactamases (IMP, NDM or VIM) and non-metallo (KPC) carbapenemases, as well as those combining an extended-spectrum β-lactamase (ESBL) enzyme with porin loss, present an increasingly urgent clinical danger. The aim of this study was to characterize the carbapenemases and ESBLs in carbapenem-non-susceptible (CNS) Enterobacter cloacae (E. cloacae) isolates from a Chinese teaching hospital. A total of 986 non-duplicated E. cloacae isolates collected between September 2009 and February 2012 were analyzed via antimicrobial susceptibility testing. Carbapenemase and ESBL genes were examined using PCR amplification and DNA sequencing. Clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE) and dendrogram analysis. We demonstrated that CNSs were prevalent (35/986, 3.55%) in E. cloacae. Phenotypes of carbapenemases and ESBLs were respectively found in 9 (25.7%) and 23 (65.7%) of the 35 CNS E. cloacae strains. KPC-2, IMP-8, IMP-26, NDM-1, TEM-6, CTX-M-3', CTX-M-14' and SHV-12 type β-lactamases were identified in 3 (8.6%), 5 (14.3%), 1 (2.9%), 1 (2.9%), 13 (37.1%), 9 (25.7%), 8 (22.9%) and 9 (25.7%) isolates, respectively. Importantly, multiple resistance genes were found to be co-expressed in the same CNS E. cloacae isolates. PFGE and dendrogram analysis showed clonal diversity among these isolates. Our study suggested that over-production of carbapenemases and ESBLs contributed together to the CNS of E. cloacae in China. Furthermore, the decreased susceptibility to carbapenems in E. cloaca in the hospital might arise via stepwise accumulations of multiple drug-resistance determinants in different clones. The prevalence of CNS E. cloacae isolates was not caused by clonal dissemination. Most importantly, we identified a CNS E. cloacae isolate co-expressing IMP-26 and NDM-1, which is the first reported to the best of our knowledge. This is also the first

  5. Biological characterization of lead-enhanced exopolysaccharide produced by a lead resistant Enterobacter cloacae strain P2B.

    PubMed

    Naik, Milind Mohan; Pandey, Anju; Dubey, Santosh Kumar

    2012-09-01

    A lead resistant bacterial strain isolated from effluent of lead battery manufacturing company of Goa, India has been identified as Enterobacter cloacae strain P2B based on morphological, biochemical characters, FAME profile and 16S rDNA sequence data. This bacterial strain could resist lead nitrate up to 1.6 mM. Significant increase in exopolysaccharide (EPS) production was observed as the production increased from 28 to 108 mg/L dry weight when exposed to 1.6 mM lead nitrate in Tris buffered minimal medium. Fourier-transformed infrared spectroscopy of this EPS revealed presence of several functional groups involved in metal binding viz. carboxyl, hydroxyl and amide groups along with glucuronic acid. Gas chromatography coupled with mass spectrometry analysis of alditol-acetate derivatives of acid hydrolysed EPS produced in presence of 1.6 mM lead nitrate demonstrated presence of several neutral sugars such as rhamnose, arabinose, xylose, mannose, galactose and glucose, which contribute to lead binding hydroxyl groups. Scanning electron microscope coupled with energy dispersive X-ray spectrometric analysis of this lead resistant strain exposed to 1.6 mM lead nitrate interestingly revealed mucous EPS surrounding bacterial cells which sequestered 17 % lead (as weight %) extracellularly and protected the bacterial cells from toxic effects of lead. This lead resistant strain also showed multidrug resistance. Thus these results significantly contribute to better understanding of structure, function and environmental application of lead-enhanced EPSs produced by bacteria. This lead-enhanced biopolymer can play a very important role in bioremediation of several heavy metals including lead.

  6. New Delhi Metallo-β-Lactamase 1(NDM-1), the Dominant Carbapenemase Detected in Carbapenem-Resistant Enterobacter cloacae from Henan Province, China

    PubMed Central

    Liu, Xuchun; Lang, Shaolei; Feng, Xianju; Liu, Hong-Min

    2015-01-01

    The emergence of New Delhi metallo-β-lactamase 1 (NDM-1) has become established as a major public health threat and represents a new challenge in the treatment of infectious diseases. In this study, we report a high incidence and endemic spread of NDM-1-producing carbapenem-resistant Enterobacter cloacae isolates in Henan province, China. Eight (72.7%) out of eleven non-duplicated carbapenem-resistant E. cloacae isolates collected between June 2011 and May 2013 were identified as NDM-1 positive. The blaNDM-1 gene surrounded by an entire ISAba125 element and a bleomycin resistance gene bleMBL in these isolates were carried by diverse conjugatable plasmids (IncA/C, IncN, IncHI2 and untypeable) ranging from ~55 to ~360 kb. Molecular epidemiology analysis revealed that three NDM-1-producing E. cloacae belonged to the same multilocus sequence type (ST), ST120, two of which were classified as extensively drug-resistant (XDR) isolates susceptible only to tigecycline and colistin. The two XDR ST120 E. cloacae isolates co-harbored blaNDM-1, armA and fosA3 genes and could transfer resistance to carbapenems, fosfomycin and aminoglycosides simultaneously via a conjugation experiment. Our study demonstrated NDM-1 was the most prevalent metallo-β-lactamase (MBL) among carbapenem-resistant E.cloacae isolates and identified a potential endemic clone of ST120 in Henan province. These findings highlight the need for enhanced efforts to monitor the further spread of NDM-1 and XDR ST120 E. cloacae in this region. PMID:26263489

  7. Comparative evaluation of fermentative hydrogen production using Enterobacter cloacae and mixed culture: effect of Pd (II) ion and phytogenic palladium nanoparticles.

    PubMed

    Mohanraj, Sundaresan; Anbalagan, Krishnasamy; Kodhaiyolii, Shanmugam; Pugalenthi, Velan

    2014-12-20

    Palladium nanoparticles (PdNPs) were synthesized from PdCl2 using Coriandrum sativum leaf extract. The transmission electron microscopy (TEM) images confirm that the formation of PdNPs was mainly spherical in shape, with an average size of 87 nm. The influence of the PdCl2 and synthesized PdNPs on fermentative hydrogen production from glucose using Enterobacter cloacae and mixed culture was evaluated. In PdCl2 supplemented experiments, the hydrogen yields of E. cloacae and mixed culture were 1.39 ± 0.07 and 2.11 ± 0.11 mol H2/mol glucose, respectively, with 5.0 mg/L of PdCl2. The resulting hydrogen yield (P < 0.05) was lower than that of the control experiment (without supplementation), due to the soluble metabolites shift. However, the highest hydrogen yields of E. cloacae and mixed culture were 1.48 ± 0.04 and 2.48 ± 0.09 mol H2/mol glucose, respectively at 5.0 mg/L of PdNPs supplementation. The enhancement of biohydrogen production using mixed culture was significantly higher than that of E. cloacae as the same concentration of PdNPs. PMID:25456058

  8. Expression of Zinc Transporter Genes in Rice as Influenced by Zinc-Solubilizing Enterobacter cloacae Strain ZSB14

    PubMed Central

    Krithika, Selvaraj; Balachandar, Dananjeyan

    2016-01-01

    Zinc (Zn) deficiency in major food crops has been considered as an important factor affecting the crop production and subsequently the human health. Rice (Oryza sativa) is sensitive to Zn deficiency and thereby causes malnutrition to most of the rice-eating Asian populations. Application of zinc solubilizing bacteria (ZSB) could be a sustainable agronomic approach to increase the soil available Zn which can mitigate the yield loss and consequently the nutritional quality of rice. Understanding the molecular interactions between rice and unexplored ZSB is useful for overcoming Zn deficiency problems. In the present study, the role of zinc solubilizing bacterial strain Enterobacter cloacae strain ZSB14 on regulation of Zn-regulated transporters and iron (Fe)-regulated transporter-like protein (ZIP) genes in rice under iron sufficient and deficient conditions was assessed by quantitative real-time reverse transcription PCR. The expression patterns of OsZIP1, OsZIP4, and OsZIP5 in root and shoot of rice were altered due to the Zn availability as dictated by Zn sources and ZSB inoculation. Fe sufficiency significantly reduced the root and shoot OsZIP1 expression, but not the OsZIP4 and OsZIP5 levels. Zinc oxide in the growth medium up-regulated all the assessed ZIP genes in root and shoot of rice seedlings. When ZSB was inoculated to rice seedlings grown with insoluble zinc oxide in the growth medium, the expression of root and shoot OsZIP1, OsZIP4, and OsZIP5 was reduced. In the absence of zinc oxide, ZSB inoculation up-regulated OsZIP1 and OsZIP5 expressions. Zinc nutrition provided to the rice seedling through ZSB-bound zinc oxide solubilization was comparable to the soluble zinc sulfate application which was evident through the ZIP genes’ expression and the Zn accumulation in root and shoot of rice seedlings. These results demonstrate that ZSB could play a crucial role in zinc fertilization and fortification of rice. PMID:27092162

  9. Expression of Zinc Transporter Genes in Rice as Influenced by Zinc-Solubilizing Enterobacter cloacae Strain ZSB14.

    PubMed

    Krithika, Selvaraj; Balachandar, Dananjeyan

    2016-01-01

    Zinc (Zn) deficiency in major food crops has been considered as an important factor affecting the crop production and subsequently the human health. Rice (Oryza sativa) is sensitive to Zn deficiency and thereby causes malnutrition to most of the rice-eating Asian populations. Application of zinc solubilizing bacteria (ZSB) could be a sustainable agronomic approach to increase the soil available Zn which can mitigate the yield loss and consequently the nutritional quality of rice. Understanding the molecular interactions between rice and unexplored ZSB is useful for overcoming Zn deficiency problems. In the present study, the role of zinc solubilizing bacterial strain Enterobacter cloacae strain ZSB14 on regulation of Zn-regulated transporters and iron (Fe)-regulated transporter-like protein (ZIP) genes in rice under iron sufficient and deficient conditions was assessed by quantitative real-time reverse transcription PCR. The expression patterns of OsZIP1, OsZIP4, and OsZIP5 in root and shoot of rice were altered due to the Zn availability as dictated by Zn sources and ZSB inoculation. Fe sufficiency significantly reduced the root and shoot OsZIP1 expression, but not the OsZIP4 and OsZIP5 levels. Zinc oxide in the growth medium up-regulated all the assessed ZIP genes in root and shoot of rice seedlings. When ZSB was inoculated to rice seedlings grown with insoluble zinc oxide in the growth medium, the expression of root and shoot OsZIP1, OsZIP4, and OsZIP5 was reduced. In the absence of zinc oxide, ZSB inoculation up-regulated OsZIP1 and OsZIP5 expressions. Zinc nutrition provided to the rice seedling through ZSB-bound zinc oxide solubilization was comparable to the soluble zinc sulfate application which was evident through the ZIP genes' expression and the Zn accumulation in root and shoot of rice seedlings. These results demonstrate that ZSB could play a crucial role in zinc fertilization and fortification of rice. PMID:27092162

  10. Effect of Transcriptional Activators SoxS, RobA, and RamA on Expression of Multidrug Efflux Pump AcrAB-TolC in Enterobacter cloacae

    PubMed Central

    Pérez, Astrid; Poza, Margarita; Aranda, Jesús; Latasa, Cristina; Medrano, Francisco Javier; Tomás, María; Romero, Antonio; Lasa, Iñigo

    2012-01-01

    Control of membrane permeability is a key step in regulating the intracellular concentration of antibiotics. Efflux pumps confer innate resistance to a wide range of toxic compounds such as antibiotics, dyes, detergents, and disinfectants in members of the Enterobacteriaceae. The AcrAB-TolC efflux pump is involved in multidrug resistance in Enterobacter cloacae. However, the underlying mechanism that regulates the system in this microorganism remains unknown. In Escherichia coli, the transcription of acrAB is upregulated under global stress conditions by proteins such as MarA, SoxS, and Rob. In the present study, two clinical isolates of E. cloacae, EcDC64 (a multidrug-resistant strain overexpressing the AcrAB-TolC efflux pump) and Jc194 (a strain with a basal AcrAB-TolC expression level), were used to determine whether similar global stress responses operate in E. cloacae and also to establish the molecular mechanisms underlying this response. A decrease in susceptibility to erythromycin, tetracycline, telithromycin, ciprofloxacin, and chloramphenicol was observed in clinical isolate Jc194 and, to a lesser extent in EcDC64, in the presence of salicylate, decanoate, tetracycline, and paraquat. Increased expression of the acrAB promoter in the presence of the above-described conditions was observed by flow cytometry and reverse transcription-PCR, by using a reporter fusion protein (green fluorescent protein). The expression level of the AcrAB promoter decreased in E. cloacae EcDC64 derivates deficient in SoxS, RobA, and RamA. Accordingly, the expression level of the AcrAB promoter was higher in E. cloacae Jc194 strains overproducing SoxS, RobA, and RamA. Overall, the data showed that SoxS, RobA, and RamA regulators were associated with the upregulation of acrAB, thus conferring antimicrobial resistance as well as a stress response in E. cloacae. In summary, the regulatory proteins SoxS, RobA, and RamA were cloned and sequenced for the first time in this species. The

  11. Epidemiological fingerprinting of Enterobacter cloacae by small-fragment restriction endonuclease analysis and pulsed-field gel electrophoresis of genomic restriction fragments.

    PubMed Central

    Haertl, R; Bandlow, G

    1993-01-01

    A cluster of infections caused by Enterobacter cloacae was observed among preterm neonates in a neonatal intensive care unit (NICU) of a pediatric hospital in Osnabrück, Germany. The presence of similar antimicrobial susceptibility patterns among the bacterial isolates prompted an investigation to determine whether a limited spread of a single strain existed. All 12 E. cloacae isolates from the NICU and 50 nonrelated strains were fingerprinted by small-fragment restriction endonuclease analysis (SF-REA) of EcoRI DNA digests. Selected isolates were further characterized by pulsed-field gel electrophoresis (PFGE) of NotI- or XbaI-generated genomic restriction fragments. Epidemiologically unrelated strains were clearly discriminated by both methods. Results achieved by SF-REA and PFGE revealed that of the 12 isolates from the NICU, 11 belonged to the same genotypic cluster. Since all reagents and equipment for both techniques are commercially available, DNA fingerprinting by SF-REA or PFGE is proposed as a useful tool in the microbiology laboratory for investigating the epidemiological relatedness of E. cloacae strains of clinical and environmental origin. Images PMID:8093251

  12. A comparative study on phosphotransferase activity of acid phosphatases from Raoultella planticola and Enterobacter aerogenes on nucleosides, sugars, and related compounds.

    PubMed

    Médici, Rosario; Garaycoechea, Juan I; Valino, Ana L; Pereira, Claudio A; Lewkowicz, Elizabeth S; Iribarren, Adolfo M

    2014-04-01

    Natural and modified nucleoside-5'-monophosphates and their precursors are valuable compounds widely used in biochemical studies. Bacterial nonspecific acid phosphatases (NSAPs) are a group of enzymes involved in the hydrolysis of phosphoester bonds, and some of them exhibit phosphotransferase activity. NSAP containing Enterobacter aerogenes and Raoultella planticola whole cells were evaluated in the phosphorylation of a wide range of nucleosides and nucleoside precursors using pyrophosphate as phosphate donor. To increase the productivity of the process, we developed two genetically modified strains of Escherichia coli which overexpressed NSAPs of E. aerogenes and R. planticola. These new recombinant microorganisms (E. coli BL21 pET22b-phoEa and E. coli BL21 pET22b-phoRp) showed higher activity than the corresponding wild-type strains. Reductions in the reaction times from 21 h to 60 min, from 4 h to 15 min, and from 24 h to 40 min in cases of dihydroxyacetone, inosine, and fludarabine, respectively, were obtained.

  13. Susceptibility of the multi-drug resistant strain of Enterobacter aerogenes EA289 to the terpene alcohols from Cistus ladaniferus essential oil.

    PubMed

    Guinoiseau, Elodie; Lorenzi, Vannina; Luciani, Anne; Tomi, Félix; Casanova, Joseph; Berti, Liliane

    2011-08-01

    The essential oil (EO) of Cistus ladaniferus was separated into non polar, moderately polar and polar fractions by column chromatography. The EO and its fractions were analysed by gas chromatography in combination with retention indices [GC-(RI)] and 13C nuclear magnetic resonance (13C NMR) spectroscopy. A minimum inhibitory concentration (MIC) assay was used to evaluate their antibacterial activity against Gram-positive and Gram-negative pathogens of clinical relevance, including a multi-drug resistant (MDR) strain. The most polar fraction, constituted by mono- and sesquiterpene alcohols, strongly inhibited the growth of all tested bacteria with MIC values ranging from 0.05 to 0.8 mg/mL. More importantly, this fraction displayed high activity against the MDR strain of Enterobacter aerogenes EA289. Transmission electron microscopy (TEM) observations of the MDR bacteria treated with the terpene alcohol-rich fraction revealed cell wall distortion with an outer cytoplasmic membrane detachment. The susceptibility of the MDR strain of E. aerogenes EA289 to the polar fraction of C. ladaniferus oil suggests the possible use of these natural products to treat infections caused by highly resistant bacteria.

  14. Outbreak of Extended-Spectrum Beta-Lactamase Producing Enterobacter cloacae with High MICs of Quaternary Ammonium Compounds in a Hematology Ward Associated with Contaminated Sinks

    PubMed Central

    Chapuis, Angélique; Amoureux, Lucie; Bador, Julien; Gavalas, Arthur; Siebor, Eliane; Chrétien, Marie-Lorraine; Caillot, Denis; Janin, Marion; de Curraize, Claire; Neuwirth, Catherine

    2016-01-01

    Objective: To investigate an outbreak of extended-spectrum beta-lactamase (ESBL) producing Enterobacter cloacae that occurred in the Hematology ward (24-bed unit) of the François Mitterrand University Hospital (Dijon, France) between January 2011 and December 2013. The outbreak involved 43 patients (10 infected and 33 colonized). Design: We performed environmental analysis to detect multiresistant E. cloacae for comparison with clinical isolates (genotyping by pulsed-field gel electrophoresis and MLST as well as ESBL-typing) and determined the MICs of the quaternary ammonium compounds (QACs) alkyldimethylbenzylammonium chloride (ADBAC) and didecyldimethylammonium chloride (DDAC). A bleach-based cleaning-disinfection program was implemented in December 2012 after mechanical removal of the biofilm in all sinks. Results: We have detected 17 ESBL-producing E. cloacae in patients sink drains, shower drains and medical sink drains. Sequencing of the bla genes performed on 60 strains recovered from patients and environment (n = 43 clinical and n = 17 environmental) revealed that bla CTX−M15 was predominant (37 isolates) followed by bla CTX−M9 plus bla SHV−12 (20 isolates). We observed a great diversity among the isolates: 14 pulsotypes (11 STs) in clinical isolates and 9 pulsotypes (7 STs) in environmental isolates. Six pulsotypes were identical between clinical and environmental isolates. MICs of the quaternary ammonium compounds widely used for disinfection were very high in clinical and environmental isolates. Immediately after the implementation of the disinfection program we noticed a substantial fall in cases number. Our findings demonstrate the role of drains as important reservoir of ESBL-producing E. cloacae and highlight the necessity to settle drains accessible to achieve correct cleaning as well as to use disinfectant with proved activity against nosocomial pathogens. PMID:27462306

  15. Biochemical properties of a carbapenem-hydrolyzing beta-lactamase from Enterobacter cloacae and cloning of the gene into Escherichia coli.

    PubMed Central

    Nordmann, P; Mariotte, S; Naas, T; Labia, R; Nicolas, M H

    1993-01-01

    A clinical isolate of Enterobacter cloacae, strain NOR-1, exhibited resistance to imipenem and remained susceptible to extended-spectrum cephalosporins. Clavulanic acid partially restored the susceptibility of the strain to imipenem. Two beta-lactamases with isoelectric points (pI) of 6.9 and > 9.2 were detected in strain E. cloacae NOR-1; the higher pI corresponded to AmpC cephalosporinase. Plasmid DNA was not detected in E. cloacae NOR-1 and imipenem resistance could not be transferred into Escherichia coli JM109. The carbapenem-hydrolyzing beta-lactamase gene was cloned into plasmid pACYC184. One recombinant plasmid, pPTN1, harbored a 5.3-kb Sau3A fragment from E. cloacae NOR-1 expressing the carbapenem-hydrolyzing beta-lactamase. This enzyme (pI 6.9) hydrolyzed ampicillin, cephalothin, and imipenem more rapidly than it did meropenem and aztreonam, but it hydrolyzed extended-spectrum cephalosporins only weakly and did not hydrolyze cefoxitin. Hydrolytic activity was partially inhibited by clavulanic acid, sulbactam, and tazobactam, was nonsusceptible to chelating agents such as EDTA and 1,10-o-phenanthroline, and was independent of the presence of ZnCl2. Its relative molecular mass was 30,000 Da. Induction experiments concluded that the carbapenem-hydrolyzing beta-lactamase biosynthesis was inducible by cefoxitin and imipenem. Subcloning experiments with HindIII partial digests of pPTN1 resulted in a recombinant plasmid, designated pPTN2, which contained a 1.3-kb insert from pPTN1 and which conferred resistance to beta-lactam antibiotics. Hybridization studies performed with a 1.2-kb HindIII fragment from pPtN2 failed to determine any homology with ampC of E. cloacae, with other known beta-lactamase genes commonly found in members of the family Enterobacteriaceae (bla(TEM-1)) and bla(SHV-3) derivatives), and with previously described carbapenemase genes such as those from Xanthomonas maltophilia, Bacillus cereus, Bacteroides fragilis (cfiA), and Aeromonas

  16. Quantifying the effect of hand wash duration, soap use, ground beef debris, and drying methods on the removal of Enterobacter aerogenes on hands.

    PubMed

    Jensen, Dane A; Danyluk, Michelle D; Harris, Linda J; Schaffner, Donald W

    2015-04-01

    Hand washing is recognized as a crucial step in preventing foodborne disease transmission by mitigating crosscontamination among hands, surfaces, and foods. This research was undertaken to establish the importance of several keys factors (soap, soil, time, and drying method) in reducing microorganisms during hand washing. A nonpathogenic nalidixic acid-resistant Enterobacter aerogenes surrogate for Salmonella was used to assess the efficacy of using soap or no soap for 5 or 20 s on hands with or without ground beef debris and drying with paper towel or air. Each experiment consisted of 20 replicates, each from a different individual with ∼ 6 log CFU/ml E. aerogenes on their hands. A reduction of 1.0 ± 0.4 and 1.7 ± 0.8 log CFU of E. aerogenes was observed for a 5-s wash with no soap and a 20-s wash with soap, respectively. When there was no debris on the hands, there was no significant difference between washing with and without soap for 20 s (P > 0.05). Likewise, there was no significant difference in the reductions achieved when washing without soap, whether or not debris was on the hands (P > 0.05). A significantly greater reduction (P < 0.05) in E. aerogenes (0.5 log CFU greater reduction) was observed with soap when there was ground beef debris on the hands. The greatest difference (1.1 log CFU greater average reduction) in effectiveness occurred when ground beef debris was on the hands and a 20-s wash with water was compared with a 20-s wash with soap. Significantly greater (P < 0.05) reductions were observed with paper towel drying compared with air (0.5 log CFU greater reductions). Used paper towels may contain high bacterial levels (>4.0 log CFU per towel) when hands are highly contaminated. Our results support future quantitative microbial risk assessments needed to effectively manage risks of foodborne illness in which food workers' hands are a primary cause.

  17. Quantifying the effect of hand wash duration, soap use, ground beef debris, and drying methods on the removal of Enterobacter aerogenes on hands.

    PubMed

    Jensen, Dane A; Danyluk, Michelle D; Harris, Linda J; Schaffner, Donald W

    2015-04-01

    Hand washing is recognized as a crucial step in preventing foodborne disease transmission by mitigating crosscontamination among hands, surfaces, and foods. This research was undertaken to establish the importance of several keys factors (soap, soil, time, and drying method) in reducing microorganisms during hand washing. A nonpathogenic nalidixic acid-resistant Enterobacter aerogenes surrogate for Salmonella was used to assess the efficacy of using soap or no soap for 5 or 20 s on hands with or without ground beef debris and drying with paper towel or air. Each experiment consisted of 20 replicates, each from a different individual with ∼ 6 log CFU/ml E. aerogenes on their hands. A reduction of 1.0 ± 0.4 and 1.7 ± 0.8 log CFU of E. aerogenes was observed for a 5-s wash with no soap and a 20-s wash with soap, respectively. When there was no debris on the hands, there was no significant difference between washing with and without soap for 20 s (P > 0.05). Likewise, there was no significant difference in the reductions achieved when washing without soap, whether or not debris was on the hands (P > 0.05). A significantly greater reduction (P < 0.05) in E. aerogenes (0.5 log CFU greater reduction) was observed with soap when there was ground beef debris on the hands. The greatest difference (1.1 log CFU greater average reduction) in effectiveness occurred when ground beef debris was on the hands and a 20-s wash with water was compared with a 20-s wash with soap. Significantly greater (P < 0.05) reductions were observed with paper towel drying compared with air (0.5 log CFU greater reductions). Used paper towels may contain high bacterial levels (>4.0 log CFU per towel) when hands are highly contaminated. Our results support future quantitative microbial risk assessments needed to effectively manage risks of foodborne illness in which food workers' hands are a primary cause. PMID:25836392

  18. FIRST REPORT OF METALLO-β-LACTAMASES PRODUCING Enterobacter spp. STRAINS FROM VENEZUELA

    PubMed Central

    Martínez, Dianny; Rodulfo, Hectorina E.; Rodríguez, Lucy; Caña, Luisa E.; Medina, Belkis; Guzman, Militza; Carreño, Numirin; Marcano, Daniel; Donato, Marcos De

    2014-01-01

    Clinical strains of Enterobacter were isolated from Cumana's Central Hospital in Venezuela, and classified as E. cloacae (21), E. aerogenes (7), E. intermedium (1), E. sakazakii (1) and three unclassified. The strains showed high levels of resistance, especially to SXT (58.1%), CRO (48.8%), CAZ (46.6%), PIP (46.4%), CIP (45.2%) and ATM (43.3%). This is the first report for South America of bla VIM-2 in two E. cloacae and one Enterobacter sp., which also showed multiple mechanisms of resistance. Both E. cloacae showed bla TEM-1, but only one showed bla CTX-M-15 gene, while no bla SHV was detected. PMID:24553611

  19. First report of metallo-β-lactamases producing Enterobacter spp. strains from Venezuela.

    PubMed

    Martínez, Dianny; Rodulfo, Hectorina E; Rodríguez, Lucy; Caña, Luisa E; Medina, Belkis; Guzman, Militza; Carreño, Numirin; Marcano, Daniel; De Donato, Marcos

    2014-01-01

    Clinical strains of Enterobacter were isolated from Cumana's Central Hospital in Venezuela, and classified as E. cloacae (21), E. aerogenes (7), E. intermedium (1), E. sakazakii (1) and three unclassified. The strains showed high levels of resistance, especially to SXT (58.1%), CRO (48.8%), CAZ (46.6%), PIP (46.4%), CIP (45.2%) and ATM (43.3%). This is the first report for South America of blaVIM-2 in two E. cloacae and one Enterobacter sp., which also showed multiple mechanisms of resistance. Both E. cloacae showed blaTEM-1, but only one showed blaCTX-M-15 gene, while no blaSHV was detected. PMID:24553611

  20. Inducible cephalosporinase production in clinical isolates of Enterobacter cloacae is controlled by a regulatory gene that has been deleted from Escherichia coli.

    PubMed Central

    Honoré, N; Nicolas, M H; Cole, S T

    1986-01-01

    Cephalosporin hyper-resistant Enterobacter cloacae strains are isolated with increasing frequency from hospital infections. Resistance is principally due to the chromosomal ampC gene encoding a cephalosporinase. In contrast to Escherichia coli which expresses ampC constitutively from a promoter located in the upstream frdD gene, E. cloacae displays inducible ampC expression. By cloning the ampC gene it was shown that a linked genetic locus, ampR, mediated the induction by beta-lactams. In the absence of the antibiotic the 30,500 dalton AmpR protein represses ampC expression. The ampR gene shows a highly compact arrangement and is situated between the divergently expressed ampC gene and the frd operon from which it is separated by a bifunctional transcription terminator. The promoters for ampR and ampC substantially overlap and mRNA analyses showed that on induction transcription from the ampC promoter increased greatly whereas that from ampR did not. Two regions of sequence homology flank the ampR gene and it is proposed that a homologous recombination event between these in an ancestral enteric bacterium may have led to the deletion of ampR from the E. coli genome. Images Fig. 2. Fig. 4. PMID:3030737

  1. The rhizome of the multidrug-resistant Enterobacter aerogenes genome reveals how new "killer bugs" are created because of a sympatric lifestyle.

    PubMed

    Diene, Seydina M; Merhej, Vicky; Henry, Mireille; El Filali, Adil; Roux, Véronique; Robert, Catherine; Azza, Saïd; Gavory, Frederick; Barbe, Valérie; La Scola, Bernard; Raoult, Didier; Rolain, Jean-Marc

    2013-02-01

    Here, we sequenced the 5,419,609 bp circular genome of an Enterobacter aerogenes clinical isolate that killed a patient and was resistant to almost all current antibiotics (except gentamicin) commonly used to treat Enterobacterial infections, including colistin. Genomic and phylogenetic analyses explain the discrepancies of this bacterium and show that its core genome originates from another genus, Klebsiella. Atypical characteristics of this bacterium (i.e., motility, presence of ornithine decarboxylase, and lack of urease activity) are attributed to genomic mosaicism, by acquisition of additional genes, such as the complete 60,582 bp flagellar assembly operon acquired "en bloc" from the genus Serratia. The genealogic tree of the 162,202 bp multidrug-resistant conjugative plasmid shows that it is a chimera of transposons and integrative conjugative elements from various bacterial origins, resembling a rhizome. Moreover, we demonstrate biologically that a G53S mutation in the pmrA gene results in colistin resistance. E. aerogenes has a large RNA population comprising 8 rRNA operons and 87 cognate tRNAs that have the ability to translate transferred genes that use different codons, as exemplified by the significantly different codon usage between genes from the core genome and the "mobilome." On the basis of our findings, the evolution of this bacterium to become a "killer bug" with new genomic repertoires was from three criteria that are "opportunity, power, and usage" to indicate a sympatric lifestyle: "opportunity" to meet other bacteria and exchange foreign sequences since this bacteria was similar to sympatric bacteria; "power" to integrate these foreign sequences such as the acquisition of several mobile genetic elements (plasmids, integrative conjugative element, prophages, transposons, flagellar assembly system, etc.) found in his genome; and "usage" to have the ability to translate these sequences including those from rare codons to serve as a translator of

  2. The rhizome of the multidrug-resistant Enterobacter aerogenes genome reveals how new "killer bugs" are created because of a sympatric lifestyle.

    PubMed

    Diene, Seydina M; Merhej, Vicky; Henry, Mireille; El Filali, Adil; Roux, Véronique; Robert, Catherine; Azza, Saïd; Gavory, Frederick; Barbe, Valérie; La Scola, Bernard; Raoult, Didier; Rolain, Jean-Marc

    2013-02-01

    Here, we sequenced the 5,419,609 bp circular genome of an Enterobacter aerogenes clinical isolate that killed a patient and was resistant to almost all current antibiotics (except gentamicin) commonly used to treat Enterobacterial infections, including colistin. Genomic and phylogenetic analyses explain the discrepancies of this bacterium and show that its core genome originates from another genus, Klebsiella. Atypical characteristics of this bacterium (i.e., motility, presence of ornithine decarboxylase, and lack of urease activity) are attributed to genomic mosaicism, by acquisition of additional genes, such as the complete 60,582 bp flagellar assembly operon acquired "en bloc" from the genus Serratia. The genealogic tree of the 162,202 bp multidrug-resistant conjugative plasmid shows that it is a chimera of transposons and integrative conjugative elements from various bacterial origins, resembling a rhizome. Moreover, we demonstrate biologically that a G53S mutation in the pmrA gene results in colistin resistance. E. aerogenes has a large RNA population comprising 8 rRNA operons and 87 cognate tRNAs that have the ability to translate transferred genes that use different codons, as exemplified by the significantly different codon usage between genes from the core genome and the "mobilome." On the basis of our findings, the evolution of this bacterium to become a "killer bug" with new genomic repertoires was from three criteria that are "opportunity, power, and usage" to indicate a sympatric lifestyle: "opportunity" to meet other bacteria and exchange foreign sequences since this bacteria was similar to sympatric bacteria; "power" to integrate these foreign sequences such as the acquisition of several mobile genetic elements (plasmids, integrative conjugative element, prophages, transposons, flagellar assembly system, etc.) found in his genome; and "usage" to have the ability to translate these sequences including those from rare codons to serve as a translator of

  3. Epidemiology and molecular characterization of extended-spectrum beta-lactamase-producing Enterobacter spp., Pantoea agglomerans, and Serratia marcescens isolates from a Bulgarian hospital.

    PubMed

    Markovska, Rumyana Donkova; Stoeva, Temenuga Jekova; Bojkova, Kalina Dineva; Mitov, Ivan Gergov

    2014-04-01

    Forty-two extended-spectrum beta-lactamase (ESBL)-producing isolates of Enterobacter aerogenes, Enterobacter cloacae, Pantoea agglomerans, and Serratia marcescens, collected consecutively during the period January-November 2011 from the University Hospital in Varna, Bulgaria, were studied to characterize their ESBLs by isoelectric focusing, group-specific PCR, and sequencing. The epidemiological relationship was evaluated by random amplified polymorphic DNA analysis (RAPD). Transferability of ESBL genes was determined by conjugation experiments. Plasmid analysis was done by replicon typing and PstI fingerprinting. The overall rate of ESBL production was 20%. The most widespread enzyme was CTX-M-3, found in 64%. It was dominant in E. aerogenes (100%) and S. marcescens (83%). SHV-12, CTX-M-3, and CTX-M-15 were found among E. cloacae isolates in 50%, 35%, and 45%, respectively. Three main CTX-M-3-producing epidemic clones of E. aerogenes and S. marcescens have been detected. Among E. cloacae isolates, six different RAPD profiles were discerned. The plasmids harboring blaCTX-M-3 belonged to IncL/M type and demonstrated similar PstI fingerprinting profiles. IncFII plasmids were detected in two CTX-M-15-producing E. cloacae isolates. Our results demonstrate wide intrahospital dissemination of clonal E. aerogenes and S. marcescens isolates, carrying IncL/M conjugative plasmids.

  4. Successive emergence of extended-spectrum beta-lactamase-producing and carbapenemase-producing Enterobacter aerogenes isolates in a university hospital.

    PubMed

    Biendo, M; Canarelli, B; Thomas, D; Rousseau, F; Hamdad, F; Adjide, C; Laurans, G; Eb, F

    2008-03-01

    Sixty-two clinical isolates of Enterobacter aerogenes resistant to expanded-spectrum cephalosporins were collected between July 2003 and May 2005. Among these isolates, 23 (37.1%) were imipenem (IPM) susceptible, and 39 (62.9%) were IPM insusceptible, of which 89.7% (35/39) were resistant and 10.3% (4/39) were intermediate. Isolate genotypes were compared by pulsed-field gel electrophoresis. Of 62 isolates, 48 belonged to epidemic pulsotype A (77.4%). This pulsotype included 37.5% and 58.4% of beta-lactam phenotypes b and a, respectively. Nine isolates (14.5%) belonged to pulsotype E, which included 22.3% and 77.7% of phenotypes b and a, respectively. The beta-lactamases with pIs of 5.4, 6.5, 8.2, and 8.2 corresponded to extended-spectrum beta-lactamases (ESBLs) TEM-20, TEM-24, SHV-5, and SHV-12, respectively. Of 39 IPM-insusceptible E. aerogenes isolates, 26 (66.6%) were determined to be metallo-beta-lactamase producers, by using a phenotypic method. Of these isolates, 24 harbored a bla(IMP-1) gene encoding a protein with a pI of >9.5, and two carried the bla(VIM-2) gene encoding a protein with a pI of 5.3, corresponding to beta-lactamases IMP-1 and VIM-2, respectively. The remaining 13 (33.4%) isolates were negative for the bla(IMP-1) and bla(VIM-2) genes but showed an alteration of their outer membrane proteins (OMPs). Ten of these isolates produced the two possible OMPs (32 and 42 kDa), with IPM MICs between 8 and 32 microg/ml, and three others produced only a 32-kDa OMP with IPM MICs >32 microg/ml. This work demonstrates that, in addition to resistance to expanded-spectrum cephalosporins, IPM resistance can occur in ESBL-producing E. aerogenes isolates by carbapenemase production or by the loss of porin in the outer membrane.

  5. Characterization of ESBL (SHV-12) producing clinical isolate of Enterobacter aerogenes from a tertiary care hospital in Nigeria

    PubMed Central

    2010-01-01

    Background We studied the beta-lactamases of an E. aerogenes isolate recovered from the blood of a two-year-old patient. The isolate demonstrated a disk-diffusion phenotype typical for an AmpC-ESBL co-producer. Methods Microbiology studies were performed according to standard protocols. The resistance gene was identified by transconjugation and cloning experiments. Results By transconjugation only a narrow spectrum beta-lactamase (TEM-1) encoded on a small plasmid was transmitted. The ESBL was cloned and expressed in an E. coli host. Sequence analysis of the recombinant plasmid revealed blaSHV-12 associated to the insertion sequence, IS26. Conclusion This is the first study demonstrated the occurrence of SHV-12 in Nigeria. PMID:20067633

  6. Malonate-bound structure of the glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) and characterization of the native Fe[superscript 2+] metal-ion preference

    SciTech Connect

    Jackson, Colin J.; Hadler, Kieran S.; Carr, Paul D.; Oakley, Aaron J.; Yip, Sylvia; Schenk, Gerhard; Ollis, David L.

    2011-09-28

    The structure of a malonate-bound form of the glycerophosphodiesterase from Enterobacter aerogenes, GpdQ, has been refined at a resolution of 2.2 {angstrom} to a final R factor of 17.1%. The structure was originally solved to 2.9 {angstrom} resolution using SAD phases from Zn{sup 2+} metal ions introduced into the active site of the apoenzyme [Jackson et al. (2007), J. Mol. Biol. 367, 1047-1062]. However, the 2.9 {angstrom} resolution was insufficient to discern significant details of the architecture of the binuclear metal centre that constitutes the active site. Furthermore, kinetic analysis revealed that the enzyme lost a significant amount of activity in the presence of Zn2+, suggesting that it is unlikely to be a catalytically relevant metal ion. In this communication, a higher resolution structure of GpdQ is presented in which malonate is visibly coordinated in the active site and analysis of the native metal-ion preference is presented using atomic absorption spectroscopy and anomalous scattering. Catalytic implications of the structure and its Fe{sup 2+} metal-ion preference are discussed.

  7. NDM-1 encoded by a pNDM-BJ01-like plasmid p3SP-NDM in clinical Enterobacter aerogenes.

    PubMed

    Chen, Zhenhong; Li, Hongxia; Feng, Jiao; Li, Yuxue; Chen, Xin; Guo, Xuemin; Chen, Weijun; Wang, Li; Lin, Lei; Yang, Huiying; Yang, Wenhui; Wang, Jie; Zhou, Dongsheng; Liu, Changting; Yin, Zhe

    2015-01-01

    A carbapenem-nonsusceptible Enterobacter aerogenes strain named 3-SP was isolated from a human case of pneumonia in a Chinese teaching hospital. NDM-1 carbapenemase is produced by a pNDM-BJ01-like conjugative plasmid designated p3SP-NDM to account for carbapenem resistance of 3-SP. p3SP-NDM was fully sequenced and compared with all publically available pNDM-BJ01-like plasmids. The genetic differences between p3SP-NDM and pNDM-BJ01 include only 18 single nucleotide polymorphisms, a 1 bp deletion and a 706 bp deletion. p3SP-NDM and pNDM-BJ01 harbor an identical Tn125 element organized as ISAba125, bla NDM-1, ble MBL, ΔtrpF, dsbC, cutA, ΔgroES, groEL, ISCR27, and ISAba125. The bla NDM-1 surrounding regions in these pNDM-BJ01-like plasmids have a conserved linear organization ISAba14-aphA6-Tn125-unknown IS, with considerable genetic differences identified within or immediately downstream of Tn125. All reported pNDM-BJ01-like plasmids are exclusively found in Acinetobacter, whereas this is the first report of identification of a pNDM-BJ01-like plasmid in Enterobacteriaceae.

  8. Malonate-bound structure of the glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) and characterization of the native Fe[supscript 2+] metal-ion preference

    SciTech Connect

    Jackson, Colin J.; Hadler, Kieran S.; Carr, Paul D.; Oakley, Aaron J.; Yip, Sylvia; Schenk, Gerhard; Ollis, David L.

    2010-09-20

    The structure of a malonate-bound form of the glycerophosphodiesterase from Enterobacter aerogenes, GpdQ, has been refined at a resolution of 2.2 {angstrom} to a final R factor of 17.1%. The structure was originally solved to 2.9 {angstrom} resolution using SAD phases from Zn{sup 2+} metal ions introduced into the active site of the apoenzyme [Jackson et al. (2007), J. Mol. Biol. 367, 1047-1062]. However, the 2.9 {angstrom} resolution was insufficient to discern significant details of the architecture of the binuclear metal centre that constitutes the active site. Furthermore, kinetic analysis revealed that the enzyme lost a significant amount of activity in the presence of Zn{sup 2+}, suggesting that it is unlikely to be a catalytically relevant metal ion. In this communication, a higher resolution structure of GpdQ is presented in which malonate is visibly coordinated in the active site and analysis of the native metal-ion preference is presented using atomic absorption spectroscopy and anomalous scattering. Catalytic implications of the structure and its Fe{sup 2+} metal-ion preference are discussed.

  9. UV-B Radiation Stress Causes Alterations in Whole Cell Protein Profile and Expression of Certain Genes in the Rice Phyllospheric Bacterium Enterobacter cloacae.

    PubMed

    Kumar, Jay; Babele, Piyoosh K; Singh, Divya; Kumar, Ashok

    2016-01-01

    Among the different types of UV radiation, UV-B radiation (280-315 nm) has gained much attention mainly due to its increasing incidence on the Earth's surface leading to imbalances in natural ecosystems. This study deals with the effects of UV-B radiation on the proteome and gene expression in a rice phyllospheric bacterium, Enterobacter cloacae. Of the five bacteria isolated from rice leaves, E. cloacae showed the highest level of resistance to UV-B and total killing occurred after 8 h of continuous exposure to UV-B. Reactive oxygen species were induced by UV-B exposure and increased with increasing duration of exposure. Protein profiling by SDS-PAGE and 2-dimensional gel electrophoresis (2-DE) revealed major changes in the number as well as expression of proteins. Analysis of 2-DE gel spots indicated up/down-regulation of several proteins under the stress of UV-B radiation. Thirteen differentially expressed proteins including two hypothetical proteins were identified by MALDI-TOF MS and assigned to eight functional categories. Both the hypothetical proteins (gi 779821175 and gi 503938301) were over-expressed after UV-B irradiation; gi 503938301 was characterized as a member of FMN reductase superfamily whereas gi 779821175 seems to be a structural protein as it did not show any functional domain. That the expression of certain proteins under UV-B stress is indeed up-regulated was confirmed by qRT-PCR. Transcript analysis of selected gene including genes of hypothetical proteins (cp011650 and cp002886) showed over-expression under UV-B stress as compared to untreated control cultures. Although this study deals with a limited number of proteins, identification of differentially expressed proteins reported herein may prove useful in future studies especially for assessing their significance in the protection mechanism of bacteria against UV-B radiation stress.

  10. UV-B Radiation Stress Causes Alterations in Whole Cell Protein Profile and Expression of Certain Genes in the Rice Phyllospheric Bacterium Enterobacter cloacae

    PubMed Central

    Kumar, Jay; Babele, Piyoosh K.; Singh, Divya; Kumar, Ashok

    2016-01-01

    Among the different types of UV radiation, UV-B radiation (280-315 nm) has gained much attention mainly due to its increasing incidence on the Earth’s surface leading to imbalances in natural ecosystems. This study deals with the effects of UV-B radiation on the proteome and gene expression in a rice phyllospheric bacterium, Enterobacter cloacae. Of the five bacteria isolated from rice leaves, E. cloacae showed the highest level of resistance to UV-B and total killing occurred after 8 h of continuous exposure to UV-B. Reactive oxygen species were induced by UV-B exposure and increased with increasing duration of exposure. Protein profiling by SDS-PAGE and 2-dimensional gel electrophoresis (2-DE) revealed major changes in the number as well as expression of proteins. Analysis of 2-DE gel spots indicated up/down-regulation of several proteins under the stress of UV-B radiation. Thirteen differentially expressed proteins including two hypothetical proteins were identified by MALDI-TOF MS and assigned to eight functional categories. Both the hypothetical proteins (gi 779821175 and gi 503938301) were over-expressed after UV-B irradiation; gi 503938301 was characterized as a member of FMN reductase superfamily whereas gi 779821175 seems to be a structural protein as it did not show any functional domain. That the expression of certain proteins under UV-B stress is indeed up-regulated was confirmed by qRT-PCR. Transcript analysis of selected gene including genes of hypothetical proteins (cp011650 and cp002886) showed over-expression under UV-B stress as compared to untreated control cultures. Although this study deals with a limited number of proteins, identification of differentially expressed proteins reported herein may prove useful in future studies especially for assessing their significance in the protection mechanism of bacteria against UV-B radiation stress. PMID:27672388

  11. UV-B Radiation Stress Causes Alterations in Whole Cell Protein Profile and Expression of Certain Genes in the Rice Phyllospheric Bacterium Enterobacter cloacae.

    PubMed

    Kumar, Jay; Babele, Piyoosh K; Singh, Divya; Kumar, Ashok

    2016-01-01

    Among the different types of UV radiation, UV-B radiation (280-315 nm) has gained much attention mainly due to its increasing incidence on the Earth's surface leading to imbalances in natural ecosystems. This study deals with the effects of UV-B radiation on the proteome and gene expression in a rice phyllospheric bacterium, Enterobacter cloacae. Of the five bacteria isolated from rice leaves, E. cloacae showed the highest level of resistance to UV-B and total killing occurred after 8 h of continuous exposure to UV-B. Reactive oxygen species were induced by UV-B exposure and increased with increasing duration of exposure. Protein profiling by SDS-PAGE and 2-dimensional gel electrophoresis (2-DE) revealed major changes in the number as well as expression of proteins. Analysis of 2-DE gel spots indicated up/down-regulation of several proteins under the stress of UV-B radiation. Thirteen differentially expressed proteins including two hypothetical proteins were identified by MALDI-TOF MS and assigned to eight functional categories. Both the hypothetical proteins (gi 779821175 and gi 503938301) were over-expressed after UV-B irradiation; gi 503938301 was characterized as a member of FMN reductase superfamily whereas gi 779821175 seems to be a structural protein as it did not show any functional domain. That the expression of certain proteins under UV-B stress is indeed up-regulated was confirmed by qRT-PCR. Transcript analysis of selected gene including genes of hypothetical proteins (cp011650 and cp002886) showed over-expression under UV-B stress as compared to untreated control cultures. Although this study deals with a limited number of proteins, identification of differentially expressed proteins reported herein may prove useful in future studies especially for assessing their significance in the protection mechanism of bacteria against UV-B radiation stress. PMID:27672388

  12. UV-B Radiation Stress Causes Alterations in Whole Cell Protein Profile and Expression of Certain Genes in the Rice Phyllospheric Bacterium Enterobacter cloacae

    PubMed Central

    Kumar, Jay; Babele, Piyoosh K.; Singh, Divya; Kumar, Ashok

    2016-01-01

    Among the different types of UV radiation, UV-B radiation (280-315 nm) has gained much attention mainly due to its increasing incidence on the Earth’s surface leading to imbalances in natural ecosystems. This study deals with the effects of UV-B radiation on the proteome and gene expression in a rice phyllospheric bacterium, Enterobacter cloacae. Of the five bacteria isolated from rice leaves, E. cloacae showed the highest level of resistance to UV-B and total killing occurred after 8 h of continuous exposure to UV-B. Reactive oxygen species were induced by UV-B exposure and increased with increasing duration of exposure. Protein profiling by SDS-PAGE and 2-dimensional gel electrophoresis (2-DE) revealed major changes in the number as well as expression of proteins. Analysis of 2-DE gel spots indicated up/down-regulation of several proteins under the stress of UV-B radiation. Thirteen differentially expressed proteins including two hypothetical proteins were identified by MALDI-TOF MS and assigned to eight functional categories. Both the hypothetical proteins (gi 779821175 and gi 503938301) were over-expressed after UV-B irradiation; gi 503938301 was characterized as a member of FMN reductase superfamily whereas gi 779821175 seems to be a structural protein as it did not show any functional domain. That the expression of certain proteins under UV-B stress is indeed up-regulated was confirmed by qRT-PCR. Transcript analysis of selected gene including genes of hypothetical proteins (cp011650 and cp002886) showed over-expression under UV-B stress as compared to untreated control cultures. Although this study deals with a limited number of proteins, identification of differentially expressed proteins reported herein may prove useful in future studies especially for assessing their significance in the protection mechanism of bacteria against UV-B radiation stress.

  13. In Vivo Reversion to the Wild-Type β-Lactam Resistance Phenotype Mediated by a Plasmid Carrying ampR and qnrA1 in Enterobacter cloacae

    PubMed Central

    González-López, J. J.; Sabaté, M.; Lavilla, S.; Larrosa, M. N.; Bartolomé, R. M.; Prats, G.

    2006-01-01

    Resistance to β-lactams and quinolones in two isogenic Enterobacter cloacae isolates was studied. One was susceptible to cefoxitin and amoxicillin-clavulanate. The other one showed its natural β-lactam resistance pattern. Both isolates had a nonfunctional AmpR regulator. However, within the second one, the presence of a plasmid carrying ampR and qnrA1 allowed reversion to the wild-type β-lactam resistance phenotype and decreased susceptibility to fluoroquinolones. PMID:16940123

  14. Risk factors for Enterobacter septicemia in a neonatal unit: case-control study.

    PubMed

    Fok, T F; Lee, C H; Wong, E M; Lyon, D J; Wong, W; Ng, P C; Cheung, K L; Cheng, A F

    1998-11-01

    Thirty cases of Enterobacter aerogenes or Enterobacter cloacae septicemia diagnosed over a 32-month period in a tertiary care neonatal unit were enrolled in a case-control study. Each case patient was matched with two controls (patients occupying the cots nearest the case patient when the latter developed septicemia). Of the 32 perinatal characteristics evaluated, 11 were identified by univariate analysis to be significantly associated with the infection. These included parents being residents of the Vietnamese refugee camps, respiratory distress syndrome, necrotizing enterocolitis, umbilical arterial catheterization, umbilical venous catheterization, bladder catheterization, mechanical ventilation, antibiotic treatment, peripheral venous catheterization, nasogastric intubation, and parenteral nutrition. Multivariate analysis, however, showed that preceding bladder catheterization and ongoing parenteral nutrition were the only independent risk factors for enterobacter septicemia. Strict aseptic technique in the preparation of parenteral nutrition fluid and avoidance of bladder catheterization are measures that may reduce the risk of enterobacter sepsis for newborns.

  15. Occurrence of a novel L-2,4-diaminobutyrate decarboxylase activity in some species of Enterobacteriaceae, and purification and characterization of the enzymes of Enterobacter aerogenes and Serratia marcescens.

    PubMed

    Yamamoto, S; Mutoh, N; Ikai, H; Nagasaka, M

    1996-10-01

    L-2,4-Diaminobutyrate decarboxylase (DABA DC) is a novel enzyme yielding 1,3-diaminopropane (DAP) from DABA, which has previously been purified from strains of the genera Vibrio and Acinetobacter. In this study, we also detected DABA DC activity in the species of Enterobacteriaceae: E. aerogenes, E. cloacae, E. agglomerans, Serratia marcescens, S. liquefaciens, Klebsiella pneumoniace, K. oxytoca and Citrobacter freundii, all of which produced DAP in sufficient amounts. Subsequently, the DABA DCs of E. aerogenes and S. marcescens were purified to homogeneity and characterized. Two separate enzymes had similar properties with respect to chromatographic behaviors, and were a dimer with subunits of identical molecular mass of about 51 kDa. The maximal activity of each enzyme was obtained at pH 8.0-8.25. Both enzymes required pyridoxal 5'-phosphate and Mg2+ for full activity, and were highly specific for L-DABA. There was immunological similarity, but not identity between these proteins, as determined by Ouchterlony double diffusion analysis with antiserum against the E. aerogenes DABA DC. They showed the same N-terminal amino acid sequence up to the 8th residue (S-K-L-N-P-I-L-A-). These enzymes were different in molecular mass, N-terminal amino acid sequence and antigenicity from DABA DCs of Acientobacter and Vibrio species.

  16. Resolution of Distinct Membrane-Bound Enzymes from Enterobacter cloacae SLD1a-1 That Are Responsible for Selective Reduction of Nitrate and Selenate Oxyanions

    PubMed Central

    Ridley, Helen; Watts, Carys A.; Richardson, David J.; Butler, Clive S.

    2006-01-01

    Enterobacter cloacae SLD1a-1 is capable of reductive detoxification of selenate to elemental selenium under aerobic growth conditions. The initial reductive step is the two-electron reduction of selenate to selenite and is catalyzed by a molybdenum-dependent enzyme demonstrated previously to be located in the cytoplasmic membrane, with its active site facing the periplasmic compartment (C. A. Watts, H. Ridley, K. L. Condie, J. T. Leaver, D. J. Richardson, and C. S. Butler, FEMS Microbiol. Lett. 228:273-279, 2003). This study describes the purification of two distinct membrane-bound enzymes that reduce either nitrate or selenate oxyanions. The nitrate reductase is typical of the NAR-type family, with α and β subunits of 140 kDa and 58 kDa, respectively. It is expressed predominantly under anaerobic conditions in the presence of nitrate, and while it readily reduces chlorate, it displays no selenate reductase activity in vitro. The selenate reductase is expressed under aerobic conditions and expressed poorly during anaerobic growth on nitrate. The enzyme is a heterotrimeric (αβγ) complex with an apparent molecular mass of ∼600 kDa. The individual subunit sizes are ∼100 kDa (α), ∼55 kDa (β), and ∼36 kDa (γ), with a predicted overall subunit composition of α3β3γ3. The selenate reductase contains molybdenum, heme, and nonheme iron as prosthetic constituents. Electronic absorption spectroscopy reveals the presence of a b-type cytochrome in the active complex. The apparent Km for selenate was determined to be ∼2 mM, with an observed Vmax of 500 nmol SeO42− min−1 mg−1 (kcat, ∼5.0 s−1). The enzyme also displays activity towards chlorate and bromate but has no nitrate reductase activity. These studies report the first purification and characterization of a membrane-bound selenate reductase. PMID:16885262

  17. Spread of Enterobacter cloacae carrying blaNDM-1, blaCTX-M-15, blaSHV-12 and plasmid-mediated quinolone resistance genes in a surgical intensive care unit in Croatia.

    PubMed

    Petrosillo, N; Vranić-Ladavac, M; Feudi, C; Villa, L; Fortini, D; Barišić, N; Bedenić, B; Ladavac, R; D'Arezzo, S; Andrašević, A Tambić; Capone, A

    2016-03-01

    The objective of this study was to describe a hospital cluster of NDM-1-producing Enterobacter cloacae infections observed in the surgical intensive care unit (ICU) of a tertiary-care hospital at Pula, Croatia. NDM-1-producing E. cloacae strains isolated from clinical samples were screened by PCR for the presence of carbapenemases. Genetic relatedness of NDM-1-producing E. cloacae strains was determined by multilocus sequence typing (MLST). During the period October 2013 to April 2014, four patients, with overlapping hospital stay in the surgical ICU, developed severe infections caused by E. cloacae demonstrated to produce carbapenemases. According to MLST, all strains belonged to ST133 and were positive by PCR for the blaNDM-1 carbapenemase gene, for blaCTX-M-15 and blaSHV-12 extended-spectrum β-lactamase (ESBL) genes, and for blaTEM-1 and blaOXA-1 narrow-spectrum β-lactamase genes. They were negative for other carbapenemases genes including blaOXA-48, blaVIM and blaKPC as well as for AmpC and the armA and rmtB aminoglycoside resistance genes. All strains were positive for the HI2 replicon, suggesting that an IncHI2 plasmid is likely the plasmid carrying the blaNDM-1 gene. Infection control measures were implemented after the first case although they were not effective in avoiding spread of this organism to other patients in the surgical ICU. In conclusion, the evolving epidemiology of NDM-producing micro-organisms and the interspecies diffusion of this resistance mechanism to emerging pathogens such as E. cloacae necessitate the setting up of strong and urgent joint measures to control the spread of NDM carbapenemase especially in the ICU setting. PMID:27436392

  18. Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells.

    PubMed

    Husain, Islam; Sharma, Anjana; Kumar, Suresh; Malik, Fayaz

    2016-01-01

    Asparaginase is an important antileukemic agent extensively used worldwide but the intrinsic glutaminase activity of this enzymatic drug is responsible for serious life threatening side effects. Hence, glutaminase free asparaginase is much needed for upgradation of therapeutic index of asparaginase therapy. In the present study, glutaminase free asparaginase produced from Enterobacter cloacae was purified to apparent homogeneity. The purified enzyme was found to be homodimer of approximately 106 kDa with monomeric size of approximately 52 kDa and pI 4.5. Purified enzyme showed optimum activity between pH 7-8 and temperature 35-40°C, which is close to the internal environment of human body. Monovalent cations such as Na+ and K+ enhanced asparaginase activity whereas divalent and trivalent cations, Ca2+, Mg2+, Zn2+, Mn2+, and Fe3+ inhibited the enzyme activity. Kinetic parameters Km, Vmax and Kcat of purified enzyme were found to be 1.58×10-3 M, 2.22 IU μg-1 and 5.3 × 104 S-1, respectively. Purified enzyme showed prolonged in vitro serum (T1/2 = ~ 39 h) and trypsin (T1/2 = ~ 32 min) half life, which is therapeutically remarkable feature. The cytotoxic activity of enzyme was examined against a panel of human cancer cell lines, HL-60, MOLT-4, MDA-MB-231 and T47D, and highest cytotoxicity observed against HL-60 cells (IC50 ~ 3.1 IU ml-1), which was comparable to commercial asparaginase. Cell and nuclear morphological studies of HL-60 cells showed that on treatment with purified asparaginase symptoms of apoptosis were increased in dose dependent manner. Cell cycle progression analysis indicates that enzyme induces apoptosis by cell cycle arrest in G0/G1 phase. Mitochondrial membrane potential loss showed that enzyme also triggers the mitochondrial pathway of apoptosis. Furthermore, the enzyme was found to be nontoxic for human noncancerous cells FR-2 and nonhemolytic for human erythrocytes. PMID:26891220

  19. Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells

    PubMed Central

    Husain, Islam; Sharma, Anjana; Kumar, Suresh; Malik, Fayaz

    2016-01-01

    Asparaginase is an important antileukemic agent extensively used worldwide but the intrinsic glutaminase activity of this enzymatic drug is responsible for serious life threatening side effects. Hence, glutaminase free asparaginase is much needed for upgradation of therapeutic index of asparaginase therapy. In the present study, glutaminase free asparaginase produced from Enterobacter cloacae was purified to apparent homogeneity. The purified enzyme was found to be homodimer of approximately 106 kDa with monomeric size of approximately 52 kDa and pI 4.5. Purified enzyme showed optimum activity between pH 7–8 and temperature 35–40°C, which is close to the internal environment of human body. Monovalent cations such as Na+ and K+ enhanced asparaginase activity whereas divalent and trivalent cations, Ca2+, Mg2+, Zn2+, Mn2+, and Fe3+ inhibited the enzyme activity. Kinetic parameters Km, Vmax and Kcat of purified enzyme were found to be 1.58×10−3 M, 2.22 IU μg-1 and 5.3 × 104 S-1, respectively. Purified enzyme showed prolonged in vitro serum (T1/2 = ~ 39 h) and trypsin (T1/2 = ~ 32 min) half life, which is therapeutically remarkable feature. The cytotoxic activity of enzyme was examined against a panel of human cancer cell lines, HL-60, MOLT-4, MDA-MB-231 and T47D, and highest cytotoxicity observed against HL-60 cells (IC50 ~ 3.1 IU ml-1), which was comparable to commercial asparaginase. Cell and nuclear morphological studies of HL-60 cells showed that on treatment with purified asparaginase symptoms of apoptosis were increased in dose dependent manner. Cell cycle progression analysis indicates that enzyme induces apoptosis by cell cycle arrest in G0/G1 phase. Mitochondrial membrane potential loss showed that enzyme also triggers the mitochondrial pathway of apoptosis. Furthermore, the enzyme was found to be nontoxic for human noncancerous cells FR-2 and nonhemolytic for human erythrocytes. PMID:26891220

  20. MALDI-TOF MS as a Tool To Detect a Nosocomial Outbreak of Extended-Spectrum-β-Lactamase- and ArmA Methyltransferase-Producing Enterobacter cloacae Clinical Isolates in Algeria.

    PubMed

    Khennouchi, Nour Chems el Houda; Loucif, Lotfi; Boutefnouchet, Nafissa; Allag, Hamoudi; Rolain, Jean-Marc

    2015-10-01

    Enterobacter cloacae is among the most important pathogens responsible for nosocomial infections and outbreaks. In this study, 77 Enterobacter isolates were collected: 27 isolates from Algerian hospitals (in Constantine, Annaba, and Skikda) and 50 isolates from Marseille, France. All strains were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Antibiotic susceptibility testing was performed by the disk diffusion method. PCR was used to detect extended-spectrum-beta-lactamase (ESBL)-encoding, fluoroquinolone resistance-encoding, and aminoglycoside-modifying enzyme (AME) genes. Epidemiological typing was performed using MALDI-TOF MS with data mining approaches, along with multilocus sequence typing (MLST). Sixty-eight isolates (27 from Algeria, 41 from Marseille) were identified by MALDI-TOF MS as E. cloacae. Resistance to antibiotics in the Algerian isolates was significantly higher than that in the strains from Marseille, especially for beta-lactams and aminoglycosides. Eighteen of the 27 Algerian isolates and 11 of the 41 Marseille isolates possessed at least one ESBL-encoding gene: blaCTX-M and/or blaTEM. AME genes were detected in 20 of the 27 Algerian isolates and 8 of the 41 Marseille isolates [ant(2″)-Ia, aac(6')-Ib-cr, aadA1, aadA2, and armA]. Conjugation experiments showed that armA was carried on a transferable plasmid. MALDI-TOF typing showed three separate clusters according to the geographical distribution and species level. An MLST-based phylogenetic tree showed a clade of 14 E. cloacae isolates from a urology unit clustering together in the MALDI-TOF dendrogram, suggesting the occurrence of an outbreak in this unit. In conclusion, the ability of MALDI-TOF to biotype strains was confirmed, and surveillance measures should be implemented, especially for Algerian patients hospitalized in France.

  1. MALDI-TOF MS as a Tool To Detect a Nosocomial Outbreak of Extended-Spectrum-β-Lactamase- and ArmA Methyltransferase-Producing Enterobacter cloacae Clinical Isolates in Algeria

    PubMed Central

    Khennouchi, Nour Chems el Houda; Loucif, Lotfi; Boutefnouchet, Nafissa; Allag, Hamoudi

    2015-01-01

    Enterobacter cloacae is among the most important pathogens responsible for nosocomial infections and outbreaks. In this study, 77 Enterobacter isolates were collected: 27 isolates from Algerian hospitals (in Constantine, Annaba, and Skikda) and 50 isolates from Marseille, France. All strains were identified by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Antibiotic susceptibility testing was performed by the disk diffusion method. PCR was used to detect extended-spectrum-beta-lactamase (ESBL)-encoding, fluoroquinolone resistance-encoding, and aminoglycoside-modifying enzyme (AME) genes. Epidemiological typing was performed using MALDI-TOF MS with data mining approaches, along with multilocus sequence typing (MLST). Sixty-eight isolates (27 from Algeria, 41 from Marseille) were identified by MALDI-TOF MS as E. cloacae. Resistance to antibiotics in the Algerian isolates was significantly higher than that in the strains from Marseille, especially for beta-lactams and aminoglycosides. Eighteen of the 27 Algerian isolates and 11 of the 41 Marseille isolates possessed at least one ESBL-encoding gene: blaCTX-M and/or blaTEM. AME genes were detected in 20 of the 27 Algerian isolates and 8 of the 41 Marseille isolates [ant(2″)-Ia, aac(6′)-Ib-cr, aadA1, aadA2, and armA]. Conjugation experiments showed that armA was carried on a transferable plasmid. MALDI-TOF typing showed three separate clusters according to the geographical distribution and species level. An MLST-based phylogenetic tree showed a clade of 14 E. cloacae isolates from a urology unit clustering together in the MALDI-TOF dendrogram, suggesting the occurrence of an outbreak in this unit. In conclusion, the ability of MALDI-TOF to biotype strains was confirmed, and surveillance measures should be implemented, especially for Algerian patients hospitalized in France. PMID:26239991

  2. Molecular characteristics of extended-spectrum beta-lactamases and qnr determinants in Enterobacter species from Japan.

    PubMed

    Kanamori, Hajime; Yano, Hisakazu; Hirakata, Yoichi; Hirotani, Ayako; Arai, Kazuaki; Endo, Shiro; Ichimura, Sadahiro; Ogawa, Miho; Shimojima, Masahiro; Aoyagi, Tetsuji; Hatta, Masumitsu; Yamada, Mitsuhiro; Gu, Yoshiaki; Tokuda, Koichi; Kunishima, Hiroyuki; Kitagawa, Miho; Kaku, Mitsuo

    2012-01-01

    The incidence of extended-spectrum β-lactamases (ESBLs) has been increasing worldwide, but screening criteria for detection of ESBLs are not standardized for AmpC-producing Enterobacteriaceae such as Enterobacter species. In this study, we investigated the prevalence of ESBLs and/or AmpC β-lactamases in Japanese clinical isolates of Enterobacter spp. and the association of plasmid-mediated quinolone resistance (PMQR) determinants with ESBL producers. A total of 364 clinical isolates of Enterobacter spp. collected throughout Japan between November 2009 and January 2010 were studied. ESBL-producing strains were assessed by the CLSI confirmatory test and the boronic acid disk test. PCR and sequencing were performed to detect CTX-M, TEM, and SHV type ESBLs and PMQR determinants. For ESBL-producing Enterobacter spp., pulsed-field gel electrophoresis (PFGE) was performed using XbaI restriction enzyme. Of the 364 isolates, 22 (6.0%) were ESBL producers. Seven isolates of Enterobacter cloacae produced CTX-M-3, followed by two isolates producing SHV-12. Two isolates of Enterobacter aerogenes produced CTX-M-2. Of the 22 ESBL producers, 21 had the AmpC enzyme, and six met the criteria for ESBL production in the boronic acid test. We found a significant association of qnrS with CTX-M-3-producing E. cloacae. The 11 ESBL-producing Enterobacter spp. possessing bla(CTX-M), bla(SHV), or bla(TEM) were divided into six unique PFGE types. This is the first report about the prevalence of qnr determinants among ESBL-producing Enterobacter spp. from Japan. Our results suggest that ESBL-producing Enterobacter spp. with qnr determinants are spreading in Japan.

  3. Comparative evaluation of the VITEK 2, disk diffusion, etest, broth microdilution, and agar dilution susceptibility testing methods for colistin in clinical isolates, including heteroresistant Enterobacter cloacae and Acinetobacter baumannii strains.

    PubMed

    Lo-Ten-Foe, Jerome R; de Smet, Anne Marie G A; Diederen, Bram M W; Kluytmans, Jan A J W; van Keulen, Peter H J

    2007-10-01

    Increasing antibiotic resistance in gram-negative bacteria has recently renewed interest in colistin as a therapeutic option. The increasing use of colistin necessitates the availability of rapid and reliable methods for colistin susceptibility testing. We compared seven methods of colistin susceptibility testing (disk diffusion, agar dilution on Mueller-Hinton [MH] and Isosensitest agar, Etest on MH and Isosensitest agar, broth microdilution, and VITEK 2) on 102 clinical isolates collected from patient materials during a selective digestive decontamination or selective oral decontamination trial in an intensive-care unit. Disk diffusion is an unreliable method to measure susceptibility to colistin. High error rates and low levels of reproducibility were observed in the disk diffusion test. The colistin Etest, agar dilution, and the VITEK 2 showed a high level of agreement with the broth microdilution reference method. Heteroresistance for colistin was observed in six Enterobacter cloacae isolates and in one Acinetobacter baumannii isolate. This is the first report of heteroresistance to colistin in E. cloacae isolates. Resistance to colistin in these isolates seemed to be induced upon exposure to colistin rather than being caused by stable mutations. Heteroresistant isolates could be detected in the broth microdilution, agar dilution, Etest, or disk diffusion test. The VITEK 2 displayed low sensitivity in the detection of heteroresistant subpopulations of E. cloacae. The VITEK 2 colistin susceptibility test can therefore be considered to be a reliable tool to determine susceptibility to colistin in isolates of genera that are known not to exhibit resistant subpopulations. In isolates of genera known to (occasionally) exhibit heteroresistance, an alternative susceptibility testing method capable of detecting heteroresistance should be used.

  4. Modification of rock/fluid and fluid/fluid interfaces during MEOR processes, using two biosurfactant producing strains of Bacillus stearothermophilus SUCPM#14 and Enterobacter cloacae: a mechanistic study.

    PubMed

    Sarafzadeh, Pegah; Zeinolabedini Hezave, Ali; Mohammadi, Sahar; Niazi, Ali; Ayatollahi, Shahab

    2014-05-01

    During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding experiments, interfacial tension, viscosity, pH and Amott wettability index measurements. At the second stage, comparing functionality of B. stearothermophilus SUCPM#14 (a gram-positive type) with the previously examined strain namely Enterobacter cloacae as a gram-negative type, proposed this hypothesis that the cell structure significantly affects the interfacial behaviors. New designed protocols were utilized to check the individual effects of cells, bioproducts and interaction of these together on the oil/water and also fluids/rock interfaces. The final results showed that the cells of B. stearothermophilus SUCPM#14 adhere more into the oil/water interface compared to E. cloacae and change its rheological properties; e.g. its elastic properties which affect the ultimate microbial oil recovery efficiency. Eventually, contradicting results revealed that biosurfactant produced by E. cloacae was able to considerably reduce the interfacial tension and alter the wettability of the rock (to neutral conditions) while biosurfactant produced by B. stearothermophilus SUCPM#14 was not very effective.

  5. Modification of rock/fluid and fluid/fluid interfaces during MEOR processes, using two biosurfactant producing strains of Bacillus stearothermophilus SUCPM#14 and Enterobacter cloacae: a mechanistic study.

    PubMed

    Sarafzadeh, Pegah; Zeinolabedini Hezave, Ali; Mohammadi, Sahar; Niazi, Ali; Ayatollahi, Shahab

    2014-05-01

    During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding experiments, interfacial tension, viscosity, pH and Amott wettability index measurements. At the second stage, comparing functionality of B. stearothermophilus SUCPM#14 (a gram-positive type) with the previously examined strain namely Enterobacter cloacae as a gram-negative type, proposed this hypothesis that the cell structure significantly affects the interfacial behaviors. New designed protocols were utilized to check the individual effects of cells, bioproducts and interaction of these together on the oil/water and also fluids/rock interfaces. The final results showed that the cells of B. stearothermophilus SUCPM#14 adhere more into the oil/water interface compared to E. cloacae and change its rheological properties; e.g. its elastic properties which affect the ultimate microbial oil recovery efficiency. Eventually, contradicting results revealed that biosurfactant produced by E. cloacae was able to considerably reduce the interfacial tension and alter the wettability of the rock (to neutral conditions) while biosurfactant produced by B. stearothermophilus SUCPM#14 was not very effective. PMID:24373916

  6. Adhesive properties and antibiotic resistance of Klebsiella, Enterobacter, and Serratia clinical isolates involved in nosocomial infections.

    PubMed Central

    Livrelli, V; De Champs, C; Di Martino, P; Darfeuille-Michaud, A; Forestier, C; Joly, B

    1996-01-01

    Intestinal colonization by Klebsiella, Enterobacter, and Serratia (KES) strains is a crucial step in the development of nosocomial infections. We studied the adhesive properties, antibiotic resistance, and involvement in colonization or infection of 103 KES clinical isolates: 30 Klebsiella pneumoniae (29%), 16 Klebsiella oxytoca (15%), 30 Enterobacter aerogenes (29%), 14 Enterobacter cloacae (14%), and 13 Serratia sp. (13%) isolates. Half of them were resistant to several antimicrobial agents, including aminoglycosides and beta-lactam antibiotics. A total of 27 of 30 K. pneumoniae isolates (90%) adhered to the human cell line Intestine-407 (Int-407), while none of the K. oxytoca or E. aerogenes isolates and only 2 of the E. cloacae isolates adhered. Three adhesive patterns were observed for K. pneumoniae: an aggregative adhesion in 57% of the isolates, a diffuse adhesion in only one isolate, and a new pattern, localized adhesion, in 30% of the isolates. While most of the sensitive strains adhered with the aggregative phenotype, the localized pattern was associated with resistant K. pneumoniae isolates producing the CAZ-5 beta-lactamase. Furthermore, 45% of such localized-adhesion isolates were involved in severe infections. The distributions of type 1 and type 3 fimbriae, enteroaggregative E. coli, and cf29, pap, and afa/Dr adhesin-encoding genes were determined by using specific DNA probes. No relationship was found between the adhesive pattern and the production of specific fimbriae, suggesting that several unrecognized adhesive factors are involved. Our study indicates that special adhesive properties associated with resistance to antimicrobial agents could account for the pathogenicity of certain nosocomial strains. PMID:8818891

  7. Enterobacter and Klebsiella species isolated from fresh vegetables marketed in Valencia (Spain) and their clinically relevant resistances to chemotherapeutic agents.

    PubMed

    Falomir, María Pilar; Rico, Hortensia; Gozalbo, Daniel

    2013-12-01

    Occurrence of antibiotic-resistant pathogenic or commensal enterobacteria in marketed agricultural foodstuffs may contribute to their incorporation into the food chain and constitutes an additional food safety concern. In this work, we have determined the clinically relevant resistances to 11 common chemotherapeutic agents in Enterobacter and Klebsiella isolates from fresh vegetables from various sources (supermarkets and greengrocers' shops in Valencia, Spain). A total of 96 isolates were obtained from 160 vegetables analyzed (50% positive samples): 68 Enterobacter isolates (59 E. cloacae, two E. aerogenes, two E. cancerogenus, one E. gergoviae, and four E. sakazakii, currently Cronobacter spp.), and 28 Klebsiella isolates (19 K. oxytoca and 9 K. pneumoniae). Only seven isolates were susceptible to all agents tested, and no resistances to ceftazidime, ciprofloxacin, gentamicin, and chloramphenicol were detected. Most isolates were resistant to amoxicillin/clavulanic acid (74 [58 Enterobacter and 16 Klebsiella]) or to ampicillin (80 [55/25]). Other resistances were less frequent: nitrofurantoin (13 isolates [12/1]), tetracycline (6 [5/1]), co-trimoxazole (3 [3/0]), cefotaxime (1 [1/0]), and streptomycin (2 [1/1]). Multiresistant isolates to two (56 [41/15]), three (10 E. cloacae isolates), four (one E. cloacae and one K. pneumoniae isolate), and five (two E. cloacae isolates) chemotherapeutic agents were also detected. The presence of potential pathogens points to marketed fresh produce, which often is eaten raw, as a risk factor for consumer health. In addition, these results support the usefulness of these bacterial species as indicators of the spreading of antibiotic resistances into the environment, particularly in the food chain, and suggest their role as carriers of resistance determinants from farms to consumers, which may constitute an additional "silent" food safety concern. Therefore, there is a need to improve the hygienic quality of marketed fresh

  8. [Phenotypic and genotypic characterization of resistance to third-generation cephalosporins in Enterobacter spp].

    PubMed

    Bertona, E; Radice, M; Rodríguez, C H; Barberis, C; Vay, C; Famiglietti, A; Gutkind, G

    2005-01-01

    Enterobacter spp. are becoming increasingly frequent nosocomial pathogens with multiple resistance mechanism to beta-lactam antibiotics. We carried out the phenotypic and genotypic characterization of beta-lactamases in 27 Enterobacter spp. (25 Enterobacter cloacae y 2 Enterobacter aerogenes), as well as the ability of different extended spectrum-lactamase (ESBL) screening methods. Resistance to third generation cephalosporins was observed in 15/27 (63%) isolates. Twelve resistant isolates produced high level chromosomal encoded AmpC beta-lactamase; 6 of them were also producers of PER-2. Resistance to third generation cephalosporins in the remaining 3 isolates was due to the presence of ESBLs, PER-2 in 2 cases, and CTX-M-2 in the other. Only CTX-M-2 production was detected with all tested cephalosporins using difusion synergy tests, while cefepime improved ESBLs detection in 7/8 PER-2 producers, 4/8 in the inhibitor approximation test and 7/8 with double disk test using cefepime containing disk with and without clavulanic acid. Dilution method, including cephalosporins with and without the inhibitor detected 1/9 ESBLs producers.

  9. Association of Novel Nonsynonymous Single Nucleotide Polymorphisms in ampD with Cephalosporin Resistance and Phylogenetic Variations in ampC, ampR, ompF, and ompC in Enterobacter cloacae Isolates That Are Highly Resistant to Carbapenems

    PubMed Central

    Ellington, Matthew J.; Hopkins, Katie L.; Turton, Jane F.; Doumith, Michel; Loy, Richard; Staves, Peter; Hinic, Vladimira; Frei, Reno; Woodford, Neil

    2016-01-01

    In Enterobacter cloacae, the genetic lesions associated with derepression of the AmpC β-lactamase include diverse single nucleotide polymorphisms (SNPs) and/or indels in the ampD and ampR genes and SNPs in ampC, while diverse SNPs in the promoter region or SNPs/indels within the coding sequence of outer membrane proteins have been described to alter porin production leading to carbapenem resistance. We sought to define the underlying mechanisms conferring cephalosporin and carbapenem resistance in a collection of E. cloacae isolates with unusually high carbapenem resistance and no known carbapenemase and, in contrast to many previous studies, considered the SNPs we detected in relation to the multilocus sequence type (MLST)-based phylogeny of our collection. Whole-genome sequencing was applied on the most resistant isolates to seek novel carbapenemases, expression of ampC was measured by reverse transcriptase PCR, and porin translation was detected by SDS-PAGE. SNPs occurring in ampC, ampR, ompF, and ompC genes (and their promoter regions) were mostly phylogenetic variations, relating to the isolates' sequence types, whereas nonsynonymous SNPs in ampD were associated with derepression of AmpC and cephalosporin resistance. The additional loss of porins resulted in high-level carbapenem resistance, underlining the clinical importance of chromosomal mutations among carbapenem-resistant E. cloacae. PMID:26856839

  10. Accumulation of plasmid-mediated fluoroquinolone resistance genes, qepA and qnrS1, in Enterobacter aerogenes co-producing RmtB and class A beta-lactamase LAP-1.

    PubMed

    Park, Yeon-Joon; Yu, Jin Kyung; Kim, Sang-Il; Lee, Kyungwon; Arakawa, Yoshichika

    2009-01-01

    A new plasmid-mediated fluoroquinolone efflux pump gene, qepA, is known to be associated with the rmtB gene, which confers high-level resistance to aminoglycosides. We investigated the qepA gene in 573 AmpC-producing Enterobacteriaceae including one Citrobacter freundii known to harbor rmtB. Of them, two clonally unrelated E. aerogenes harbored qepA. Both isolates co-harbored rmtB, qnrS1, qepA, and bla(LAP-1) on an IncFI type plasmid. The qepA was flanked by two copies of IS26 containing ISCR3C, tnpA, tnpR, bla(TEM), and rmtB. The qnrS1 and bla(LAP-1) were located upstream of qepA. All the resistance determinants (qepA, qnrS1, rmtB, and bla(LAP-1)) were co-transferred to E. coli J53 by filter mating from both isolates. Although the prevalence of qepA is currently low, considering the presence of ISCR3C and the possibility of co-selection and co-transferability of plasmids, more active surveillance for these multi-drug resistant bacteria and prudent use of antimicrobials are needed.

  11. Phage-mediated Shiga toxin (Stx) horizontal gene transfer and expression in non-Shiga toxigenic Enterobacter and Escherichia coli strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    M12X01451, an Enterobacter cloacae strain recently identified from a clinical specimen, produces a new Stx1e that was not neutralized by existing anti-Stx1 monoclonal antibodies. Acquisition of stx by Ent. cloacae is rare and information regarding the origin and stability of the stx1e in M12X01451 i...

  12. Atypical internal yellowing of papaya fruit in Hawaii caused by Enterobacter sakazakii

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Internal yellowing (IY), characterized by yellow discolored tissue around the papaya (Carica papaya) seed cavity, diffuse margins and the presence of a distinctly rotten odor, was first reported in 1987. These symptoms were associated with the causal agent Enterobacter cloacae. Here we report the fo...

  13. Enterobacter asburiae sp. nov., a new species found in clinical specimens, and reassignment of Erwinia dissolvens and Erwinia nimipressuralis to the genus Enterobacter as Enterobacter dissolvens comb. nov. and Enterobacter nimipressuralis comb. nov.

    PubMed Central

    Brenner, D J; McWhorter, A C; Kai, A; Steigerwalt, A G; Farmer, J J

    1986-01-01

    Enterobacter asburiae sp. nov. is a new species that was formerly referred to as Enteric Group 17 and that consists of 71 strains, 70 of which were isolated from humans. Enterobacter asburiae sp. nov. strains gave positive reactions in tests for methyl red, citrate utilization (Simmons and Christensen's), urea hydrolysis, L-ornithine decarboxylase, growth in KCN, acid and gas production from D-glucose, and acid production from L-arabinose, cellobiose, glycerol (negative in 1 to 2 days, positive in 3 to 7 days), lactose, D-mannitol, alpha-methyl-D-glucoside, salicin, D-sorbitol, sucrose, trehalose, and D-xylose. They gave negative reactions in the Voges-Proskauer test and in tests for indole, H2S production, phenylalanine, L-lysine decarboxylase, motility, gelatin, utilization of malonate, lipase, DNase, tyrosine clearing, acid production from adonitol, D-arabitol, dulcitol, erythritol, i(myo)-inositol, melibiose, and L-rhamnose. They gave variable reactions in tests for L-arginine dihydrolase (25% positive after 2 days) and acid production from raffinose (69% positive after 2 days). Thirty-four Enterobacter asburiae sp. nov. strains were tested for DNA relatedness by the hydroxyapatite method with 32PO4-labeled DNA from the designated type strain (1497-78, ATCC 35953). The strains were 69 to 100% related in 60 degrees C reactions and 63 to 100% related in 75 degrees C reactions. Divergence within related sequences was 0 to 2.5%. Relatedness of Enterobacter asburiae sp. nov. to 84 strains of members of the Enterobacteriaceae was 5 to 63%, with closest relatedness to strains of Enterobacter cloacae, Erwinia dissolvens, Enterobacter taylorae, Enterobacter agglomerans, Erwinia nimipressuralis, and Enterobacter gergoviae. All strains tested were susceptible to gentamicin and sulfdiazine, and most were susceptible to chloramphenicol, colistin, kanamycin, nalidixic acid, carbenicillin and streptomycin. All strains were resistant to ampicillan, cephalothin, and penicillin

  14. Concomitant rock phosphate dissolution and lead immobilization by phosphate solubilizing bacteria (Enterobacter sp.).

    PubMed

    Park, Jin Hee; Bolan, Nanthi; Megharaj, Mallavarapu; Naidu, Ravi

    2011-04-01

    This paper examines the potential value of phosphate solubilizing bacteria (Enterobacter cloacae) in the dissolution of rock phosphate (RP) and subsequent immobilization of lead (Pb) in both bacterial growth medium and soils. Enterobacter sp. showed resistance to Pb and the bacterium solubilized 17.5% of RP in the growth medium. Enterobacter sp. did not enhance Pb immobilization in solution because of acidification of bacterial medium, thereby inhibiting the formation of P-induced Pb precipitation. However, in the case of soil, Enterobacter sp. increased Pb immobilization by 6.98, 25.6 and 32.0% with the RP level of 200, 800 and 1600 mg P/kg, respectively. The immobilization of Pb in Pb-spiked soils was attributed to pyromorphite formation as indicated by XRD analysis. Inoculation of phosphate solubilizing bacteria with RP in soil can be used as an alternative technique to soluble P compounds which can cause eutrophication of surface water.

  15. Pathology of cloaca anomalies with case correlation.

    PubMed

    Gupta, Anita; Bischoff, Andrea

    2016-04-01

    During the fourth week of human embryo development, a transient common channel known as a cloaca is formed from which three cavities with three external orifices arises. Cloaca anomalies occur when there is failure of separation of the rectum, vagina, and urethra channel resulting in a single drain into the perineum. In our previous institutional studies, Runck et al. compared human and mouse cloaca development and found early mis-patterning of the embryonic cloaca deranged hedgehog and bone morphogenetic proteins (BMP) signaling. Also, our group reported the embryological correlation of the epithelial and stromal histology found in step sections of the common channel in 14 cloaca malformations in humans. In this review, we present the pathology of a 4-year-old female with a cloaca and VACTERL complex, and summarize our current knowledge of cloaca pathology. Furthermore, we suggest that careful pathological examination of cloaca specimens in conjunction with surgical orientation may result in a better understanding of the etiology of this condition. PMID:26969228

  16. Molecular identification of aiiA homologous gene from endophytic Enterobacter species and in silico analysis of putative tertiary structure of AHL-lactonase.

    PubMed

    Rajesh, P S; Rai, V Ravishankar

    2014-01-01

    The aiiA homologous gene known to encode AHL- lactonase enzyme which hydrolyze the N-acylhomoserine lactone (AHL) quorum sensing signaling molecules produced by Gram negative bacteria. In this study, the degradation of AHL molecules was determined by cell-free lysate of endophytic Enterobacter species. The percentage of quorum quenching was confirmed and quantified by HPLC method (p<0.0001). Amplification and sequence BLAST analysis showed the presence of aiiA homologous gene in endophytic Enterobacter asburiae VT65, Enterobacter aerogenes VT66 and Enterobacter ludwigii VT70 strains. Sequence alignment analysis revealed the presence of two zinc binding sites, "HXHXDH" motif as well as tyrosine residue at the position 194. Based on known template available at Swiss-Model, putative tertiary structure of AHL-lactonase was constructed. The result showed that novel endophytic strains of Enterobacter genera encode the novel aiiA homologous gene and its structural importance for future study.

  17. Risk factors and treatment outcomes of bloodstream infection caused by extended-spectrum cephalosporin-resistant Enterobacter species in adults with cancer.

    PubMed

    Huh, Kyungmin; Kang, Cheol-In; Kim, Jungok; Cho, Sun Young; Ha, Young Eun; Joo, Eun-Jeong; Chung, Doo Ryeon; Lee, Nam Yong; Peck, Kyong Ran; Song, Jae-Hoon

    2014-02-01

    Treatment of Enterobacter infection is complicated due to its intrinsic resistance to cephalosporins. Medical records of 192 adults with cancer who had Enterobacter bacteremia were analyzed retrospectively to evaluate the risk factors for and the treatment outcomes in extended-spectrum cephalosporin (ESC)-resistant Enterobacter bacteremia in adults with cancer. The main outcome measure was 30-day mortality. Of the 192 patients, 53 (27.6%) had bloodstream infections caused by ESC-resistant Enterobacter species. Recent use of a third-generation cephalosporin, older age, tumor progression at last evaluation, recent surgery, and nosocomial acquisition were associated with ESC-resistant Enterobacter bacteremia. The 30-day mortality rate was significantly higher in the resistant group. Multivariate analysis showed that respiratory tract infection, tumor progression, septic shock at presentation, Enterobacter aerogenes as the culprit pathogen, and diabetes mellitus were independent risk factors for mortality. ESC resistance was significantly associated with mortality in patients with E. aerogenes bacteremia, although not in the overall patient population.

  18. Dechlorination of DDT by Aerobacter aerogenes

    USGS Publications Warehouse

    1966-01-01

    Dechlorination of DDT to DDD in higher animals requires the presence of molecular oxygen, but in microorganisms the presence of oxygen hinders dechlorination. In cell-free preparations of Aerobacter aerogenes, the use of selected metabolic inhibitors indicated that reduced Fe(II) cytochrome oxidase was responsible for DDT dechlorination. This finding may possibly explain. the persistence of DDT residues in soils and sediments.

  19. The aerogen-π bonds involving π systems

    NASA Astrophysics Data System (ADS)

    Gao, Meng; Cheng, Jianbo; Li, Wenzuo; Xiao, Bo; Li, Qingzhong

    2016-05-01

    Ab initio calculations have been performed to study the complexes of XeOF2 and a series of π systems including ethyne, ethene, benzene, pyrrole, furan, and thiophene. More than two structures were obtained for each complex with an aerogen-π bond. The configuration of complex has a significant effect on its stability. The strength of aerogen-π interaction is comparable with that of lone pair-aerogen interaction and conventional hydrogen bonds. A breakdown of the aerogen-π interaction attributes its stability to approximately equal parts electrostatic and polarization energies, with a relatively smaller contribution from dispersion energy.

  20. Influence of host seed on metabolic activity by Enterobacter cloacae in the spermosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little is known regarding the influences of nutrients released from plants on the metabolic activity of colonizing microbes. To gain a better understanding of these influences, we used bioluminescence- and oxygen consumption-based methods to compare bacterial metabolic activity expressed during col...

  1. Group IIC Intron with an Unusual Target of Integration in Enterobacter cloacae

    PubMed Central

    Rodríguez-Martínez, José-Manuel; Poirel, Laurent

    2012-01-01

    A potential role of group IIC-attC introns in integron gene cassette formation, that is, the way in which they could provide the attC sequence essential for recombination, has been proposed. Group IIC introns usually target the attC site of gene cassettes and more specifically their inverse core. Here we characterized a novel group IIC intron targeting the core site of the aadA1 gene cassette attC site (aadA1-qacEΔ1 gene cassette junction) from enterobacterial isolates. Intron mobility (retrohoming) was analyzed using a two-plasmid assay performed in Escherichia coli. Intron mobility assays confirmed the mobilization-integration of the group II intron into the core site of the aadA2, blaVIM-2, blaCARB-2, aac(6′)-Ib, dfrXVb, arr2, cmlA4, and aadB gene cassettes but not into the attI site. This mobility was dependent on maturase activity. Reverse transcriptase PCR showed that this intron was transcriptionally active, and an intermediate circular form was detected by inverse PCR. This element was linked to the blaVEB-1 extended-spectrum β-lactamase gene in a high number of enterobacterial isolates. A phylogenetic tree showed that the identified element was located in a branch separate from group IIC-attC introns, being an IIC intron possessing the ability to integrate using the core site of the attC sites as target. PMID:22020643

  2. Sequence and properties of pentaerythritol tetranitrate reductase from Enterobacter cloacae PB2.

    PubMed Central

    French, C E; Nicklin, S; Bruce, N C

    1996-01-01

    Pentaerythritol tetranitrate reductase, which reductively liberates nitrite from nitrate esters, is related to old yellow enzyme. Pentaerythritol tetranitrate reductase follows a ping-pong mechanism with competitive substrate inhibition by NADPH, is strongly inhibited by steroids, and is capable of reducing the unsaturated bond of 2-cyclohexen-1-one. PMID:8932320

  3. Occurrence and analysis of irp2 virulence gene in isolates of Klebsiella pneumoniae and Enterobacter spp. from microbiota and hospital and community-acquired infections.

    PubMed

    Souza Lopes, Ana Catarina; Rodrigues, Juliana Falcão; Cabral, Adriane Borges; da Silva, Maíra Espíndola; Leal, Nilma Cintra; da Silveira, Vera Magalhães; de Morais Júnior, Marcos Antônio

    2016-07-01

    Eighty-five isolates of Klebsiella pneumoniae and Enterobacter spp., originating from hospital- and community-acquired infections and from oropharyngeal and faecal microbiota from patients in Recife-PE, Brazil, were analyzed regarding the presence of irp2 gene. This is a Yersinia typical gene involved in the synthesis of siderophore yersiniabactin. DNA sequencing confirmed the identity of irp2 gene in five K. pneumoniae, five Enterobacter aerogenes and one Enterobacter amnigenus isolates. To our knowledge in the current literature, this is the first report of the irp2 gene in E. amnigenus, a species considered an unusual human pathogen, and in K. pneumoniae and E. aerogenes isolates from the normal microbiota and from community infections, respectively. Additionally, the analyses of nucleotide and amino acid sequences suggest the irp2 genes derived from isolates used in this study are more closely related to that of Yersinia pestis P.CE882 than to that of Yersinia enterocolitica 8081. These data demonstrated that K. pneumoniae and Enterobacter spp. from normal microbiota and from community- and hospital-acquired infections possess virulence factors important for the establishment of extra-intestinal infections. PMID:27133266

  4. Partial hydrolysis of dieldrin by Aerobacter aerogenes

    USGS Publications Warehouse

    Wedemeyer, G.

    1968-01-01

    Although dieldrin (1,2,3 ,4,10,10-hexachloro- 6,7-epoxy-1 ,4 ,4a ,5 ,6 ,7 ,8, 8a-octahydro-1 ,4-endo, exo-5, 8-dimethanonaphthalene) metabolism by mammals (F. Korte and H. Arent, Life Sci. 4:2017, 1965) and insects (D. F. Heath and M. Vanderkar, Brit. J. Ind. Med. 21:269, 1964) has been reported, little is known about the degradation of this important pesticide by microorganisms. Korte et al. (Ann. Chem. Liebigs 656:135, 1962) and Chacko et al. (Science 154: 893, 1966) reported that a number of ubiquitous microorganisms were incapable of degrading dieldrin; however, more recently Matsumura and Boush (Science 156:959, 1967) isolated several species of Pseudomonas and Bacillus which could degrade dieldrin, from a number of soil samples having similar activity. They did not specifically attempt to identify the dieldrin metabolites formed, but they did suggest, on the basis of an identical RF value with an authentic control that 6,7-trans-dihydroxydihydroaldrin (aldrin diol) might be a major product. Work carried out concurrently in this laboratory has shown that another ubiquitous bacterium, Aerobacter aerogenes, converts dieldrin in vitro to a compound chromatographically

  5. Utilization of arginine by Klebsiella aerogenes.

    PubMed

    Friedrich, B; Magasanik, B

    1978-02-01

    Klebsiella aerogenes utilized arginine as the sole source of carbon or nitrogen for growth. Arginine was degraded to 2-ketoglutarate and not to succinate, since a citrate synthaseless mutant grows on arginine as the only nitrogen source. When glucose was the energy source, all four nitrogen atoms of arginine were utilized. Three of them apparently did not pass through ammonia but were transferred by transamination, since a mutant unable to produce glutamate by glutamate synthase or glutamate dehydrogenase utilized three of four nitrogen atoms of arginine. Urea was not involved as intermediate, since a unreaseless mutant did not accumulate urea and grew on arginine as efficiently as the wild-type strain. Ornithine appeared to be an intermediate, because cells grown either on glucose and arginine or arginine alone could convert arginine in the presence of hydroxylamine to ornithine. This indicates that an amidinotransferase is the initiating enzyme of arginine breakdown. In addition, the cells contained a transaminase specific for ornithine. In contrast to the hydroxylamine-dependent reaction, this activity could be demonstrated in extracts. The arginine-utilizing system (aut) is apparently controlled like the enzymes responsible for the degradation of histidine (hut) through induction, catabolite repression, and activation by glutamine synthetase.

  6. Enterobacter soli sp. nov.: a lignin-degrading γ-proteobacteria isolated from soil.

    PubMed

    Manter, Daniel K; Hunter, William J; Vivanco, Jorge M

    2011-03-01

    A Gram-negative bacterium that formed cream-colored colonies designated strain LF7 was isolated from soil collected in the Tambopata National Reserve in Madre de Dios, Peru. 16S rRNA sequence comparisons indicate that LF7 is a novel Enterobacter sp. closely related to E. asburiae JCM 6051(T) [AB004744] and E. aerogenes JCM 1235(T) [AB004750] based on their sequence homologies (p-distance: 1.06 and 1.19%, respectively). DNA G + C content was 52.8 mol% which is within the range reported for E. asburiae (55-57 mol%). The major cellular fatty acids present in the LF7 strain were C(16:0) (27.3%), C(16:1) ω7c and/or C(16:1) ω6c (16.3%), C(18:1) ω7c (16.1%), C(17:0) cyclo (12.4%), C(14:0) 3-OH and/or C(16:1) iso-I (8.9%), C(14:0) (7.6%), C(12:0) (3.9%), C(17:0) (2.4%), C(13:0) 3-OH and/or C(15:1) iso-H (1.7%), C(13:0) (1.1%), and C(18:2) ω6,9c and/or C(18:0) ante (0.5%). The cellular fatty acid profile, G + C content, phenotypic and biochemical characteristics were consistent with its placement in the genus Enterobacter. The name Enterobacter soli is proposed for this bacterium.

  7. Study of bio-degradation and bio-decolourization of azo dye by Enterobacter sp. SXCR.

    PubMed

    Prasad, Shiv Shankar; Aikat, Kaustav

    2014-01-01

    The objective of this study was to evaluate the decolourization potential of textile dyes by a relatively newly identified bacteria species, Enterobacter sp. SXCR which was isolated from the petroleum polluted soil samples. The bacterial strain was identified by 16S rRNA gene sequence analysis. The effects of operational conditions like initial dye concentration, pH, and temperature were optimized to develop an economically feasible decolourization process. The isolate was able to decolourize sulphonated azo dye (Congo red) over a wide range (0.1-1 gl(-1)), pH 5-9, and temperature 22-40 degrees C in static condition. Anaerobic condition with minimal salt medium supplemented with 2 gl(-1) glucose, pH 7 and 34 degrees C were considered to be the optimum decolourizing condition. The bacterial isolate SXCR showed a strong ability to decolourize dye (0.2 gl(-1)) within 93 h. The biodegradation was monitored by UV-vis, fourier transform infra-red spectroscopy (FTIR) spectroscopy and high performance liquid chromatography (HPLC). Furthermore, the involvement of azoreductase in the decolourization process was identified in this strain. Cells of Enterobacter cloacae were immobilized by entrapment in calcium-alginate beads. Immobilized bacterial cells were able to reduced azo bonds enzymatically and used as a biocatalyst for decolourization of azo dye Congo red. Michaelis-Menten kinetics was used to describe the correlation between the decolourization rate and the dye concentration.

  8. Single-electron aerogen bonds: Do they exist?

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba; Solimannejad, Mohammad

    2016-08-01

    A novel type of σ-hole interaction is characterized between some noble gas containing molecules (KrOF2, KrO3, XeOF2 and XeO3) and methyl (CH3) or ethyl (C2H5) radical by means of ab initio calculations. This interaction is named as single-electron aerogen bond (SEAB), in view of the concepts of aerogen bond and single-electron bond interactions. The properties of SEABs are studied by molecular electrostatic potential, quantum theory of atom in molecules, natural bonding orbital and noncovalent interaction index analyses. The formation of an O⋯H interaction tends to increase the strength of the SEAB, when they coexist in a ternary complex.

  9. Ribitol dehydrogenase from Klebsiella aerogenes. Purification and subunit structure

    PubMed Central

    Taylor, Susan S.; Rigby, Peter W. J.; Hartley, Brian S.

    1974-01-01

    Ribitol dehydrogenase has been purified to homogeneity from several strains of Klebsiella aerogenes. One strain yields 3–6g of pure enzyme from 1kg of cells. The enzyme is a tetramer of four subunits, mol.wt. 27000. Preliminary studies of the activity of the enzyme are reported. Peptide `maps' together with the amino acid composition indicate that the subunits are identical. ImagesPLATE 2PLATE 1 PMID:4618776

  10. Molecular Analysis of Tetracycline Resistance in Pasteurella aerogenes

    PubMed Central

    Kehrenberg, Corinna; Schwarz, Stefan

    2001-01-01

    Tetracycline-resistant Pasteurella aerogenes isolates obtained from the intestinal tract of swine were investigated for their tet genes by PCR analysis and hybridization experiments. In contrast to Pasteurella isolates from the respiratory tract, tet(H) genes were detected in the chromosomal DNA of only 2 of the 24 isolates, one of which also carried two copies of a tet(B) gene. All other P. aerogenes isolates carried tet(B) genes, which are the predominant tet genes among Enterobacteriaceae. A single isolate harbored a tet(B) gene as part of a truncated Tn10 element on the 4.8-kb plasmid pPAT2. Comparative analysis of the pPAT2 sequence suggested that the Tn10 relic on plasmid pPAT2 is the result of several illegitimate recombination events. The remaining 21 P. aerogenes isolates carried one or two copies of the tet(B) gene in their chromosomal DNA. In the majority of the cases, these tet(B) genes were associated with copies of Tn10 as confirmed by their SfuI and BamHI hybridization patterns. No correlation between the number of tet gene copies and the MICs of tetracycline, doxycyline and minocycline was observed. PMID:11557485

  11. The TyrR transcription factor regulates the divergent akr-ipdC operons of Enterobacter cloacae UW5.

    PubMed

    Coulson, Thomas J D; Patten, Cheryl L

    2015-01-01

    The TyrR transcription factor regulates genes involved in the uptake and biosynthesis of aromatic amino acids in Enterobacteriaceae. Genes may be positively or negatively regulated depending on the presence or absence of each aromatic amino acid, all three of which function as cofactors for TyrR. In this report we detail the transcriptional control of two divergently transcribed genes, akr and ipdC, by TyrR, elucidated by promoter fusion expression assays and electrophoretic mobility shift assays to assess protein-DNA interactions. Expression of both genes was shown to be controlled by TyrR via interactions with two TyrR boxes located within the akr-ipdC intergenic region. Expression of ipdC required TyrR bound to the proximal strong box, and is strongly induced by phenylalanine, and to a lesser extent by tryptophan and tyrosine. Down-regulation of akr was reliant on interactions with the weak box, and may also require a second, as yet unidentified protein for further repression. Tyrosine enhanced repression of akr. Electrophoretic mobility shift assays demonstrated that TyrR interacts with both the strong and weak boxes, and that binding of the weak box in vitro requires an intact adjacent strong box. While the strong box shows a high degree of conservation with the TyrR binding site consensus sequence, the weak box has atypical spacing of the two half sites comprising the palindromic arms. Site-directed mutagenesis demonstrated sequence-specific interaction between TyrR and the weak box. This is the first report of TyrR-controlled expression of two divergent protein-coding genes, transcribed from independent promoters. Moreover, the identification of a predicted aldo-keto reductase as a member of the TyrR regulon further extends the function of the TyrR regulon. PMID:25811953

  12. The TyrR Transcription Factor Regulates the Divergent akr-ipdC Operons of Enterobacter cloacae UW5

    PubMed Central

    Coulson, Thomas J. D.; Patten, Cheryl L.

    2015-01-01

    The TyrR transcription factor regulates genes involved in the uptake and biosynthesis of aromatic amino acids in Enterobacteriaceae. Genes may be positively or negatively regulated depending on the presence or absence of each aromatic amino acid, all three of which function as cofactors for TyrR. In this report we detail the transcriptional control of two divergently transcribed genes, akr and ipdC, by TyrR, elucidated by promoter fusion expression assays and electrophoretic mobility shift assays to assess protein-DNA interactions. Expression of both genes was shown to be controlled by TyrR via interactions with two TyrR boxes located within the akr-ipdC intergenic region. Expression of ipdC required TyrR bound to the proximal strong box, and is strongly induced by phenylalanine, and to a lesser extent by tryptophan and tyrosine. Down-regulation of akr was reliant on interactions with the weak box, and may also require a second, as yet unidentified protein for further repression. Tyrosine enhanced repression of akr. Electrophoretic mobility shift assays demonstrated that TyrR interacts with both the strong and weak boxes, and that binding of the weak box in vitro requires an intact adjacent strong box. While the strong box shows a high degree of conservation with the TyrR binding site consensus sequence, the weak box has atypical spacing of the two half sites comprising the palindromic arms. Site-directed mutagenesis demonstrated sequence-specific interaction between TyrR and the weak box. This is the first report of TyrR-controlled expression of two divergent protein-coding genes, transcribed from independent promoters. Moreover, the identification of a predicted aldo-keto reductase as a member of the TyrR regulon further extends the function of the TyrR regulon. PMID:25811953

  13. Molecular epidemiological survey of Citrobacter freundii misidentified as Cronobacter spp. (Enterobacter sakazakii) and Enterobacter hormaechei isolated from powdered infant milk formula.

    PubMed

    Giammanco, Giovanni M; Aleo, Aurora; Guida, Ivana; Mammina, Caterina

    2011-04-01

    A total of 75 powdered infant milk formula (PIF) samples collected from pharmacies and drugstores in Western Sicily, Italy, and representative of 12 different brands were analyzed in this study to evaluate their microbiological quality. According to the U.S. Food and Drug Administration protocol, 32 samples out of 75 were contaminated by enterobacteria. Commercial biochemical API(r) 20E-system identification method indicated that six PIF samples were presumptively contaminated by Cronobacter spp., but further characterization by alpha-glucosidase based polymerase chain reaction (PCR) assay identification strongly suggested that these strains did not belong to the genus Cronobacter. Phylogenetic analysis of partial 16S rRNA (rrs) sequences combined with the results of biochemical tests allowed to identify the six strains as Citrobacter freundii. Similarly, rrs sequence analysis identified as Enterobacter hormaechei 23 strains originally ascribed to Enterobacter cloacae by the API 20E system. Characterization of C. freundii and E. hormaechei PIF isolates by the DiversiLab(r) repetitive sequence-based PCR (rep-PCR) typing method revealed a variety of amplification patterns, but the recovery of the same rep-PCR genotype in several products might indicate a special adaptation of genetic clones to this food or cross-contamination through common ingredients. Antibiotic-resistance profiles were also determined, but none of the strains tested was resistant to third-generation cephalosporins or fluoroquinolones and extended-spectrum beta-lactamase activity was not detected. Our results confirm that E. hormaechei contamination of PIF is widespread, thus making it a cause for concern. Similarly to what was demonstrated for E. hormaechei, we suggest that C. freundii also may be an under-reported cause of bacterial infection, especially in high-risk neonates, due to misidentification.

  14. Chemical Kinetic and Molecular Genetic Study of Selenium Oxyanion Reduction by Enterobactor cloacae SLD1a-1

    SciTech Connect

    Ma,J.; Kobayashi, D.; Yee, N.

    2007-01-01

    Microbial processes play an important role in the redox transformations of toxic selenium oxyanions. In this study, we employed chemical kinetic and molecular genetic techniques to investigate the mechanisms of Se(IV) and Se(VI) reduction by the facultative anaerobe Enterobacter cloacae SLD1a-1. The rates of microbial selenium oxyanion reduction were measured as a function of initial selenium oxyanion concentration (0-1.0 mM) and temperature (10-40 C), and mutagenesis studies were performed to identify the genes involved in the selenium oxyanion reduction pathway. The results indicate that Se(IV) reduction is significantly more rapid than the reduction of Se(VI). The kinetics of the reduction reactions were successfully quantified using the Michaelis-Menten kinetic equation. Both the rates of Se(VI) and Se(IV) reduction displayed strong temperature-dependence with Ea values of 121 and 71.2 kJ/mol, respectively. X-ray absorption near-edge spectra collected for the precipitates formed by Se(VI) and Se(IV) reduction confirmed the formation of Se(0). A miniTn5 transposon mutant of E. cloacae SLD1a-1 was isolated that had lost the ability to reduce Se(VI) but was not affected in Se(IV) reduction activity. Nucleotide sequence analysis revealed the transposon was inserted within a tatC gene, which encodes for a central protein in the twin arginine translocation system. Complementation by the wild-type tatC sequence restored the ability of mutant strains to reduce Se(VI). The results suggest that Se(VI) reduction activity is dependent on enzyme export across the cytoplasmic membrane and that reduction of Se(VI) and Se(IV) are catalyzed by different enzymatic systems.

  15. Klebsiella and Enterobacter organisms isolated from horses.

    PubMed

    Platt, H; Atherton, J G; Orskov, I

    1976-12-01

    An account is given of K. pneumoniae capsule types occurring in horses, with particular reference to strains originating from the genital tract in the mare and the external genitalia of the stallion. A survey of the prevalence of K. pneumoniae and E. aerogenes strains in the preputial flora of healthy stallions is described. The majority of horses were found to be carriers of these organisms. The cultural characteristics of these preputial strains are described and compared with those of K. pneumoniae strains associated with epidemic metritis in mares. The epidemiological significance of certain K. pneumoniae capsule types is discussed.

  16. Regulation of Nitrate Assimilation and Nitrate Respiration in Aerobacter aerogenes

    PubMed Central

    Van 'T Riet, J.; Stouthamer, A. H.; Planta, R. J.

    1968-01-01

    The influence of growth conditions on assimilatory and respiratory nitrate reduction in Aerobacter aerogenes was studied. The level of nitrate reductase activity in cells, growing in minimal medium with nitrate as the sole nitrogen source, was much lower under aerobic than anaerobic conditions. Further, the enzyme of the aerobic cultures was very sensitive to sonic disintegration, as distinct from the enzyme of anaerobic cultures. When a culture of A. aerogenes was shifted from anaerobic growth in minimal medium with nitrate and NH4+ to aerobiosis in the same medium, but without NH4+, the production of nitrite stopped instantaneously and the total activity of nitrate reductase decreased sharply. Moreover, there was a lag in growth of about 3 hr after such a shift. After resumption of growth, the total enzymatic activity increased again slowly and simultaneously became gradually sensitive to sonic disintegration. These findings show that oxygen inactivates the anaerobic nitrate reductase and represses its further formation; only after a de novo synthesis of nitrate reductase with an assimilatory function will growth be resumed. The enzyme in aerobic cultures was not significantly inactivated by air, only by pure oxygen. The formation of the assimilatory enzyme complex was repressed, however, by NH4+, under both aerobic and anaerobic conditions. The results indicate that the formation of the assimilatory enzyme complex and that of the respiratory enzyme complex are regulated differently. We suggest that both complexes have a different composition, but that the nitrate reductase in both cases is the same protein. PMID:5726295

  17. [Isolation and characterization of injured coliforms from the drinking water distribution network of La Plata, Argentina].

    PubMed

    Basualdo, J A; Córdoba, M A; De Luca, M M; Roccia, I L; Pezzani, B C; Vay, C; Ageron, E; Grimont, P A

    2001-01-01

    We screened the La Plata drinking water distribution network for fecal and total coliform bacterial indicator by purification procedures, cultivating 66 membrane-filtered samples from the two networks on m-T7 agar. Subterranean and river-derived water yielded 13 and 18 confirmed gram-negative bacillus isolates, with 54% and 72% representing total coliforms, respectively. Those from the former source were Klebsiella oxytoca, Enterobacter agglomerans, and Enterobacter aerogenes and from the latter Klebsiella oxytoca, Enterobacter agglomerans, and Enterobacter cloacae, genomic group 3. Since 58% of the samples were positive using m-T7 medium it is suggested that the inclusion in standard quality control protocols should be implemented.

  18. Purification and characterization of a GH43 β-xylosidase from Enterobacter sp. identified and cloned from forest soil bacteria.

    PubMed

    Campos, Eleonora; Negro Alvarez, María José; Sabarís di Lorenzo, Gonzalo; Gonzalez, Sergio; Rorig, Marcela; Talia, Paola; Grasso, Daniel H; Sáez, Felicia; Manzanares Secades, Paloma; Ballesteros Perdices, Mercedes; Cataldi, Angel A

    2014-01-01

    The use of lignocellulosic biomass for second generation biofuels requires optimization of enzymatic breakdown of plant cell walls. In this work, cellulolytic bacteria were isolated from a native and two cultivated forest soil samples. Amplification of glycosyl hydrolases was attempted by using a low stringency-degenerate primer PCR strategy, using total soil DNA and bulk DNA pooled from positive colonies as template. A set of primers was designed based on Acidothermus cellulolyticus genome, by search of conserved domains of glycosyl hydrolases (GH) families of interest. Using this approach, a fragment containing an open reading frame (ORF) with 98% identity to a putative GH43 beta-xylosidase coding gene from Enterobacter cloacae was amplified and cloned. The full protein was expressed in Escherichia coli as N-terminal or C-terminal His-tagged fusions and purified under native conditions. Only N-terminal fusion protein, His-Xyl43, presented beta-xylosidase activity. On pNPX, optimal activity was achieved at pH 6 and 40 °C and Km and Kcat values were 2.92 mM and 1.32 seg(-1), respectively. Activity was also demonstrated on xylobiose (X2), with Km 17.8 mM and Kcat 380 s(-1). These results demonstrated that Xyl43 is a functional beta-xylosidase and it is the first evidence of this activity for Enterobacter sp.

  19. Purification and characterization of a GH43 β-xylosidase from Enterobacter sp. identified and cloned from forest soil bacteria.

    PubMed

    Campos, Eleonora; Negro Alvarez, María José; Sabarís di Lorenzo, Gonzalo; Gonzalez, Sergio; Rorig, Marcela; Talia, Paola; Grasso, Daniel H; Sáez, Felicia; Manzanares Secades, Paloma; Ballesteros Perdices, Mercedes; Cataldi, Angel A

    2014-01-01

    The use of lignocellulosic biomass for second generation biofuels requires optimization of enzymatic breakdown of plant cell walls. In this work, cellulolytic bacteria were isolated from a native and two cultivated forest soil samples. Amplification of glycosyl hydrolases was attempted by using a low stringency-degenerate primer PCR strategy, using total soil DNA and bulk DNA pooled from positive colonies as template. A set of primers was designed based on Acidothermus cellulolyticus genome, by search of conserved domains of glycosyl hydrolases (GH) families of interest. Using this approach, a fragment containing an open reading frame (ORF) with 98% identity to a putative GH43 beta-xylosidase coding gene from Enterobacter cloacae was amplified and cloned. The full protein was expressed in Escherichia coli as N-terminal or C-terminal His-tagged fusions and purified under native conditions. Only N-terminal fusion protein, His-Xyl43, presented beta-xylosidase activity. On pNPX, optimal activity was achieved at pH 6 and 40 °C and Km and Kcat values were 2.92 mM and 1.32 seg(-1), respectively. Activity was also demonstrated on xylobiose (X2), with Km 17.8 mM and Kcat 380 s(-1). These results demonstrated that Xyl43 is a functional beta-xylosidase and it is the first evidence of this activity for Enterobacter sp. PMID:23838121

  20. Enterobacter morus sp. nov., a novel Enterobacter species associated with bacterial wilt on mulberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A mulberry pathogenetic bacterial strain R18-2T isolated from the diseased mulberry root was analyzed by a polyphasic taxonomic study. Comparative 16S rRNA gene sequence analysis combined with rpoB gene sequence analysis allocated the strain R18-2T to the genus Enterobacter. The strain was Gram nega...

  1. Inorganic phosphate accumulation and cadmium detoxification in Klebsiella aerogenes NCTC 418 growing in continuous culture

    SciTech Connect

    Aiking, H.; Stijnman, A.; van Garderen, C.; van Heerikhuizen, H.; van Riet, J.

    1984-02-01

    Klebsiella aerogenes NCTC-418, growing in the presence of cadmium under glucose-, sulfate-, or phosphate-limited conditions in continuous culture, exhibits two different cadmium detoxifying mechanisms. In addition to sulfide formation, increased accumulation of P/sub i/ is demonstrated as a novel mechanism. Intracellular cadmium is always quantitatively counterbalanced by a concerted increase in both inorganic sulfide and P/sub i/ contents of the cells. This led to the conclusion that production of sulfide and accumulation of P/sub i/ are detoxification mechanisms present in K. aerogenes but that their relative importance is crucially dependent on the strain and the growth conditions employed.

  2. Use of aiiA gene amplification for AHL-lactonase production from endophytic bacterium Enterobacter species.

    PubMed

    Rajesh, P S; Rai, V Ravishankar

    2015-01-01

    AHL-lactonase has gained renewed interest due to biotechnological applications such as antiquorum sensing, antibiofilm strategies, biofouling, etc. In our study, the production of AHL-lactonase from endophytic bacteria Enterobacter aerogenes VT66 was optimized by response surface methodology (RSM) using central composite design (CCD) for four different cultural conditions. The relative activity of AHL-lactonase was correlated with amplification of aiiA homologous gene amplification with respect to cultural conditions. Statistical analysis by ANOVA of the quadratic regression model showed that the RSM model constructed is highly significant, as indicated by F-test with a low probability value (p(model) < 0.0001) and high regression coefficient (0.9997) as well as lower coefficient of variation (1.86%) indicate that suitability of variable parameters. The quadratic regression model of AHL-lactonase production in terms of relative activity was built and the optimal cultural conditions for maximum enzyme production were determined as 32.5 °C temperature, pH 7.0, 350 μM of substrate concentration and 33 h of incubation time. The enhanced AHL-lactonase yielded 1.33 fold increases in relative activity and it positively correlated with the amplification of aiiA gene. PMID:25451751

  3. Phage-mediated Shiga toxin (Stx) horizontal gene transfer and expression in non-Shiga toxigenic Enterobacter and Escherichia coli strains.

    PubMed

    Khalil, Rowaida K S; Skinner, Craig; Patfield, Stephanie; He, Xiaohua

    2016-07-01

    Enterobacter cloacae M12X01451 strain recently identified from a clinical specimen produces a new Stx1 subtype (Stx1e) that was not neutralized by existing anti-Stx1 monoclonal antibodies. Acquisition of stx by Ent. cloacae is rare and origin/stability of stx1e in M12X01451 is not known. In this study, we confirmed the ability of Stx1a- and Stx1e-converting phages from an Escherichia coli O157:H7 strain RM8530 and M12X01451 respectively to infect several E. coli and Ent. cloacae strains. stx1e was detected in 97.5% and 72.5% of progenies of strains lysogenized by stx1e phage after 10 (T10) and 20 (T20) subcultures, versus 65% and 17.5% for stx1a gene. Infection of M12X01451 and RM8530 with each other's phages generated double lysogens containing both phages. stx1a was lost after T10, whereas the stx1e was maintained even after T20 in M12X01451 lysogens. In RM8530 lysogens, the acquired stx1e was retained with no mutations, but 20% of stx1a was lost after T20 ELISA and western blot analyses demonstrated that Stx1e was produced in all strains lysogenized by stx1e phage; however, Stx1a was not detected in any lysogenized strain. The study results highlight the potential risks of emerging Stx-producing strains via bacteriophages either in the human gastrointestinal tract or in food production environments, which are matters of great concern and may have serious impacts on human health.

  4. Induction by Klebsiella aerogenes of a Melanin-Like Pigment in Cryptococcus neoformans

    PubMed Central

    Frases, Susana; Chaskes, Stuart; Dadachova, Ekaterina; Casadevall, Arturo

    2006-01-01

    While studying the interaction of Cryptococcus neoformans with Dictyostelium discoideum, we noticed that yeast colonies in agar with a feeder lawn of Klebsiella aerogenes were brown. This finding was intriguing because C. neoformans colonies are not pigmented unless they are provided with precursors for melanization. Strains of all C. neoformans serotypes produced brown pigment in response to K. aerogenes at 22, 30, and 37°C. Pigment production required fungal laccase and was suppressed by high concentrations of glucose. Treatment of brown cells with guanidinium isothiocyanate and hot concentrated HCl yielded particulate material that had the physical and chemical characteristics of melanins. No pigment formation was observed when C. neoformans was exposed to live Escherichia coli or heat-killed K. aerogenes. Analysis of K. aerogenes supernatants revealed the presence of dopamine, which can be a substrate for melanin synthesis by C. neoformans. Our findings illustrate a remarkable interaction between a pathogenic fungus and a gram-negative bacterium, in which the bacterium produces a substrate that promotes fungal melanization. This observation provides a precedent that could explain the source of a substrate for C. neoformans melanization in the environment. PMID:16461709

  5. Induction by Klebsiella aerogenes of a melanin-like pigment in Cryptococcus neoformans.

    PubMed

    Frases, Susana; Chaskes, Stuart; Dadachova, Ekaterina; Casadevall, Arturo

    2006-02-01

    While studying the interaction of Cryptococcus neoformans with Dictyostelium discoideum, we noticed that yeast colonies in agar with a feeder lawn of Klebsiella aerogenes were brown. This finding was intriguing because C. neoformans colonies are not pigmented unless they are provided with precursors for melanization. Strains of all C. neoformans serotypes produced brown pigment in response to K. aerogenes at 22, 30, and 37 degrees C. Pigment production required fungal laccase and was suppressed by high concentrations of glucose. Treatment of brown cells with guanidinium isothiocyanate and hot concentrated HCl yielded particulate material that had the physical and chemical characteristics of melanins. No pigment formation was observed when C. neoformans was exposed to live Escherichia coli or heat-killed K. aerogenes. Analysis of K. aerogenes supernatants revealed the presence of dopamine, which can be a substrate for melanin synthesis by C. neoformans. Our findings illustrate a remarkable interaction between a pathogenic fungus and a gram-negative bacterium, in which the bacterium produces a substrate that promotes fungal melanization. This observation provides a precedent that could explain the source of a substrate for C. neoformans melanization in the environment.

  6. The new species Enterobacter oryziphilus sp. nov. and Enterobacter oryzendophyticus sp. nov. are key inhabitants of the endosphere of rice

    PubMed Central

    2013-01-01

    Background Six independent Gram-negative, facultatively anaerobic, non-spore-forming, nitrogen-fixing rod-shaped isolates were obtained from the root endosphere of rice grown at the International Rice Research Institute (IRRI) and investigated in a polyphasic taxonomic study. Results The strains produced fatty acid patterns typical for members of the family Enterobacteriaceae. Comparative sequence analyses of the 16S rRNA as well as rpoB genes allocated the strains to two well-defined groups within the genus Enterobacter, family Enterobacteriaceae. The analyses indicated Enterobacter radicincitans, Enterobacter arachidis and Enterobacter oryzae to be the closest related species. An RpoB (translated) protein comparison supported the placement in the genus Enterobacter and the relatedness of our isolates to the aforementioned species. Genomic DNA:DNA hybridization analyses and biochemical analyses provided further evidence that the novel strains belong to two new species within the genus Enterobacter. The two species can be differentiated from each other and from existing enteric species by acid production from L-rhamnose and D-melibiose, decarboxylation of ornithine and utilization of D-alanine, D-raffinose L-proline and L-aspartic acid, among other characteristics. Members of both species revealed capacities to colonise rice roots, including plant-growth-promoting capabilities such as an active supply of fixed nitrogen to the plant and solubilisation of inorganic phosphorus, next to traits allowing adaptation to the plant. Conclusions Two novel proposed enterobacterial species, denominated Enterobacter oryziphilus sp. nov. (type strain REICA_142T=LMG 26429T=NCCB 100393T) and Enterobacter oryzendophyticus sp. nov. (type strain REICA_082T=LMG 26432T =NCCB 100390T) were isolated from rice roots. Both species are capable of promoting rice growth by supplying nitrogen and phosphorus. PMID:23865888

  7. Biohydrogen production by co-fermentation of crude glycerol and apple pomace hydrolysate using co-culture of Enterobacter aerogenes and Clostridium butyricum.

    PubMed

    Pachapur, Vinayak Laxman; Sarma, Saurabh Jyoti; Brar, Satinder Kaur; Le Bihan, Yann; Buelna, Gerardo; Verma, Mausam

    2015-10-01

    Co-substrate utilization of various wastes with complementary characteristics can provide a complete medium for higher hydrogen production. This study evaluated potential of apple pomace hydrolysate (APH) co-fermented with crude glycerol (CG) for increased H2 production and decreased by-products formation. The central composite design (CCD) along with response surface methodology (RSM) was used as tool for optimization and 15 g/L of CG, 5 g/L of APH and 15% (v/v) inoculum were found to be optimum to produce as high as 26.07 ± 1.57 mmol H2/L of medium. The p-value of 0.0017 indicated that APH at lower concentration had a significant effect on H2 production. By using CG as sole carbon source, reductive pathway of glycerol metabolism was favored with 19.46 mmol H2/L. However, with APH, oxidative pathway was favored with higher H2 production (26.07 ± 1.57 mmol/L) and decrease in reduced by-products (1,3-propanediol and ethanol) formation. APH inclusion enhanced H2 production, and decreased substrate inhibition. PMID:26142996

  8. Nanoparticles functionalized with ampicillin destroy multiple-antibiotic-resistant isolates of Pseudomonas aeruginosa and Enterobacter aerogenes and methicillin-resistant Staphylococcus aureus.

    PubMed

    Brown, Ashley N; Smith, Kathryn; Samuels, Tova A; Lu, Jiangrui; Obare, Sherine O; Scott, Maria E

    2012-04-01

    We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nanoparticles (AuNP) were antimicrobial only when ampicillin was bound to their surfaces. Both AuNP and AgNP functionalized with ampicillin were effective broad-spectrum bactericides against Gram-negative and Gram-positive bacteria. Most importantly, when AuNP and AgNP were functionalized with ampicillin they became potent bactericidal agents with unique properties that subverted antibiotic resistance mechanisms of multiple-drug-resistant bacteria.

  9. Biohydrogen production by co-fermentation of crude glycerol and apple pomace hydrolysate using co-culture of Enterobacter aerogenes and Clostridium butyricum.

    PubMed

    Pachapur, Vinayak Laxman; Sarma, Saurabh Jyoti; Brar, Satinder Kaur; Le Bihan, Yann; Buelna, Gerardo; Verma, Mausam

    2015-10-01

    Co-substrate utilization of various wastes with complementary characteristics can provide a complete medium for higher hydrogen production. This study evaluated potential of apple pomace hydrolysate (APH) co-fermented with crude glycerol (CG) for increased H2 production and decreased by-products formation. The central composite design (CCD) along with response surface methodology (RSM) was used as tool for optimization and 15 g/L of CG, 5 g/L of APH and 15% (v/v) inoculum were found to be optimum to produce as high as 26.07 ± 1.57 mmol H2/L of medium. The p-value of 0.0017 indicated that APH at lower concentration had a significant effect on H2 production. By using CG as sole carbon source, reductive pathway of glycerol metabolism was favored with 19.46 mmol H2/L. However, with APH, oxidative pathway was favored with higher H2 production (26.07 ± 1.57 mmol/L) and decrease in reduced by-products (1,3-propanediol and ethanol) formation. APH inclusion enhanced H2 production, and decreased substrate inhibition.

  10. Characterization of extended-spectrum β-lactamase (ESBL)-producing Klebsiella, Enterobacter, and Citrobacter obtained in environmental samples of a Tunisian hospital.

    PubMed

    Dziri, Raoudha; Klibi, Naouel; Alonso, Carla Andrea; Said, Leila Ben; Bellaaj, Ridha; Slama, Karim Ben; Boudabous, Abdellatif; Torres, Carmen

    2016-10-01

    The assessment of the hospital environment as a reservoir of ESBL-producing Enterobacteriaceae in Tunisian hospitals is scarcely analyzed, except for Escherichia coli. The aim of this study was to evaluate the presence of ESBL-producing non-E. coli Enterobacteriaceae (ESBL-EbNoEc) in 300 samples of abiotic surfaces and the hands of patients and staff of a Tunisian Hospital, and to characterize the ESBL genes of the recovered isolates. ESBL-EbNoEc were recovered in 28 of 300 (9.3%) analyzed samples and were identified as Klebsiella pneumoniae (n= 11), Enterobacter cloacae (n=11), Citrobacter freundii (n=4) and Klebsiella oxytoca (n=2). The bla genes identified by PCR and sequencing among the strains were as follows: 11 K.pneumoniae strains [blaCTX-M-15+ blaTEM-1+ blaSHV-11 (n=6); blaCTX-M-15+ blaTEM-1+ blaSHV-28 (n=3); blaCTX-M-15+ blaTEM-1+ blaSHV-1 (n=2)], 11 E. cloacae strains [blaCTX-M-15 (n=6); blaCTX-M-15+ blaTEM-1b (n=2); blaCTX-M-15+ blaTEM-1b+ blaOXA-1 (n=1);blaCTX-M-15+ blaOXA-1 (n=1);blaSHV-12 (n=1)], 4 C. freundii strains [blaCTX-M-15] and 2 K. oxytoca strains [blaCTX-M-15 (n=1); blaSHV-12 (n=1)]. The ISEcp1 and orf477 sequences were identified upstream and downstream of the blaCTX-M-15 gene, respectively, in 3 K. pneumoniae and 3 E. cloacae isolates. The PFGE analysis demonstrated three unrelated pulsotypes in K. pneumoniae strains and five pulsotypes in E. cloacae. The uncontrolled dissemination of ESBL-producing bacteria, even in the hospital environment, has become a real problem and new strategies and hygienic rules are needed to stop this bacterial dissemination. PMID:27492133

  11. Congenital cloaca: Long-term follow-up results with emphasis on outcomes beyond childhood.

    PubMed

    Rintala, Risto J

    2016-04-01

    Persistent cloaca remains a challenge for pediatric surgeons and urologists. Reconstructive surgery of cloacal malformations aims to repair the anorectum, urinary tract, and genital organs, and achieve fecal and urinary continence as well as functional genital tract capable for sexual activity and pregnancy. Unfortunately, even in most experienced hands these goals are not always accomplished. The endpoint of the functional development of bowel, urinary, and genital functions is the completion of patient's growth and sexual maturity. It is unlikely that there will be any significant functional improvement beyond these time points. About half of the patients with cloaca attain fecal and urinary continence after their growth period. The remaining half stay clean or dry by adjunctive measures such as bowel management by enemas or ACE channel, and continent urinary diversion or intermittent catheterization. Problems related to genital organs such as obstructed menstruations, amenorrhea, and introitus stenosis are common and often require secondary surgery. Encouragingly, most adolescent and adult patients are capable of sexual life despite often complex vaginal primary and secondary reconstructions. Also, cloacal malformation does not preclude pregnancies, although they still are quite rare. Pregnant patients with cloaca require special care and follow-up to guarantee uncomplicated pregnancy and preservation of anorectal and urinary functions. Cesarean section is recommended for cloaca patients. The self-reported quality of life of cloaca patients appears to be comparable to that of female patients with less complex anorectal malformations. PMID:26969236

  12. Is Aerogen-π Interaction Capable of Initiating the Noncovalent Chemistry of Group 18?

    PubMed

    Miao, Junjian; Song, Bo; Gao, Yi

    2015-12-01

    The interactions between atoms of noble gases and π systems are generally considered as van der Waals interaction, which have not attracted attention yet. Herein, we present high-level ab initio calculations to show the unexpected noncovalent interaction between a covalently bonded noble gas atom and a delocalized aromatic π electron using XeO3⋅benzene as the prototype. The CCSD(T)/CBS reference data show its strength amounting to -10.2 kcal mol(-1), comparable to a typical H-bond or an anion-π interaction. The energy decomposition analysis reveals that the aerogen-π interaction is favored by the electrostatic interaction (27.7%), the induction (13.4%), and the dispersion (21.6%). This interaction may prompt us to consider the noncovalent chemistry of aerogen derivatives in the near future. PMID:26282579

  13. Enhanced Aerogen-π Interaction by a Cation-π Force.

    PubMed

    Miao, Junjian; Song, Bo; Gao, Yi

    2016-02-18

    The interaction between a noble gas atom and an aromatic π-electron system, which mainly originates from the London dispersion force, is very weak and has not attracted enough attention yet. Herein, we reported a type of notably enhanced aerogen-π interaction between cation-π systems and noble gas atoms. The binding strength of a divalent cation-π system with a xenon atom is comparable to a moderate hydrogen bond (up to ca. 7 kcal mol(-1)), whereas krypton and argon atoms produce slightly weaker interactions. Energy-decomposition analysis reveals that the induction interaction is responsible for the stabilization of divalent cation-π⋅Xe species besides the dispersion interaction. Our results might be helpful to increase the understanding of some unsolved mysteries of aerogens. PMID:26699400

  14. Is Aerogen-π Interaction Capable of Initiating the Noncovalent Chemistry of Group 18?

    PubMed

    Miao, Junjian; Song, Bo; Gao, Yi

    2015-12-01

    The interactions between atoms of noble gases and π systems are generally considered as van der Waals interaction, which have not attracted attention yet. Herein, we present high-level ab initio calculations to show the unexpected noncovalent interaction between a covalently bonded noble gas atom and a delocalized aromatic π electron using XeO3⋅benzene as the prototype. The CCSD(T)/CBS reference data show its strength amounting to -10.2 kcal mol(-1), comparable to a typical H-bond or an anion-π interaction. The energy decomposition analysis reveals that the aerogen-π interaction is favored by the electrostatic interaction (27.7%), the induction (13.4%), and the dispersion (21.6%). This interaction may prompt us to consider the noncovalent chemistry of aerogen derivatives in the near future.

  15. New monoclonal antibodies against a novel subtype of Shiga toxin 1 produced by Enterobacter cloacae and their use in analysis of human serum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin (Stx) is a major virulence factor for several bacterial pathogens that cause potentially fatal illness, including Escherichia coli and Shigella spp. The continual emergence of new subtypes of Stxs presents challenges in clinical diagnosis of infections caused by Shiga toxin-producing org...

  16. Anthranilate synthase/anthranilate 5-phosphoribosyl 1-pyrophosphate phosphoribosyltransferase from Aerobacter aerogenes

    PubMed Central

    Egan, A. F.; Gibson, F.

    1972-01-01

    1. Anthranilate synthase and phosphoribosyltransferase from Aerobacter aerogenes purify simultaneously and sediment together on sucrose gradients, showing that they occur as an enzyme aggregate. Both activities of the intact aggregate are subject to inhibition by tryptophan. 2. By using appropriate auxotrophic mutants it was shown that an intact active enzyme aggregate is formed when the components come from separate mutant strains. An intact active aggregate can also be formed when one component is from Escherichia coli and the other from A. aerogenes. 3. Phosphoribosyltransferase of A. aerogenes is active when not in an aggregate with anthranilate synthase, but is not subject to tryptophan inhibition, indicating that the inhibitor site is on the anthranilate synthase component. 4. Anthranilate synthase can be active and sensitive to tryptophan inhibition when complexed with an inactive phosphoribosyltransferase. 5. Kinetic studies on the anthranilate synthase activity show that tryptophan is a competitive inhibitor with respect to chorismate and a non-competitive inhibitor with respect to either glutamine or NH4+ ions. This is consistent with a sequential mechanism of the ordered type in which chorismate is the first reactant. PMID:4352716

  17. Complete Genome Sequence of a Clinical Isolate of Enterobacter asburiae

    PubMed Central

    Liu, Feng; Yang, Jian; Xiao, Yan; Li, Li; Jin, Qi

    2016-01-01

    We report here the complete genome sequence of Enterobacter asburiae strain ENIPBJ-CG1, isolated from a bone marrow transplant patient. The size of the genome sequence is approximately 4.65 Mb, with a G+C content of 55.76%, and it is predicted to contain 4,790 protein-coding genes. PMID:27284137

  18. Cloaca, the most severe degree of imperforate anus: experience with 195 cases.

    PubMed Central

    Hendren, W H

    1998-01-01

    OBJECTIVE: To provide a follow-up of 195 patients with cloacal malformations seen by the author from 1959 to 1998. SUMMARY BACKGROUND DATA: Cloaca, which occurs in approximately 1 of 50,000 births, is the most complex type of imperforate anus with confluence of the rectum, vagina, and bladder in a urogenital sinus. Functional results for the bowel, the genital tract, and the urinary tract were formerly poor. Cloacal exstrophy, which is an even more complex spectrum of malformations, was uniformly fatal until 1960. In addition to imperforate anus, these babies have an omphalocele, two exstrophic bladders, between which there is an open cecum, and a blindly ending colon hanging down in the pelvis from the cecum. Although both of these diagnoses contain the word "cloaca," which is Latin for sewer, they are really two separate entities in terms of surgical management. Cloaca and cloacal exstrophy in most cases are very different anatomic problems. However, there are variants that are like a hybrid, which is the rationale for reporting together an experience with both entities. METHODS: Records were reviewed of 154 patients with cloaca and 41 patients with cloacal exstrophy to assess anorectal function, urinary continence, and sexual function where available. RESULTS: Follow-up was available in 141 cloaca patients: 82 have spontaneous bowel movements and satisfactory control, 38 use enemas to evacuate, 9 have a colostomy, 7 have fecal soiling, and 5 are too recently operated to evaluate. Regarding urinary control, 83 void spontaneously, 40 catheterize to empty, 4 have urinary diversion, 1 has a continent diversion, 5 patients are wet, and 8 are too recently operated to judge. Twenty-four patients are now adults, 17 of who have experienced coitus and 7 have not. Seven have had babies, all except one by cesarean section. Results of surgery for cloacal exstrophy are not as good, but are encouraging nonetheless for an anomaly that was uniformly fatal before 1960. Of the 41

  19. Characterization of PaxA and Its Operon: a Cohemolytic RTX Toxin Determinant from Pathogenic Pasteurella aerogenes

    PubMed Central

    Kuhnert, Peter; Heyberger-Meyer, Bénédicte; Nicolet, Jacques; Frey, Joachim

    2000-01-01

    Pasteurella aerogenes is known as a commensal bacterium or as an opportunistic pathogen, as well as a primary pathogen found to be involved in abortion cases of humans, swine, and other mammals. Using broad-range DNA probes for bacterial RTX toxin genes, we cloned and subsequently sequenced a new operon named paxCABD encoding the RTX toxin PaxA in P. aerogenes. The pax operon is organized analogous to the classical RTX operons containing the activator gene paxC upstream of the structural toxin gene paxA, which is followed by the secretion protein genes paxB and paxD. The highest sequence similarity of paxA with known RTX toxin genes is found with apxIIIA (82%). PaxA is structurally similar to ApxIIIA and also shows functional analogy to ApxIIIA, since it shows cohemolytic activity with the sphingomyelinase of Staphylococcus aureus, known as the CAMP effect, but is devoid of direct hemolytic activity. In addition, it shows to some extent immunological cross-reactions with ApxIIIA. P. aerogenes isolated from various specimens showed that the pax operon was present in about one-third of the strains. All of the pax-positive strains were specifically related to swine abortion cases or septicemia of newborn piglets. These strains were also shown to produce the PaxA toxin as determined by the CAMP phenomenon, whereas none of the pax-negative strains did. This indicated that the PaxA toxin is involved in the pathogenic potential of P. aerogenes. The examined P. aerogenes isolates were phylogenetically analyzed by 16S rRNA gene (rrs) sequencing in order to confirm their species. Only a small heterogeneity (<0.5%) was observed between the rrs genes of the strains originating from geographically distant farms and isolated at different times. PMID:10603361

  20. Production of gluconic acid and 2-ketogluconic acid by Klebsiella aerogenes NCTA 418.

    PubMed

    Neijssel, O M; Tempest, D W

    1975-10-27

    2-Ketogluconic acid and, to a lesser extent, gluconic acid were found to be major products of glucose catabolism by phosphate-limited cultures of Klebsiella aerogenes NCTC 418, and together accounted for up to 46% of the glucose carbon that was metabolized. Although the concentrations of both acids increased substantially at low growth rates, their specific rates of synthesis decreased markedly, ad did the proportion of glucose converted into these products. Determination of the affinity constant, for glucose, of phosphate-limited organisms showed it ot be not significantly different from that of glucose-limited organisms (KS less than or equal to 50 muM), indicative of the phosphotransferase uptake system. And since these organisms possessed an active glucose 6-phosphate dehydrogenase, and had no detectable glucose dehydrogenase activity, it was concluded that gluconic acid and 2-keto-gluconic acid arose from their corresponding phosphorylated metabolites, and not directly from glucose.

  1. Biodegradation of dichlorodiphenyltrichloroethane: intermediates in dichlorodiphenylacetic acid metabolism by aerobacter aerogenes

    USGS Publications Warehouse

    Wedemeyer, Gary

    1967-01-01

    The final product of dichlorodiphenyltrichloroethane (DDT) degradation by vertebrates is commonly considered to be dichlorodiphenylacetic acid, DDA. Recently, certain organisms have been found to degrade further DDA to dichlorobenzophenone (DBP), but the possibility that such degradation was due to microbial action could not be excluded. Significantly, dichlorobenzhydrol (DBH), dichlorophenylmethane (DPM), and dichlorodiphenylethylene (DDE) have been tentatively identified in rats fed DDA. Since DDA as well as DDT is degraded by the ubiquitous microorganism Aerobacter aerogenes, it seemed reasonable that the intestinal microflora might be involved in DBP formation, DPM and DBH being intermediates in its pathway from DDA. Since DDA is a (3,y-unsaturated acid, ketone formation via an alkene and an alcohol would be expected.

  2. Diffusely infiltrated lymphoid areas of the bursa of Fabricius (DIA) and of the cloaca: an embryological study with morphological analogies.

    PubMed Central

    Dolfi, A; Lupetti, M; Bianchi, F; Michelucci, S

    1988-01-01

    The aim of the present experiment was to verify whether the origin of the DIA is ectodermal or endodermal. A rabbit serum against the epithelial cells of the final portion of the cloaca was prepared. The indirect immunofluorescence method was applied to strips obtained with a cryostat, carefully cut in such a way as to include a part of the cloaca, the burso-cloacal stalk, the DIA, and the bursal plicae. In this way, it was possible to demonstrate that the epithelium of the cloaca, of the burso-cloacal stalk, and of the DIA exhibited an intense fluorescence that could not be observed at the level of the epithelium of the bursal plicae. These findings would appear to indicate that the DIA, like the cloaca and the burso-cloacal stalk, is ectodermal in origin. Furthermore, histological study revealed that the DIA exhibits close structural analogies with the dorsal wall of the cloaca. In both areas, unorganized lymphoid infiltrations of the tunica propria can be seen, and the epithelium does not show any follicle-associated epithelial cells. The glands often assume the aspect of dilated crypts containing intestinal transit material. The epithelium of these glands reveals lymphoid infiltrations at various points, and it is not uncommon to detect accumulations of cells in their lumina. Several groups of eosinophilic granulocytes can also be observed in the tunica propria of these two areas, with a clear predominance at the level of the DIA. These similarities between the cloaca and the DIA might lead one to suppose the existence of a functional as well as a morphological correspondence. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 PMID:3417544

  3. Exploring "aerogen-hydride" interactions between ZOF2 (Z = Kr, Xe) and metal hydrides: An ab initio study

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba

    2016-06-01

    In this work, a new σ-hole interaction formed between ZOF2 (Z = Kr and Xe) as the Lewis acid and a series of metal-hydrides HMX (M = Be, Mg, Zn and X = H, F, CN, CH3) is reported. The nature of this interaction, called "aerogen-hydride" interaction, is unveiled by molecular electrostatic potential, non-covalent interaction, quantum theory of atoms in molecules and natural bond orbital analyses. Our results indicate that the aerogen-hydride interactions are quite strong and can be comparable in strength to other σ-hole bonds. An important charge-transfer interaction is also associated with the formation of OF2Z⋯HMX complexes.

  4. Complete genome sequence of “Enterobacter lignolyticus” SCF1

    SciTech Connect

    DeAngelis, Kristen M.; D'Haeseleer, Patrik; Chivian, Dylan; Fortney, Julian L.; Khudyakov, Jane I.; Simmons, Blake A.; Woo, Hannah; Arkin, Adam P.; Davenport, Karen W.; Goodwin, Lynne A.; Chen, Amy; Ivanova, Natalia; Kyrpides, Nikos C.; Mavromatis, Konstantinos; Woyke, Tanja; Hazen, Terry C.

    2011-09-23

    In an effort to discover anaerobic bacteria capable of lignin degradation, we isolated 'Ente-robacter lignolyticus' SCF1 on minimal media with alkali lignin as the sole source of carbon. This organism was isolated anaerobically from tropical forest soils collected from the Short Cloud Forest site in the El Yunque National Forest in Puerto Rico, USA, part of the Luquillo Long-Term Ecological Research Station. At this site, the soils experience strong fluctuations in redox potential and are net methane producers. Because of its ability to grow on lignin anae-robically, we sequenced the genome. The genome of 'E. lignolyticus' SCF1 is 4.81 Mbp with no detected plasmids, and includes a relatively small arsenal of lignocellulolytic carbohy-drate active enzymes. Lignin degradation was observed in culture, and the genome revealed two putative laccases, a putative peroxidase, and a complete 4-hydroxyphenylacetate degra-dation pathway encoded in a single gene cluster.

  5. Generation of Enterobacter sp. YSU Auxotrophs Using Transposon Mutagenesis

    PubMed Central

    Caguiat, Jonathan James

    2014-01-01

    Prototrophic bacteria grow on M-9 minimal salts medium supplemented with glucose (M-9 medium), which is used as a carbon and energy source. Auxotrophs can be generated using a transposome. The commercially available, Tn5-derived transposome used in this protocol consists of a linear segment of DNA containing an R6Kγ replication origin, a gene for kanamycin resistance and two mosaic sequence ends, which serve as transposase binding sites. The transposome, provided as a DNA/transposase protein complex, is introduced by electroporation into the prototrophic strain, Enterobacter sp. YSU, and randomly incorporates itself into this host’s genome. Transformants are replica plated onto Luria-Bertani agar plates containing kanamycin, (LB-kan) and onto M-9 medium agar plates containing kanamycin (M-9-kan). The transformants that grow on LB-kan plates but not on M-9-kan plates are considered to be auxotrophs. Purified genomic DNA from an auxotroph is partially digested, ligated and transformed into a pir+ Escherichia coli (E. coli) strain. The R6Kγ replication origin allows the plasmid to replicate in pir+ E. coli strains, and the kanamycin resistance marker allows for plasmid selection. Each transformant possesses a new plasmid containing the transposon flanked by the interrupted chromosomal region. Sanger sequencing and the Basic Local Alignment Search Tool (BLAST) suggest a putative identity of the interrupted gene. There are three advantages to using this transposome mutagenesis strategy. First, it does not rely on the expression of a transposase gene by the host. Second, the transposome is introduced into the target host by electroporation, rather than by conjugation or by transduction and therefore is more efficient. Third, the R6Kγ replication origin makes it easy to identify the mutated gene which is partially recovered in a recombinant plasmid. This technique can be used to investigate the genes involved in other characteristics of Enterobacter sp. YSU or of a

  6. Kinetic characterization of a novel acid ectophosphatase from Enterobacter asburiae.

    PubMed

    Sato, Vanessa Sayuri; Galdiano Júnior, Renato F; Rodrigues, Gisele Regina; Lemos, Eliana G M; Pizauro Junior, João Martins

    2016-02-01

    Expression of acid ectophosphatase by Enterobacter asburiae, isolated from Cattleya walkeriana (Orchidaceae) roots and identified by the 16S rRNA gene sequencing analysis, was strictly regulated by phosphorus ions, with its optimal activity being observed at an inorganic phosphate concentration of 7 mM. At the optimum pH 3.5, intact cells released p-nitrophenol at a rate of 350.76 ± 13.53 nmol of p-nitrophenolate (pNP)/min/10(8) cells. The membrane-bound enzyme was obtained by centrifugation at 100,000 × g for 1 h at 4 °C. p-Nitrophenylphosphate (pNPP) hydrolysis by the enzyme follows "Michaelis-Menten" kinetics with V = 61.2 U/mg and K0.5 = 60 μM, while ATP hydrolysis showed V = 19.7 U/mg, K0.5 = 110 μM, and nH = 1.6 and pyrophosphate hydrolysis showed V = 29.7 U/mg, K0.5 = 84 μM, and nH = 2.3. Arsenate and phosphate were competitive inhibitors with K i = 0.6 mM and K i = 1.8 mM, respectively. p-Nitrophenyl phosphatase (pNPPase) activity was inhibited by vanadate, while p-hydroxymercuribenzoate, EDTA, calcium, copper, and cobalt had no inhibitory effects. Magnesium ions were stimulatory (K0.5 = 2.2 mM and nH = 0.5). Production of an acid ectophosphatase can be a mechanism for the solubilization of mineral phosphates by microorganisms such as Enterobacter asburiae that are versatile in the solubilization of insoluble minerals, which, in turn, increases the availability of nutrients for plants, particularly in soils that are poor in phosphorus. PMID:26832666

  7. Isolation of Cronobacter spp. (Enterobacter Sakazakii) from Artisanal Mozzarella

    PubMed Central

    Rippa, Paola; Battaglia, Luciana; Parisi, Nicola

    2014-01-01

    Cronobacter spp. (Enterobacter sakazakii) is an opportunistic bacterial pathogen capable of causing disease and even fatalities in newborn infants within the first weeks of life if consumed as part of the diet. Premature and immunocompromised newborn infants are at particular risk. The microorganism has been isolated from a variety of foods including contaminated infant milk formula powder and milk powder substitute. The study aimed to evaluate the level of microbiological contamination in 47 samples of mozzarella cheese made with cow’s milk collected from artisan cheese producers in Southern Italy. Samples were collected from commercial sales points and underwent qualitative and quantitative microbiological analyses to test for the bacterial contaminants most commonly found in milk and cheese products. The 47 samples underwent qualitative and quantitative microbiological tests according to ISO UNI EN standards. Analyses focused on Staphylococcus aures, Salmonella spp., Listeria monocytogenes, Pseudomonas spp., E. coli, Yersinia spp., total coliforms and Cronobacter sakazakii. The ISO/TS 22964:2006 method was used to investigate possible contamination by C. sakazakii. Biochemical identification was carried out using an automated system for identification and susceptibility tests. None of the samples examined resulted positive for Salmonella spp. or Listeria spp. Only one sample resulted positive for Staphylococcus aureus. Pseudomonas spp. was isolated in 10 (21%) of 47 samples. High levels of total coliforms were found in 10 of 47 samples. Cronobacter spp. (Enterobacter sakazakii) was isolated in one sample. This is the first study to confirm isolation of C. sakazakii in artisan mozzarella cheese made from cow’s milk. The presence of C. sakazakii could be related to external contamination during the phases of production or to the use of contaminated milk. Since mozzarella is recommended in the diet of children and adults of all ages, this present study helps

  8. Regulation of glutamine synthetase, aspartokinase, and total protein turnover in Klebsiella aerogenes.

    PubMed

    Fulks, R M; Stadtman, E R

    1985-12-13

    When suspensions of Klebsiella aerogenes are incubated in a nitrogen-free medium there is a gradual decrease in the levels of acid-precipitable protein and of aspartokinase III (lysine-sensitive) and aspartokinase I (threonine-sensitive) activities. In contrast, the level of glutamine synthetase increases slightly and then remains constant. Under these conditions, the glutamine synthetase and other proteins continue to be synthesized as judged by the incorporation of [14C]leucine into the acid-precipitable protein fraction and into protein precipitated by anti-glutamine synthetase antibodies, by the fact that growth-inhibiting concentrations of chloramphenicol also inhibit the incorporation of [14C]leucine into protein and into protein precipitated by anti-glutamine synthetase antibody, and by the fact that chloramphenicol leads to acceleration in the loss of aspartokinases I and III and promotes a net decrease in the level of glutamine synthetase and its cross-reactive protein. The loss of aspartokinases I and III in cell suspensions is stimulated by glucose and is inhibited by 2,4-dinitrophenol. Glucose also stimulates the loss of aspartokinases and glutamine synthetase in the presence of chloramphenicol. Cell-free extracts of K. aerogenes catalyze rapid inactivation of endogenous glutamine synthetase as well as exogenously added pure glutamine synthetase. This loss of glutamine synthetase is not associated with a loss of protein that cross-reacts with anti-glutamine synthetase antibodies. The inactivation of glutamine synthetase in extracts is not due to adenylylation. It is partially prevented by sulfhydryl reagents, Mn2+, antimycin A, 2,4-dinitrophenol, EDTA, anaerobiosis and by dialysis. Following 18 h dialysis, the capacity of extracts to catalyze inactivation of glutamine synthetase is lost but can be restored by the addition of Fe2+ (or Ni2+) together with ATP (or other nucleoside di- and triphosphates. After 40-60 h dialysis Fe3+ together with NADH (but

  9. Aerogenic vaccination with a Burkholderia mallei auxotroph protects against aerosol-initiated glanders in mice.

    PubMed

    Ulrich, Ricky L; Amemiya, Kei; Waag, David M; Roy, Chad J; DeShazer, David

    2005-03-14

    Burkholderia mallei is an obligate mammalian pathogen that causes the zoonotic disease glanders. Two live attenuated B. mallei strains, a capsule mutant and a branched-chain amino acid auxotroph, were evaluated for use as vaccines against aerosol-initiated glanders in mice. Animals were aerogenically vaccinated and serum samples were obtained before aerosol challenge with a high-dose (>300 times the LD50) of B. mallei ATCC 23344. Mice vaccinated with the capsule mutant developed a Th2-like Ig subclass antibody response and none survived beyond 5 days. In comparison, the auxotrophic mutant elicited a Th1-like Ig subclass antibody response and 25% of the animals survived for 1 month postchallenge. After a low-dose (5 times the LD50) aerosol challenge, the survival rates of auxotroph-vaccinated and unvaccinated animals were 50 and 0%, respectively. Thus, live attenuated strains that promote a Th1-like Ig response may serve as promising vaccine candidates against aerosol infection with B. mallei.

  10. Purification, characterization, and in vivo reconstitution of Klebsiella aerogenes urease apoenzyme.

    PubMed Central

    Lee, M H; Mulrooney, S B; Hausinger, R P

    1990-01-01

    Urease was purified from recombinant Klebsiella aerogenes which was grown in the absence of nickel. The protein was inactive and contained no transition metals, yet it possessed the same heteropolymeric structure as native enzyme, demonstrating that Ni is not required for intersubunit association. Ni did, however, substantially increase the stability of the intact metalloprotein (Tm = 79 degrees C) compared with apoenzyme (Tm = 62 degrees C), as revealed by differential scanning calorimetric analysis. An increased number of histidine residues were accessible to diethyl pyrocarbonate in apourease compared with holoenzyme, consistent with possible Ni ligation by histidinyl residues. Addition of Ni to purified apourease did not yield active enzyme; however, urease apoenzyme was very slowly activated in vivo by addition of Ni ions to Ni-free cell cultures, even after treatment of the cells with spectinomycin to inhibit protein synthesis. In contrast, sonicated cells and cells treated with dinitrophenol or dicyclohexylcarbodiimide were incapable of activating apourease. These results indicate that apourease activation is an energy-dependent process that is destroyed by cell disruption. PMID:2142939

  11. Growth and heavy metal removal by Klebsiella aerogenes at different pH and temperature

    SciTech Connect

    Al-Shahwani, M.F.; Jazrawi, S.F.; Al-Rawi, E.H.; Ayar, N.S.

    1984-01-01

    A strain of Klebsiella aerogenes isolated from Rustamiyah Station for treatment of wastewater was examined for its ability to grow in a media supplemented with maximum tolerance concentrations of Pb/sup + +/, Zn/sup + +/, Ni/sup + +/, and Cd/sup + +/, separately, at different temperatures and initial pH. The results indicated that at 28/sup 0/C during the first 24 hr, Pb/sup + +/ and Ni/sup + +/ had no effect on the growth of the bacteria, while the presence of Zn/sup + +/ and Cd/sup + +/ decreased the cell count. The growth reached a maximum level after the second day and started to decrease gradually. The bacterial count at 37/sup 0/C was less than that at 28/sup 0/C. No bacterial multiplication occurred at 44/sup 0/C. There was little difference between heavy metal removal at 28 and 37/sup 0/C. At 44/sup 0/C, little removal took place. In general, slightly acidic or neutral medium was better for both bacterial growth and metal removal.

  12. Detoxification of mercury, cadmium, and lead in Klebsiella aerogenes NCTC 418 growing in continuous culture

    SciTech Connect

    Aiking, H.; Govers, H.; van 'T Riet, J.

    1985-11-01

    Klebsiella aerogenes NCTC 418 growing in the presence of cadmium under glucose-, sulfate-, or phosphate-limited conditions in continuous culture exhibited sulfide formation and P/sub i/ accumulation as the only demonstrable detoxification mechanisms. In the presence of mercury under similar conditions only HgS formation could be confirmed, by an increased sensitivity to mercury under sulfate-limited conditions, among others. The fact that the cells were most sensitive to cadmium under conditions of phosphate limitation and most sensitive to mercury under conditions of sulfate limitation led to the hypothesis that these inorganic detoxification mechanisms generally depended on a kind of facilitated precipitation. The process was coined thus because heavy metals were probably accumulated and precipitated near the cell perimeter due to the relatively high local concentrations of sulfide and phosphate there. Depending on the growth-limiting nutrient, mercury proved to be 25-fold (phosphate limitation), 75-fold (glycerol limitation), or 150-fold (sulfate limitation) more toxic than cadmium to this organism. In the presence of lead, PbS formation was suggested. since no other detoxification mechanisms were detected, for example, rendering heavy metal ions innocuous as metallo-organic compounds, it was concluded that formation of heavy metal precipitates is crucially important to this organism. In addition, it was observed that several components of a defined mineral medium were able to reduce mercuric ions to elemental mercury. This abiotic mercury volatilization was studied in detail, and its general and environmental implications are discussed.

  13. Biodegradation of ichlorodiphenyltrichloroe-thane: Intermediates in dichlorodiphenylacetic acid metabolism by Aerobacter aerogenes

    USGS Publications Warehouse

    1967-01-01

    The final product of dichlorodiphenyltrichloroethane (DDT) degradation by vertebrates is commonly considered to be dichlorodiphenylacetic acid, DDA (J. E. Peterson and W. H. Robison, Toxicol. Appl. Pharmacol. 6:321, 1964). Recently, certain organisms (A. S. Perry, S. Miller, and A. J. Buckner. J. Agr. Food Chem. 11:457, 1963; J. D. Pinto, M. N. Comien, and M. S. Dunn. J. Biol. Chem. 240:2148, 1965) have been found to degrade further DDA to dichlorobenzophenone (DBP), but the possibility that such degradation was due to microbial action could not be excluded. Significantly, dichlorobenzhydrol (DBH), dichlorophenylmethane (DPM), and dichlorodiphenylethylene (DDE) have been tentatively identified in rats fed DDA (Pinto et al., J. Biol. Chem. 240:2148, 1965). Since DDA as well as DDT is degraded by the ubiquitous microorganism Aerobacter aerogenes (G. Wedemeyer, Appl. Microbiol. 15:569, 1967; J. L. Mendel, and M. S. Walton, Science 151:1527, 1966), it seemed reasonable that the intestinal microflora might be involved in DBP formation, DPM and DBH being intermediates in its pathway from DDA. Since DDA is a (3,y-unsaturated acid, ketone formation via an alkene and an alcohol would be expected (S. G. Waley, Mechanisms of Organic and Enzymatic Reactions, Oxford University Press, London, England 1962).

  14. Recombination-induced suppression of cell division following P1-mediated generalized transduction in Klebsiella aerogenes.

    PubMed

    Bender, R A; Sambucetti, L C

    1983-01-01

    Klebsiella aerogenes recombinants resulting from bacteriophage P1-mediated generalized transduction failed to increase in number for approximately six generations after transduction. Nevertheless these recombinants continued to grow and became sensitive to penicillin after a transient resistance, suggesting that the cells were growing as long, non-dividing filaments. When filamentous cells were isolated from transduced cultures by gradient centrifugation, recombinants were 1000-fold more frequent among the filaments than among the normal-sized cells. The suppression of cell-division lasted for six generations whether markers near the origin (gln, ilv) or terminus (his, trp) of chromosome replication were used, despite a 50-fold difference in transduction frequencies for these markers. The suppression of cell division was a host response to recombination rather than to P1 invasion since cells lysogenized by P1 in these same experiments showed only a short (two generation) suppression of cell division. We speculate that the suppression of cell-division is an SOS response triggered by the degraded DNA not incorporated in the final recombinant. We demonstrate that both the filamentation and the transient penicillin resistance of recombinant cells can be exploited to enrich greatly for recombinants, raising transduction frequencies to as high as 10(-3).

  15. Biohydrogen production by dark fermentation of glycerol using Enterobacter and Citrobacter Sp.

    PubMed

    Maru, Biniam T; Constanti, Magda; Stchigel, Alberto M; Medina, Francesc; Sueiras, Jesus E

    2013-01-01

    Glycerol is an attractive substrate for biohydrogen production because, in theory, it can produce 3 mol of hydrogen per mol of glycerol. Moreover, glycerol is produced in substantial amounts as a byproduct of producing biodiesel, the demand for which has increased in recent years. Therefore, hydrogen production from glycerol was studied by dark fermentation using three strains of bacteria: namely, Enterobacter spH1, Enterobacter spH2, and Citrobacter freundii H3 and a mixture thereof (1:1:1). It was found that, when an initial concentration of 20 g/L of glycerol was used, all three strains and their mixture produced substantial amounts of hydrogen ranging from 2400 to 3500 mL/L, being highest for C. freundii H3 (3547 mL/L) and Enterobacter spH1 (3506 mL/L). The main nongaseous fermentation products were ethanol and acetate, albeit in different ratios. For Enterobacter spH1, Enterobacter spH2, C. freundii H3, and the mixture (1:1:1), the ethanol yields (in mol EtOH/mol glycerol consumed) were 0.96, 0.67, 0.31, and 0.66, respectively. Compared to the individual strains, the mixture (1:1:1) did not show a significantly higher hydrogen level, indicating that there was no synergistic effect. Enterobacter spH1 was selected for further investigation because of its higher yield of hydrogen and ethanol.

  16. Fermentation of polysaccharides by Klebsiella and other facultative bacilli

    SciTech Connect

    Ochuba, G.U.; Von Riesen, V.L.

    1980-05-01

    Fermentations of 10 polysaccharides by species of the family Enterobacteriaceae were examined. Algin, guar, karaya, xanthan, and xylan were not fermented by any of the strains tested. Most of the activity was found in the tribe Klebsielleae. Klebseilla oxytoca fermented amylopectin (97% of the strains studied), carrageenan (100%), inulin (68%), polypectate (100%), and tragacanth (100%). Klebsiella pneumoniae fermented amylopectin (91%), carrageenan (100%), and tragacanth (86%). Carraggeenan was also fermented by Enterobacter aerogenes (100%), Enterobacter agglomerans (63%), Enterobacter cloacae (95%), and pectobacterium (38%). pectobacterium shared polypectate fermentation (100%) with K. oxytoca. With one exception, Serratia strains were negative on all polysaccharides. These results, along with other evidence, indicate that (i) the genus Klebsiella is biochemically the most versatile genus of the tribe, (ii) because of its distinct characteristics, K. oxytoca warrants species designation separate from K. pneumoniae, and (iii) some food additives generally considered indigestible can be metabolized by a few species of facultative bacilli, whereas others appear to be resistant.

  17. Fermentation of polysaccharides by Klebsielleae and other facultative bacilli.

    PubMed

    Ochuba, G U; von Riesen, V L

    1980-05-01

    Fermentations of 10 polysaccharides by species of the family Enterobacteriaceae were examined. Algin, guar, karaya, xanthan, and xylan were not fermented by any of the strains tested. Most of the activity was found in the tribe Klebsielleae. Klebsiella oxytoca fermented amylopectin (97% of the strains studied), carrageenan (100%), inulin (68%), polypectate (100%), and tragacanth (100%). Klebsiella pneumoniae fermented amylopectin (91%), carrageenan (100%), and tragacanth (86%). Carrageenan was also fermented by Enterobacter aerogenes (100%), Enterobacter agglomerans (63%), Enterobacter cloacae (95%), and Pectobacterium (38%). Pectobacterium shared polypectate fermentation (100%) with K. oxytoca. With one exception, Serratia strains were negative on all polysaccharides. These results, along with other evidence, indicate that (i) the genus Klebsiella is biochemically the most versatile genus of the tribe, (ii) because of its distinct characteristics, K. oxytoca warrants species designation separate from K. pneumoniae, and (iii) some food additives generally considered indigestible can be metabolized by a few species of facultative bacilli, whereas others appear to be resistant.

  18. Isolation and identification of Enterobacter sakazakii in infant milk formulas.

    PubMed

    Torres-Chavolla, Edith; Ramírez-Cerda, Elsa; Gutiérrez-Rojo, Rosalba

    2007-01-01

    Enterobacter sakazakii is a pathogen of increasing medical concern, due to it being implicated in cases of meningitis, sepis, and necrotizing enterocolitis associated with the consumption of contaminated infant milk formula. At present, the method adopted by the Mexican food industry for the isolation and identification of E. sakazakii is based on the methodology of the United States Food and Drug Administration (FDA). However, this procedure is laborious and requires 7 days to obtain a confirmative result. The objective of this study was to determine the presence of E. sakazakii in two types of powdered infant milk formula, using an alternative method that requires less time and a smaller sample size than the FDA protocol. We adapted Leuschner's procedure by eliminating violet red bile glucose agar (VRBG) plates and instead adopting white light incubation to stimulate yellow pigment development. This allowed for isolation of E. sakazakii from powdered infant milk formula using a smaller sample and requiring only 5 days for analysis. Results showed that 92% of formula 1 and 32% of formula 2 was positive for E. sakazakii. The high contamination level of E. sakazakii suggests the need for monitoring hygienic conditions in the manufacturing plant and to assess the prevalence of E. sakazakii in powdered infant milk formulas sold in México. PMID:17600483

  19. Re-examination of the taxonomic status of Enterobacter helveticus, Enterobacter pulveris and Enterobacter turicensis as members of the genus Cronobacter and their reclassification in the genera Franconibacter gen. nov. and Siccibacter gen. nov. as Franconibacter helveticus comb. nov., Franconibacter pulveris comb. nov. and Siccibacter turicensis comb. nov., respectively

    PubMed Central

    Grim, Christopher J.; Gopinath, Gopal R.; Mammel, Mark K.; Sathyamoorthy, Venugopal; Trach, Larisa H.; Chase, Hannah R.; Fanning, Séamus; Tall, Ben D.

    2014-01-01

    Recently, a taxonomical re-evaluation of the genus Enterobacter, based on multi-locus sequence typing (MLST) analysis, has led to the proposal that the species Enterobacter pulveris, Enterobacter helveticus and Enterobacter turicensis should be reclassified as novel species of the genus Cronobacter. In the present work, new genome-scale analyses, including average nucleotide identity, genome-scale phylogeny and k-mer analysis, coupled with previously reported DNA–DNA hybridization values and biochemical characterization strongly indicate that these three species of the genus Enterobacter are not members of the genus Cronobacter, nor do they belong to the re-evaluated genus Enterobacter. Furthermore, data from this polyphasic study indicated that all three species constitute two new genera. We propose reclassifying Enterobacter pulveris and Enterobacter helveticus in the genus Franconibacter gen. nov. as Franconibacter pulveris comb. nov. (type strain 601/05T = LMG 24057T = DSM 19144T) and Franconibacter helveticus comb. nov. (type strain 513/05T = LMG 23732T = DSM 18396T), respectively, and Enterobacter turicensis in the genus Siccibacter gen. nov. as Siccibacter turicensis comb. nov. (type strain 508/05T = LMG 23730T = DSM 18397T). PMID:25028159

  20. Comparison of Media for the Isolation of Enterobacter sakazakii▿

    PubMed Central

    Iversen, Carol; Forsythe, Stephen J.

    2007-01-01

    Enterobacter sakazakii is associated with neonatal infections and is occasionally present at low levels (<1 CFU/g) in powdered infant formula milk (IFM). It has been previously reported that some E. sakazakii strains do not grow in standard media for Enterobacteriaceae and coliform bacteria; therefore, a reliable method is needed for recovery of the organism. Three E. sakazakii enrichment broths—Enterobacteriaceae enrichment broth (EE), E. sakazakii selective broth (ESSB), and modified lauryl sulfate broth (mLST)—were compared with a novel broth designed for maximum recovery of E. sakazakii, E. sakazakii enrichment broth (ESE). One hundred seventy-seven strains (100%) grew in ESE, whereas between 2 and 6% of strains did not grow in EE, mLST, or ESSB. E. sakazakii possesses α-glucosidase activity, and a number of selective, chromogenic agars for E. sakazakii isolation based on this enzyme have been developed. E. sakazakii isolation agar produced fewer false-positive colonies than did Druggan-Forsythe-Iversen agar. However, the latter supported the growth of more E. sakazakii strains. It was also determined that 2% of E. sakazakii strains did not produce yellow pigmentation on tryptone soya agar at 25°C, a characteristic frequently cited in the identification of E. sakazakii. The recovery of desiccated E. sakazakii (0.2 to 2000 CFU/25 g) from powdered IFM in the presence of a competing flora was determined with various enrichment broths and differential selective media. Current media designed for the isolation and presumptive identification of E. sakazakii do not support the growth of all currently known E. sakazakii phenotypes; therefore, improvements in the proposed methods are desirable. PMID:17071794

  1. Prevalence of a plasmid-mediated type II dihydrofolate reductase gene among trimethoprim-resistant urinary pathogens in Greek hospitals.

    PubMed

    Tsakris, A; Vatopoulos, A C; Johnson, A P; Pitt, T L; Legakis, N J; Tzouvelekis, L S

    1992-04-01

    The genetic basis of trimethoprim resistance was examined in 24 Klebsiella pneumoniae, 27 Enterobacter cloacae, five Enterobacter aerogenes and nine Serratia marcescens urinary isolates from five hospitals in Greece. Analysis of the 65 isolates by serotyping and phage-typing identified 53 distinct strains. Thirty-eight isolates (15 K. pneumoniae, 19 E. cloacae, two E. aerogenes and two S. marcescens) hybridized with a probe specific for a gene encoding type II dihydrofolate reductase (DHFR). Three of the K. pneumoniae and four of the E. cloacae isolates which reacted with this probe also hybridized with probes specific for type I DHFR and transposon Tn7. Two E. cloacae isolates hybridized only with the probe for type I DHFR, while a further three isolates hybridized only with the type I DHFR and Tn7 probes. None of the isolates hybridized with a probe for type V DHFR. The plasmids in transconjugants derived from 40 isolates were analysed by digestion with restriction enzymes and Southern blotting. Eighteen (45%) of the donors (12 K. pneumoniae and 6 E. cloacae) produced transconjugants containing plasmids of about 95 kb in size, while transconjugants from the other donors had plasmids in the range 100-185 kb. Of the 18 transconjugants containing a 95 kb plasmid, 15 had similar restriction endonuclease digest patterns, although they varied in terms of the range of antimicrobial resistances which they encoded. When EcoRI digests of these 15 plasmids were hybridized with the type II DHFR probe, a 23 kb common band reacted with the probe.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Gross anatomical features of the gastrointestinal tract (GIT) of blue-and-yellow macaws (Ara ararauna) - oesophagus to cloaca.

    PubMed

    Aizawa, J; Tivane, C; Rodrigues, M N; Wagner, P G; Campos, D B; Guerra, R R; Miglino, M A

    2013-12-01

    Morphological studies of the gastrointestinal tract of blue-and-yellow macaws (Ara ararauna) are scarce. In view of the paucity of information regarding the digestive tract of macaws, this study aims to describe the gross anatomical features (oesophagus to cloaca) as part of a broad study of the gastrointestinal tract (GIT) of these birds. Three animals (two males and one female) adult macaws were anatomically dissected from the oropharynx to the cloaca to expose the GIT. The oesophagus was identified as a muscle-membranous tube continuous with the crop, which was intimately attached to the skin. The internal longitudinal folds of the cervical oesophagus were sparser cranial to the crop and less evident compared to the portion caudal to the crop. The duodenum began in the pylorus and was grey-coloured exhibiting a large lumen. The jejunum was formed by loops in a spiral-fashion model supported by mesojejunum. The ileum was also composed by small loops and was continuous with the colo-rectum forming the large intestine, because the caeca were absent. The large intestine was short, median in position, suspended in the dorsal wall of the abdominal cavity by mesentery and ended in the cloaca. The GIT was similar to the basic patterns in birds, in general, and also presented new unreported morphological data that might be important when studying nutrition and health of the macaws.

  3. Enterobacter spp.: pathogens poised to flourish at the turn of the century.

    PubMed Central

    Sanders, W E; Sanders, C C

    1997-01-01

    Knowledge of the genus Enterobacter and its role in human disease has expanded exponentially in recent years. The incidence of infection in the hospital and the community has increased. New clinical syndromes have been recognized. Enterobacter spp. have also been implicated as causes of other syndromes that traditionally have been associated almost exclusively with more easily treatable pathogens, such as group A streptococci and staphylococci. Rapid emergence of multiple-drug resistance has been documented in individual patients during therapy and in populations and environments with strong selective pressure from antimicrobial agents, especially the cephalosporins. Therapeutic options for patients infected with multiply resistant strains have become severely limited. Carbapenems or, alternatively, fluoroquinolones are the most predictively active options, although resistance to both classes has been observed on rare occasions. Enterobacter spp. appear well adapted for survival and even proliferation as the turn of the century approaches. PMID:9105752

  4. Estimation of cultivable bacterial diversity in the cloacae and pharynx in Eurasian griffon vultures (Gyps fulvus).

    PubMed

    Vela, Ana I; Casas-Díaz, Encarna; Fernández-Garayzábal, José F; Serrano, Emmanuel; Agustí, Susana; Porrero, María C; Sánchez del Rey, Verónica; Marco, Ignasi; Lavín, Santiago; Domínguez, Lucas

    2015-04-01

    In this work, we describe the biodiversity of cloacal and pharynx culture-based bacteria (commensal and pathogenic), in 75 Eurasian griffon vultures (Gyps fulvus) from two geographic areas. We address the question of whether the cultivable microbiota of vultures is organised into assemblages occurring by chance. In addition, we assess bacterial diversity in both anatomic regions and geographic areas. Bacterial diversity was represented by 26 Gram-negative and 20 Gram-positive genera. The most common genera were Escherichia, Enterococcus, Staphylococcus, Clostridium and Lactococcus. Escherichia coli and Enterococcus faecalis were the most common species in cloacal and pharyngeal samples. Staphylococcus and Erysipelothrix were isolated from the pharynx and Salmonella and Corynebacterium from the cloacae, and no Campylobacter was isolated from the cloacal swabs. Ten cloacal swabs were positive for Salmonella, of which five isolates were Salmonella enterica serotype 4,(5),12:i:-, one isolate was S. enterica serotype Derby, three isolates were S. enterica serotype 61:k:1,5,7 and one isolate was S. enterica serotype Infantis. The null modelling approach revealed that the commensal bacteria of vultures are not structured in assemblages. On the other hand, differences in bacterial genus and species richness between cloacal and pharyngeal samples or between geographic areas were clear, with the pharynx in vultures from both geographic areas being richer. The results of this study indicate also that vultures can serve as a reservoir of certain pathogenic zoonotic bacteria. The dissemination of these zoonotic pathogens in wildlife could be prevented by periodic sanitary surveys.

  5. Aerobic bacterial microbiota isolated from the cloaca of the European pond turtle (Emys orbicularis) in Poland.

    PubMed

    Nowakiewicz, Aneta; Ziółkowska, Grażyna; Zięba, Przemysław; Dziedzic, Barbara Majer; Gnat, Sebastian; Wójcik, Mariusz; Dziedzic, Roman; Kostruba, Anna

    2015-01-01

    We conducted a comparative analysis of the aerobic cloacal bacteria of European pond turtles (Emys orbicularis) living in their natural environment and juvenile turtles reared under controlled conditions in a breeding center. We included 130 turtles in the study. The aerobic bacteria isolated from the cloaca of the juvenile turtles were less diverse and more prevalent than the bacteria isolated from free-living adults. We isolated 17 bacterial species from juvenile captive turtles, among which the dominant species were Cellulomonas flavigena (77/96), Enterococcus faecalis (96/96), Escherichia coli (58/96), and Proteus mirabilis (41/96). From the adult, free-living turtles, we isolated 36 bacterial species, some of which are a potential threat to public health (e.g., Salmonella enterica serovars Newport, Daytona, and Braenderup; Listeria monocytogenes; Yersinia enterocolitica; Yersinia ruckeri; Klebsiella pneumoniae; Vibrio fluvialis; and Serratia marcescens), and pathogens that are etiologic agents of diseases of ectothermic animals (e.g., Aeromonas sobria, Aeromonas caviae, Hafnia alvei, Edwardsiella tarda, and Citrobacter braakii; the last two species were isolated from both groups of animals). The cloacal bacterial biota of the European pond turtle was characterized by numerous species of bacteria, and its composition varied with turtle age and environmental conditions. The small number of isolated bacteria that are potential human pathogens may indicate that the European pond turtle is of relatively minor importance as a threat to public health.

  6. Development of the cloaca, hemipenes, and hemiclitores in the green anole, Anolis carolinensis.

    PubMed

    Gredler, Marissa L; Sanger, Thomas J; Cohn, Martin J

    2015-01-01

    In most amniotes, the intromittent organ is a single phallus; however, squamates (lizards, snakes, and amphisbaenians) have paired hemiphalluses. All amniotes studied to date initiate external genital development with the formation of paired genital swellings. In mammals, archosaurs, and turtles, these swellings merge to form a single genital tubercle, the precursor of the penis and clitoris; however, in squamates, the paired genital buds remain separate, giving rise to the hemiphalluses (hemipenes in males and hemiclitores in females). Although the molecular genetics and sexual differentiation of the genital tubercle have been investigated in mammals and birds, little is known about hemiphallus development. Here we describe development of the cloaca and hemiphallus in the green anole, Anolis carolinensis. Each hemiphallus originates as a protuberance that emerges at the ventral base of the hindlimb bud. Development of the hemipenes resembles penis development; however, differences exist in their tissue composition, morphogenesis, and gene expression patterns. These findings reveal aspects of phallus development that appear to be evolutionarily labile, both within squamates and more broadly among reptiles, and identify features that are conserved across amniotes. Our results, together with parallel studies in other reptilian taxa, suggest potential mechanisms for the diversification of external genital form. PMID:24960313

  7. Dkk1 in the Peri-Cloaca Mesenchyme Regulates Formation of Anorectal and Genitourinary Tracts

    PubMed Central

    MacDonald, Bryan T.; Borer, Joseph G.; Li, Xue

    2013-01-01

    Anorectal malformation (ARM) is a common birth defect but the developmental history and the underlying molecular mechanism are poorly understood. Using murine genetic models, we report here that a signaling molecule Dickkopf-1 (Dkk1) is a critical regulator. The anorectal and genitourinary tracts are major derivatives of caudal hindgut, or the cloaca. Dkk1 is highly expressed in the dorsal peri-cloacal mesenchymal (dPCM) progenitors. We show that deletion of Dkk1 causes the imperforate anus with rectourinary fistula. Mutant genital tubercles exhibit a preputial hypospadias phenotype and premature urethral canalization. Dkk1 mutants have an ectopic expansion of the dPCM tissue, which correlates with an aberrant increase of cell proliferation and survival. This ectopic tissue is detectable before the earliest sign of the anus formation, suggesting that it is most likely the primary or early cause of the defect. Deletion of Dkk1 results in an elevation of the Wnt/ß-catenin activity. Signaling molecules Shh, Fgf8 and Bmp4 are also upregulated. Furthermore, genetic hyperactivation of Wnt/ß-catenin signal pathway in the cloacal mesenchyme partially recapitulates Dkk1 mutant phenotypes. Together, these findings underscore the importance of DKK1 in regulating behavior of dPCM progenitors, and suggest that formation of anus and urethral depends on Dkk1-mediated dynamic inhibition of the canonical Wnt/ß-catenin signal pathway. PMID:24479159

  8. Aerobic bacterial microbiota isolated from the cloaca of the European pond turtle (Emys orbicularis) in Poland.

    PubMed

    Nowakiewicz, Aneta; Ziółkowska, Grażyna; Zięba, Przemysław; Dziedzic, Barbara Majer; Gnat, Sebastian; Wójcik, Mariusz; Dziedzic, Roman; Kostruba, Anna

    2015-01-01

    We conducted a comparative analysis of the aerobic cloacal bacteria of European pond turtles (Emys orbicularis) living in their natural environment and juvenile turtles reared under controlled conditions in a breeding center. We included 130 turtles in the study. The aerobic bacteria isolated from the cloaca of the juvenile turtles were less diverse and more prevalent than the bacteria isolated from free-living adults. We isolated 17 bacterial species from juvenile captive turtles, among which the dominant species were Cellulomonas flavigena (77/96), Enterococcus faecalis (96/96), Escherichia coli (58/96), and Proteus mirabilis (41/96). From the adult, free-living turtles, we isolated 36 bacterial species, some of which are a potential threat to public health (e.g., Salmonella enterica serovars Newport, Daytona, and Braenderup; Listeria monocytogenes; Yersinia enterocolitica; Yersinia ruckeri; Klebsiella pneumoniae; Vibrio fluvialis; and Serratia marcescens), and pathogens that are etiologic agents of diseases of ectothermic animals (e.g., Aeromonas sobria, Aeromonas caviae, Hafnia alvei, Edwardsiella tarda, and Citrobacter braakii; the last two species were isolated from both groups of animals). The cloacal bacterial biota of the European pond turtle was characterized by numerous species of bacteria, and its composition varied with turtle age and environmental conditions. The small number of isolated bacteria that are potential human pathogens may indicate that the European pond turtle is of relatively minor importance as a threat to public health. PMID:25380369

  9. Comparison of two multimetal resistant bacterial strains: Enterobacter sp. YSU and Stenotrophomonas maltophilia ORO2.

    PubMed

    Holmes, Andrew; Vinayak, Anubhav; Benton, Cherise; Esbenshade, Aaron; Heinselman, Carlisle; Frankland, Daniel; Kulkarni, Samatha; Kurtanich, Adrienne; Caguiat, Jonathan

    2009-11-01

    The Y-12 plant in Oak Ridge, TN, which manufactured nuclear weapons during World War II and the Cold War, contaminated East Fork Poplar Creek with heavy metals. The multimetal resistant bacterial strain, Stenotrophomonas maltophilia Oak Ridge strain O2 (S. maltophilia O2), was isolated from East Fork Poplar Creek. Sequence analysis of 16s rDNA suggested that our working strain of S. maltophilia O2 was a strain of Enterobacter. Phylogenetic tree analysis and biochemical tests confirmed that it belonged to an Enterobacter species. This new strain was named Enterobacter sp. YSU. Using a modified R3A growth medium, R3A-Tris, the Hg(II), Cd(II), Zn(II), Cu(II), Au(III), Cr(VI), Ag(I), As(III), and Se(IV) MICs for a confirmed strain of S. maltophilia O2 were 0.24, 0.33, 5, 5, 0.25, 7, 0.03, 14, and 40 mM, respectively, compared to 0.07, 0.24, 0.8, 3, 0.05, 0.4, 0.08, 14, and 40 mM, respectively, for Enterobacter sp. YSU. Although S. maltophilia O2 was generally more metal resistant than Enterobacter sp. YSU, in comparison to Escherichia coli strain HB101, Enterobacter sp. YSU was resistant to Hg(II), Cd(II), Zn(II), Au(III), Ag(I), As(III), and Se(IV). By studying metal resistances in these two strains, it may be possible to understand what makes one microorganism more metal resistant than another microorganism. This work also provided benchmark MICs that can be used to evaluate the metal resistance properties of other bacterial isolates from East Fork Poplar Creek and other metal contaminated sites.

  10. Comparison of two multimetal resistant bacterial strains: Enterobacter sp. YSU and Stenotrophomonas maltophilia ORO2.

    PubMed

    Holmes, Andrew; Vinayak, Anubhav; Benton, Cherise; Esbenshade, Aaron; Heinselman, Carlisle; Frankland, Daniel; Kulkarni, Samatha; Kurtanich, Adrienne; Caguiat, Jonathan

    2009-11-01

    The Y-12 plant in Oak Ridge, TN, which manufactured nuclear weapons during World War II and the Cold War, contaminated East Fork Poplar Creek with heavy metals. The multimetal resistant bacterial strain, Stenotrophomonas maltophilia Oak Ridge strain O2 (S. maltophilia O2), was isolated from East Fork Poplar Creek. Sequence analysis of 16s rDNA suggested that our working strain of S. maltophilia O2 was a strain of Enterobacter. Phylogenetic tree analysis and biochemical tests confirmed that it belonged to an Enterobacter species. This new strain was named Enterobacter sp. YSU. Using a modified R3A growth medium, R3A-Tris, the Hg(II), Cd(II), Zn(II), Cu(II), Au(III), Cr(VI), Ag(I), As(III), and Se(IV) MICs for a confirmed strain of S. maltophilia O2 were 0.24, 0.33, 5, 5, 0.25, 7, 0.03, 14, and 40 mM, respectively, compared to 0.07, 0.24, 0.8, 3, 0.05, 0.4, 0.08, 14, and 40 mM, respectively, for Enterobacter sp. YSU. Although S. maltophilia O2 was generally more metal resistant than Enterobacter sp. YSU, in comparison to Escherichia coli strain HB101, Enterobacter sp. YSU was resistant to Hg(II), Cd(II), Zn(II), Au(III), Ag(I), As(III), and Se(IV). By studying metal resistances in these two strains, it may be possible to understand what makes one microorganism more metal resistant than another microorganism. This work also provided benchmark MICs that can be used to evaluate the metal resistance properties of other bacterial isolates from East Fork Poplar Creek and other metal contaminated sites. PMID:19688378

  11. Whole-genome sequence of Enterobacter sp. strain SST3, an endophyte isolated from Jamaican sugarcane (Saccharum sp.) stalk tissue.

    PubMed

    Gan, Han Ming; McGroty, Sean E; Chew, Teong Han; Chan, Kok Gan; Buckley, Larry J; Savka, Michael A; Hudson, André O

    2012-11-01

    Enterobacter sp. strain SST3 is an endophytic bacterium isolated from Saccharum spp. Here we present its annotated draft genome that may shed light on its role as a bacterial endophyte of sugarcane. To our knowledge, this is the first genome announcement of a sugarcane-associated bacterium from the genus Enterobacter.

  12. Non contiguous-finished genome sequence and description of Enterobacter massiliensis sp. nov.

    PubMed Central

    Lagier, Jean-Christophe; El Karkouri, Khalid; Mishra, Ajay Kumar; Robert, Catherine; Raoult, Didier; Fournier, Pierre-Edouard

    2013-01-01

    Enterobacter massiliensis strain JC163T sp. nov. is the type strain of E. massiliensis sp. nov., a new species within the genus Enterobacter. This strain, whose genome is described here, was isolated from the fecal flora of a healthy Senegalese patient. E. massiliensis is an aerobic rod. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 4,922,247 bp long genome (1 chromosome but no plasmid) exhibits a G+C content of 55.1% and contains 4,644 protein-coding and 80 RNA genes, including 5 rRNA genes. PMID:24019988

  13. E240V substitution increases catalytic efficiency toward ceftazidime in a new natural TEM-type extended-spectrum beta-lactamase, TEM-149, from Enterobacter aerogenes and Serratia marcescens clinical isolates.

    PubMed

    Perilli, Mariagrazia; Celenza, Giuseppe; De Santis, Francesca; Pellegrini, Cristina; Forcella, Chiara; Rossolini, Gian Maria; Stefani, Stefania; Amicosante, Gianfranco

    2008-03-01

    The aim of this study was to characterize a novel extended-spectrum beta-lactamase that belongs to the TEM family, the TEM-149 enzyme, and that was isolated from the urine of two hospitalized patients from different hospitals in southern Italy. The peculiarity of this enzyme was the finding of a valine residue at position 240. The array of amino acid substitutions found in TEM-149 was as follows: E104K, R164S, M182T, and E240V. A reversion of a threonine residue at position 182 was also performed to create a new mutant, TEM-149 T182M, in order to assess the contribution of this substitution on the kinetic profile and the stability of TEM-149. The bla TEM-149 and bla TEM-149/T182M genes were cloned into pBC-SK, and the corresponding enzymes were purified from recombinant Escherichia coli HB101 by the same procedure. Both enzymes hydrolyzed all beta-lactams tested, with a preference for ceftazidime, which was found to be the best substrate. By comparison of the kinetic parameters of the TEM-149 and the TEM-149 T182M enzymes, a reduction of the catalytic efficiency for the TEM-149 T182M mutant was observed against all substrates tested except benzylpenicillin, cefotaxime, and aztreonam. Tazobactam, clavulanic acid, and sulbactam were good inhibitors of the TEM-149 beta-lactamase.

  14. Disruption of the temporally regulated cloaca endodermal β-catenin signaling causes anorectal malformations

    PubMed Central

    Miyagawa, S; Harada, M; Matsumaru, D; Tanaka, K; Inoue, C; Nakahara, C; Haraguchi, R; Matsushita, S; Suzuki, K; Nakagata, N; Ng, R C-L; Akita, K; Lui, V C-H; Yamada, G

    2014-01-01

    The cloaca is temporally formed and eventually divided by the urorectal septum (URS) during urogenital and anorectal organ development. Although congenital malformations, such as anorectal malformations (ARMs), are frequently observed during this process, the underlying pathogenic mechanisms remain unclear. β-Catenin is a critical component of canonical Wnt signaling and is essential for the regulation of cell differentiation and morphogenesis during embryogenesis. The expression of β-catenin is observed in endodermal epithelia, including URS epithelia. We modulated the β-catenin gene conditionally in endodermal epithelia by utilizing tamoxifen-inducible Cre driver line (ShhCreERT2). Both β-catenin loss- and gain-of-function (LOF and GOF) mutants displayed abnormal clefts in the perineal region and hypoplastic elongation of the URS. The mutants also displayed reduced cell proliferation in the URS mesenchyme. In addition, the β-catenin GOF mutants displayed reduced apoptosis and subsequently increased apoptosis in the URS epithelium. This instability possibly resulted in reduced expression levels of differentiation markers, such as keratin 1 and filaggrin, in the perineal epithelia. The expression of bone morphogenetic protein (Bmp) genes, such as Bmp4 and Bmp7, was also ectopically induced in the epithelia of the URS in the β-catenin GOF mutants. The expression of the Msx2 gene and phosphorylated-Smad1/5/8, possible readouts of Bmp signaling, was also increased in the mutants. Moreover, we introduced an additional mutation for a Bmp receptor gene: BmprIA. The ShhCreERT2/+; β-cateninflox(ex3)/+; BmprIAflox/− mutants displayed partial restoration of URS elongation compared with the β-catenin GOF mutants. These results indicate that some ARM phenotypes in the β-catenin GOF mutants were caused by abnormal Bmp signaling. The current analysis revealed the close relation of endodermal β-catenin signaling to the ARM phenotypes. These results are considered to

  15. Estimation of cultivable bacterial diversity in the cloacae and pharynx in Eurasian griffon vultures (Gyps fulvus).

    PubMed

    Vela, Ana I; Casas-Díaz, Encarna; Fernández-Garayzábal, José F; Serrano, Emmanuel; Agustí, Susana; Porrero, María C; Sánchez del Rey, Verónica; Marco, Ignasi; Lavín, Santiago; Domínguez, Lucas

    2015-04-01

    In this work, we describe the biodiversity of cloacal and pharynx culture-based bacteria (commensal and pathogenic), in 75 Eurasian griffon vultures (Gyps fulvus) from two geographic areas. We address the question of whether the cultivable microbiota of vultures is organised into assemblages occurring by chance. In addition, we assess bacterial diversity in both anatomic regions and geographic areas. Bacterial diversity was represented by 26 Gram-negative and 20 Gram-positive genera. The most common genera were Escherichia, Enterococcus, Staphylococcus, Clostridium and Lactococcus. Escherichia coli and Enterococcus faecalis were the most common species in cloacal and pharyngeal samples. Staphylococcus and Erysipelothrix were isolated from the pharynx and Salmonella and Corynebacterium from the cloacae, and no Campylobacter was isolated from the cloacal swabs. Ten cloacal swabs were positive for Salmonella, of which five isolates were Salmonella enterica serotype 4,(5),12:i:-, one isolate was S. enterica serotype Derby, three isolates were S. enterica serotype 61:k:1,5,7 and one isolate was S. enterica serotype Infantis. The null modelling approach revealed that the commensal bacteria of vultures are not structured in assemblages. On the other hand, differences in bacterial genus and species richness between cloacal and pharyngeal samples or between geographic areas were clear, with the pharynx in vultures from both geographic areas being richer. The results of this study indicate also that vultures can serve as a reservoir of certain pathogenic zoonotic bacteria. The dissemination of these zoonotic pathogens in wildlife could be prevented by periodic sanitary surveys. PMID:25388757

  16. Draft Genome Sequence of Enterobacter ludwigii NCR3, a Heavy Metal–Resistant Rhizobacterium

    PubMed Central

    Egidi, Eleonora; Wood, Jennifer L.; Aracic, Sanja; Kannan, Ruban; McDonald, Lachlan; Bell, Carolyn A.; Fox, Edward M.; Liu, Wuxing

    2016-01-01

    We report here the draft genome of Enterobacter ludwigii NCR3, a Gram-negative bacterium isolated from the Carpobrotus rossii (Haw.) Schwantes rhizosphere. The analysis of the ~4.8-Mb draft genome shows that this strain harbors several genes associated with heavy metal resistance and plant growth–promoting activity, suggesting its potential application in microbe-assisted phytoremediation.

  17. Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07.

    PubMed

    Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

    2016-01-01

    Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis. PMID:26911736

  18. The status of the species Enterobacter siamensisKhunthongpan et al. 2014. Request for an Opinion.

    PubMed

    Kämpfer, Peter; Doijad, Swapnil; Chakraborty, Trinad; Glaeser, Stefanie P

    2016-01-01

    In the course of a taxonomic study describing novel species of the genus Enterobacter it was found that the 16S rRNA gene sequence of the type strain of Enterobacter siamensis, obtained both directly from the authors of the publication on Enterobacter siamensis and from the Korean Collection for Type Cultures (C2361T and KCTC 23282T, respectively), was not congruent with the 16S rRNA gene sequence deposited in the GenBank database under the accession number HQ888848, which was applied for phylogenetic analysis in the species proposal. The remaining deposit in the Japanese type culture collection, NBRC 107138T, showed an identical 16S rRNA gene sequence to the other two cultures and overall, this sequence differed at 35 positions in comparison with the 1429 bp sequence published under the accession number HQ888848.Therefore, the type strain of this species cannot be included in any further scientific comparative study. It is proposed that the Judicial Commission of the International Committee on Systematics of Prokaryotes place the name Enterobacter siamensis on the list of rejected names, if a suitable replacement for the type strain is not found or a neotype strain is not proposed within two years following the publication of this Request for an Opinion.

  19. Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07

    PubMed Central

    Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

    2016-01-01

    Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis. PMID:26911736

  20. Structure of wild-type and mutant repressors and of the control region of the rbt operon of Klebsiella aerogenes.

    PubMed

    Wu, J; Anderton-Loviny, T; Smith, C A; Hartley, B S

    1985-05-01

    Pentitol metabolism in Klebsiella aerogenes is encoded by continuous ribitol (rbt) and D-arabitol (dal) operons transcribed in bipolar fashion and sandwiched between long stretches of homologous DNA. The operons are separated by a central control region (2.2 kb) which encodes both the repressors and all the control sequences. The rbt repressor (270 amino acids) shows homology to the Escherichia coli lac repressor and other DNA-binding proteins. It is transcribed from the strand opposite the rbt operon and the intervening control region (254-bp) contains features which reflect the complex regulation. A rbt-constitutive mutant strain used in previous studies of experimental enzyme evolution encodes a truncated rbt-peptide of 133 residues due to a frameshift mutation. PMID:3891331

  1. Vibrio furnissii (formerly aerogenic biogroup of Vibrio fluvialis), a new species isolated from human feces and the environment.

    PubMed

    Brenner, D J; Hickman-Brenner, F W; Lee, J V; Steigerwalt, A G; Fanning, G R; Hollis, D G; Farmer, J J; Weaver, R E; Joseph, S W; Seidler, R J

    1983-10-01

    Strains formerly classified as the aerogenic (gas-producing) biogroup of Vibrio fluvialis were shown by DNA relatedness to be a separate species. The species was named Vibrio furnissii sp. nov. (type strain ATCC 35016 = CDC B3215). Three strains of V. furnissii were 79% or more related to the type strain of V. furnissii and about 50% related to the type strain of V. fluvialis. V. fluvialis strains were 40 to 64% related to the type strain of V. furnissii. Divergence in related sequences was only 0.0 to 1.5% among strains of V. furnissii and among strains of V. fluvialis but was 5.0 to 8.0% in interspecific reactions between V. fluvialis and V. furnissii. V. furnissii was aerogenic (produced gas from the fermentation of carbohydrates), whereas V. fluvialis was anaerogenic (did not produce gas from the fermentation of carbohydrates). Another test of some help in differentiating the two species was fermentation of L-rhamnose (57% positive for V. furnissii and negative for V. fluvialis). In addition to the reactions above, V. furnissii is distinguished from other salt-requiring vibrios on the basis of its positive reactions in tests for Møller L-arginine, L-arabinose, maltose, and D-mannitol and its negative reactions for Møller L-lysine and L-ornithine, lactose, and Voges-Proskauer. V. furnissii has been isolated from patients with acute gastroenteritis in at least two outbreaks of food poisoning; its role as a cause of diarrhea needs further study.

  2. Dysregulation of Wnt inhibitory factor 1 (Wif1) expression resulted in aberrant Wnt-β-catenin signaling and cell death of the cloaca endoderm, and anorectal malformations

    PubMed Central

    Ng, R C-L; Matsumaru, D; Ho, A S-H; Garcia-Barceló, M-M; Yuan, Z-W; Smith, D; Kodjabachian, L; Tam, P K-H; Yamada, G; Lui, V C-H

    2014-01-01

    In mammalian urorectal development, the urorectal septum (urs) descends from the ventral body wall to the cloaca membrane (cm) to partition the cloaca into urogenital sinus and rectum. Defective urs growth results in human congenital anorectal malformations (ARMs), and their pathogenic mechanisms are unclear. Recent studies only focused on the importance of urs mesenchyme proliferation, which is induced by endoderm-derived Sonic Hedgehog (Shh). Here, we showed that the programmed cell death of the apical urs and proximal cm endoderm is particularly crucial for the growth of urs during septation. The apoptotic endoderm was closely associated with the tempo-spatial expression of Wnt inhibitory factor 1 (Wif1), which is an inhibitor of Wnt-β-catenin signaling. In Wif1lacZ/lacZ mutant mice and cultured urorectum with exogenous Wif1, cloaca septation was defective with undescended urs and hypospadias-like phenotypes, and such septation defects were also observed in Shh−/− mutants and in endodermal β-catenin gain-of-function (GOF) mutants. In addition, Wif1 and Shh were expressed in a complementary manner in the cloaca endoderm, and Wif1 was ectopically expressed in the urs and cm associated with excessive endodermal apoptosis and septation defects in Shh−/− mutants. Furthermore, apoptotic cells were markedly reduced in the endodermal β-catenin GOF mutant embryos, which counteracted the inhibitory effects of Wif1. Taken altogether, these data suggest that regulated expression of Wif1 is critical for the growth of the urs during cloaca septation. Hence, Wif1 governs cell apoptosis of urs endoderm by repressing β-catenin signal, which may facilitate the protrusion of the underlying proliferating mesenchymal cells towards the cm for cloaca septation. Dysregulation of this endodermal Shh-Wif1-β-catenin signaling axis contributes to ARM pathogenesis. PMID:24632949

  3. A theoretical evidence for cooperative enhancement in aerogen-bonding interactions: Open-chain clusters of KrOF2 and XeOF2

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Vessally, Esmail

    2016-10-01

    The cooperativity of aerogen-bonding interactions is studied in open-chain (KrOF2)n=2-6 and (XeOF2)n=2-6 clusters. The formation mechanism and bonding properties of these clusters are investigated by means of molecular electrostatic potentials, natural bond orbital and noncovalent interaction index analyses. The small variation of average interaction energy from the pentamer to hexamer cluster reveals that cooperativity effects are almost completely saturated in the larger clusters. The cooperative effects in the clusters also make an increase in the average 83Kr or 129Xe chemical shielding isotropies and total spin-spin coupling constants across the aerogen-bonding.

  4. Activity of eravacycline against Enterobacteriaceae and Acinetobacter baumannii, including multidrug-resistant isolates, from New York City.

    PubMed

    Abdallah, Marie; Olafisoye, Olawole; Cortes, Christopher; Urban, Carl; Landman, David; Quale, John

    2015-03-01

    Eravacycline demonstrated in vitro activity against a contemporary collection of more than 4,000 Gram-negative pathogens from New York City hospitals, with MIC50/MIC90 values, respectively, for Escherichia coli of 0.12/0.5 μg/ml, Klebsiella pneumoniae of 0.25/1 μg/ml, Enterobacter aerogenes of 0.25/1 μg/ml, Enterobacter cloacae 0.5/1 μg/ml, and Acinetobacter baumannii of 0.5/1 μg/ml. Activity was retained against multidrug-resistant isolates, including those expressing KPC and OXA carbapenemases. For A. baumannii, eravacycline MICs correlated with increased expression of the adeB gene. PMID:25534744

  5. Antimicrobial and cytotoxic activities from Jatropha dioica roots.

    PubMed

    Silva-Belmares, Yesenia; Rivas-Morales, Catalina; Viveros-Valdez, Ezequiel; de la Cruz-Galicia, María Guadalupe; Carranza-Rosales, Pilar

    2014-05-01

    The antimicrobial and cytotoxic activities of organic extracts obtained from roots of the medicinal plant Jatropha dioica (Euphorbiaceae) were investigated. In order to evaluate their antimicrobial activity, the organic extracts were tested against clinical isolates of the human pathogens Bacillus cereus, Escherichia coli, Salmonella typhi, Staphylococcus aureus, Enterobacter aerogenes, Enterobacter cloacae, Salmonella typhimurium, Cryptococcus neoformans, Candida albicans, Candida parapsilosis and Sporothrix schenckii. Results revealed that the hexane extract possess the stronger activity and a broader microbicide spectrum compared to the acetone and ethanol extracts. The activity of hexane extract may be attributed in part to the presence of β-sitosterol, the major compound identified by bioautography. The hexane extract, as well as the bioactive fraction were not cytotoxic when assays were profiled against the normal cell lines Chang, OK and LLCPK-1 (IC50>1000 μg mL(-1)). PMID:26031013

  6. Chemical composition and antibacterial activity of Lavandula coronopifolia essential oil against antibiotic-resistant bacteria.

    PubMed

    Ait Said, L; Zahlane, K; Ghalbane, I; El Messoussi, S; Romane, A; Cavaleiro, C; Salgueiro, L

    2015-01-01

    The aim of this study was to analyse the composition of the essential oil (EO) of Lavandula coronopifolia from Morocco and to evaluate its in vitro antibacterial activity against antibiotic-resistant bacteria isolated from clinical infections. The antimicrobial activity was assessed by a broth micro-well dilution method using multiresistant clinical isolates of 11 pathogenic bacteria: Klebsiella pneumoniae subsp. pneumoniae, Klebsiella ornithinolytica, Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Providencia rettgeri, Citrobacter freundii, Hafnia alvei, Salmonella spp., Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus. The main compounds of the oil were carvacrol (48.9%), E-caryophyllene (10.8%) and caryophyllene oxide (7.7%). The oil showed activity against all tested strains with minimal inhibitory concentration (MIC) values ranging between 1% and 4%. For most of the strains, the MIC value was equivalent to the minimal bactericidal concentration value, indicating a clear bactericidal effect of L. coronopifolia EO. PMID:25174508

  7. Integrated evaluation of aerogenic pollution by air-transported heavy metals (Pb, Cd, Ni, Zn, Mn and Cu) in the analysis of the main deposit media.

    PubMed

    Baltrėnaitė, Edita; Baltrėnas, Pranas; Lietuvninkas, Arvydas; Serevičienė, Vaida; Zuokaitė, Eglė

    2014-01-01

    The composition of the ambient air is constantly changing; therefore, the monitoring of ambient air quality to detect the changes caused by aerogenic pollutants makes the essential part of general environmental monitoring. To achieve more effective improvement of the ambient air quality, the Directive 2008/50/EC on 'Ambient Air Quality and Cleaner Air for Europe' was adopted by the European Parliament and the European Council. It informed the public and enterprises about a negative effect of pollution on humans, animals and plants, as well as about the need for monitoring aerogenic pollutants not only at the continuous monitoring stations but also by using indicator methods, i.e. by analysing natural deposit media. The problem of determining the relationship between the accumulation level of pollutants by a deposit medium and the level of air pollution and its risks is constantly growing in importance. The paper presents a comprehensive analysis of the response of the main four deposit media, i.e. snow cover, soil, pine bark and epigeic mosses, to the long-term pollution by aerogenic pollutants which can be observed in the area of oil refinery influence. Based on the quantitative expressions of the amounts of the accumulated pollutants in the deposit media, the territory of the oil refinery investigated in this paper has been referred to the areas of mild or moderate pollution.

  8. Genome Sequence of the Plant Growth Promoting Endophytic Bacterium Enterobacter sp. 638

    SciTech Connect

    Taghavi, S.; van der Lelie, D.; Hoffman, A.; Zhang, Y.-B.; Walla, M. D.; Vangronsveld, J.; Newman, L.; Monchy, S.

    2010-05-13

    Enterobacter sp. 638 is an endophytic plant growth promoting gamma-proteobacterium that was isolated from the stem of poplar (Populus trichocarpa x deltoides cv. H11-11), a potentially important biofuel feed stock plant. The Enterobacter sp. 638 genome sequence reveals the presence of a 4,518,712 bp chromosome and a 157,749 bp plasmid (pENT638-1). Genome annotation and comparative genomics allowed the identification of an extended set of genes specific to the plant niche adaptation of this bacterium. This includes genes that code for putative proteins involved in survival in the rhizosphere (to cope with oxidative stress or uptake of nutrients released by plant roots), root adhesion (pili, adhesion, hemagglutinin, cellulose biosynthesis), colonization/establishment inside the plant (chemiotaxis, flagella, cellobiose phosphorylase), plant protection against fungal and bacterial infections (siderophore production and synthesis of the antimicrobial compounds 4-hydroxybenzoate and 2-phenylethanol), and improved poplar growth and development through the production of the phytohormones indole acetic acid, acetoin, and 2,3-butanediol. Metabolite analysis confirmed by quantitative RT-PCR showed that, the production of acetoin and 2,3-butanediol is induced by the presence of sucrose in the growth medium. Interestingly, both the genetic determinants required for sucrose metabolism and the synthesis of acetoin and 2,3-butanediol are clustered on a genomic island. These findings point to a close interaction between Enterobacter sp. 638 and its poplar host, where the availability of sucrose, a major plant sugar, affects the synthesis of plant growth promoting phytohormones by the endophytic bacterium. The availability of the genome sequence, combined with metabolome and transcriptome analysis, will provide a better understanding of the synergistic interactions between poplar and its growth promoting endophyte Enterobacter sp. 638. This information can be further exploited to

  9. Bioethanol production from mannitol by a newly isolated bacterium, Enterobacter sp. JMP3.

    PubMed

    Wang, Jing; Kim, Young Mi; Rhee, Hong Soon; Lee, Min Woo; Park, Jong Moon

    2013-05-01

    In this study a new bacterium capable of growing on brown seaweed Laminaria japonica, Enterobacter sp. JMP3 was isolated from the gut of turban shell, Batillus cornutus. In anaerobic condition, it produced high yields of ethanol (1.15 mol-EtOH mol-mannitol(-1)) as well as organic acids from mannitol, the major carbohydrate component of L. japonica. Based on carbon distribution and metabolic flux analysis, it was revealed that mannitol was more favorable than glucose for ethanol production due to their different redox states. This indicates that L. japonica is one of the promising feedstock for bioethanol production. Additionally, the mannitol dehydrogenation pathway in Enterobacter sp. JMP3 was examined and verified. Finally, an attempt was made to explore the possibility of controlling ethanol production by altering the redox potential via addition of external NADH in mannitol fermentation. PMID:23186687

  10. Bioethanol production from mannitol by a newly isolated bacterium, Enterobacter sp. JMP3.

    PubMed

    Wang, Jing; Kim, Young Mi; Rhee, Hong Soon; Lee, Min Woo; Park, Jong Moon

    2013-05-01

    In this study a new bacterium capable of growing on brown seaweed Laminaria japonica, Enterobacter sp. JMP3 was isolated from the gut of turban shell, Batillus cornutus. In anaerobic condition, it produced high yields of ethanol (1.15 mol-EtOH mol-mannitol(-1)) as well as organic acids from mannitol, the major carbohydrate component of L. japonica. Based on carbon distribution and metabolic flux analysis, it was revealed that mannitol was more favorable than glucose for ethanol production due to their different redox states. This indicates that L. japonica is one of the promising feedstock for bioethanol production. Additionally, the mannitol dehydrogenation pathway in Enterobacter sp. JMP3 was examined and verified. Finally, an attempt was made to explore the possibility of controlling ethanol production by altering the redox potential via addition of external NADH in mannitol fermentation.

  11. Genome Sequence of the Plant Growth Promoting Endophytic Bacterium Enterobacter sp. 638

    PubMed Central

    Taghavi, Safiyh; van der Lelie, Daniel; Hoffman, Adam; Zhang, Yian-Biao; Walla, Michael D.; Vangronsveld, Jaco; Newman, Lee; Monchy, Sébastien

    2010-01-01

    Enterobacter sp. 638 is an endophytic plant growth promoting gamma-proteobacterium that was isolated from the stem of poplar (Populus trichocarpa×deltoides cv. H11-11), a potentially important biofuel feed stock plant. The Enterobacter sp. 638 genome sequence reveals the presence of a 4,518,712 bp chromosome and a 157,749 bp plasmid (pENT638-1). Genome annotation and comparative genomics allowed the identification of an extended set of genes specific to the plant niche adaptation of this bacterium. This includes genes that code for putative proteins involved in survival in the rhizosphere (to cope with oxidative stress or uptake of nutrients released by plant roots), root adhesion (pili, adhesion, hemagglutinin, cellulose biosynthesis), colonization/establishment inside the plant (chemiotaxis, flagella, cellobiose phosphorylase), plant protection against fungal and bacterial infections (siderophore production and synthesis of the antimicrobial compounds 4-hydroxybenzoate and 2-phenylethanol), and improved poplar growth and development through the production of the phytohormones indole acetic acid, acetoin, and 2,3-butanediol. Metabolite analysis confirmed by quantitative RT–PCR showed that, the production of acetoin and 2,3-butanediol is induced by the presence of sucrose in the growth medium. Interestingly, both the genetic determinants required for sucrose metabolism and the synthesis of acetoin and 2,3-butanediol are clustered on a genomic island. These findings point to a close interaction between Enterobacter sp. 638 and its poplar host, where the availability of sucrose, a major plant sugar, affects the synthesis of plant growth promoting phytohormones by the endophytic bacterium. The availability of the genome sequence, combined with metabolome and transcriptome analysis, will provide a better understanding of the synergistic interactions between poplar and its growth promoting endophyte Enterobacter sp. 638. This information can be further exploited to

  12. Enterobacteriaceae in mouth and cloaca of podocnemis expansa and P. Unifilis (testudines: chelonia) populations of national park of araguaia plains, Brazil.

    PubMed

    de Morais, Paula Benevides; de Souza, Denise Rodrigues; de Sousa, Francisca Maria Pinheiro; de Oliveira, Kleverson Wessel; Pimenta, Raphael Sanzio

    2011-04-01

    Shigella flexnerii and Escherichia coli were the most frequent Gram-negative bacteria found in the mouth cavity and cloacae of the turtles Podocnemis expansa and P. unifilis on beaches in the National Park of Araguaia, Brazil. Reptiles are known as Salmonella carriers, despite rarely isolated in these turtles.

  13. Enterobacteriaceae in mouth and cloaca of podocnemis expansa and P. Unifilis (testudines: chelonia) populations of national park of araguaia plains, Brazil

    PubMed Central

    de Morais, Paula Benevides; de Souza, Denise Rodrigues; de Sousa, Francisca Maria Pinheiro; de Oliveira, Kleverson Wessel; Pimenta, Raphael Sanzio

    2011-01-01

    Shigella flexnerii and Escherichia coli were the most frequent Gram-negative bacteria found in the mouth cavity and cloacae of the turtles Podocnemis expansa and P. unifilis on beaches in the National Park of Araguaia, Brazil. Reptiles are known as Salmonella carriers, despite rarely isolated in these turtles. PMID:24031664

  14. Dechlorination of 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane by Aerobacter aerogenes

    USGS Publications Warehouse

    Wedemeyer, Gary

    1967-01-01

    Whole cells or cell-free extracts of Aerobacter aerogenes catalyze the degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in vitro to at least seven metabolites: 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD); 1-chloro-2,2-bis(p-chlorophenyl)ethylene (DDMU); 1-chloro-2,2-bis(p-chlorophenyl)ethane (DDMS); unsym-bis(p-chlorophenyl)ethylene (DDNU); 2,2-bis(p-chlorophenyl)acetate (DDA); and 4,4′-dichlorobenzophenone (DBP). The use of metabolic inhibitors together with pH and temperature studies indicated that discrete enzymes are involved. By use of the technique of sequential analysis, the metabolic pathway was shown to be: DDT → DDD →DDMU →DDMS → DDNU → DDA → DBP, or DDT → DDE. Dechlorination was marginally enhanced by light-activated flavin mononucleotide.

  15. Host-pathogen interactions in specific pathogen-free chickens following aerogenous infection with Chlamydia psittaci and Chlamydia abortus.

    PubMed

    Kalmar, Isabelle; Berndt, Angela; Yin, Lizi; Chiers, Koen; Sachse, Konrad; Vanrompay, Daisy

    2015-03-15

    Although Chlamydia (C.) psittaci infections are recognized as an important factor causing economic losses and impairing animal welfare in poultry production, the specific mechanisms leading to severe clinical outcomes are poorly understood. In the present study, we comparatively investigated pathology and host immune response, as well as systemic dissemination and expression of essential chlamydial genes in the course of experimental aerogeneous infection with C. psittaci and the closely related C. abortus, respectively, in specific pathogen-free chicks. Clinical signs appeared sooner and were more severe in the C. psittaci-infected group. Compared to C. abortus infection, more intense systemic dissemination of C. psittaci correlated with higher and faster infiltration of immune cells, as well as more macroscopic lesions and epithelial pathology, such as hyperplasia and erosion. In thoracic air sac tissue, mRNA expression of immunologically relevant factors, such as IFN-γ, IL-1β, IL-6, IL-17, IL-22, LITAF and iNOS was significantly stronger up-regulated in C. psittaci- than in C. abortus-infected birds between 3 and 14 days post-infection. Likewise, transcription rates of the chlamydial genes groEL, cpaf and ftsW were consistently higher in C. psittaci during the acute phase. These findings illustrate that the stronger replication of C. psittaci in its natural host also evoked a more intense immune response than in the case of C. abortus infection.

  16. Inoculation of hybrid poplar with the endophytic bacterium Enterobacter sp. 638 increases biomass but does not impact leaf level physiology

    SciTech Connect

    Rogers, A.; McDonald, K.; Muehlbauer, M. F.; Hoffman, A.; Koenig, K.; Newman, L.; Taghavi, S.; Van Der Lelie, D.

    2011-01-01

    Endophytic bacteria have been shown to provide several advantages to their host, including enhanced growth. Inoculating biofuel species with endophytic bacteria is therefore an attractive option to increase the productivity of biofuel feedstocks. Here, we investigated the effect of inoculating hard wood cuttings of Populus deltoides Bartr. x Populus. nigra L. clone OP367 with Enterobacter sp. 638. After 17 weeks, plants inoculated with Enterobacter sp. 638 had 55% greater total biomass than un-inoculated control plants. Study of gas exchange and fluorescence in developing and mature leaves over a diurnal cycle and over a 5 week measurement campaign revealed no effects of inoculation on photosynthesis, stomatal conductance, photosynthetic water use efficiency or the maximum and operating efficiency of photosystem II. However, plants inoculated with Enterobacter sp. 638 had a canopy that was 39% larger than control plants indicating that the enhanced growth was fueled by increased leaf area, not by improved physiology. Leaf nitrogen content was determined at two stages over the 5 week measurement period. No effect of Enterobacter sp. 638 on leaf nitrogen content was found indicating that the larger plants were acquiring sufficient nitrogen. Enterobacter sp. 638 lacks the genes for N{sub 2} fixation, therefore the increased availability of nitrogen likely resulted from enhanced nitrogen acquisition by the 84% larger root system. These data show that Enterobacter sp. 638 has the potential to dramatically increase productivity in poplar. If fully realized in the production environment, these results indicate that an increase in the environmental and economic viability of poplar as a biofuel feedstock is possible when inoculated with endophytic bacteria like Enterobacter sp. 638.

  17. Close genetic linkage of the determinants of the ribitol and D-arabitol catabolic pathways in Klebsiella aerogenes.

    PubMed

    Charnetzky, W T; Mortlock, R P

    1974-07-01

    Klebsiella aerogenes strain W70 has separate inducible pathways for the degradation of the pentitols ribitol and d-arabitol. These pathways are closely linked genetically as determined by transduction with phage PW52. There are two regulatory sites for the ribitol catabolic pathway as defined by loci for mutations to constitutive synthesis of ribitol dehydrogenase and d-ribulokinase, rbtB and rbtC. The two control sites are separated by a site represented by the dalB22 mutation. This mutation deprives the cell of the ability to induce synthesis of d-arabitol dehydrogenase and d-xylulokinase activities. Two additional regulatory mutations for the d-arabitol pathway, dalC31 and dalC37, map to the opposite side of rbtB13 relative to dalB22. The order of the genetic sites thus far determined for this region is dalK-dalD-dalC31, dalC37-rbtB13-dalB22-rbtC14-rbtD-rbtK, where dalK and dalD represent structural genes for the kinase and dehydrogenase of the d-arabitol pathway, respectively, and rbtK and rbtD represent the corresponding genes for the ribitol pathway. The two mutations that lead to constitutive synthesis of the d-arabitol-induced enzymes, dalC31 and dalC37, have different phenotypes with regard to their response to xylitol. The growth of dalC31 is inhibited by xylitol, but the toxicity can be reduced by increasing the levels of ribitol dehydrogenase either by induction with ribitol or by selection of a ribitol dehydrogenase-constitutive mutation.

  18. Evidence supporting dissimilatory and assimilatory lignin degradation in Enterobacter lignolyticus SCF1

    SciTech Connect

    DeAngelis, Kristen M.; Sharma, Deepak; Varney, Rebecca; Simmons, Blake A.; Isern, Nancy G.; Markillie, Lye Meng; Nicora, Carrie D.; Norbeck, Angela D.; Taylor, Ronald C.; Aldrich, Joshua T.; Robinson, Errol W.

    2013-08-29

    The anaerobic isolate Enterobacter lignolyticus SCF1 was initially cultivated based on anaerobic growth on lignin as sole carbon source. The source of the isolated bacteria was from tropical forest soils that decompose litter rapidly with low and fluctuating redox potentials, making it likely that bacteria using oxygen-independent enzymes play an important role in decomposition. We have examined differential expression of the anaerobic isolate Enterobacter lignolyticus SCF1 during growth on lignin. After 48 hours of growth, we used transcriptomics and proteomics to define the enzymes and other regulatory machinery that these organisms use to degrade lignin, as well as metabolomics to measure lignin degradation and monitor the use of lignin and iron as terminal electron acceptors that facilitate more efficient use of carbon. Proteomics revealed accelerated xylose uptake and metabolism under lignin-amended growth, and lignin degradation via the 4-hydroxyphenylacetate degradation pathway, catalase/peroxidase enzymes, and the glutathione biosynthesis and glutathione S-transferase proteins. We also observed increased production of NADH-quinone oxidoreductase, other electron transport chain proteins, and ATP synthase and ATP-binding cassette (ABC) transporters. Our data shows the advantages of a multi-omics approach, where incomplete pathways identified by genomics were completed, and new observations made on coping with poor carbon availability. The fast growth, high efficiency and specificity of enzymes employed in bacterial anaerobic litter deconstruction makes these soils useful templates for improving biofuel production.

  19. Exopolysaccharide produced by Enterobacter sp. YG4 reduces uranium induced nephrotoxicity.

    PubMed

    K, Nagaraj; Devasya, Rekha Punchapady; Bhagwath, Arun Ananthapadmanabha

    2016-01-01

    Uranium nephrotoxicity is a health concern with very few treatment options. Bacterial exopolysaccharides (EPS) possess multiple biological activities and appear as prospective candidates for treating uranium nephrotoxicity. This study focuses on the ability of an EPS produced by a bacterial strain Enterobacter sp. YG4 to reduce uranium nephrotoxicity in vivo. This bacterium was isolated from the gut contents of a slug Laevicaulis alte (Férussac). Based on the aniline blue staining reaction and infrared spectral analysis, the EPS was identified as β-glucan and its molecular weight was 11.99×10(6)Da. The EPS showed hydroxyl radical scavenging ability and total antioxidant capacity in vitro. To assess the protection provided by the EPS against uranium nephrotoxicity, a single dose of 2mg/kg uranyl nitrate was injected intraperitoneally to albino Wistar rats. As intervention, the EPS was administered orally (100mg/kg/day) for 4 consecutive days. The rats were sacrificed on the fifth day and analyses were conducted. Increased serum creatinine and urea nitrogen levels and histopathological alterations in kidneys were observed in uranyl nitrate treated animals. All these alterations were reduced with the administration of Enterobacter sp. YG4 EPS, emphasizing a novel approach in treating uranium nephrotoxicity.

  20. 42 CFR 493.911 - Bacteriology.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... freundii Enterobacter aerogenes Escherichia coli Klebsiella pneumoniae Proteus mirabilis Salmonella... characteristics to be interpreted by Gram stain. The program determines the reportable bacteria to be detected...

  1. 42 CFR 493.911 - Bacteriology.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... freundii Enterobacter aerogenes Escherichia coli Klebsiella pneumoniae Proteus mirabilis Salmonella... characteristics to be interpreted by Gram stain. The program determines the reportable bacteria to be detected...

  2. 42 CFR 493.911 - Bacteriology.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... freundii Enterobacter aerogenes Escherichia coli Klebsiella pneumoniae Proteus mirabilis Salmonella... characteristics to be interpreted by Gram stain. The program determines the reportable bacteria to be detected...

  3. 42 CFR 493.911 - Bacteriology.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... freundii Enterobacter aerogenes Escherichia coli Klebsiella pneumoniae Proteus mirabilis Salmonella... characteristics to be interpreted by Gram stain. The program determines the reportable bacteria to be detected...

  4. 42 CFR 493.911 - Bacteriology.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... freundii Enterobacter aerogenes Escherichia coli Klebsiella pneumoniae Proteus mirabilis Salmonella... characteristics to be interpreted by Gram stain. The program determines the reportable bacteria to be detected...

  5. Draft Genome Sequence of Endophytic Bacterium Enterobacter asburiae PDA134, Isolated from Date Palm (Phoenix dactylifera L.) Roots.

    PubMed

    Yaish, Mahmoud W

    2016-01-01

    In this report, a draft of the Enterobacter asburiae strain PDA134 genome was sequenced. This bacterial strain was isolated from the root tissue of a date palm, where it has the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and indole-3-acetic acid (IAA) under salinity stress. PMID:27540071

  6. Inactivation of pqq Genes of Enterobacter Intermedium 60-2G Reduces Antifungal Activity and Induction of Systemic Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enterobacter intermedium 60-2G, a phosphate solubilizing bacterium, has the ability to induce systemic resistance in plants against soft rot pathogen Erwinia carotovora. Phosphate solubilization is mediated by the production of organic acids. Glucose dehydrogenase, an enzyme which utilizes pyrroloq...

  7. Draft Genome Sequence of Endophytic Bacterium Enterobacter asburiae PDA134, Isolated from Date Palm (Phoenix dactylifera L.) Roots

    PubMed Central

    2016-01-01

    In this report, a draft of the Enterobacter asburiae strain PDA134 genome was sequenced. This bacterial strain was isolated from the root tissue of a date palm, where it has the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and indole-3-acetic acid (IAA) under salinity stress. PMID:27540071

  8. Plant growth promotion and root colonization by EPS producing Enterobacter sp. RZS5 under heavy metal contaminated soil.

    PubMed

    Sayyed, R Z; Patel, P R; Shaikh, S S

    2015-02-01

    The heavy metal resistant bacterium isolated from field soil and identified as Enterobacter sp. RZS5 tolerates a high concentration (100-2000 μM) of various heavy metal ions such as Mn2+, Ni2+, Zn2+, Cu2+, CO2+ and Fe2+ when grown in such environment and produces exopolysaccharides (EPS). Here, we have demonstrated EPS production by Enterobacter sp. RZS5 during 60 h of growth in yeast extract mannitol broth (YEMB). The yield increased by two fold after the addition of 60 μM of Ca2+; 50 μM of Fe2+ and 60 μM of Mg2+ ions in YEMB, and the optimization of physico-chemical parameters. EPS was extracted with 30% (v/v) of isopropanol as against the commonly used 50% (v/v) isopropanol method. EPS-rich broth promoted seed germination, shoot height, root length, number of leaves and chlorophyll content of wheat (Triticum aestivum) seed and peanut (Arachis hypogaea) seed. The higher colony-forming unit of Enterobacter sp. in soil inoculated with EPS rich broth of Enterobacter sp. indicated the root colonizing potential and rhizosphere competence of the isolate. The FTIR spectra of the EPS extract confirmed the presence of the functional group characteristics of EPS known to exhibit a high binding affinity towards certain metal ions. This overall growth and vigour in plants along with the effective root colonization, reflected the potential of the isolate as an efficient bio-inoculant in bioremediation.

  9. [Labelling of nif-plasmid pEA9 from Enterobacter agglomerans 339].

    PubMed

    Liu, Cheng-jun; Klingmüller, Walter

    2002-07-01

    The authors describe the in vivo labelling of the plasmid pEA9 in Enterobacter agglomerans 339 with a kanamycin resistance gene. For labelling purposes the donor plasmid pST5 was constructed. This plasmid contains the nif ENX region from pEA9,in which a kanamycin resistance gene is cloned.pST5 was transformed into E.a.339 and subsequently cured from the host. Curing was achieved with AP medium. Fourty strains that had lost pST5,but retained the kanamycin resistance, could be isolated. It showed that none of these clones contained co-integrates of pST5 and pEA9. This is evident that in all clones the kanamycin resistance gene was integrated into pEA9 by homologous recombination.

  10. Enterobacter sacchari sp. nov., a nitrogen-fixing bacterium associated with sugar cane (Saccharum officinarum L.).

    PubMed

    Zhu, Bo; Zhou, Qing; Lin, Li; Hu, Chunjin; Shen, Ping; Yang, Litao; An, Qianli; Xie, Guanlin; Li, Yangrui

    2013-07-01

    Five nitrogen-fixing bacterial strains (SP1(T), NN143, NN144, NN208 and HX148) were isolated from stem, root or rhizosphere soil of sugar cane (Saccharum officinarum L.) plants. Cells were Gram-negative, motile, rods with peritrichous flagella. DNA G+C content was 55.0 ± 0.5 mol%. Sequence determinations and phylogenetic analysis of 16S rRNA gene and rpoB indicated that the strains were affiliated with the genus Enterobacter and most closely related to E. radicincitans DSM 16656(T) and E. oryzae LMG 24251(T). Fluorimetric determination of thermal denaturation temperatures after DNA-DNA hybridization, enterobacterial repetitive intergenic consensus PCR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry differentiated the whole-genome, genotype and protein profiles from those of E. radicincitans and E. oryzae. The strains' cell fatty acid composition differentiated them from E. radicincitans and E. oryzae by containing a higher level of summed feature 2 (C16 : 1ω7c and/or C16 : 1ω6c) and a lower level of C17 : 0 cyclo. Their physiological and biochemical profiles differentiated them from E. radicincitans by being positive for methyl red test, ornithine decarboxylase and utilization of putrescine, D-arabitol, L-fucose and methyl α-D-glucoside and being negative for arginine dihydrolase, and differentiated them from E. oryzae by being positive for aesculin hydrolysis and utilization of putrescine, D-arabitol and L-rhamnose and being negative for arginine dihydrolase, lysine decarboxylase and utilization of mucate. The five strains therefore represent a novel species, for which the name Enterobacter sacchari sp. nov. is proposed, with the type strain SP1(T) ( = CGMCC 1.12102(T) = LMG 26783(T)).

  11. Cloning and characterization of newly isolated lipase from Enterobacter sp. Bn12

    PubMed Central

    Farrokh, Parisa; Yakhchali, Bagher; Karkhane, Ali Asghar

    2014-01-01

    A mesophilic Enterobacter sp. Bn12 producing an alkaline thermostable lipase was isolated from soil in Tehran, Iran. The lipase gene (ELBn12) was identified from a genomic library. Sequence analysis of the DNA fragment revealed an open reading frame of 879 bp encoding a lipase with a molecular mass of 31.3 kDa. The deduced amino acid sequence showed 96% identity with a lipase of Enterobacter sp. Ag1 and the identity of their DNA sequences was 88.9%. ELBn12 belongs to the lipase subfamily I.1 and its catalytic triad consists of Ser82, Asp237 and His259. The lipase was expressed in Escherichia coli (BL21) pLysS and partially purified by anion exchange chromatography. The maximum activity of ELBn12 was obtained at temperature of 60 °C and pH 8.0 towards tricaprylin (C8) and its specific activity was around 2900 U/mg. ELBn12 was stable within a broad pH range from 6.0 to 11.0. The enzyme showed high stability in both polar and nonpolar organic solvents at 50% (v/v). The lipase activity was enhanced in the presence of 10 mM of Ca2+, Mg2+ and K+, while heavy metals (Fe3+ and Zn2+) had strong inhibitory effect. ELBn12 showed high activity in the presence of 1% (w/v) nonionic surfactants, however ionic surfactants inhibited the lipolytic activity. ELBn12 characteristics show that it has a potential to be used in various industrial processes. PMID:25242958

  12. Enterobacter sacchari sp. nov., a nitrogen-fixing bacterium associated with sugar cane (Saccharum officinarum L.).

    PubMed

    Zhu, Bo; Zhou, Qing; Lin, Li; Hu, Chunjin; Shen, Ping; Yang, Litao; An, Qianli; Xie, Guanlin; Li, Yangrui

    2013-07-01

    Five nitrogen-fixing bacterial strains (SP1(T), NN143, NN144, NN208 and HX148) were isolated from stem, root or rhizosphere soil of sugar cane (Saccharum officinarum L.) plants. Cells were Gram-negative, motile, rods with peritrichous flagella. DNA G+C content was 55.0 ± 0.5 mol%. Sequence determinations and phylogenetic analysis of 16S rRNA gene and rpoB indicated that the strains were affiliated with the genus Enterobacter and most closely related to E. radicincitans DSM 16656(T) and E. oryzae LMG 24251(T). Fluorimetric determination of thermal denaturation temperatures after DNA-DNA hybridization, enterobacterial repetitive intergenic consensus PCR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry differentiated the whole-genome, genotype and protein profiles from those of E. radicincitans and E. oryzae. The strains' cell fatty acid composition differentiated them from E. radicincitans and E. oryzae by containing a higher level of summed feature 2 (C16 : 1ω7c and/or C16 : 1ω6c) and a lower level of C17 : 0 cyclo. Their physiological and biochemical profiles differentiated them from E. radicincitans by being positive for methyl red test, ornithine decarboxylase and utilization of putrescine, D-arabitol, L-fucose and methyl α-D-glucoside and being negative for arginine dihydrolase, and differentiated them from E. oryzae by being positive for aesculin hydrolysis and utilization of putrescine, D-arabitol and L-rhamnose and being negative for arginine dihydrolase, lysine decarboxylase and utilization of mucate. The five strains therefore represent a novel species, for which the name Enterobacter sacchari sp. nov. is proposed, with the type strain SP1(T) ( = CGMCC 1.12102(T) = LMG 26783(T)). PMID:23291881

  13. Cloning and characterization of newly isolated lipase from Enterobacter sp. Bn12.

    PubMed

    Farrokh, Parisa; Yakhchali, Bagher; Karkhane, Ali Asghar

    2014-01-01

    A mesophilic Enterobacter sp. Bn12 producing an alkaline thermostable lipase was isolated from soil in Tehran, Iran. The lipase gene (ELBn12) was identified from a genomic library. Sequence analysis of the DNA fragment revealed an open reading frame of 879 bp encoding a lipase with a molecular mass of 31.3 kDa. The deduced amino acid sequence showed 96% identity with a lipase of Enterobacter sp. Ag1 and the identity of their DNA sequences was 88.9%. ELBn12 belongs to the lipase subfamily I.1 and its catalytic triad consists of Ser82, Asp237 and His259. The lipase was expressed in Escherichia coli (BL21) pLysS and partially purified by anion exchange chromatography. The maximum activity of ELBn12 was obtained at temperature of 60 °C and pH 8.0 towards tricaprylin (C8) and its specific activity was around 2900 U/mg. ELBn12 was stable within a broad pH range from 6.0 to 11.0. The enzyme showed high stability in both polar and nonpolar organic solvents at 50% (v/v). The lipase activity was enhanced in the presence of 10 mM of Ca(2+), Mg(2+) and K(+), while heavy metals (Fe(3+) and Zn(2+)) had strong inhibitory effect. ELBn12 showed high activity in the presence of 1% (w/v) nonionic surfactants, however ionic surfactants inhibited the lipolytic activity. ELBn12 characteristics show that it has a potential to be used in various industrial processes. PMID:25242958

  14. The combination Enterobacter agglomerans is to be cited as Enterobacter agglomerans (Beijerinck 1888) Ewing and Fife 1972 and the combination Pantoea agglomerans is to be cited as Pantoea agglomerans (Beijerinck 1888) Gavini et al. 1989. Opinion 90. Judicial Commission of the International Committee on Systematics of Prokaryotes.

    PubMed

    Tindall, B J

    2014-10-01

    The Judicial Commission affirms that, according to information presented to it, the combination Enterobacter agglomerans is to be cited as Enterobacter agglomerans (Beijerinck 1888) Ewing and Fife 1972 and the combination Pantoea agglomerans is to be cited as Pantoea agglomerans (Beijerinck 1888) Gavini et al. 1989.

  15. Self-transmissible nif plasmid (pEA9) of Enterobacter agglomerans 339: molecular cloning and evidence for the existence of similar nif clusters on dissimilar plasmids in Enterobacter strains.

    PubMed

    Steibl, H D; Siddavattam, D; Klingmüller, W

    1995-11-01

    A cosmid library was generated to the 200-kb self-transmissible nif plasmid pEA9 isolated from Enterobacter agglomerans 339. The cosmid clone identified to contain the complete nif cluster was used to determine the nif gene organization and the physical map. The restriction pattern and nif gene organization of this nif cluster showed remarkable similarities to the nif cluster identified on the 110-kb plasmid pEA3 of Enterobacter agglomerans 333. Nucleotide sequence of several randomly selected regions of the nif cluster of pEA9 showed 96% similarity when compared to the known sequences of the nif cluster of pEA3. However, the homology ended abruptly at the flanking regions of the nif clusters and no similarity could be detected with the rest of the DNA of these plasmids. This reveals the existence of similar nif clusters on dissimilar plasmids, implying the horizontal transfer of the entire nif gene cluster.

  16. High-quality draft genome sequence of Enterobacter sp. Bisph2, a glyphosate-degrading bacterium isolated from a sandy soil of Biskra, Algeria.

    PubMed

    Benslama, Ouided; Boulahrouf, Abderrahmane

    2016-06-01

    Enterobacter sp. strain Bisph2 was isolated from a sandy soil from Biskra, Algeria and exhibits glyphosate-degrading activity. Multilocus sequence analysis of the 16S rRNA, rpoB, hsp60, gyrB and dnaJ genes demonstrated that Bisph2 might be a member of a new species of the genus Enterobacter. Genomic sequencing of Bisph2 was used to better clarify the relationships among Enterobacter species. Annotation and analysis of the genome sequence showed that the 5.535.656 bp genome of Enterobacter sp. Bisph2 consists in one chromosome and no detectable plasmid, has a 53.19% GC content and 78% of genes were assigned a putative function. The genome contains four prophages of which 3 regions are intact and no CRISPER was detected. The nucleotide sequence of this genome was deposited into DDBJ/EMBL/GenBank under the accession JXAF00000000. PMID:27222800

  17. High-quality draft genome sequence of Enterobacter sp. Bisph2, a glyphosate-degrading bacterium isolated from a sandy soil of Biskra, Algeria.

    PubMed

    Benslama, Ouided; Boulahrouf, Abderrahmane

    2016-06-01

    Enterobacter sp. strain Bisph2 was isolated from a sandy soil from Biskra, Algeria and exhibits glyphosate-degrading activity. Multilocus sequence analysis of the 16S rRNA, rpoB, hsp60, gyrB and dnaJ genes demonstrated that Bisph2 might be a member of a new species of the genus Enterobacter. Genomic sequencing of Bisph2 was used to better clarify the relationships among Enterobacter species. Annotation and analysis of the genome sequence showed that the 5.535.656 bp genome of Enterobacter sp. Bisph2 consists in one chromosome and no detectable plasmid, has a 53.19% GC content and 78% of genes were assigned a putative function. The genome contains four prophages of which 3 regions are intact and no CRISPER was detected. The nucleotide sequence of this genome was deposited into DDBJ/EMBL/GenBank under the accession JXAF00000000.

  18. My 40-Year History with Cronobacter/Enterobacter sakazakii – Lessons Learned, Myths Debunked, and Recommendations

    PubMed Central

    Farmer, John J.

    2015-01-01

    Much has been learned about organism in the Cronobacter/Enterobacter sakazakii complex since I first named and described Enterobacter sakazakii in 1980. However, there are still wide knowledge gaps. One of the most serious is that are still many uncertainties associated with assessing the public health risk posed by these bacteria, particularly in neonatal meningitis. Over the last few decades, Cronobacter contamination of commercial powdered infant formula products has apparently been reduced, but it is still an ongoing problem. The powdered infant formula industry still cannot produce powdered formula that is free of bacterial contamination with Cronobacter, other Enterobacteriaceae, other pathogenic bacteria, and other microorganisms. Until this happens, infants and other will be at risk of becoming infected when they ingest contaminated formula. PMID:26640778

  19. Transcriptional Responses to Sucrose Mimic the Plant-Associated Life Style of the Plant Growth Promoting Endophyte Enterobacter sp. 638

    SciTech Connect

    Taghavi, Safiyh; Wu, Xiao; Ouyang, Liming; Zhang, Yian Biao; Stadler, Andrea; McCorkle, Sean; Zhu, Wei; Maslov, Sergei; van der Lelie, Daniel

    2015-01-21

    Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involved in motility (e.g. flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Lastly, targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability.

  20. Transcriptional Responses to Sucrose Mimic the Plant-Associated Life Style of the Plant Growth Promoting Endophyte Enterobacter sp. 638

    DOE PAGES

    Taghavi, Safiyh; Wu, Xiao; Ouyang, Liming; Zhang, Yian Biao; Stadler, Andrea; McCorkle, Sean; Zhu, Wei; Maslov, Sergei; van der Lelie, Daniel

    2015-01-21

    Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involvedmore » in motility (e.g. flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Lastly, targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability.« less

  1. Transcriptional Responses to Sucrose Mimic the Plant-Associated Life Style of the Plant Growth Promoting Endophyte Enterobacter sp. 638

    PubMed Central

    Taghavi, Safiyh; Wu, Xiao; Ouyang, Liming; Stadler, Andrea; McCorkle, Sean; Zhu, Wei; Maslov, Sergei; van der Lelie, Daniel

    2015-01-01

    Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involved in motility (e.g. flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability. PMID:25607953

  2. Biological decolorization of the reactive dyes Reactive Black 5 by a novel isolated bacterial strain Enterobacter sp. EC3.

    PubMed

    Wang, Hui; Zheng, Xiao-Wei; Su, Jian-Qiang; Tian, Yun; Xiong, Xiao-Jing; Zheng, Tian-Ling

    2009-11-15

    Studies were carried out on the decolorization of the reactive dye Reactive Black 5 by a newly isolated bacterium, EC3. Phenotypic characterization and phylogenetic analysis based on 16S rDNA sequence comparisons indicate that this strain belonged to the genus Enterobacter. The optimal conditions for the decolorizing activity of Enterobacter sp. EC3 were anaerobic conditions with glucose supplementation, at pH 7.0, and 37 degrees C. The maximum decolorization efficiency against Reactive Black 5 achieved in this study was 92.56%. Ultra-violet and visible (UV-vis) analyses before and after decolorization and the colorless bacterial biomass after decolorization suggested that decolorization was due to biodegradation, rather than inactive surface adsorption. The bacterial strain also showed a strong ability to decolorize various reactive textile dyes, including both azo and anthraquinone dyes. To our knowledge, it is the first time that a bacterial strain of Enterobacter sp. has been reported with decolorizing ability against both azo and anthraquinone dyes.

  3. Synthesis and antimicrobial activity of some netropsin analogues.

    PubMed

    Khalaf, Abedawn I; Ebrahimabadi, Abdolrasoul H; Drummond, Allan J; Anthony, Nahoum G; Mackay, Simon P; Suckling, Colin J; Waigh, Roger D

    2004-11-01

    Nine novel lexitropsins were synthesized by linking two netropsin-like moieties through three different dicarboxylic acids; 9,10-dihydro-2,7-phenanthrenedicarboxylic acid; [(3-[[(carboxymethyl)amino]carbonyl]benzoyl)amino]acetic acid and indole-2,5-dicarboxylic acid. The netropsin residues were modified by the use of N-isopentylpyrrole, 5-methylthiophene or 5-isopropylthiazole heterocyclic building blocks in place of the usual N-methylpyrrole. The compounds were tested against five gram-positive bacteria: Staphylococcus aureus, Streptomyces faecalis, methicillin resistant Staphylococcus aureus, Enterobacter cloacae, Mycobacterium fortuitum, three gram-negative bacteria: Klebsiella aerogenes, Proteus vulgaris, Escherichia coli and three fungi: Aspergillus niger, Candida albicans and Aspergillus nidulans. Some of the compounds showed significant inhibitory effects on the growth of the microorganisms. PMID:15505717

  4. Global transcriptome response to ionic liquid by a tropical rain forest soil bacterium, Enterobacter lignolyticus.

    PubMed

    Khudyakov, Jane I; D'haeseleer, Patrik; Borglin, Sharon E; Deangelis, Kristen M; Woo, Hannah; Lindquist, Erika A; Hazen, Terry C; Simmons, Blake A; Thelen, Michael P

    2012-08-01

    To process plant-based renewable biofuels, pretreatment of plant feedstock with ionic liquids has significant advantages over current methods for deconstruction of lignocellulosic feedstocks. However, ionic liquids are often toxic to the microorganisms used subsequently for biomass saccharification and fermentation. We previously isolated Enterobacter lignolyticus strain SCF1, a lignocellulolytic bacterium from tropical rain forest soil, and report here that it can grow in the presence of 0.5 M 1-ethyl-3-methylimidazolium chloride, a commonly used ionic liquid. We investigated molecular mechanisms of SCF1 ionic liquid tolerance using a combination of phenotypic growth assays, phospholipid fatty acid analysis, and RNA sequencing technologies. Potential modes of resistance to 1-ethyl-3-methylimidazolium chloride include an increase in cyclopropane fatty acids in the cell membrane, scavenging of compatible solutes, up-regulation of osmoprotectant transporters and drug efflux pumps, and down-regulation of membrane porins. These findings represent an important first step in understanding mechanisms of ionic liquid resistance in bacteria and provide a basis for engineering microbial tolerance.

  5. Behavior of Enterobacter pulveris in amorphous and crystalline powder matrices treated with supercritical carbon dioxide.

    PubMed

    Callanan, M; Paes, M; Iversen, C; Kleijn, R; Bravo Almeida, C; Peñaloza, W; Johnson, N; Vuataz, G; Michel, M

    2012-11-01

    The resistance of an Enterobacter pulveris strain to combined heat and supercritical carbon dioxide (scCO(2)) treatments in different powder matrices was examined. The strain proved resistant to scCO(2) treatment up to 50 MPa pressure at temperatures >73 °C for at least 20 min in a commercial infant formula. Water availability was shown to be important for the observed thermotolerance, because introduction of water in the scCO(2) gas flow during treatment resulted in a 1 log(10) cfu/g reduction of the initial inoculum. Interestingly, similar tolerance to heat and scCO(2) treatment was observed in a less complex matrix, a maltodextrin powder. In contrast, the bacterial strain proved sensitive to lower temperatures (55-65 °C) over shorter times (≤10 min) in a dextrose powder composed of crystalline particles. Therefore, the microorganism demonstrates heat sensitivity in the crystalline powder matrix closer to that of nonpowder liquid matrices. These data demonstrate the increased heat tolerance of the bacterium specifically in amorphous powders and indicate that this characteristic is not dependent on fat and other components commonly found in infant formula. The information is important in designing strategies to deal with contamination of powders with Enterobacteriacae, including pathogenic Cronobacter spp.

  6. Behavior of Enterobacter pulveris in amorphous and crystalline powder matrices treated with supercritical carbon dioxide.

    PubMed

    Callanan, M; Paes, M; Iversen, C; Kleijn, R; Bravo Almeida, C; Peñaloza, W; Johnson, N; Vuataz, G; Michel, M

    2012-11-01

    The resistance of an Enterobacter pulveris strain to combined heat and supercritical carbon dioxide (scCO(2)) treatments in different powder matrices was examined. The strain proved resistant to scCO(2) treatment up to 50 MPa pressure at temperatures >73 °C for at least 20 min in a commercial infant formula. Water availability was shown to be important for the observed thermotolerance, because introduction of water in the scCO(2) gas flow during treatment resulted in a 1 log(10) cfu/g reduction of the initial inoculum. Interestingly, similar tolerance to heat and scCO(2) treatment was observed in a less complex matrix, a maltodextrin powder. In contrast, the bacterial strain proved sensitive to lower temperatures (55-65 °C) over shorter times (≤10 min) in a dextrose powder composed of crystalline particles. Therefore, the microorganism demonstrates heat sensitivity in the crystalline powder matrix closer to that of nonpowder liquid matrices. These data demonstrate the increased heat tolerance of the bacterium specifically in amorphous powders and indicate that this characteristic is not dependent on fat and other components commonly found in infant formula. The information is important in designing strategies to deal with contamination of powders with Enterobacteriacae, including pathogenic Cronobacter spp. PMID:22959935

  7. Global transcriptome response to ionic liquid by a tropical rain forest soil bacterium, Enterobacter lignolyticus.

    PubMed

    Khudyakov, Jane I; D'haeseleer, Patrik; Borglin, Sharon E; Deangelis, Kristen M; Woo, Hannah; Lindquist, Erika A; Hazen, Terry C; Simmons, Blake A; Thelen, Michael P

    2012-08-01

    To process plant-based renewable biofuels, pretreatment of plant feedstock with ionic liquids has significant advantages over current methods for deconstruction of lignocellulosic feedstocks. However, ionic liquids are often toxic to the microorganisms used subsequently for biomass saccharification and fermentation. We previously isolated Enterobacter lignolyticus strain SCF1, a lignocellulolytic bacterium from tropical rain forest soil, and report here that it can grow in the presence of 0.5 M 1-ethyl-3-methylimidazolium chloride, a commonly used ionic liquid. We investigated molecular mechanisms of SCF1 ionic liquid tolerance using a combination of phenotypic growth assays, phospholipid fatty acid analysis, and RNA sequencing technologies. Potential modes of resistance to 1-ethyl-3-methylimidazolium chloride include an increase in cyclopropane fatty acids in the cell membrane, scavenging of compatible solutes, up-regulation of osmoprotectant transporters and drug efflux pumps, and down-regulation of membrane porins. These findings represent an important first step in understanding mechanisms of ionic liquid resistance in bacteria and provide a basis for engineering microbial tolerance. PMID:22586090

  8. Kinetics of production and characterization of the fucose-containing exopolysaccharide from Enterobacter A47.

    PubMed

    Torres, Cristiana A V; Marques, Rodolfo; Antunes, Sílvia; Alves, Vítor D; Sousa, Isabel; Ramos, Ana Maria; Oliveira, Rui; Freitas, Filomena; Reis, Maria A M

    2011-12-20

    A fucose-containing exopolysaccharide (EPS) was produced by the bacterium Enterobacter A47 using glycerol byproduct from the biodiesel industry. The analysis of kinetic data suggested a partially growth associated EPS synthesis model. Although the EPS was composed of fucose, galactose and glucose at all cultivation stages, their relative proportion has varied considerably during the run. At the beginning (24h), glucose was the main component (82.4 wt.%), being fucose and galactose minor components (5.0 wt.% and 10.9 wt.%, respectively), while at the end (96 h) it was composed of 26.0 wt.% fucose, 28.9 wt.% galactose and 43.7 wt.% glucose. The acyl groups content and composition have also changed, reaching their maximum content (19.2wt.%) at the end of the run. Moreover, the molecular weight has increased linearly during the run (from 8×10(5) to 5×10(6)). The changes observed in EPS composition and molecular weight have also had an impact upon the polymer's intrinsic viscosity, as shown by its linear increase from 3.95 to 10.72 dL g(-1). The results suggest that the culture might have synthesized at least two distinct EPS, with different sugar composition and average molecular weight, which predominated at different cultivation stages.

  9. Production, characteristics and applications of phytase from a rhizosphere isolated Enterobacter sp. ACSS.

    PubMed

    Chanderman, Ashira; Puri, Adarsh Kumar; Permaul, Kugen; Singh, Suren

    2016-10-01

    Optimization of process parameters for phytase production by Enterobacter sp. ACSS led to a 4.6-fold improvement in submerged fermentation, which was enhanced further in fed-batch fermentation. The purified 62 kDa monomeric phytase was optimally active at pH 2.5 and 60 °C and retained activity over a wide range of temperature (40-80 °C) and pH (2.0-6.0) with a half-life of 11.3 min at 80 °C. The kinetic parameters K m, V max, K cat, and K cat/K m of the pure phytase were 0.21 mM, 131.58 nmol mg(-1) s(-1), 1.64 × 10(3) s(-1), and 7.81 × 10(6) M(-1) s(-1), respectively. The enzyme was fairly stable in the presence of pepsin under physiological conditions. It was stimulated by Ca(+2), Mg(+2) and Mn(+2), but inhibited by Zn(+2), Cu(+2), Fe(+2), Pb(+2), Ba(+2) and surfactants. The enzyme can be applied in dephytinizing animal feeds, and the baking industry. PMID:27250653

  10. Decreasing Enterobacter sakazakii (Cronobacter spp.) food contamination level with bacteriophages: prospects and problems

    PubMed Central

    Zuber, Sophie; Boissin‐Delaporte, Catherine; Michot, Lise; Iversen, Carol; Diep, Benjamin; Brüssow, Harald; Breeuwer, Pieter

    2008-01-01

    Summary Enterobacter sakazakii (Cronobacter spp.) is an opportunistic pathogen, which can cause rare, but life‐threatening infections in neonates and infants through feeding of a contaminated milk formula. We isolated 67 phages from environmental samples and tested their lytic host range on a representative collection of 40 E. sakazakii strains. A cocktail of five phages prevented the outgrowth of 35 out of 40 test strains in artificially contaminated infant formula. Two E. sakazakii phages represented prolate head Myoviridae. Molecular tests identified them as close relatives of Escherichia coli phage T4. The remaining three phages represented isometric head Myoviridae with large genome size of 140 and 200 kb, respectively, which belonged to two different DNA hybridization groups. A high dose of 108 pfu ml−1 of phage could effectively sterilize a broth contaminated with both high and low pathogen counts (106 and 102 cfu ml−1). In contrast, broth inoculated with 104 phage and 102 bacteria per ml first showed normal bacterial growth until reaching a cell titre of 105 cfu ml−1. Only when crossing this threshold, phage replication started, but it could not reduce the contamination level below 100 cfu ml−1. Phages could be produced with titres of 1010 pfu ml−1 in broth culture, but they were not stable upon freeze‐drying. Addition of trehalose or milk formula stabilized the phage preparation, which then showed excellent storage stability even at elevated temperature. PMID:21261874

  11. Nitrogen-fixing Enterobacter agglomerans isolated from guts of wood-eating termites.

    PubMed Central

    Potrikus, C J; Breznak, J A

    1977-01-01

    Two strains of facultatively anaerobic, N2-fixing bacteria were isolated from guts of Coptotermes formosanus and identified as Enterobacter agglomerans. The deoxyribonucleic acid base composition of isolates was 52.6 and 53.1 mol% guanine plus cytosine. Both isolates and a known strain of E. agglomerans carried out a mixed acid type of glucose fermentation. N2 fixation by E. agglomerans was inhibited by O2; consequently, N2 served as an N source only for cells growing anaerobically in media lacking a major source of combined N. However, peptone, NH4Cl, or KNO3 served as an N source under either aerobic or anaerobic conditions. It was estimated that 2 x 10(2) cells of E. agglomerans were present per termite gut. This value was 100-fold lower than expected, based on N2 fixation, low recoveries of E. agglomerans may be related to the marked decrease in N2 fixation rates observed when intact termites or their extracted guts were manipulated for the isolation of bacteria. It was concluded that the N2-fixing activity of E. agglomerans may be important to the N economy of C. formosanus. PMID:848958

  12. Inactivation of Enterobacter sakazakii of dehydrated infant formula by gamma-irradiation

    NASA Astrophysics Data System (ADS)

    Lee, Ju-Woon; Oh, Sang-Hee; Byun, Eui-Baek; Kim, Jae-Hun; Kim, Jang-Ho; Woon, Jae-Ho; Byun, Myung-Woo

    2007-11-01

    Enterobacter sakazakii has been implicated as a causal organism in a severe form of neonatal meningitis, with reported mortality rates of 20%. The population at greatest risk is immunocompromised infants of any age. Dried infant formula has been identified as a potential source of the organism in both outbreaks and sporadic cases. The objective of this study was to investigate theirradiation effect of the inactivation on E. sakazakii (ATCC 29544) of a dehydrated infant formula. The D10-values were 0.22-0.27 and 0.76 kGy for broth and dehydrated infant formula, respectively. The irradiation at 5.0 kGy was able to completely eliminate the E. sakazakii inoculated at 8.0 to 9.0 log CFU g -1 onto a dehydrated infant formula. There was no regrowth for all samples during the time they were stored at 10 °C for 6 h after rehydration. The present results indicated that a gamma-irradiation could potentially be used to inactivate E. sakazakii in a dehydrated powdered infant formula.

  13. A Novel CTX-M β-Lactamase (CTX-M-8) in Cefotaxime-Resistant Enterobacteriaceae Isolated in Brazil

    PubMed Central

    Bonnet, R.; Sampaio, J. L. M.; Labia, R.; De Champs, C.; Sirot, D.; Chanal, C.; Sirot, J.

    2000-01-01

    To estimate the diversity of extended-spectrum β-lactamases in Brazil, 18 strains from different species of the family Enterobacteriaceae exhibiting a positive double-disk synergy test were collected by a clinical laboratory from several hospitals in Rio de Janeiro, Brazil, in 1996 and 1997. Four strains (Proteus mirabilis, Enterobacter cloacae, Enterobacter aerogenes, and Citrobacter amalonaticus) hybridized with a 550-bp CTX-M probe. The P. mirabilis strain produced a CTX-M-2 enzyme. The E. cloacae, E. aerogenes, and C. amalonaticus isolates harbored a bla gene which was identified by cloning and sequencing as a blaCTX-M gene. E. coli HB101 transconjugants and the E. coli DH5α transformant harboring a recombinant plasmid produced a CTX-M β-lactamase with an isoelectric point of 7.6 conferring a resistance phenotype characterized by a higher level of resistance to cefotaxime than to ceftazidime, as observed with the other CTX-M enzymes. The deduced protein sequence showed a novel Ambler class A CTX-M enzyme, named CTX-M-8, which had 83 to 88% identity with the previously described CTX-M enzymes. The phylogenic study of the CTX-M family including CTX-M-8 revealed four CTX-M types, CTX-M-8 being the first member of a new phylum of CTX-M enzymes. The evolutionary distances between the four types of CTX-M were large, suggesting that the four clusters branched off early from a distant unknown enzyme and that intermediate enzymes probably existed. PMID:10858358

  14. [Post-marketing surveillance of antibacterial activities of cefozopran against various clinical isolates--II. Gram-negative bacteria].

    PubMed

    Igari, Jun; Oguri, Toyoko; Hiramatsu, Nobuyoshi; Akiyama, Kazumitsu; Koyama, Tsuneo

    2002-02-01

    As a post-marketing surveillance, the in vitro antibacterial activities of cefozopran (CZOP), an agent of cephems, against various clinical isolates were yearly evaluated and compared with those of other cephems, oxacephems, penicillins, monobactams, and carbapenems. Changes in CZOP susceptibility for the bacteria were also evaluated with the bacterial resistance ratio calculated with the breakpoint MIC. Twenty-five species (3,362 strains) of Gram-negative bacteria were isolated from the clinical materials annually collected from 1996 to 2000, and consisted of Moraxella (Branhamella) catarrhalis (n = 136), Haemophilus influenzae (n = 289), Escherichia coli (n = 276), Klebsiella pneumoniae (n = 192), Klebsiella oxytoca (n = 157), Enterobacter cloacae (n = 189), Enterobacter aerogenes (n = 93), Serratia marcescens (n = 172), Serratia liquefaciens (n = 24), Citrobacter freundii (n = 177), Citrobacter koseri (n = 70), Proteus mirabilis (n = 113), Proteus vulgaris (n = 89), Morganella morganii (n = 116), Providencia spp. (n = 41), Pseudomonas aeruginosa (n = 290), Pseudomonas fluorescens (n = 56), Pseudomonas putida (n = 63), Acinetobacter baumannii (n = 146), Acinetobacter lwoffii (n = 34), Burkholderia cepacia (n = 101), Stenotrophomonas maltophilia (n = 169), Bacteroides fragilis group (n = 196), and Prevotella/Porphyromonas (n = 173). An antibacterial activity of CZOP against E. coli, K. pneumoniae, K. oxytoca, and S. marcescens was potent and consistent with or more preferable than the study results obtained until the new drug application approval. MIC90 of CZOP against M.(B.) catarrhalis, C. koseri, and P. aeruginosa was not considerably changed and consistent with the study results obtained until the new drug application approval. MIC90 of CZOP against E. cloacae, E. aerogenes, and P. mirabilis increased year by year. The increase in MIC90 of CZOP against E. aerogenes and P. mirabilis, however, was not considered to be an obvious decline in susceptibility. In

  15. Efficacy of the thin agar layer method for the recovery of stressed Cronobacter spp. (Enterobacter sakazakii).

    PubMed

    Osaili, Tareq M; Al-Nabulsi, Anas A; Shaker, Reyad R; Al-Holy, Murad M; Al-Haddaq, Mohammed S; Olaimat, Amin N; Ayyash, Mutamed M; Al Ta'ani, Mahmoud K; Forsythe, Stephen J

    2010-10-01

    Cronobacter spp. (Enterobacter sakazakii) are emerging opportunistic pathogens for all age groups, and are of particular concern when it comes to infants. Prior to contaminating food, the organism may be exposed to a variety of stresses, leading to a generation of sublethally injured cells that may not be detected by selective media unless a protracted recovery period is included in the isolation procedure. This study evaluated the efficacy of the thin agar layer (TAL) method for the recovery of Cronobacter cells that had been exposed to various stress conditions. Five strains of C. sakazakii and C. muytjensii were exposed to starvation, heat, cold, acid, alkaline, chlorine, or ethanol, with or without further exposure to desiccation stress. The recovery of the stressed cells was determined on tryptone soy agar (TSA; nonselective control medium), violet red bile glucose agar (VRBGA; selective agar), Druggan-Forsythe-Iversen (DFI; selective agar), and TAL media (viz., VRBGA overlaid with TSA, and DFI overlaid with TSA). Regardless of stress type, there were no significant differences among the recoveries of stressed desiccated Cronobacter spp. cultures on TSA, DFI+TSA, and VRBGA+TSA, but there was significantly less recovery on VRBGA. The recovery of prestressed desiccated Cronobacter spp. on DFI+TSA was similar to that on TSA, whereas the recovery on VRBGA+TSA was lower. DFI+TSA performed better than VRBGA+TSA did in differentiating Cronobacter spp. within mixed bacterial cultures. The results of this study suggest the use of the TAL method DFI+TSA as an improved method for the direct recovery of stressed Cronobacter spp.

  16. Optimization of biodegradable plastic production on sugar cane molasses in Enterobacter sp. SEL2

    PubMed Central

    Naheed, Nighat; Jamil, Nazia

    2014-01-01

    Contaminated environments have a large number of bacteria which can accumulate PHA as their energy reserves. Out of 54 isolated bacterial strains from three groups of contaminated sites 48 were found PHA positive. The sites were grouped on the basis of the type of carbon sources i.e. sugars, fatty acids and much diverse type. Strains MFD5, MFD11, UML3, USL2, SEL2, SEL3, SEL10 and PFW1 produced 69.9 ± 0.29, 75.27 ± 0.45, 65.43 ± 0.1, 72.54 ± 0.27, 76.61 ± 0.28, 61.81 ± 0.05, 71.16 ± 0.09 and 74.92 ± 0.5 percent of PHA to their constant cell weight (CCW) respectively in PHA detection media supplemented with 2% glucose. Molasses, whey, crumbs hydrolysate and palm oil were checked as inexpensive carbon sources. Molasses alone could supply the required nutrients for growth and PHA production. Strain SEL2 produced 47.36 ± 0.45% PHA using 2% molasses at 37 °C and pH 7.0. Upon production optimization the best accumulation (80.95 ± 0.01%) was observed in PHA detection media with 0.2% nitrogen source, 3% molasses, pH 5.0 and 37 °C by the strain SEL2. The overall effect of the presence of increased molasses concentration in the media was positive it increased the accumulation period till 72 h. Enterobacter sp. SEL2 (JF901810) is first time being reported for PHA production. PMID:25242924

  17. Optimization of biodegradable plastic production on sugar cane molasses in Enterobacter sp. SEL2.

    PubMed

    Naheed, Nighat; Jamil, Nazia

    2014-01-01

    Contaminated environments have a large number of bacteria which can accumulate PHA as their energy reserves. Out of 54 isolated bacterial strains from three groups of contaminated sites 48 were found PHA positive. The sites were grouped on the basis of the type of carbon sources i.e. sugars, fatty acids and much diverse type. Strains MFD5, MFD11, UML3, USL2, SEL2, SEL3, SEL10 and PFW1 produced 69.9 ± 0.29, 75.27 ± 0.45, 65.43 ± 0.1, 72.54 ± 0.27, 76.61 ± 0.28, 61.81 ± 0.05, 71.16 ± 0.09 and 74.92 ± 0.5 percent of PHA to their constant cell weight (CCW) respectively in PHA detection media supplemented with 2% glucose. Molasses, whey, crumbs hydrolysate and palm oil were checked as inexpensive carbon sources. Molasses alone could supply the required nutrients for growth and PHA production. Strain SEL2 produced 47.36 ± 0.45% PHA using 2% molasses at 37 °C and pH 7.0. Upon production optimization the best accumulation (80.95 ± 0.01%) was observed in PHA detection media with 0.2% nitrogen source, 3% molasses, pH 5.0 and 37 °C by the strain SEL2. The overall effect of the presence of increased molasses concentration in the media was positive it increased the accumulation period till 72 h. Enterobacter sp. SEL2 (JF901810) is first time being reported for PHA production. PMID:25242924

  18. Inhibition of growth of Enterobacter sakazakii in reconstituted infant formula by the lactoperoxidase system.

    PubMed

    Gurtler, Joshua B; Beuchat, Larry R

    2007-09-01

    Neonatal bacteremia and meningitis caused by the opportunistic pathogen Enterobacter sakazakii have been associated with the consumption of reconstituted powdered infant formula. Lactoperoxidase (LPO), present in mammalian milk, is known to inhibit the growth of enteric pathogens. We undertook a study to determine if the lactoperoxidase system (LPOS) will inhibit the growth of E. sakazakii in a milk-based powdered infant formula reconstituted with water. Initially at 0.04 CFU/ml, E. sakazakii grew to 2.40 to 2.74 log CFU/ml in reconstituted infant formula held at 30 or 37 degrees C for 8 h and to 0.6 log CFU/ ml in formula held for 12 h at 21 degrees C. The pathogen was not detected (less than 1 CFU/227 ml) by enrichment of formula treated with 10 to 30 microg/ml LPO and stored for 24 h at 37 degrees C or 30 microg/ml LPO and stored for 24 h at 30 degrees C. Populations of E. sakazakii, initially at 4.40 log CFU/ml of reconstituted infant formula containing 5 microg/ml LPO, did not increase significantly (P > 0.05) for up to 12 h at 21 and 30 degrees C. Populations either decreased significantly or were unchanged in formula supplemented with 10 microg/ml LPO and stored at 21, 30, or 37 degrees C for up to 24, 8, and 8 h, respectively. Results indicate that LPOS can be used to control the growth of E. sakazakii in reconstituted infant formula, thereby potentially reducing the risk of neonatal infections resulting from consumption of formula that may be contaminated with the pathogen.

  19. Biodegradation of Chlorpyrifos by Enterobacter Strain B-14 and Its Use in Bioremediation of Contaminated Soils

    PubMed Central

    Singh, Brajesh K.; Walker, Allan; Morgan, J. Alun W.; Wright, Denis J.

    2004-01-01

    Six chlorpyrifos-degrading bacteria were isolated from an Australian soil and compared by biochemical and molecular methods. The isolates were indistinguishable, and one (strain B-14) was selected for further analysis. This strain showed greatest similarity to members of the order Enterobacteriales and was closest to members of the Enterobacter asburiae group. The ability of the strain to mineralize chlorpyrifos was investigated under different culture conditions, and the strain utilized chlorpyrifos as the sole source of carbon and phosphorus. Studies with ring or uniformly labeled [14C]chlorpyrifos in liquid culture demonstrated that the isolate hydrolyzed chlorpyrifos to diethylthiophospshate (DETP) and 3, 5, 6-trichloro-2-pyridinol, and utilized DETP for growth and energy. The isolate was found to possess mono- and diphosphatase activities along with a phosphotriesterase activity. Addition of other sources of carbon (glucose and succinate) resulted in slowing down of the initial rate of degradation of chlorpyrifos. The isolate degraded the DETP-containing organophosphates parathion, diazinon, coumaphos, and isazofos when provided as the sole source of carbon and phosphorus, but not fenamiphos, fonofos, ethoprop, and cadusafos, which have different side chains. Studies of the molecular basis of degradation suggested that the degrading ability could be polygenic and chromosome based. Further studies revealed that the strain possessed a novel phosphotriesterase enzyme system, as the gene coding for this enzyme had a different sequence from the widely studied organophosphate-degrading gene (opd). The addition of strain B-14 (106 cells g−1) to soil with a low indigenous population of chlorpyrifos-degrading bacteria treated with 35 mg of chlorpyrifos kg−1 resulted in a higher degradation rate than was observed in noninoculated soils. These results highlight the potential of this bacterium to be used in the cleanup of contaminated pesticide waste in the

  20. Survival Strategies of the Plant-Associated Bacterium Enterobacter sp. Strain EG16 under Cadmium Stress

    PubMed Central

    Chen, Yanmei; Li, Yaying; Lin, Qingqi; Bai, Jun; Tang, Lu; Wang, Shizhong; Ying, Rongrong

    2016-01-01

    Plant-associated bacteria are of great interest because of their potential use in phytoremediation. However, their ability to survive and promote plant growth in metal-polluted soils remains unclear. In this study, a soilborne Cd-resistant bacterium was isolated and identified as Enterobacter sp. strain EG16. It tolerates high external Cd concentrations (Cd2+ MIC, >250 mg liter−1) and is able to produce siderophores and the plant hormone indole-3-acetic acid (IAA), both of which contribute to plant growth promotion. Surface biosorption in this strain accounted for 31% of the total Cd accumulated. The potential presence of cadmium sulfide, shown by energy-dispersive X-ray (EDX) analysis, suggested intracellular Cd binding as a Cd response mechanism of the isolate. Cd exposure resulted in global regulation at the transcriptomic level, with the bacterium switching to an energy-conserving mode by inhibiting energy-consuming processes while increasing the production of stress-related proteins. The stress response system included increased import of sulfur and iron, which become deficient under Cd stress, and the redirection of sulfur metabolism to the maintenance of intracellular glutathione levels in response to Cd toxicity. Increased production of siderophores, responding to Cd-induced Fe deficiency, not only is involved in the Cd stress response systems of EG16 but may also play an important role in promoting plant growth as well as alleviating the Cd-induced inhibition of IAA production. The newly isolated strain EG16 may be a suitable candidate for microbially assisted phytoremediation due to its high resistance to Cd and its Cd-induced siderophore production, which is likely to contribute to plant growth promotion. PMID:26729719

  1. Optimization of biodegradable plastic production on sugar cane molasses in Enterobacter sp. SEL2.

    PubMed

    Naheed, Nighat; Jamil, Nazia

    2014-01-01

    Contaminated environments have a large number of bacteria which can accumulate PHA as their energy reserves. Out of 54 isolated bacterial strains from three groups of contaminated sites 48 were found PHA positive. The sites were grouped on the basis of the type of carbon sources i.e. sugars, fatty acids and much diverse type. Strains MFD5, MFD11, UML3, USL2, SEL2, SEL3, SEL10 and PFW1 produced 69.9 ± 0.29, 75.27 ± 0.45, 65.43 ± 0.1, 72.54 ± 0.27, 76.61 ± 0.28, 61.81 ± 0.05, 71.16 ± 0.09 and 74.92 ± 0.5 percent of PHA to their constant cell weight (CCW) respectively in PHA detection media supplemented with 2% glucose. Molasses, whey, crumbs hydrolysate and palm oil were checked as inexpensive carbon sources. Molasses alone could supply the required nutrients for growth and PHA production. Strain SEL2 produced 47.36 ± 0.45% PHA using 2% molasses at 37 °C and pH 7.0. Upon production optimization the best accumulation (80.95 ± 0.01%) was observed in PHA detection media with 0.2% nitrogen source, 3% molasses, pH 5.0 and 37 °C by the strain SEL2. The overall effect of the presence of increased molasses concentration in the media was positive it increased the accumulation period till 72 h. Enterobacter sp. SEL2 (JF901810) is first time being reported for PHA production.

  2. Analysis of a Soluble (UreD:UreF:UreG)2 Accessory Protein Complex and Its Interactions with Klebsiella aerogenes Urease by Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Farrugia, Mark A.; Han, Linjie; Zhong, Yueyang; Boer, Jodi L.; Ruotolo, Brandon T.; Hausinger, Robert P.

    2013-09-01

    Maturation of the nickel-containing urease of Klebsiella aerogenes is facilitated by the UreD, UreF, and UreG accessory proteins along with the UreE metallo-chaperone. A fusion of the maltose binding protein and UreD (MBP-UreD) was co-isolated with UreF and UreG in a soluble complex possessing a (MBP-UreD:UreF:UreG)2 quaternary structure. Within this complex a UreF:UreF interaction was identified by chemical cross-linking of the amino termini of its two UreF protomers, as shown by mass spectrometry of tryptic peptides. A pre-activation complex was formed by the interaction of (MBP-UreD:UreF:UreG)2 and urease. Mass spectrometry of intact protein species revealed a pathway for synthesis of the urease pre-activation complex in which individual hetero-trimer units of the (MBP-UreD:UreF:UreG)2 complex bind to urease. Together, these data provide important new insights into the structures of protein complexes associated with urease activation.

  3. Inactivation of Enterobacter sakazakii, Bacillus cereus, and Salmonella typhimurium in powdered weaning food by electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Hong, Yun-Hee; Park, Ji-Yong; Park, Jong-Hyun; Chung, Myong-Soo; Kwon, Ki-Sung; Chung, Kyungsook; Won, Misun; Song, Kyung-Bin

    2008-09-01

    Inactivation of Enterobacter sakazakii, Bacillus cereus, and Salmonella typhimurium were evaluated in powdered weaning food using electron-beam irradiation. E. sakazakii, B. cereus, and S. typhimurium were eliminated by irradiation at 16, 8, and 8 kGy, respectively. The D10-vlaues of E. sakazakii, B. cereus, and S. typhimurium inoculated on powdered weaning food were 4.83, 1.22, and 0.98 kGy, respectively. The results suggest that electron-beam irradiation should inhibit the growth of pathogenic bacteria on baby food without impairing qualities.

  4. [Utility of pyrrolidonyl-arylamidase detection for typing Enterobacteriaceae and non-fermenting Gram-negative bacteria].

    PubMed

    Nicola, F; Centorbi, H; Bantar, C; Smayevsky, J; Bianchini, H

    1995-01-01

    Detection of pyrrolidonyl-aryl-amidase activity (PYR) is an important tool to identify gram-positive cocci, such as staphylococci, enterococci, streptococci, and other related genera. However, only few studies evaluating its usefulness with gram-negative rods have been published. Thus, a prospective study including 542 and 215 unique clinical isolates of Enterobacteriaceae and non-fermentative gram-negative rods, respectively, was undertaken. Strains were identified by conventional methods. PYR test was performed using a commercial kit, according to the manufacturer recommendations. Positive results were uniformly obtained for the PYR test with the following species: Citrobacter spp, Klebsiella spp, Enterobacter aerogenes, Enterobacter agglomerans group, Serratia marcescens and S. odorifera. On the other hand, negative results were uniformly displayed by E. coli (including inactive E. coli), Protease group, Salmonellia spp, Shigella spp, Acinetobacter spp, Burkholderia (Pseudomonas) cepacia and Flavobacterium spp. Variable results were shown in Pseudomonas aeruginosa, Stenotrophomonas (xanthomonas) malthophilia, Kluyvera cryocrescens, and Enterobacter cloacae. PYR test proved to be a reliable and simple tool to rapidly distinguish certain species belonging to Enterobacteriaceae (ie. Citrobacter freundii from Salmonella spp, and inactive E. coli from K. ozaenae). Further studies, including a wide diversity of species, are required to assess usefulness of the PYR test for the identification of non-fermentative gram-negative rods.

  5. Survival of Enterobacter sakazakii in powdered infant formula as affected by composition, water activity, and temperature.

    PubMed

    Gurtler, Joshua B; Beuchat, Larry R

    2007-07-01

    A study was done to determine survival characteristics of Enterobacter sakazakii in four milk-based and two soybean-based powdered infant formulas. A 10-strain mixture of E. sakazakii was inoculated into the six infant formulas at water activity (aw) 0.25 to 0.30, 0.31 to 0.33, and 0.43 to 0.50 to give low (0.80 log CFU/g) and high (4.66 to 4.86 log CFU/g) populations. At an initial population of 0.80 log CFU/g, E. sakazakii was detected by enrichment in six of six, four of six, and one of six formulas stored for 12 months at 4, 21, and 30 degrees C, respectively. In four of six formulas at aw values of 0.25 to 0.30, initially high populations decreased significantly (P < or = 0.05), although by less than 1 log CFU/g, within 6 months at 4 degrees C. Populations decreased significantly in all formulas in the aw range of 0.25 to 0.50 during storage for 1 month at 21 or 30 degrees C and again between 1 and 6 months in most formulas. Significant reductions occurred between 6 and 12 months in some formulas. At all storage temperatures, reductions in populations tended to be greater in formulas at aw 0.43 to 0.50 than in formulas at aw 0.25 to 0.30. The rate of inactivation of E. sakazakii in formulas was not markedly influenced by formula composition. Cells from mucoid and nonmucoid colonies formed by two strains on violet red bile glucose agar supplemented with pyruvate were inoculated into a milk-based powdered infant formula and a soybean-based powdered infant formula having a high aw range of 0.43 to 0.86 and stored at 4, 21, and 30 degrees C for up to 36 weeks. With few exceptions, populations of both strains decreased significantly in both formulas within 2 weeks at all temperatures; rates of death increased with increased aw and storage temperature. The presence of mucoidal extracellular materials on the surface of E. sakazakii cells was not associated with protection against death. This study shows that the retention of viability of E. sakazakii in powdered

  6. Impact of probiotic drugs, based on Enterobacter faecium autostrains, on human intestinal microflora in confined habitat

    NASA Astrophysics Data System (ADS)

    Viacheslav, Ilyin; Batov, Alexey; Usanova, Nonna

    The aim of research: Investigation of influence of probiotic drugs based on autostrains of Enter-obacter faecium, selected from the crew in long term isolation experiment in confined habitat. It is known that during long-term presence in confined habitat the risk of infectious diseases increases. One of the main infectious risk occurs during first 20 days of isolation as a result of exchange of strains and stress-mediated disbacterioses. Therefore it is necessary to evaluate activities of probiotics to avoid this risk. Furthermore, in case of super long term autonomous flight there should be possibilities of application of autochthonous microflora strains as pro-biotics to strengthen colonial resistance of crews. Materials and methods: In the experiment there were used probiotic drugs based on autostrains of E. faecium, selected from the crew before the experiment. Probiotic drugs were consumed during 30 days since the beginning of the experiment with the break of consumption between 10th to 19th day. Results: Comparing the state of intestinal microflora of the crew on the baseline and 14th day of experiment re-vealed remarkable changes of microflora: the increasing of concentration of bifidobacteria and E. faecium (approximately 10 times), elimination of hemolytic streptococcus, yeasts, reduction of the rate of S.aureus, hemolytic gramnegative non-fermenting rods, lactobacilli and normal E.coli. On the 45th day of isolation, 15 days after finishing of auto-strains administration, there fere signs of restoration of disbacteriosis: the quantitative decreasing lactobacilli, bifidobacteria and normal E.coli, increasing of the rate of S.aureus, hemolytic gramnegative nonfermentive rods. Conclusion: Thus we managed to avoid risk of pathogenicity potential growth in first 2 decades of isolation. Application of probiotic, based on the autostrains of E. faecium leads to insignificant changes of concentration of lactobacteries, bifidobacteries, normal E. coli and to

  7. Mutational and Computational Evidence That a Nickel-Transfer Tunnel in UreD Is Used for Activation of Klebsiella aerogenes Urease.

    PubMed

    Farrugia, Mark A; Wang, Beibei; Feig, Michael; Hausinger, Robert P

    2015-10-20

    Nickel-containing urease from Klebsiella aerogenes requires four accessory proteins for proper active site metalation. The metallochaperone UreE delivers nickel to UreG, a GTPase that forms a UreD/UreF/UreG complex, which binds to urease apoprotein via UreD. Prior in silico analysis of the homologous, structurally characterized UreH/UreF/UreG complex from Helicobacter pylori identified a water tunnel originating at a likely nickel-binding motif in UreG, passing through UreF, and exiting UreH, suggestive of a role for the channel in providing the metal to urease apoprotein for its activation; however, no experimental support was reported for the significance of this tunnel. Here, specific variants were designed to disrupt a comparable 34.6 Å predicted internal tunnel, alternative channels, and surface sites for UreD. Cells producing a set of tunnel-disrupting variants of UreD exhibited greatly reduced urease specific activities, whereas other mutants had no appreciable effect on activity. Affinity pull-down studies of cell-free extracts from tunnel-disrupting mutant cultures showed no loss of UreD interactions with urease or UreF/UreG. The nickel contents of urease samples enriched from activity-deficient cultures were decreased, while zinc and iron incorporation increased. Molecular dynamics simulations revealed size restrictions in the internal channels of the UreD variants. These findings support the role of a molecular tunnel in UreD as a direct facilitator of nickel transfer into urease, illustrating a new paradigm in active site metallocenter assembly.

  8. Mutational and Computational Evidence That a Nickel-Transfer Tunnel in UreD Is Used for Activation of Klebsiella aerogenes Urease.

    PubMed

    Farrugia, Mark A; Wang, Beibei; Feig, Michael; Hausinger, Robert P

    2015-10-20

    Nickel-containing urease from Klebsiella aerogenes requires four accessory proteins for proper active site metalation. The metallochaperone UreE delivers nickel to UreG, a GTPase that forms a UreD/UreF/UreG complex, which binds to urease apoprotein via UreD. Prior in silico analysis of the homologous, structurally characterized UreH/UreF/UreG complex from Helicobacter pylori identified a water tunnel originating at a likely nickel-binding motif in UreG, passing through UreF, and exiting UreH, suggestive of a role for the channel in providing the metal to urease apoprotein for its activation; however, no experimental support was reported for the significance of this tunnel. Here, specific variants were designed to disrupt a comparable 34.6 Å predicted internal tunnel, alternative channels, and surface sites for UreD. Cells producing a set of tunnel-disrupting variants of UreD exhibited greatly reduced urease specific activities, whereas other mutants had no appreciable effect on activity. Affinity pull-down studies of cell-free extracts from tunnel-disrupting mutant cultures showed no loss of UreD interactions with urease or UreF/UreG. The nickel contents of urease samples enriched from activity-deficient cultures were decreased, while zinc and iron incorporation increased. Molecular dynamics simulations revealed size restrictions in the internal channels of the UreD variants. These findings support the role of a molecular tunnel in UreD as a direct facilitator of nickel transfer into urease, illustrating a new paradigm in active site metallocenter assembly. PMID:26401965

  9. Improvement of plant growth and seed yield in Jatropha curcas by a novel nitrogen-fixing root associated Enterobacter species

    PubMed Central

    2013-01-01

    Background Jatropha curcas L. is an oil seed producing non-leguminous tropical shrub that has good potential to be a fuel plant that can be cultivated on marginal land. Due to the low nutrient content of the targeted plantation area, the requirement for fertilizer is expected to be higher than other plants. This factor severely affects the commercial viability of J. curcas. Results We explored the feasibility to use endophytic nitrogen-fixing bacteria that are native to J. curcas to improve plant growth, biomass and seed productivity. We demonstrated that a novel N-fixing endophyte, Enterobacter sp. R4-368, was able to colonize in root and stem tissues and significantly promoted early plant growth and seed productivity of J. curcas in sterilized and non-sterilized soil. Inoculation of young seedling led to an approximately 57.2% increase in seedling vigour over a six week period. At 90 days after planting, inoculated plants showed an average increase of 25.3%, 77.7%, 27.5%, 45.8% in plant height, leaf number, chlorophyll content and stem volume, respectively. Notably, inoculation of the strain led to a 49.0% increase in the average seed number per plant and 20% increase in the average single seed weight when plants were maintained for 1.5 years in non-sterilized soil in pots in the open air. Enterobacter sp. R4-368 cells were able to colonize root tissues and moved systemically to stem tissues. However, no bacteria were found in leaves. Promotion of plant growth and leaf nitrogen content by the strain was partially lost in nifH, nifD, nifK knockout mutants, suggesting the presence of other growth promoting factors that are associated with this bacterium strain. Conclusion Our results showed that Enterobacter sp. R4-368 significantly promoted growth and seed yield of J. curcas. The application of the strains is likely to significantly improve the commercial viability of J. curcas due to the reduced fertilizer cost and improved oil yield. PMID:24083555

  10. Q-PCR Based Culture-Independent Enumeration and Detection of Enterobacter: An Emerging Environmental Human Pathogen in Riverine Systems and Potable Water.

    PubMed

    Patel, Chandra B; Shanker, Rishi; Gupta, Vijai K; Upadhyay, Ram S

    2016-01-01

    The availability of safe and pristine water is a global challenge when large numbers of natural and anthropogenic water resources are being depleted with faster rate. The remaining water resources are severely contaminated with various kinds of contaminants including microorganisms. Enterobacter is one of the fecal coliform bacteria of family Enterobacteriaceae. Enterobacter was earlier used as an indicator bacterium along with other fecal Coliforms namely Escherichia coli, Citrobacter, and Klebsiella, but it is now known to cause various diseases in human beings. In this study, we have collected 55 samples from potable water and riverine system and proved their presence using their conserved sequences of 16S rRNA and 23S rRNA genes with the help of SYBR green real-time PCR, which showed very high specificity for the detection of Enterobacter. The Enterobacter counts in potable water were found to 1290 ± 32.89 to 1460 ± 39.42 cfu/100 ml. The Enterobacter levels in surface water were 1.76 × 10(4) ± 492, 1.33 × 10(4) ± 334, 1.15 × 10(4) ± 308, 2.56 × 10(4) ± 802, 2.89 × 10(4) ± 962, 8.16 × 10(4) ± 3443 cfu/100 ml; the levels of Enterobacter contamination associated with hydrophytes were 4.80 × 10(4) ± 1804, 3.48 × 10(4) ± 856, 8.50 × 10(4) ± 2074, 8.09 × 10(4) ± 1724, 6.30 × 10(4) ± 1738, 3.68 × 10(4) ± 949 cfu/10 g and the Enterobacter counts in sediments of the river, were 2.36 × 10(4) ± 703, 1.98 × 10(4) ± 530, 9.92 × 10(4) ± 3839, 6.80 × 10(4) ± 2230, 8.76 × 10(4) ± 3066 and 2.34 × 10(4) ± 732 cfu/10 g at the sampling Site #1, Site #2, Site #3, Site #4, Site #5, and Site #6, respectively. The assay could be used for the regular monitoring of potable water and other water reservoirs to check waterborne outbreaks. PMID:26925044

  11. Q-PCR Based Culture-Independent Enumeration and Detection of Enterobacter: An Emerging Environmental Human Pathogen in Riverine Systems and Potable Water

    PubMed Central

    Patel, Chandra B.; Shanker, Rishi; Gupta, Vijai K.; Upadhyay, Ram S.

    2016-01-01

    The availability of safe and pristine water is a global challenge when large numbers of natural and anthropogenic water resources are being depleted with faster rate. The remaining water resources are severely contaminated with various kinds of contaminants including microorganisms. Enterobacter is one of the fecal coliform bacteria of family Enterobacteriaceae. Enterobacter was earlier used as an indicator bacterium along with other fecal Coliforms namely Escherichia coli, Citrobacter, and Klebsiella, but it is now known to cause various diseases in human beings. In this study, we have collected 55 samples from potable water and riverine system and proved their presence using their conserved sequences of 16S rRNA and 23S rRNA genes with the help of SYBR green real-time PCR, which showed very high specificity for the detection of Enterobacter. The Enterobacter counts in potable water were found to 1290 ± 32.89 to 1460 ± 39.42 cfu/100 ml. The Enterobacter levels in surface water were 1.76 × 104 ± 492, 1.33 × 104 ± 334, 1.15 × 104 ± 308, 2.56 × 104 ± 802, 2.89 × 104 ± 962, 8.16 × 104 ± 3443 cfu/100 ml; the levels of Enterobacter contamination associated with hydrophytes were 4.80 × 104 ± 1804, 3.48 × 104 ± 856, 8.50 × 104 ± 2074, 8.09 × 104 ± 1724, 6.30 × 104 ± 1738, 3.68 × 104 ± 949 cfu/10 g and the Enterobacter counts in sediments of the river, were 2.36 × 104 ± 703, 1.98 × 104 ± 530, 9.92 × 104 ± 3839, 6.80 × 104 ± 2230, 8.76 × 104 ± 3066 and 2.34 × 104 ± 732 cfu/10 g at the sampling Site #1, Site #2, Site #3, Site #4, Site #5, and Site #6, respectively. The assay could be used for the regular monitoring of potable water and other water reservoirs to check waterborne outbreaks. PMID:26925044

  12. Evaluation of yeast dietary supplementation in broilers challenged or not with Salmonella on growth performance, cecal microbiota composition and Salmonella in ceca, cloacae and carcass skin.

    PubMed

    Mountzouris, K C; Dalaka, E; Palamidi, I; Paraskeuas, V; Demey, V; Theodoropoulos, G; Fegeros, K

    2015-10-01

    The dietary supplementation of Saccharomyces cerevisiae var. boulardii was evaluated in broilers challenged or not challenged with Salmonella Enteritidis (SE) using a 2 × 2 factorial arrangement. Depending on yeast inclusion at 0 (C) or 1 × 10⁹ cfu/kg diet (Y) and SE challenge (0 or log 6.3 cfu/bird) on d 15, the experiment had four treatments C, Y, C-SE, and Y-SE, respectively. Each treatment had seven replicate floor pens with 15 broilers. Growth performance responses were determined weekly and overall for the 5 week experimental period. Salmonella levels and prevalence in ceca, cloacae, and carcass skin were determined by culture procedures, while cecal microbiota was determined by real time PCR. Yeast supplementation had no effect (PY > 0.05) on growth performance. For the overall post SE-challenge period (i.e., wk 3 to wk 5), Salmonella reduced body weight gain (BWG) (PSE < 0.001), feed intake (FI) (PSE = 0.032), and the European production efficiency (EPEF) factor (PSE = 0.005). Broilers Y-SE had higher (P < 0.001) overall BW gain compared to C-SE ones. Overall mortality was 2.14% and did not differ (P > 0.05) between treatments. Reduced Salmonella levels in the cloacae (P = 0.014) and on the breast skin (P = 0.006) and lower prevalence on the neck skin (P = 0.007) were noted for treatment Y-SE compared to C-SE. Yeast supplementation did not have an effect (P > 0.05) on cecal microbiota composition at d 1 and d 21 post SE-challenge. On the contrary, SE-challenge reduced cecal levels of total bacteria (PSE = 0.002), E. coli (PSE = 0.006), Bifidobacterium spp. (PSE = 0.006), Bacteroides spp. (PSE = 0.010), and Clostridial populations belonging to cluster I and cluster XIVa, (PSE = 0.047 and PSE = 0.001, respectively) on d 1 post SE-challenge. At 21 d post SE-challenge, only the levels of cecal Lactobacillus spp. (PSE = 0.001) and Bifidobacterium spp. (PSE = 0.049) were reduced compared to the non SE-challenged groups. In conclusion, yeast supplementation in

  13. Entericidin is required for a probiotic treatment (Enterobacter sp. strain C6-6) to protect trout from cold-water disease challenge.

    PubMed

    Schubiger, Carla B; Orfe, Lisa H; Sudheesh, Ponnerassery S; Cain, Kenneth D; Shah, Devendra H; Call, Douglas R

    2015-01-01

    Flavobacterium psychrophilum causes bacterial cold-water disease in multiple fish species, including salmonids. An autochthonous Enterobacter strain (C6-6) inhibits the in vitro growth of F. psychrophilum, and when ingested as a putative probiotic, it provides protection against injection challenge with F. psychrophilum in rainbow trout. In this study, low-molecular-mass (≤3 kDa) fractions from both Enterobacter C6-6 and Escherichia coli K-12 culture supernatants inhibited the growth of F. psychrophilum. The ≤3-kDa fraction from Enterobacter C6-6 was analyzed by SDS-PAGE, and subsequent tandem mass spectroscopy identified EcnB, which is a small membrane lipoprotein that is a putative pore-forming toxin. Agar plate diffusion assays demonstrated that ecnAB knockout strains of both Enterobacter C6-6 and E. coli K-12 no longer inhibited F. psychrophilum (P < 0.001), while ecnAB-complemented knockout strains recovered the inhibitory phenotype (P < 0.001). In fish experiments, the engineered strains (C6-6 ΔecnAB and C6-6 ΔecnAB) and the wild-type strain (C6-6) were added to the fish diet every day for 38 days. On day 11, the fish were challenged by injection with a virulent strain of F. psychrophilum (CSF 259-93). Fish that were fed C6-6 had significantly longer survival than fish fed the ecnAB knockout strain (P < 0.0001), while fish fed the complemented knockout strain recovered the probiotic phenotype (P = 0.61). This entericidin is responsible for the probiotic activity of Enterobacter C6-6, and it may present new opportunities for therapeutic and prophylactic treatments against similarly susceptible pathogens. PMID:25381243

  14. Development of Multiple-Locus Variable-Number Tandem-Repeat Analysis for the Molecular Subtyping of Enterobacter sakazakii▿

    PubMed Central

    Mullane, N. R.; Ryan, M.; Iversen, C.; Murphy, M.; O'Gaora, P.; Quinn, T.; Whyte, P.; Wall, P. G.; Fanning, S.

    2008-01-01

    The genomic content of Enterobacter sakazakii strain ATCC BAA-894 was analyzed for variable-number tandem repeats (VNTRs). In this study we report the development of a multiple-locus VNTR analysis (MLVA) strategy for the subtyping of E. sakazakii. The method is based on a GeneScan analysis of four VNTR loci labeled with multiple fluorescent dyes. This approach was applied to a collection of 112 isolates representing all 16 of the currently defined E. sakazakii biogroups. MLVA successfully discriminated among these isolates and compared favorably with pulsed-field gel electrophoresis. The method was relatively fast and easy to perform. The potential value of MLVA as an epidemiological tool is discussed. PMID:18083860

  15. Performance of Media for Recovering Stressed Cells of Enterobacter sakazakii as Determined Using Spiral Plating and Ecometric Techniques

    PubMed Central

    Gurtler, J. B.; Beuchat, L. R.

    2005-01-01

    A study was done to determine the performance of differential, selective media for supporting resuscitation and colony development by stressed cells of Enterobacter sakazakii. Cells of four strains of E. sakazakii isolated from powdered infant formula were exposed to five stress conditions: heat (55°C for 5 min), freezing (−20°C for 24 h, thawed, frozen again at −20°C for 2 h, thawed), acidic pH (3.54), alkaline pH (11.25), and desiccation in powdered infant formula (water activity, 0.25; 21°C for 31 days). Control and stressed cells were spiral plated on tryptic soy agar supplemented with 0.1% pyruvate (TSAP, a nonselective control medium); Leuschner, Baird, Donald, and Cox (LBDC) agar (a differential, nonselective medium); Oh and Kang agar (OK); fecal coliform agar (FCA); Druggan-Forsythe-Iversen (DFI) medium; violet red bile glucose (VRBG) agar; and Enterobacteriaceae enrichment (EE) agar. With the exception of desiccation-stressed cells, suspensions of stressed cells were also plated on these media and on R&F Enterobacter sakazakii chromogenic plating (RF) medium using the ecometric technique. The order of performance of media for recovering control and heat-, freeze-, acid-, and alkaline-stressed cells by spiral plating was TSAP > LBDC > FCA > OK, VRBG > DFI > EE; the general order for recovering desiccated cells was TSAP, LBDC, FCA, OK > DFI, VRBG, EE. Using the ecometric technique, the general order of growth indices of stressed cells was TSAP, LBDC > FCA > RF, VRBG, OK > DFI, EE. The results indicate that differential, selective media vary greatly in their abilities to support resuscitation and colony formation by stressed cells of E. sakazakii. The orders of performance of media for recovering stressed cells were similar using spiral plating and ecometric techniques, but results from spiral plating should be considered more conclusive. PMID:16332738

  16. Clavulanic acid: a beta-lactamase-inhiting beta-lactam from Streptomyces clavuligerus.

    PubMed

    Reading, C; Cole, M

    1977-05-01

    A novel beta-lactamase inhibitor has been isolated from Streptomyces clavuligerus ATCC 27064 and given the name clavulanic acid. Conditions for the cultivation of the organism and detection and isolation of clavulanic acid are described. This compound resembles the nucleus of a penicillin but differs in having no acylamino side chain, having oxygen instead of sulfur, and containing a beta-hydroxyethylidine substituent in the oxazolidine ring. Clavulanic acid is a potent inhibitor of many beta-lactamases, including those found in Escherichia coli (plasmid mediated), Klebsiella aerogenes, Proteus mirabilis, and Staphylococcus aureus, the inhibition being of a progressive type. The cephalosporinase type of beta-lactamase found in Pseudomonas aeruginosa and Enterobacter cloacae P99 and the chromosomally mediated beta-lactamase of E. coli are less well inhibited. The minimum inhibitory concentrations of ampicillin and cephaloridine against beta-lactamase-producing, penicillin-resistant strains of S. aureus, K. aerogenes, P. mirabilis, and E. coli have been shown to be considerably reduced by the addition of low concentrations of clavulanic acid.

  17. Clavulanic Acid: a Beta-Lactamase-Inhibiting Beta-Lactam from Streptomyces clavuligerus

    PubMed Central

    Reading, C.; Cole, M.

    1977-01-01

    A novel β-lactamase inhibitor has been isolated from Streptomyces clavuligerus ATCC 27064 and given the name clavulanic acid. Conditions for the cultivation of the organism and detection and isolation of clavulanic acid are described. This compound resembles the nucleus of a penicillin but differs in having no acylamino side chain, having oxygen instead of sulfur, and containing a β-hydroxyethylidine substituent in the oxazolidine ring. Clavulanic acid is a potent inhibitor of many β-lactamases, including those found in Escherichia coli (plasmid mediated), Klebsiella aerogenes, Proteus mirabilis, and Staphylococcus aureus, the inhibition being of a progressive type. The cephalosporinase type of β-lactamase found in Pseudomonas aeruginosa and Enterobacter cloacae P99 and the chromosomally mediated β-lactamase of E. coli are less well inhibited. The minimum inhibitory concentrations of ampicillin and cephaloridine against β-lactamase-producing, penicillin-resistant strains of S. aureus, K. aerogenes, P. mirabilis, and E. coli have been shown to be considerably reduced by the addition of low concentrations of clavulanic acid. Images PMID:879738

  18. Enhancement of the catalytic activity of ferulic acid decarboxylase from Enterobacter sp. Px6-4 through random and site-directed mutagenesis.

    PubMed

    Lee, Hyunji; Park, Jiyoung; Jung, Chaewon; Han, Dongfei; Seo, Jiyoung; Ahn, Joong-Hoon; Chong, Youhoon; Hur, Hor-Gil

    2015-11-01

    The enzyme ferulic acid decarboxylase (FADase) from Enterobacter sp. Px6-4 catalyzes the decarboxylation reaction of lignin monomers and phenolic compounds such as p-coumaric acid, caffeic acid, and ferulic acid into their corresponding 4-vinyl derivatives, that is, 4-vinylphenol, 4-vinylcatechol, and 4-vinylguaiacol, respectively. Among various ferulic acid decarboxylase enzymes, we chose the FADase from Enterobacter sp. Px6-4, whose crystal structure is known, and produced mutants to enhance its catalytic activity by random and site-directed mutagenesis. After three rounds of sequential mutations, FADase(F95L/D112N/V151I) showed approximately 34-fold higher catalytic activity than wild-type for the production of 4-vinylguaiacol from ferulic acid. Docking analyses suggested that the increased activity of FADase(F95L/D112N/V151I) could be due to formation of compact active site compared with that of the wild-type FADase. Considering the amount of phenolic compounds such as lignin monomers in the biomass components, successfully bioengineered FADase(F95L/D112N/V151I) from Enterobacter sp. Px6-4 could provide an ecofriendly biocatalytic tool for producing diverse styrene derivatives from biomass.

  19. Enhancement of the catalytic activity of ferulic acid decarboxylase from Enterobacter sp. Px6-4 through random and site-directed mutagenesis.

    PubMed

    Lee, Hyunji; Park, Jiyoung; Jung, Chaewon; Han, Dongfei; Seo, Jiyoung; Ahn, Joong-Hoon; Chong, Youhoon; Hur, Hor-Gil

    2015-11-01

    The enzyme ferulic acid decarboxylase (FADase) from Enterobacter sp. Px6-4 catalyzes the decarboxylation reaction of lignin monomers and phenolic compounds such as p-coumaric acid, caffeic acid, and ferulic acid into their corresponding 4-vinyl derivatives, that is, 4-vinylphenol, 4-vinylcatechol, and 4-vinylguaiacol, respectively. Among various ferulic acid decarboxylase enzymes, we chose the FADase from Enterobacter sp. Px6-4, whose crystal structure is known, and produced mutants to enhance its catalytic activity by random and site-directed mutagenesis. After three rounds of sequential mutations, FADase(F95L/D112N/V151I) showed approximately 34-fold higher catalytic activity than wild-type for the production of 4-vinylguaiacol from ferulic acid. Docking analyses suggested that the increased activity of FADase(F95L/D112N/V151I) could be due to formation of compact active site compared with that of the wild-type FADase. Considering the amount of phenolic compounds such as lignin monomers in the biomass components, successfully bioengineered FADase(F95L/D112N/V151I) from Enterobacter sp. Px6-4 could provide an ecofriendly biocatalytic tool for producing diverse styrene derivatives from biomass. PMID:26059194

  20. Molecular epidemiology of KPC-2-producing Enterobacteriaceae (non-Klebsiella pneumoniae) isolated from Brazil.

    PubMed

    Tavares, Carolina Padilha; Pereira, Polyana Silva; Marques, Elizabeth de Andrade; Faria, Celio; de Souza, Maria da Penha Araújo Herkenhoff; de Almeida, Robmary; Alves, Carlene de Fátima Morais; Asensi, Marise Dutra; Carvalho-Assef, Ana Paula D'Alincourt

    2015-08-01

    In Brazil, since 2009, there has been an ever increasing widespread of the bla(KPC-2) gene, mainly in Klebsiella pneumoniae. This study aims to assess the molecular epidemiology and genetic background of this gene in Enterobacteriaceae (non-K. pneumoniae) species from 9 Brazilian states between 2009 and 2011. Three hundred eighty-seven isolates were analyzed exhibiting nonsusceptibility to carbapenems, in which the bla(KPC-2) gene was detected in 21.4%. By disk diffusion and E-test, these isolates exhibited high rates of resistance to most of the antimicrobials tested, including tigecycline (45.6% nonsusceptible) and polymyxin B (16.5%), the most resistant species being Enterobacter aerogenes and Enterobacter cloacae. We found great clonal diversity and a variety of bla(KPC-2)-carrying plasmids, all of them exhibiting a partial Tn4401 structure. Therefore, this study demonstrates the dissemination of KPC-2 in 9 Enterobacteriaceae species, including species that were not previously described such as Pantoea agglomerans and Providencia stuartii. PMID:25935630

  1. Extended-spectrum-β-lactamase-producing Enterobacteriaceae isolated from vegetables imported from the Dominican Republic, India, Thailand, and Vietnam.

    PubMed

    Zurfluh, Katrin; Nüesch-Inderbinen, Magdalena; Morach, Marina; Zihler Berner, Annina; Hächler, Herbert; Stephan, Roger

    2015-05-01

    To examine to what extent fresh vegetables imported into Switzerland represent carriers of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae, 169 samples of different types of fresh vegetables imported into Switzerland from the Dominican Republic, India, Thailand, and Vietnam were analyzed. Overall, 25.4% of the vegetable samples yielded one or more ESBL-producing Enterobacteriaceae, 78.3% of which were multidrug resistant. Sixty isolates were obtained: Escherichia coli, 26; Klebsiella pneumoniae, 26; Enterobacter cloacae, 6; Enterobacter aerogenes, 1; and Cronobacter sakazakii, 1. We found 29 isolates producing CTX-M-15, 8 producing CTX-M-14, 7 producing CTX-M-55, 3 producing CTX-M-65, 1 each producing CTX-M-1, CTX-M-3, CTX-M-27, and CTX-M-63, 5 producing SHV-2, 3 producing SHV-12, and 1 producing SHV-2a. Four of the E. coli isolates belonged to epidemiologically important clones: CTX-M-15-producing B2:ST131 (1 isolate), D:ST405 (1 isolate), and D:ST38 (2 isolates). One of the D:ST38 isolates belonged to the extraintestinal enteroaggregative E. coli (EAEC) D:ST38 lineage. Two of the K. pneumoniae isolates belonged to the epidemic clones sequence type 15 (ST15) and ST147. The occurrence of antibiotic-resistant pathogenic and commensal Enterobacteriaceae in imported agricultural foodstuffs constitutes a source of ESBL genes and a concern for food safety.

  2. Extended-Spectrum-β-Lactamase-Producing Enterobacteriaceae Isolated from Vegetables Imported from the Dominican Republic, India, Thailand, and Vietnam

    PubMed Central

    Zurfluh, Katrin; Nüesch-Inderbinen, Magdalena; Morach, Marina; Zihler Berner, Annina; Hächler, Herbert

    2015-01-01

    To examine to what extent fresh vegetables imported into Switzerland represent carriers of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae, 169 samples of different types of fresh vegetables imported into Switzerland from the Dominican Republic, India, Thailand, and Vietnam were analyzed. Overall, 25.4% of the vegetable samples yielded one or more ESBL-producing Enterobacteriaceae, 78.3% of which were multidrug resistant. Sixty isolates were obtained: Escherichia coli, 26; Klebsiella pneumoniae, 26; Enterobacter cloacae, 6; Enterobacter aerogenes, 1; and Cronobacter sakazakii, 1. We found 29 isolates producing CTX-M-15, 8 producing CTX-M-14, 7 producing CTX-M-55, 3 producing CTX-M-65, 1 each producing CTX-M-1, CTX-M-3, CTX-M-27, and CTX-M-63, 5 producing SHV-2, 3 producing SHV-12, and 1 producing SHV-2a. Four of the E. coli isolates belonged to epidemiologically important clones: CTX-M-15-producing B2:ST131 (1 isolate), D:ST405 (1 isolate), and D:ST38 (2 isolates). One of the D:ST38 isolates belonged to the extraintestinal enteroaggregative E. coli (EAEC) D:ST38 lineage. Two of the K. pneumoniae isolates belonged to the epidemic clones sequence type 15 (ST15) and ST147. The occurrence of antibiotic-resistant pathogenic and commensal Enterobacteriaceae in imported agricultural foodstuffs constitutes a source of ESBL genes and a concern for food safety. PMID:25724954

  3. Biological activities of Morus celtidifolia leaf extracts.

    PubMed

    Viveros-Valdez, Ezequiel; Oranday-Cárdenas, Azucena; Rivas-Morales, Catalina; Verde-Star, María Julia; Carranza-Rosales, Pilar

    2015-07-01

    The aims of this research were to examine the antibacterial, cytotoxic and antiradical/antioxidant activities of the organic extracts obtained from the leaves of the medicinal plant Morus celtidifolia (Family: Moraceae). To evaluate its antimicrobial properties, M. celtidifolia was tested against the bacteria of medical importance: Bacillus subtilis, Staphyloccocus aureus, Enterococcus faecalis, Escherichia coli, Enterobacter cloacae and Enterobacter aerogenes. Cytotoxic activity was assessed by using the brine shrimp (Artemia salina) lethality assay and also by toxicity screening against human cancer cell lines: MCF-7 (human breast adenocarcinoma) and HeLa (cervix adenocarcinoma). The free radical-scavenging activity was determined by the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay. Results revealed that the hexanic extract has antibacterial activity only against Gram positive strains, while the methanolic extract showed better cytotoxic and antioxidant activities than the non- polar extract with a median lethal dose (LD₅₀) of 125μg/ml, 90μg/ml and 75μg/ml against A. salina, MCF-7 and HeLa cells respectively, and median effective concentration (EC₅₀) of 152μg/ml on radical scavenging assay. This is the first study reporting the biological activities of leaves of Morus celtidifolia.

  4. Biological activities of Morus celtidifolia leaf extracts.

    PubMed

    Viveros-Valdez, Ezequiel; Oranday-Cárdenas, Azucena; Rivas-Morales, Catalina; Verde-Star, María Julia; Carranza-Rosales, Pilar

    2015-07-01

    The aims of this research were to examine the antibacterial, cytotoxic and antiradical/antioxidant activities of the organic extracts obtained from the leaves of the medicinal plant Morus celtidifolia (Family: Moraceae). To evaluate its antimicrobial properties, M. celtidifolia was tested against the bacteria of medical importance: Bacillus subtilis, Staphyloccocus aureus, Enterococcus faecalis, Escherichia coli, Enterobacter cloacae and Enterobacter aerogenes. Cytotoxic activity was assessed by using the brine shrimp (Artemia salina) lethality assay and also by toxicity screening against human cancer cell lines: MCF-7 (human breast adenocarcinoma) and HeLa (cervix adenocarcinoma). The free radical-scavenging activity was determined by the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay. Results revealed that the hexanic extract has antibacterial activity only against Gram positive strains, while the methanolic extract showed better cytotoxic and antioxidant activities than the non- polar extract with a median lethal dose (LD₅₀) of 125μg/ml, 90μg/ml and 75μg/ml against A. salina, MCF-7 and HeLa cells respectively, and median effective concentration (EC₅₀) of 152μg/ml on radical scavenging assay. This is the first study reporting the biological activities of leaves of Morus celtidifolia. PMID:26142508

  5. In vitro activity of ceftazidime, ceftaroline and aztreonam alone and in combination with avibactam against European Gram-negative and Gram-positive clinical isolates.

    PubMed

    Testa, Raymond; Cantón, Rafael; Giani, Tommaso; Morosini, María-Isabel; Nichols, Wright W; Seifert, Harald; Stefanik, Danuta; Rossolini, Gian Maria; Nordmann, Patrice

    2015-06-01

    Recent clinical isolates of key Gram-negative and Gram-positive bacteria were collected in 2012 from hospitalised patients in medical centres in four European countries (France, Germany, Italy and Spain) and were tested using standard broth microdilution methodology to assess the impact of 4 mg/L avibactam on the in vitro activities of ceftazidime, ceftaroline and aztreonam. Against Enterobacteriaceae, addition of avibactam significantly enhanced the level of activity of these antimicrobials. MIC(90) values (minimum inhibitory concentration that inhibits 90% of the isolates) of ceftazidime, ceftaroline and aztreonam for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii and Morganella morganii were reduced up to 128-fold or greater when combined with avibactam. A two-fold reduction in the MIC(90) of ceftazidime to 8 mg/L was noted in Pseudomonas aeruginosa isolates when combined with avibactam, whereas little effect of avibactam was noted on the MIC values of the test compounds when tested against Acinetobacter baumannii isolates. Avibactam had little effect on the excellent activity of ceftazidime, ceftaroline and aztreonam against Haemophilus influenzae. It had no impact on the in vitro activity of ceftazidime and ceftaroline against staphylococci and streptococci. This study demonstrates that addition of avibactam enhances the activities of ceftazidime, ceftaroline and aztreonam against Enterobacteriaceae and P. aeruginosa but not against A. baumannii.

  6. In vitro activity of ciprofloxacin compared with other agents against recent hospital isolates.

    PubMed

    Rubinstein, E; Mark, Z; Samra, Y; Alkan, M; Berger, S

    1986-04-01

    Ciprofloxacin's in vitro activity was tested against 385 hospital isolates originating from three geographically distinct regions. Of all strains tested, only three (1 Acinetobacter sp. and 2 Pseudomonas aeruginosa) were ciprofloxacin resistant. Ciprofloxacin was more active against Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Acinetobacter sp., Proteus sp., Shigella sp. than gentamicin, mezlocillin and cefotaxime. It was more active than azlocillin and cefsulodin against P. aeruginosa. It was more active than cloxacillin and cefamandole against staphylococci. It was as active as cefotaxime against Klebsiella pneumoniae, Citrobacter freundii and Serratia marcescens. Ciprofloxacin demonstrated similar activity in broth and solid agar. The minimal inhibitory concentrations (MIC's) of all strains were similar to the minimal bactericidal concentrations (MBC's). Ciprofloxacin's MIC was not influenced by increase of the inoculum or addition of human serum and only slightly influenced by anaerobic conditions. Decrease of the medium pH increased the MIC substantially. Ciprofloxacin exhibited a rapid bactericidal effect and had only a minimal post-antibiotic effect. These favorable in vitro characteristics of ciprofloxacin warrant further studies.

  7. Nitrogen-Fixing Bacteria from Warty Lenticellate Bark of a Mangrove Tree, Bruguiera gymnorrhiza (L.) Lamk.

    PubMed

    Uchino, F; Hambali, G G; Yatazawa, M

    1984-01-01

    Detached warty lenticellate bark of a mangrove tree species, Bruguiera gymnorrhiza (L.) Lamk. from Iriomote Island, Okinawa, a subtropical region of Japan, showed development of acetylene reduction activity when incubated in a mineral nutrient solution lacking nitrogen under an atmosphere consisting of 5% O(2), 90% N(2), and 5% C(2)H(2). The bacteria responsible for nitrogen fixation were isolated from the bark, and their capacity for acetylene reduction and the incorporation of N(2) into the bacterial cells was confirmed. Four representative strains of the isolates were subjected to taxonomic classification. Two strains were similar to Enterobacter cloacae, and another resembled Enterobacter aerogenes. The characteristics of the fourth strain were similar to those of Klebsiella planticola (Bagley et al., Curr. Microbiol. 6:105-109, 1981). The results of this investigation suggest that the acetylene reduction activity of lenticellate warts of mangrove trunk bark is due to the presence in the warts of nitrogen-fixing bacteria belonging to the family Enterobacteriaceae.

  8. In Vitro Antimicrobial Activity of a Siderophore Cephalosporin, S-649266, against Enterobacteriaceae Clinical Isolates, Including Carbapenem-Resistant Strains.

    PubMed

    Kohira, Naoki; West, Joshua; Ito, Akinobu; Ito-Horiyama, Tsukasa; Nakamura, Rio; Sato, Takafumi; Rittenhouse, Stephen; Tsuji, Masakatsu; Yamano, Yoshinori

    2015-11-16

    S-649266 is a novel siderophore cephalosporin antibiotic with a catechol moiety on the 3-position side chain. Two sets of clinical isolate collections were used to evaluate the antimicrobial activity of S-649266 against Enterobacteriaceae. These sets included 617 global isolates collected between 2009 and 2011 and 233 β-lactamase-identified isolates, including 47 KPC-, 49 NDM-, 12 VIM-, and 8 IMP-producers. The MIC90 values of S-649266 against the first set of Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, Enterobacter aerogenes, and Enterobacter cloacae isolates were all ≤1 μg/ml, and there were only 8 isolates (1.3%) among these 617 clinical isolates with MIC values of ≥8 μg/ml. In the second set, the MIC values of S-649266 were ≤4 μg/ml against 109 strains among 116 KPC-producing and class B (metallo) carbapenemase-producing strains. In addition, S-649266 showed MIC values of ≤2 μg/ml against each of the 13 strains that produced other types of carbapenemases such as SME, NMC, and OXA-48. The mechanisms of the decreased susceptibility of 7 class B carbapenemase-producing strains with MIC values of ≥16 μg/ml are uncertain. This is the first report to demonstrate that S-649266, a novel siderophore cephalosporin, has significant antimicrobial activity against Enterobacteriaceae, including strains that produce carbapenemases such as KPC and NDM-1.

  9. Molecular epidemiology of TEM-3 (CTX-1) beta-lactamase.

    PubMed Central

    Petit, A; Gerbaud, G; Sirot, D; Courvalin, P; Sirot, J

    1990-01-01

    A total of 33 clinical isolates encoding TEM-3 (CTX-1) from four French hospitals were studied. The strains belonged to seven species, Klebsiella pneumoniae (n = 24), Escherichia coli (n = 3), Serratia marcescens (n = 2), Citrobacter freundii (n = 1), Enterobacter aerogenes (n = 1), Enterobacter cloacae (n = 1), and Klebsiella oxytoca (n = 1). All the strains harbored an Inc7 or M self-transferable plasmid with a size of approximately 85 kilobases. The plasmids had closely related EcoRI, HincII, HindIII, and PvuII restriction endonuclease-generated patterns and conferred resistance to all beta-lactams, except cephamycins and imipenem; to tetracycline, because of the presence of the genes blatem-3 and tetC, respectively, as determined by hybridization with specific probes; and to sulfonamide. Depending on the presence or absence and level of expression of the genes aacA4, aadA, and dfrI and of insertion element IS15, four types of plasmids could be distinguished. Plasmid pCFF04, the prototype plasmid encoding TEM-3, was widespread and appeared, by Southern hybridization, as the progenitor of the other types of replicons. The plasmid epidemic responsible for dissemination of TEM-3 in clinical isolates of members of the family Enterobacteriaceae may have originated in S. marcescens since pCFF04 was first detected in this species. Images PMID:2327769

  10. Binding to histo-blood group antigen-expressing bacteria protects human norovirus from acute heat stress

    PubMed Central

    Li, Dan; Breiman, Adrien; le Pendu, Jacques; Uyttendaele, Mieke

    2015-01-01

    This study aims to investigate if histo-blood group antigen (HBGA) expressing bacteria have any protective role on human norovirus (NoV) from acute heat stress. Eleven bacterial strains were included, belonging to Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Clostridium difficile, Bifidobacterium adolescentis, and B. longum. HBGA expression of the bacteria as well as binding of human NoV virus-like particles (VLPs, GI.1, and GII.4 strains) to the bacteria were detected by flow cytometry. NoV VLPs pre-incubated with HBGA expressing or non-HBGA expressing bacteria were heated and detected by both direct ELISA and porcine gastric mucin-binding assay. The NoV-binding abilities of the bacteria correlated well with their HBGA expression profiles. Two HBGA expressing E. coli (LMG8223 and LFMFP861, both GI.1 and GII.4 binders) and one non-HBGA expressing E. coli (ATCC8739, neither GI.1 nor GII.4 binder) were selected for the heat treatment test with NoV VLPs. Compared with the same cell numbers of non-HBGA expressing E. coli, the presence of HBGA-expressing E. coli could always maintain higher antigen integrity, as well as mucin-binding ability of NoV VLPs of both GI.1 and GII.4 after heat-treatment at 90°C for 2 min. These results indicate that HBGA-expressing bacteria may protect NoVs during the food processing treatments, thereby facilitating their transmission. PMID:26191052

  11. Low-temperature-active and salt-tolerant β-mannanase from a newly isolated Enterobacter sp. strain N18.

    PubMed

    You, Jia; Liu, Jin-Feng; Yang, Shi-Zhong; Mu, Bo-Zhong

    2016-02-01

    A low-temperature-active and salt-tolerant β-mannanase produced by a novel mannanase-producer, Enterobacter sp. strain N18, was isolated, purified and then evaluated for its potential application as a gel-breaker in relation to viscosity reduction of guar-based hydraulic fracturing fluids used in oil field. The enzyme could lower the viscosity of guar gum solution by more than 95% within 10 min. The purified β-mannanase with molecular mass of 90 kDa displayed high activity in a broad range of pH and temperature: more than 70% of activity was retained in the pH range of 3.0-8.0 with the optimal pH 7.5, about 50% activity at 20°C with the optimal temperature 50°C. Furthermore, the enzyme retained >70% activity in the presence of 0.5-4.0 M NaCl. These properties implied that the enzyme from strain N18 had potential for serving as a gel-breaker for low temperature oil wells and other industrial fields, where chemical gel breakers were inactive due to low temperature.

  12. Interaction between plants and bacteria: glucosinolates and phyllospheric colonization of cruciferous vegetables by Enterobacter radicincitans DSM 16656.

    PubMed

    Schreiner, Monika; Krumbein, Angelika; Ruppel, Silke

    2009-01-01

    For determining interactive plant-bacterial effects between glucosinolates and phyllospheric colonization by a plant growth-promoting strain, Enterobacter radicincitans DSM 16656, in cruciferous vegetables, the extent of bacterial colonization was assessed in 5 cruciferous vegetables (Brassica juncea, Brassica campestris, Brassica oleracea var. capitata, Brassica rapa var. alboglabra, Nasturtium officinale) using a species-specific TaqMan probe and quantitative real-time PCR. Colonization ability of inoculated E. radicincitans in the phyllosphere of these species varied from inability to colonize B. rapa up to a very good colonization rate of B. campestris. In addition to morphological factors and other plant compounds, the colonization rate was affected by different individual aromatic and aliphatic glucosinolates and their concentration, revealing that both plant pathogens and plant growth-promoting bacteria were affected by glucosinolates in their colonization behavior. In contrast, after E. radicincitans inoculation neither the total nor the individual glucosinolate concentrations in the phyllosphere of the 5 cruciferous species were affected, indicating that the nonpathogenic E. radicincitans might cause only poor cell damage by metabolizing plant cell components and does not induce a plant defense response and thus subsequently an increased glucosinolate concentration in the phyllosphere. Moreover, E. radicincitans induced no stimulation of indole glucosinolate biosynthesis by additional bacterial auxin supply.

  13. Proteomic and biochemical basis for enhanced growth yield of Enterobacter sp. LCR1 on insoluble phosphate medium.

    PubMed

    Kumar, Arvind; Rai, Lal Chand

    2015-01-01

    Proteomics and biochemical analyses were used to unravel the basis for higher growth yield of Enterobacter sp. LCR1 on insoluble phosphate medium compared to soluble. Proteomic analysis using 2-DE, MALDI-TOF/MS and LC-MS revealed the involvement of nine proteins. Down-regulation of fructose bisphosphate aldolase with decreased concentrations of glucose-6-phosphate and fructose-6-phosphate indicated diminished glycolysis. However, up-regulation of phosphoglycerate mutase, increase in the activities of 6-phosphogluconate dehydratase, 2-keto-3-deoxy-6-phosphogluconate aldolase and 6-phosphogluconate dehydrogenase suggested induction of Entner-Doudoroff and pentose phosphate pathways. These pathways generate sufficient energy from gluconic acid, which is also used for biosynthesis as indicated by up-regulation of elongation factor Tu, elongation factor G and protein disulfide isomerase. Increased reactive oxygen species (ROS) formation resulting from organic acid oxidation leads to overexpressed manganese superoxide dismutase and increased activities of catalase and ascorbate peroxidase. Thus the organism uses gluconate instead of glucose for energy, while alleviating extra ROS formation by oxidative defense enzymes. PMID:25053519

  14. Low-temperature-active and salt-tolerant β-mannanase from a newly isolated Enterobacter sp. strain N18.

    PubMed

    You, Jia; Liu, Jin-Feng; Yang, Shi-Zhong; Mu, Bo-Zhong

    2016-02-01

    A low-temperature-active and salt-tolerant β-mannanase produced by a novel mannanase-producer, Enterobacter sp. strain N18, was isolated, purified and then evaluated for its potential application as a gel-breaker in relation to viscosity reduction of guar-based hydraulic fracturing fluids used in oil field. The enzyme could lower the viscosity of guar gum solution by more than 95% within 10 min. The purified β-mannanase with molecular mass of 90 kDa displayed high activity in a broad range of pH and temperature: more than 70% of activity was retained in the pH range of 3.0-8.0 with the optimal pH 7.5, about 50% activity at 20°C with the optimal temperature 50°C. Furthermore, the enzyme retained >70% activity in the presence of 0.5-4.0 M NaCl. These properties implied that the enzyme from strain N18 had potential for serving as a gel-breaker for low temperature oil wells and other industrial fields, where chemical gel breakers were inactive due to low temperature. PMID:26168907

  15. Conversion of cheese whey into a fucose- and glucuronic acid-rich extracellular polysaccharide by Enterobacter A47.

    PubMed

    Antunes, Sílvia; Freitas, Filomena; Alves, Vítor D; Grandfils, Christian; Reis, Maria A M

    2015-09-20

    Cheese whey was used as the sole substrate for the production of extracellular polysaccharides (EPS) by Enterobacter A47. An EPS concentration of 6.40 g L(-1) was reached within 3.2 days of cultivation, corresponding to a volumetric productivity of 2.00 g L(-1) d(-1). The produced EPS was mainly composed of glucuronic acid (29 mol%) and fucose (29 mol%), with lower contents of glucose and galactose (21 mol% each) and a total acyl groups content of 32 wt.%. The polymer had an average molecular weight of 1.8×10(6) Da, with a polydispersity index of 1.2, and an intrinsic viscosity of 8.0 dL g(-1). EPS aqueous solutions (1.0 wt.% in 0.01 M NaCl, at pH 8.0) presented a shear thinning behavior with a viscosity of the first Newtonian plateau approaching 0.1 Pas. This novel glucuronic acid-rich polymer possesses interesting rheological properties, which, together with its high content of glucuronic acid and fucose, two bioactive sugar monomers, confers it a great potential for use in high-value applications, such as cosmetics and pharmaceuticals. PMID:26119564

  16. Enterobacter asburiae strain L1: complete genome and whole genome optical mapping analysis of a quorum sensing bacterium.

    PubMed

    Lau, Yin Yin; Yin, Wai-Fong; Chan, Kok-Gan

    2014-01-01

    Enterobacter asburiae L1 is a quorum sensing bacterium isolated from lettuce leaves. In this study, for the first time, the complete genome of E. asburiae L1 was sequenced using the single molecule real time sequencer (PacBio RSII) and the whole genome sequence was verified by using optical genome mapping (OpGen) technology. In our previous study, E. asburiae L1 has been reported to produce AHLs, suggesting the possibility of virulence factor regulation which is quorum sensing dependent. This evoked our interest to study the genome of this bacterium and here we present the complete genome of E. asburiae L1, which carries the virulence factor gene virK, the N-acyl homoserine lactone-based QS transcriptional regulator gene luxR and the N-acyl homoserine lactone synthase gene which we firstly named easI. The availability of the whole genome sequence of E. asburiae L1 will pave the way for the study of the QS-mediated gene expression in this bacterium. Hence, the importance and functions of these signaling molecules can be further studied in the hope of elucidating the mechanisms of QS-regulation in E. asburiae. To the best of our knowledge, this is the first documentation of both a complete genome sequence and the establishment of the molecular basis of QS properties of E. asburiae.

  17. Cloning, expression and biochemical characterization of a β-carbonic anhydrase from the soil bacterium Enterobacter sp. B13.

    PubMed

    Eminoğlu, Ayşenur; Vullo, Daniela; Aşık, Aycan; Çolak, Dilşat Nigar; Supuran, Claudiu T; Çanakçı, Sabriye; Osman Beldüz, Ali

    2016-12-01

    A recombinant carbonic anhydrase (CA, EC 4.2.1.1) from the soil-dwelling bacterium Enterobacter sp. B13 was cloned and purified by Co(2+) affinity chromatography. Bioinformatic analysis showed that the new enzyme (denominated here B13-CA) belongs to the β-class CAs and to possess 95% homology with the ortholog enzyme from Escherichia coli encoded by the can gene, whereas its sequence homology with the other such enzyme from E. coli (encoded by the cynT gene) was of 33%. B13-CA was characterized kinetically as a catalyst for carbon dioxide hydration to bicarbonate and protons. The enzyme shows a significant catalytic activity, with the following kinetic parameters at 20 °C and pH of 8.3: kcat of 4.8 × 10(5) s(-1) and kcat/Km of 5.6 × 10(7) M(-1) × s(-1). This activity was potently inhibited by acetazolamide which showed a KI of 78.9 nM. Although only this compound was investigated for the moment as B13-CA inhibitor, further studies may reveal new classes of inhibitors/activators of this enzyme which may show biomedical or environmental applications, considering the posssible role of this enzyme in CaCO3 biomineralization processes. PMID:26497870

  18. Isolation and Identification Enterobacter asburiae from Consumed Powdered Infant Formula Milk (PIF) in the Neonatal Intensive Care Unit (NICU).

    PubMed

    Mardaneh, Jalal; Soltan Dallal, Mohammad Mehdi

    2016-01-01

    Enterobacter asburiae (E. asburiae) is a facultative anaerobic, non-spore-forming gram-negative rod-shaped bacterium belonging to the family of Enterobacteriaceae. It is an opportunistic pathogen that its strains are isolated from a variety of clinical and environmental specimens. Since powdered infant formula milk (PIF) is not a sterile product, it is an excellent medium for bacterial growth. The aim of this study was to isolate and identify E. asburiae from PIF in the neonatal intensive care unit (NICU) and determine antimicrobial susceptibility patterns of this bacterium. A total 125 PIF samples were purchased from drug stores between June 2011 to March 2012. E. asburiae was isolated according to FDA method. For final confirmation, biochemical tests embedded in the API-20E system were used. The drug susceptibility test was performed using the disc diffusion method according to CLSI recommendations. Out of the 125 PIF samples investigated, 2 (1.6%) samples were positive for E. asburiae. All isolated strains were uniformly susceptible to aztreonam, cefotaxim, amikacin, streptomycin, nalidixic acid, meropenem, tetracycline, ceftazidime, and colistin. Variable susceptibility was seen to the some antimicrobial agents tested. Each country should categorize its own designed guidelines for the preparation and handling of PIF adapted to the local environment. Moreover, the pathogenesis of the E. asburiae in infants hospitalized in NICU and other groups such as immunosuppressed patients and HIV infected individuals is uncertain and requires further study. PMID:26853289

  19. Occurrence of bacteriophages infecting Aeromonas, Enterobacter, and Klebsiella in water and association with contamination sources in Thailand.

    PubMed

    Wangkahad, Bencharong; Bosup, Suchada; Mongkolsuk, Skorn; Sirikanchana, Kwanrawee

    2015-06-01

    The co-residence of bacteriophages and their bacterial hosts in humans, animals, and environmental sources directed the use of bacteriophages to track the origins of the pathogenic bacteria that can be found in contaminated water. The objective of this study was to enumerate bacteriophages of Aeromonas caviae (AecaKS148), Enterobacter sp. (EnspKS513), and Klebsiella pneumoniae (KlpnKS648) in water and evaluate their association with contamination sources (human vs. animals). Bacterial host strains were isolated from untreated wastewater in Bangkok, Thailand. A double-layer agar technique was used to detect bacteriophages. All three bacteriophages were detected in polluted canal samples, with likely contamination from human wastewater, whereas none was found in non-polluted river samples. AecaKS148 was found to be associated with human fecal sources, while EnspKS513 and KlpnKS648 seemed to be equally prevalent in both human and animal fecal sources. Both bacteriophages were also present in polluted canals that could receive contamination from other fecal sources or the environment. In conclusion, all three bacteriophages were successfully monitored in Bangkok, Thailand. This study provided an example of bacteriophages for potential use as source identifiers of pathogen contamination. The results from this study will assist in controlling sources of pathogen contamination, especially in developing countries.

  20. Conversion of cheese whey into a fucose- and glucuronic acid-rich extracellular polysaccharide by Enterobacter A47.

    PubMed

    Antunes, Sílvia; Freitas, Filomena; Alves, Vítor D; Grandfils, Christian; Reis, Maria A M

    2015-09-20

    Cheese whey was used as the sole substrate for the production of extracellular polysaccharides (EPS) by Enterobacter A47. An EPS concentration of 6.40 g L(-1) was reached within 3.2 days of cultivation, corresponding to a volumetric productivity of 2.00 g L(-1) d(-1). The produced EPS was mainly composed of glucuronic acid (29 mol%) and fucose (29 mol%), with lower contents of glucose and galactose (21 mol% each) and a total acyl groups content of 32 wt.%. The polymer had an average molecular weight of 1.8×10(6) Da, with a polydispersity index of 1.2, and an intrinsic viscosity of 8.0 dL g(-1). EPS aqueous solutions (1.0 wt.% in 0.01 M NaCl, at pH 8.0) presented a shear thinning behavior with a viscosity of the first Newtonian plateau approaching 0.1 Pas. This novel glucuronic acid-rich polymer possesses interesting rheological properties, which, together with its high content of glucuronic acid and fucose, two bioactive sugar monomers, confers it a great potential for use in high-value applications, such as cosmetics and pharmaceuticals.

  1. Identification of regulated genes conferring resistance to high concentrations of glyphosate in a new strain of Enterobacter.

    PubMed

    Fei, Yun-Yan; Gai, Jun-Yi; Zhao, Tuan-Jie

    2013-12-01

    Glyphosate is a widely used herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity. Most plants and microbes are sensitive to glyphosate. However, transgenic-resistant crops that contain a modified epsps obtained from the resistant microbes have been commercially successful and therefore, new resistance genes and their adaptive regulatory mechanisms are of great interest. In this study, a soil-borne, glyphosate-resistant bacterium was selected and identified as Enterobacter. The EPSPS in this strain was found to have been altered to a resistant one. A total of 42 differentially expressed genes (DEGs) in the glyphosate were screened using microarray techniques. Under treatment, argF, sdhA, ivbL, rrfA-H were downregulated, whereas the transcripts of speA, osmY, pflB, ahpC, fusA, deoA, uxaC, rpoD and a few ribosomal protein genes were upregulated. Data were verified by quantitative real-time PCR on selected genes. All transcriptional changes appeared to protect the bacteria from glyphosate and associated osmotic, acidic and oxidative stresses. Many DEGs may have the potential to confer resistance to glyphosate alone, and some may be closely related to the shikimate pathway, reflecting the complex gene interaction network for glyphosate resistance.

  2. Effect of antimicrobial peptides on colistin-susceptible and colistin-resistant strains of Klebsiella pneumoniae and Enterobacter asburiae.

    PubMed

    Kádár, Béla; Kocsis, Béla; Kristof, Katalin; Tóth, Ákos; Szabó, Dóra

    2015-12-01

    In this study susceptibility to different antimicrobial peptides was investigated on colistin-susceptible and colistin-resistant identical pulsotype strains of KPC-2 producing Klebsiella pneumoniae ST258 as well as colistin-susceptible and colistin-resistant Enterobacter asburiae strains isolated from clinical samples. In our test, bacteria were exposed to 50 mg/ml lactoferrin, lysozyme and protamine - cationic antimicrobial peptides belonging to innate immune system and having structural similarity to polymyxins - in separate reactions. After 18 hours incubation of colonies were counted. 40% of colistin-resistant K. pneumoniae strains and 97% of colistin-susceptible counterpart strains were lysed by protamine whereas 87% and 100% colony forming unit decrease by lysozyme was seen, respectively. In the case of colistin-resistant E. asburiae strains 1 log10 cell count increase were observed after treatment with lysozyme and 1.56 log10 after lactoferrin exposure compared to the initial number whereas the colistin-susceptible showed no relevant cell count increase. Our findings suggest that acquired colistin-resistance in Enterobacteriaceae is associated with tolerance against antimicrobial peptides.

  3. Isolation and Identification Enterobacter asburiae from Consumed Powdered Infant Formula Milk (PIF) in the Neonatal Intensive Care Unit (NICU).

    PubMed

    Mardaneh, Jalal; Soltan Dallal, Mohammad Mehdi

    2016-01-01

    Enterobacter asburiae (E. asburiae) is a facultative anaerobic, non-spore-forming gram-negative rod-shaped bacterium belonging to the family of Enterobacteriaceae. It is an opportunistic pathogen that its strains are isolated from a variety of clinical and environmental specimens. Since powdered infant formula milk (PIF) is not a sterile product, it is an excellent medium for bacterial growth. The aim of this study was to isolate and identify E. asburiae from PIF in the neonatal intensive care unit (NICU) and determine antimicrobial susceptibility patterns of this bacterium. A total 125 PIF samples were purchased from drug stores between June 2011 to March 2012. E. asburiae was isolated according to FDA method. For final confirmation, biochemical tests embedded in the API-20E system were used. The drug susceptibility test was performed using the disc diffusion method according to CLSI recommendations. Out of the 125 PIF samples investigated, 2 (1.6%) samples were positive for E. asburiae. All isolated strains were uniformly susceptible to aztreonam, cefotaxim, amikacin, streptomycin, nalidixic acid, meropenem, tetracycline, ceftazidime, and colistin. Variable susceptibility was seen to the some antimicrobial agents tested. Each country should categorize its own designed guidelines for the preparation and handling of PIF adapted to the local environment. Moreover, the pathogenesis of the E. asburiae in infants hospitalized in NICU and other groups such as immunosuppressed patients and HIV infected individuals is uncertain and requires further study.

  4. Interaction between plants and bacteria: glucosinolates and phyllospheric colonization of cruciferous vegetables by Enterobacter radicincitans DSM 16656.

    PubMed

    Schreiner, Monika; Krumbein, Angelika; Ruppel, Silke

    2009-01-01

    For determining interactive plant-bacterial effects between glucosinolates and phyllospheric colonization by a plant growth-promoting strain, Enterobacter radicincitans DSM 16656, in cruciferous vegetables, the extent of bacterial colonization was assessed in 5 cruciferous vegetables (Brassica juncea, Brassica campestris, Brassica oleracea var. capitata, Brassica rapa var. alboglabra, Nasturtium officinale) using a species-specific TaqMan probe and quantitative real-time PCR. Colonization ability of inoculated E. radicincitans in the phyllosphere of these species varied from inability to colonize B. rapa up to a very good colonization rate of B. campestris. In addition to morphological factors and other plant compounds, the colonization rate was affected by different individual aromatic and aliphatic glucosinolates and their concentration, revealing that both plant pathogens and plant growth-promoting bacteria were affected by glucosinolates in their colonization behavior. In contrast, after E. radicincitans inoculation neither the total nor the individual glucosinolate concentrations in the phyllosphere of the 5 cruciferous species were affected, indicating that the nonpathogenic E. radicincitans might cause only poor cell damage by metabolizing plant cell components and does not induce a plant defense response and thus subsequently an increased glucosinolate concentration in the phyllosphere. Moreover, E. radicincitans induced no stimulation of indole glucosinolate biosynthesis by additional bacterial auxin supply. PMID:19556746

  5. Structural Basis of Enzymatic Activity for the Ferulic Acid Decarboxylase (FADase) from Enterobacter sp. Px6-4

    PubMed Central

    Liang, Lianming; Sun, Yuna; Huang, Jingwen; Li, Xuemei; Cao, Yi; Meng, Zhaohui; Zhang, Ke-Qin

    2011-01-01

    Microbial ferulic acid decarboxylase (FADase) catalyzes the transformation of ferulic acid to 4-hydroxy-3-methoxystyrene (4-vinylguaiacol) via non-oxidative decarboxylation. Here we report the crystal structures of the Enterobacter sp. Px6-4 FADase and the enzyme in complex with substrate analogues. Our analyses revealed that FADase possessed a half-opened bottom β-barrel with the catalytic pocket located between the middle of the core β-barrel and the helical bottom. Its structure shared a high degree of similarity with members of the phenolic acid decarboxylase (PAD) superfamily. Structural analysis revealed that FADase catalyzed reactions by an “open-closed” mechanism involving a pocket of 8×8×15 Å dimension on the surface of the enzyme. The active pocket could directly contact the solvent and allow the substrate to enter when induced by substrate analogues. Site-directed mutagenesis showed that the E134A mutation decreased the enzyme activity by more than 60%, and Y21A and Y27A mutations abolished the enzyme activity completely. The combined structural and mutagenesis results suggest that during decarboxylation of ferulic acid by FADase, Trp25 and Tyr27 are required for the entering and proper orientation of the substrate while Glu134 and Asn23 participate in proton transfer. PMID:21283705

  6. Reservoir and routes of transmission of Enterobacter sakazakii (Cronobacter spp.) in a milk powder-producing plant.

    PubMed

    Jacobs, C; Braun, P; Hammer, P

    2011-08-01

    Several outbreaks of Cronobacter spp. (Enterobacter sakazakii) have been described as food-borne illness in neonates and infants. Powdered infant formula has been identified as a source of infection, especially in hospital nurseries, where a bulk of formula nutrient is prepared for the whole day and instructions for preparation are not always followed correctly. Neonates who are underweight or immunosuppressed are especially at risk for an E. sakazakii infection. Considering that milk powder is the main ingredient of powdered infant formula, we analyzed the incidence and distribution of E. sakazakii in a milk powder-producing plant. We looked specifically at the spray-drying towers and roller dryers. Selected isolates from samples taken from the environment and final product were typed by pulsed-field gel electrophoresis to investigate the epidemiology of the organism within the production area of the plant. Seven pulsed-field gel electrophoresis types were detected in the spray-drying area, which presumably entered the plant through an aperture for process air and an improperly controlled roller shutter. Furthermore, textile filters for exhaust air of both the spray-drying towers were identified as internal reservoirs of the pathogen. For economic reasons, powder from the textile filters is reintroduced into the product flow; this can contaminate the final product. For the production of milk powder to be used as an ingredient of powdered infant formula, it was suggested to terminate the process of reintroducing the filtered powder into the product flow. A second transmission route was identified in the roller dryer section of the factory. It could be shown that contaminated milk concentrate could pass the process unheated, thus leading to a contamination of the product with E. sakazakii.

  7. Survival of Enterobacter sakazakii on fresh produce as affected by temperature, and effectiveness of sanitizers for its elimination.

    PubMed

    Kim, Hoikyung; Ryu, Jee-Hoon; Beuchat, Larry R

    2006-09-01

    A study was done to determine the survival characteristics of Enterobacter sakazakii on the surface of apples, cantaloupes, strawberries, lettuce, and tomatoes stored at 4, 12, and 25 degrees C for 8-28 days. Populations significantly decreased (por=50 microg/ml, were equivalent in killing E. sakazakii on apples. Populations of E. sakazakii on apples treated with 10 microg/ml chlorine dioxide for 1 or 5 min were significantly reduced (por=4.00 log CFU/apple. Reductions of >or=3.70 log CFU/tomato were achieved by treatment with 10 microg/ml chlorine or chlorine dioxide or 40 microg/ml Tsunami 200 for 5 min. Reductions in populations of E. sakazakii on lettuce treated with chlorine at 10, 50, and 100 microg/ml for 1 min ranged from 1.61 to 2.50 log CFU/sample (26+/-4 g), compared to populations remaining on lettuce washed with water. Chlorine was less effective in killing E. sakazakii on lettuce than on apples or tomatoes. Treatment of lettuce with Tsunami 200 (40 and 80 microg/ml) for 5 min caused a reduction of >or=5.31 log CFU/sample. Results provide insights to predicting survival characteristics of E. sakazakii on produce and the efficacy of sanitizers in killing the bacterium.

  8. Isolation and Antimicrobial Testing of Aeromonas spp., Citrobacter spp., Cronobacter spp., Enterobacter spp., Escherichia spp., Klebsiella spp., and Trabulsiella spp. from the Gallbladder of Pigs.

    PubMed

    Evangelopoulou, Grammato; Filioussis, Georgios; Kritas, Spyridon; Kantere, Maria; Burriel, Angeliki R

    2015-01-01

    The presence of Gram-negative bacteria species, other than Salmonella spp., in the gallbladder of pigs was examined. Isolated Gram-negative bacteria were assigned to species using the Microgen™ GnA+B-ID Systems. Of the 64 isolated strains 43 were identified as Escherichia coli, seven as Enterobacter spp., three each as Klebsiella spp., Citrobacterfreundii, Aeromonas hydrophila and Cronobacter sakazakii and one each as Escherichiafergusonii and Trabulsiella guamensis. Their antibiograms showed very high resistance to ampicillin, amoxicillin, tetracycline, chloramphenicol and sulfamethoxazole/trimethoprim. It was concluded that the pigs' gallbladder is a reservoir of potentially pathogenic Gram-negative bacteria for pork consumers.

  9. Enterobacter sakazakii in dried infant formulas and milk kitchens of maternity wards in São Paulo, Brazil.

    PubMed

    Palcich, Gabriela; Gillio, Cintia de Moraes; Aragon-Alegro, Lina Casale; Pagotto, Franco J; Farber, Jeffrey M; Landgraf, Mariza; Destro, Maria Teresa

    2009-01-01

    This study was the first conducted in Brazil to evaluate the presence of Enterobacter sakazakii in milk-based powdered infant formula manufactured for infants 0 to 6 months of age and to examine the conditions of formula preparation and service in three hospitals in São Paulo State, Brazil. Samples of dried and rehydrated infant formula, environments of milk kitchens, water, bottles and nipples, utensils, and hands of personnel were analyzed, and E. sakazakii and Enterobacteriaceae populations were determined. All samples of powdered infant formula purchased at retail contained E. sakazakii at <0.3 [corrected] most probable number (MPN)/100 g. In hospital samples, E. sakazakii was found in one unopened formula can (0.3 MPN/100 g) and in the residue from one nursing bottle from hospital A. All other cans of formula from the same lot bought at a retail store contained E. sakazakii at <0.3 [corrected] MPN/100 g. The pathogen also was found in one cleaning sponge from hospital B. Enterobacteriaceae populations ranged from 10(1) to 10(5) CFU/g in cleaning aids and <5 CFU/g in all formula types (dry or rehydrated), except for the sample that contained E. sakazakii, which also was contaminated with Enterobacteriaceae at 5 CFU/g. E. sakazakii isolates were not genetically related. In an experiment in which rehydrated formula was used as the growth medium, the temperature was that of the neonatal intensive care unit (25 degrees C), and the incubation time was the average time that formula is left at room temperature while feeding the babies (up to 4 h), a 2-log increase in levels of E. sakazakii was found in the formula. Visual inspection of the facilities revealed that the hygienic conditions in the milk kitchens needed improvement. The length of time that formula is left at room temperature in the different hospitals while the babies in the neonatal intensive care unit are being fed (up to 4 h) may allow for the multiplication of E. sakazakii and thus may lead to an

  10. Exploitation of the Medfly Gut Microbiota for the Enhancement of Sterile Insect Technique: Use of Enterobacter sp. in Larval Diet-Based Probiotic Applications

    PubMed Central

    Papadopoulos, Nikos T.; Abd-Alla, Adly M. M.; Cáceres, Carlos; Bourtzis, Kostas

    2015-01-01

    The Mediterranean fruit fly (medfly), Ceratitis capitata, is a pest of worldwide substantial economic importance, as well as a Tephritidae model for sterile insect technique (SIT) applications. The latter is partially due to the development and utilization of genetic sexing strains (GSS) for this species, such as the Vienna 8 strain, which is currently used in mass rearing facilities worldwide. Improving the performance of such a strain both in mass rearing facilities and in the field could significantly enhance the efficacy of SIT and reduce operational costs. Recent studies have suggested that the manipulation of gut symbionts can have a significant positive effect on the overall fitness of insect strains. We used culture-based approaches to isolate and characterize gut-associated bacterial species of the Vienna 8 strain under mass rearing conditions. We also exploited one of the isolated bacterial species, Enterobacter sp., as dietary supplement (probiotic) to the larval diet, and we assessed its effects on fitness parameters under the standard operating procedures used in SIT operational programs. Probiotic application of Enterobacter sp. resulted in improvement of both pupal and adult productivity, as well as reduced rearing duration, particularly for males, without affecting pupal weight, sex ratio, male mating competitiveness, flight ability and longevity under starvation. PMID:26325068

  11. Exploitation of the Medfly Gut Microbiota for the Enhancement of Sterile Insect Technique: Use of Enterobacter sp. in Larval Diet-Based Probiotic Applications.

    PubMed

    Augustinos, Antonios A; Kyritsis, Georgios A; Papadopoulos, Nikos T; Abd-Alla, Adly M M; Cáceres, Carlos; Bourtzis, Kostas

    2015-01-01

    The Mediterranean fruit fly (medfly), Ceratitis capitata, is a pest of worldwide substantial economic importance, as well as a Tephritidae model for sterile insect technique (SIT) applications. The latter is partially due to the development and utilization of genetic sexing strains (GSS) for this species, such as the Vienna 8 strain, which is currently used in mass rearing facilities worldwide. Improving the performance of such a strain both in mass rearing facilities and in the field could significantly enhance the efficacy of SIT and reduce operational costs. Recent studies have suggested that the manipulation of gut symbionts can have a significant positive effect on the overall fitness of insect strains. We used culture-based approaches to isolate and characterize gut-associated bacterial species of the Vienna 8 strain under mass rearing conditions. We also exploited one of the isolated bacterial species, Enterobacter sp., as dietary supplement (probiotic) to the larval diet, and we assessed its effects on fitness parameters under the standard operating procedures used in SIT operational programs. Probiotic application of Enterobacter sp. resulted in improvement of both pupal and adult productivity, as well as reduced rearing duration, particularly for males, without affecting pupal weight, sex ratio, male mating competitiveness, flight ability and longevity under starvation. PMID:26325068

  12. Isolation and characterization of xanthan-degrading Enterobacter sp. nov. LB37 for reducing the viscosity of xanthan in petroleum industry.

    PubMed

    Chen, Xiaoyi; Wang, Mi; Yang, Fan; Tang, Wenzhu; Li, Xianzhen

    2014-05-01

    A Gram-negative, straight rod and facultative anaerobic bacterium was isolated from soil sample. It exhibits the phenotypic characteristics consistent with its classification in the genus Enterobacter. The isolate ferment glucose to acid and gas. Arginine dihydrolase, ornithin decarboxylase and gelatinase but not deoxyribonuclease was produced by this isolate. There was no hydrogen sulfide production. On the basis of the phenotypic data, together with phylogenetic analysis based on 16S rDNA gene sequences, this strain should represent a novel species of the genus Enterobacter and was designated as LB37. The strain LB37 could degrade xanthan molecules resulting in the rapid decrease of the viscosity of xanthan solution used in oil drilling process. Endoxanthanase activity was also detected in the culture supernatant. To our knowledge, it is the first report on the microbes being involved in the xanthan degradation for oil industry. The isolate LB37 would be useful for potential application in enhanced oil recovery and oil drilling field. PMID:24326911

  13. Isolation and characterization of xanthan-degrading Enterobacter sp. nov. LB37 for reducing the viscosity of xanthan in petroleum industry.

    PubMed

    Chen, Xiaoyi; Wang, Mi; Yang, Fan; Tang, Wenzhu; Li, Xianzhen

    2014-05-01

    A Gram-negative, straight rod and facultative anaerobic bacterium was isolated from soil sample. It exhibits the phenotypic characteristics consistent with its classification in the genus Enterobacter. The isolate ferment glucose to acid and gas. Arginine dihydrolase, ornithin decarboxylase and gelatinase but not deoxyribonuclease was produced by this isolate. There was no hydrogen sulfide production. On the basis of the phenotypic data, together with phylogenetic analysis based on 16S rDNA gene sequences, this strain should represent a novel species of the genus Enterobacter and was designated as LB37. The strain LB37 could degrade xanthan molecules resulting in the rapid decrease of the viscosity of xanthan solution used in oil drilling process. Endoxanthanase activity was also detected in the culture supernatant. To our knowledge, it is the first report on the microbes being involved in the xanthan degradation for oil industry. The isolate LB37 would be useful for potential application in enhanced oil recovery and oil drilling field.

  14. Distribution of Extended-Spectrum β-Lactamases, AmpC β-Lactamases, and Carbapenemases among Enterobacteriaceae Isolates Causing Intra-Abdominal Infections in the Asia-Pacific Region: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART)

    PubMed Central

    Sheng, Wang-Huei; Badal, Robert E.

    2013-01-01

    The increasing trend of β-lactam resistance among Enterobacteriaceae is a worldwide threat. Enterobacteriaceae isolates causing intra-abdominal infections (IAI) from the Study for Monitoring Antimicrobial Resistance Trends (SMART) collected in 2008 and 2009 from the Asia-Pacific region were investigated. Detection of extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases, and carbapenemases was performed by multiplex PCR. A total of 699 Enterobacteriaceae isolates with positive genotypic results, included Escherichia coli (n = 443), Klebsiella pneumoniae (n = 187), Enterobacter cloacae (n = 45), Klebsiella oxytoca (n = 9), Citrobacter freundii (n = 5), Proteus mirabilis (n = 3), Enterobacter aerogenes (n = 2), Morganella morganii (n = 2), and one each of Enterobacter asburiae, Proteus vulgaris, and Providencia rettgeri were analyzed. Nearly 20% of these β-lactamase-producing Enterobacteriaceae isolates were from community-associated IAI. CTX-M (588 isolates, including 428 [72.8%] with CTX-M-15) was the most common ESBL, followed by SHV (n = 59) and TEM (n = 4). CMY (n = 110, including 102 [92.7%] with CMY-2) was the most common AmpC β-lactamase, followed by DHA (n = 46) and ACT/MIR (n = 40). NDM (n = 65, including 62 [95.4%] with NDM-1) was the most common carbapenemase, followed by IMP (n = 7) and OXA (n = 7). Isolates from hospital-associated IAI had more complicated β-lactamase combinations than isolates from the community. Carbapenemases were all exclusively detected in Enterobacteriaceae isolates from India, except that IMP β-lactamases were also detected in Philippines and Australia. CTX-M β-lactamases were the predominant ESBLs produced by Enterobacteriaceae causing IAI in the Asia-Pacific region. Emergence of CTX-M-15-, CMY-2-, and NDM-1-producing Enterobacteriaceae isolates is of major concern and highlights the need for further surveillance in this area. PMID:23587958

  15. Bacterial resistance to silver in wound care and medical devices.

    PubMed

    Landsdown, A B G; Williams, A

    2007-01-01

    This review discusses the molecular and genetic evidence for silver resistance in bacteria isolated from skin wounds and medical devices with reference to a case study of resistant Enterobacter cloacae from the leg ulcers of an elderly woman.

  16. Alleviation of salt stress by enterobacter sp. EJ01 in tomato and Arabidopsis is accompanied by up-regulation of conserved salinity responsive factors in plants.

    PubMed

    Kim, Kangmin; Jang, Ye-Jin; Lee, Sang-Myeong; Oh, Byung-Taek; Chae, Jong-Chan; Lee, Kui-Jae

    2014-02-01

    Microbiota in the niches of the rhizosphere zones can affect plant growth and responses to environmental stress conditions via mutualistic interactions with host plants. Specifically, some beneficial bacteria, collectively referred to as Plant Growth Promoting Rhizobacteria (PGPRs), increase plant biomass and innate immunity potential. Here, we report that Enterobacter sp. EJ01, a bacterium isolated from sea china pink (Dianthus japonicus thunb) in reclaimed land of Gyehwa-do in Korea, improved the vegetative growth and alleviated salt stress in tomato and Arabidopsis. EJ01 was capable of producing 1-aminocy-clopropane-1-carboxylate (ACC) deaminase and also exhibited indole-3-acetic acid (IAA) production. The isolate EJ01 conferred increases in fresh weight, dry weight, and plant height of tomato and Arabidopsis under both normal and high salinity conditions. At the molecular level, short-term treatment with EJ01 increased the expression of salt stress responsive genes such as DREB2b, RD29A, RD29B, and RAB18 in Arabidopsis. The expression of proline biosynthetic genes (i.e. P5CS1 and P5CS2) and of genes related to priming processes (i.e. MPK3 and MPK6) were also up-regulated. In addition, reactive oxygen species scavenging activities were enhanced in tomatoes treated with EJ01 in stressed conditions. GFP-tagged EJ01 displayed colonization in the rhizosphere and endosphere in the roots of Arabidopsis. In conclusion, the newly isolated Enterobacter sp. EJ01 is a likely PGPR and alleviates salt stress in host plants through multiple mechanisms, including the rapid up-regulation of conserved plant salt stress responsive signaling pathways.

  17. Acid and base hydrolysis of lipid A from Enterobacter agglomerans as monitored by electrospray ionization mass spectrometry: pertinence to detoxification mechanisms.

    PubMed

    Wang, Y; Cole, R B

    1996-02-01

    Lipopolysaccharides (LPS), which are endotoxins found in the cell wall of Gram-negative bacteria, are common components of organic dusts that cause or contribute to symptoms associated with organic dust diseases. The lipid A subgroup within LPS is believed to be responsible for the toxicity. Acid and base treatments, which can be effective detoxification methods, were performed on lipid A from Enterobacter agglomerans (EA), a bacterium commonly found in field cotton. Negative-ion electrospray ionization mass spectrometry was employed to characterize the post-treatment structural changes to lipid A. Acid treatment (1% acetic acid, 100 degrees C) hydrolyzed the ester side-chains of lipid A. It was found that the ester-linked palmitoyl group was the most labile to acid hydrolysis. Hydrolysis of the palmitoyl moiety conformed to pseudo-first-order chemical reaction kinetics with a rate constant for decomposition of heptacyl-lipid A from Enterobacter agglomerans of approximately 3.3 x 10(-3) min-1. An order of lability of lipid A acyl side-chains to acid hydrolysis was also deduced: R4' (palmitoyl) > R1' (myristoyl or hydroxymyristoyl) > R3 (hydroxymyristoyl at position 3) > R1 (oxymyristoyl group at position 3') > R2' (lauroyl). Base treatment (0.05 M NaOH in 95% EtOH, 65 degrees C) was shown to be more effective at cleaving ester-linked side-chains. In addition, mass spectral evidence suggests that opening of the pyranose rings of the disaccharide backbone of lipid A and/or removal of the phosphoryl groups may be occurring during base treatment. This study sheds light on mechanistic aspects of treatment procedures leading to the detoxification of endotoxins.

  18. Alleviation of Salt Stress by Enterobacter sp. EJ01 in Tomato and Arabidopsis Is Accompanied by Up-Regulation of Conserved Salinity Responsive Factors in Plants

    PubMed Central

    Kim, Kangmin; Jang, Ye-Jin; Lee, Sang-Myeong; Oh, Byung-Taek; Chae, Jong-Chan; Lee, Kui-Jae

    2014-01-01

    Microbiota in the niches of the rhizosphere zones can affect plant growth and responses to environmental stress conditions via mutualistic interactions with host plants. Specifically, some beneficial bacteria, collectively referred to as Plant Growth Promoting Rhizobacteria (PGPRs), increase plant biomass and innate immunity potential. Here, we report that Enterobacter sp. EJ01, a bacterium isolated from sea china pink (Dianthus japonicus thunb) in reclaimed land of Gyehwa-do in Korea, improved the vegetative growth and alleviated salt stress in tomato and Arabidopsis. EJ01 was capable of producing 1-aminocy-clopropane-1-carboxylate (ACC) deaminase and also exhibited indole-3-acetic acid (IAA) production. The isolate EJ01 conferred increases in fresh weight, dry weight, and plant height of tomato and Arabidopsis under both normal and high salinity conditions. At the molecular level, short-term treatment with EJ01 increased the expression of salt stress responsive genes such as DREB2b, RD29A, RD29B, and RAB18 in Arabidopsis. The expression of proline biosynthetic genes (i.e. P5CS1 and P5CS2) and of genes related to priming processes (i.e. MPK3 and MPK6) were also up-regulated. In addition, reactive oxygen species scavenging activities were enhanced in tomatoes treated with EJ01 in stressed conditions. GFP-tagged EJ01 displayed colonization in the rhizosphere and endosphere in the roots of Arabidopsis. In conclusion, the newly isolated Enterobacter sp. EJ01 is a likely PGPR and alleviates salt stress in host plants through multiple mechanisms, including the rapid up-regulation of conserved plant salt stress responsive signaling pathways. PMID:24598995

  19. Diversity of microflora in the gut and casts of tropical composting earthworms reared on different substrates.

    PubMed

    Parthasarathi, K; Ranganathan, L S; Anandi, V; Zeyer, Josef

    2007-01-01

    The diversity of fungi, bacteria, yeast, actinomycetes and protozoa were analysed in the gut and casts of Eudrilus eugeniae, Lampito mauritii, Eisenia fetida and Perionyx excavatus, both qualitatively and quantitatively as influenced by different feed substrates like clay loam soil, cowdung and pressmud. While actinomycetes (Streptomyces albus, S. somaliensis, Nocardia asteroides, N. caviae and Saccharomonosporia) were not digested by any of these species of worms, protozoa (Amoeba proteus, A. terricola, Paramecium trichium, Euglena viridis, E. orientalis, Vorticella picta and Trichomonas hominis) and yeast (Candida tropicalis, C. krusei C. albicans and Cryptococcus neoformans) were totally digested. Certain species of fungi (Saksenae vasiformis, Mucor plumbeus, Cladosporium carrionii, C. herbacium, Alternaria sp., Cunninghamella echinulata, Mycetia sterila, Syncephalostrum racemosum, Curvalaria lunata, C. geniculata and Geotrichum candidum) and bacteria (Pseudomonas aeruginosa, Bacterium antitratum, Mima polymorpha, Enterobacter aerogenes, E. cloacae, Proteus vulgaris, P. mirabilis, P. rettgeri, Escherichia coli, Staphylococus citreus, Bacillus subtilis, B. cereus, Enterococci and Micrococci) were completely digested. Certain other species were not digested fungi like Aspergillus fumigatus, A. flavus, A. ochraceous, Trichoderma koningii (except by Eeugeniae), Fusarium moniliforme (except by E. eugeniae) and Rhizopus sp., and bacteria like Klebsiella pneumoniae and Morganella morganii) and these were multiplied during the transit of the organic residues through the gut of worms. The microbial proliferation was more in the casts, due to the environment prevailing--rich in nutrient supply and large surface area available for growth and reproduction of the microbes that lead to enhanced microbial activity and humic acid contents in the casts. PMID:17717992

  20. Diversity of microflora in the gut and casts of tropical composting earthworms reared on different substrates.

    PubMed

    Parthasarathi, K; Ranganathan, L S; Anandi, V; Zeyer, Josef

    2007-01-01

    The diversity of fungi, bacteria, yeast, actinomycetes and protozoa were analysed in the gut and casts of Eudrilus eugeniae, Lampito mauritii, Eisenia fetida and Perionyx excavatus, both qualitatively and quantitatively as influenced by different feed substrates like clay loam soil, cowdung and pressmud. While actinomycetes (Streptomyces albus, S. somaliensis, Nocardia asteroides, N. caviae and Saccharomonosporia) were not digested by any of these species of worms, protozoa (Amoeba proteus, A. terricola, Paramecium trichium, Euglena viridis, E. orientalis, Vorticella picta and Trichomonas hominis) and yeast (Candida tropicalis, C. krusei C. albicans and Cryptococcus neoformans) were totally digested. Certain species of fungi (Saksenae vasiformis, Mucor plumbeus, Cladosporium carrionii, C. herbacium, Alternaria sp., Cunninghamella echinulata, Mycetia sterila, Syncephalostrum racemosum, Curvalaria lunata, C. geniculata and Geotrichum candidum) and bacteria (Pseudomonas aeruginosa, Bacterium antitratum, Mima polymorpha, Enterobacter aerogenes, E. cloacae, Proteus vulgaris, P. mirabilis, P. rettgeri, Escherichia coli, Staphylococus citreus, Bacillus subtilis, B. cereus, Enterococci and Micrococci) were completely digested. Certain other species were not digested fungi like Aspergillus fumigatus, A. flavus, A. ochraceous, Trichoderma koningii (except by Eeugeniae), Fusarium moniliforme (except by E. eugeniae) and Rhizopus sp., and bacteria like Klebsiella pneumoniae and Morganella morganii) and these were multiplied during the transit of the organic residues through the gut of worms. The microbial proliferation was more in the casts, due to the environment prevailing--rich in nutrient supply and large surface area available for growth and reproduction of the microbes that lead to enhanced microbial activity and humic acid contents in the casts.

  1. Production, Characterization, and Flocculation Mechanism of Cation Independent, pH Tolerant, and Thermally Stable Bioflocculant from Enterobacter sp. ETH-2

    PubMed Central

    Tang, Wei; Song, Liyan; Li, Dou; Qiao, Jing; Zhao, Tiantao; Zhao, Heping

    2014-01-01

    Synthetic high polymer flocculants, frequently utilized for flocculating efficiency and low cost, recently have been discovered as producing increased risk to human health and the environment. Development of a more efficient and environmentally sound alternative flocculant agent is investigated in this paper. Bioflocculants are produced by microorganisms and may exhibit a high rate of flocculation activity. The bioflocculant ETH-2, with high flocculating activity (2849 mg Kaolin particle/mg ETH-2), produced by strain Enterobacter sp. isolated from activated sludge, was systematically investigated with regard to its production, characterization, and flocculation mechanism. Analyses of microscopic observation, zeta potential and ETH-2 structure demonstrates the bridging mechanism, as opposed to charge neutralization, was responsible for flocculation of the ETH-2. ETH-2 retains high molecular weight (603 to 1820 kDa) and multi-functional groups (hydroxyl, amide and carboxyl) that contributed to flocculation. Polysaccharides mainly composed of mannose, glucose, and galactose, with a molar ratio of 1∶2.9∶9.8 were identified as the active constituents in bioflocculant. The structure of the long backbone with active sites of polysaccharides was determined as a primary basis for the high flocculation activity. Bioflocculant ETH-2 is cation independent, pH tolerant, and thermally stable, suggesting a potential fit for industrial application. PMID:25485629

  2. A comparison of polymerase chain reaction and international organization for standardization methods for determination of Enterobacter sakazakii contamination of infant formulas from Chinese mainland markets.

    PubMed

    Ye, Yingwang; Wu, Qingping; Yao, Lin; Dong, Xiaohui; Wu, Kui; Zhang, Jumei

    2009-12-01

    Enterobacter sakazakii is an emerging foodborne pathogen associated with meningitis, necrotizing enterocolitis, and sepsis in infants. One of the main transmission vehicles is the commercially available infant formulas. To provide efficient options and direction for detecting E. sakazakii in infant formulas, evaluation of different polymerase chain reaction (PCR) assays targeting the 16S-23S rDNA internal transcribed spacer (ITS), the ompA gene, and the alpha-1,4-glucosidase gene (gluA) of this organism, were compared to the International Organization for Standardization (ISO) method for detecting E. sakazakii in the 243 commercial infant formula samples. Twelve samples were found to be positive for E. sakazakii by all the PCR assays used, followed by sequencing of PCR products. Ten samples were found to be positive by the ISO method, and all 10 gave positive signals for all the PCR amplifications. In contrast, four false-positive results were generated by single-PCR of the ITS region and one false-positive result targeting the ompA gene, while two false-negative results occurred with the ISO method. Combined with selective enrichment step(s), duplex-PCR targeting ITS and ompA and targeting ompA and gluA genes or single-PCR of the gluA gene can be used to test for contamination by E. sakazakii in infant formulas before they enter the market. PCR techniques will be helpful for routine monitoring and risk assessment for large-scale screenings.

  3. Rapid Detection and Simultaneous Genotyping of Cronobacter spp. (formerly Enterobacter sakazakii) in Powdered Infant Formula Using Real-time PCR and High Resolution Melting (HRM) Analysis

    PubMed Central

    Cai, Xian-Quan; Yu, Hai-Qiong; Ruan, Zhou-Xi; Yang, Lei-Liang; Bai, Jian-Shan; Qiu, De-Yi; Jian, Zhi-Hua; Xiao, Yi-Qian; Yang, Jie-Yang; Le, Thanh Hoa; Zhu, Xing-Quan

    2013-01-01

    Cronobacter spp. is an emerging pathogen that causes meningitis, sepsis, bacteremia, and necrotizing enterocolitis in neonates and children. The present study developed an assay integrating real-time PCR and high resolution melting (HRM) analysis targeting the OmpA gene for the specific detection and rapid identification of Cronobacter spp. (formerly Enterobacter sakazakii) in powdered infant formula. Eleven Cronobacter field isolates and 25 reference strains were examined using one pair of primers, having the accuracy of 100% in reference to conventional methods. The assay was proved to be highly sensitive with a detection limit of 102 CFU/ml without pre-enrichment, and highly concordant (100%) when compared with ISO-IDF 22964 in 89 actual samples. The method performed for Cronobacter spp. detection was less than 24 h, drastically shortened, compared to several days using standard culturing method, it is probe-free and reduces a risk of PCR carryover. Moreover, all Cronobacter strains examined in this study were genotyped into two species according to their HRM profiles. The established method should provide a molecular tool for direct detection and simultaneous genotyping of Cronobacter spp. in powdered infant formula. PMID:23825624

  4. Increased growth and root Cu accumulation of Sorghum sudanense by endophytic Enterobacter sp. K3-2: Implications for Sorghum sudanense biomass production and phytostabilization.

    PubMed

    Li, Ya; Wang, Qi; Wang, Lu; He, Lin-Yan; Sheng, Xia-Fang

    2016-02-01

    Endophytic bacterial strain K3-2 was isolated from the roots of Sorghum sudanense (an bioenergy plant) grown in a Cu mine wasteland soils and characterized. Strain K3-2 was identified as Enterobacter sp. based on 16S rRNA gene sequence analysis. Strain K3-2 exhibited Cu resistance and produced 1-aminocyclopropane-1-carboxylate (ACC) deaminase, indole-3-acetic acid (IAA), siderophores, and arginine decarboxylase. Pot experiments showed that strain K3-2 significantly increased the dry weight and root Cu accumulation of Sorghum sudanense grown in the Cu mine wasteland soils. Furthermore, increase in total Cu uptake (ranging from 49% to 95%) of the bacterial inoculated-Sorghum sudanense was observed compared to the control. Notably, most of Cu (83-86%) was accumulated in the roots of Sorghum sudanense. Furthermore, inoculation with strain K3-2 was found to significantly increase Cu bioconcentration factors and the proportions of IAA- and siderophore-producing bacteria in the root interiors and rhizosphere soils of Sorghum sudanense compared with the control. Significant decrease in the available Cu content was also observed in the rhizosphere soils of the bacterial-inoculated Sorghum sudanense. The results suggest that the endophytic bacterial strain K3-2 may be exploited for promoting Sorghum sudanense biomass production and Cu phytostabilization in the Cu mining wasteland soils.

  5. Production, characterization, and flocculation mechanism of cation independent, pH tolerant, and thermally stable bioflocculant from Enterobacter sp. ETH-2.

    PubMed

    Tang, Wei; Song, Liyan; Li, Dou; Qiao, Jing; Zhao, Tiantao; Zhao, Heping

    2014-01-01

    Synthetic high polymer flocculants, frequently utilized for flocculating efficiency and low cost, recently have been discovered as producing increased risk to human health and the environment. Development of a more efficient and environmentally sound alternative flocculant agent is investigated in this paper. Bioflocculants are produced by microorganisms and may exhibit a high rate of flocculation activity. The bioflocculant ETH-2, with high flocculating activity (2849 mg Kaolin particle/mg ETH-2), produced by strain Enterobacter sp. isolated from activated sludge, was systematically investigated with regard to its production, characterization, and flocculation mechanism. Analyses of microscopic observation, zeta potential and ETH-2 structure demonstrates the bridging mechanism, as opposed to charge neutralization, was responsible for flocculation of the ETH-2. ETH-2 retains high molecular weight (603 to 1820 kDa) and multi-functional groups (hydroxyl, amide and carboxyl) that contributed to flocculation. Polysaccharides mainly composed of mannose, glucose, and galactose, with a molar ratio of 1:2.9:9.8 were identified as the active constituents in bioflocculant. The structure of the long backbone with active sites of polysaccharides was determined as a primary basis for the high flocculation activity. Bioflocculant ETH-2 is cation independent, pH tolerant, and thermally stable, suggesting a potential fit for industrial application.

  6. Degradation of acephate by Enterobacter asburiae, Bacillus cereus and Pantoea agglomerans isolated from diamondback moth Plutella xylostella (L), a pest of cruciferous crops.

    PubMed

    Ramya, Shanivarsanthe Leelesh; Venkatesan, Thiruvengadam; Murthy, Kottilingam Srinivasa; Jalali, Sushil Kumar; Varghese, Abraham

    2016-07-01

    Acephate-degrading bacterial isolates were isolated from the larval gut of diamondback moth Plutella xylostella, a notorious pest of cruciferous crops worldwide that has developed resistance to insecticides. Partial 16S rRNA gene sequencing identified the isolates as Bacillus cereus (PX-B.C.Or), Enterobacter asburiae (PXE), and Pantoae agglomerans (PX-Pt.ag.Jor). All isolates grew on minimal media (MM) in the presence of acephate at 100 and 200 ppm, with maximum growth at 200 ppm. LC-MS analyses of spent medium showed that E. asburiae degraded acephate to methamidophos and O, O-dimethyl phosporamidate and B. cereus O,S-dimethyl to phosphorothioate but P. agglomerans to an unnamed compound. All three isolates used acephate as a source of carbon and energy for growth; however, P. agglomerans used it also as source of sulphur. Strong evidence revealed that the bacterial communities present in the gut of diamondback moth might aid in acephate degradation and play a role in the development of insecticide resistance. PMID:27498509

  7. 2-ketogluconic acid secretion by incorporation of Pseudomonas putida KT 2440 gluconate dehydrogenase (gad) operon in Enterobacter asburiae PSI3 improves mineral phosphate solubilization.

    PubMed

    Kumar, Chanchal; Yadav, Kavita; Archana, G; Naresh Kumar, G

    2013-09-01

    Enterobacter asburiae PSI3 is known to efficiently solubilize rock phosphate by secretion of approximately 50 mM gluconic acid in Tris-buffered medium in the presence of 75 mM glucose and in a mixture of seven aldosugars each at 15 mM concentration, mimicking alkaline vertisol soils. Efficacy of this bacterium in the rhizosphere requires P release in the presence of low amount of sugars. To achieve this, E. asburiae PSI3 has been manipulated to express gluconate dehydrogenase (gad) operon of Pseudomonas putida KT 2440 to produce 2-ketogluconic acid. E. asburiae PSI3 harboring gad operon had 438 U of GAD activity, secreted 11.63 mM 2-ketogluconic and 21.65 mM gluconic acids in Tris-rock phosphate-buffered medium containing 45 mM glucose. E. asburiae PSI3 gad transformant solubilized 0.84 mM P from rock phosphate in TRP-buffered liquid medium. In the presence of a mixture of seven sugars each at 12 mM, the transformant brought about a drop in pH to 4.1 and released 0.53 mM P. PMID:23666029

  8. Degradation of acephate by Enterobacter asburiae, Bacillus cereus and Pantoea agglomerans isolated from diamondback moth Plutella xylostella (L), a pest of cruciferous crops.

    PubMed

    Ramya, Shanivarsanthe Leelesh; Venkatesan, Thiruvengadam; Murthy, Kottilingam Srinivasa; Jalali, Sushil Kumar; Varghese, Abraham

    2016-07-01

    Acephate-degrading bacterial isolates were isolated from the larval gut of diamondback moth Plutella xylostella, a notorious pest of cruciferous crops worldwide that has developed resistance to insecticides. Partial 16S rRNA gene sequencing identified the isolates as Bacillus cereus (PX-B.C.Or), Enterobacter asburiae (PXE), and Pantoae agglomerans (PX-Pt.ag.Jor). All isolates grew on minimal media (MM) in the presence of acephate at 100 and 200 ppm, with maximum growth at 200 ppm. LC-MS analyses of spent medium showed that E. asburiae degraded acephate to methamidophos and O, O-dimethyl phosporamidate and B. cereus O,S-dimethyl to phosphorothioate but P. agglomerans to an unnamed compound. All three isolates used acephate as a source of carbon and energy for growth; however, P. agglomerans used it also as source of sulphur. Strong evidence revealed that the bacterial communities present in the gut of diamondback moth might aid in acephate degradation and play a role in the development of insecticide resistance.

  9. Isolation of high-salinity-tolerant bacterial strains, Enterobacter sp., Serratia sp., Yersinia sp., for nitrification and aerobic denitrification under cyanogenic conditions.

    PubMed

    Mpongwana, N; Ntwampe, S K O; Mekuto, L; Akinpelu, E A; Dyantyi, S; Mpentshu, Y

    2016-01-01

    Cyanides (CN(-)) and soluble salts could potentially inhibit biological processes in wastewater treatment plants (WWTPs), such as nitrification and denitrification. Cyanide in wastewater can alter metabolic functions of microbial populations in WWTPs, thus significantly inhibiting nitrifier and denitrifier metabolic processes, rendering the water treatment processes ineffective. In this study, bacterial isolates that are tolerant to high salinity conditions, which are capable of nitrification and aerobic denitrification under cyanogenic conditions, were isolated from a poultry slaughterhouse effluent. Three of the bacterial isolates were found to be able to oxidise NH(4)-N in the presence of 65.91 mg/L of free cyanide (CN(-)) under saline conditions, i.e. 4.5% (w/v) NaCl. The isolates I, H and G, were identified as Enterobacter sp., Yersinia sp. and Serratia sp., respectively. Results showed that 81% (I), 71% (G) and 75% (H) of 400 mg/L NH(4)-N was biodegraded (nitrification) within 72 h, with the rates of biodegradation being suitably described by first order reactions, with rate constants being: 4.19 h(-1) (I), 4.21 h(-1) (H) and 3.79 h(-1) (G), respectively, with correlation coefficients ranging between 0.82 and 0.89. Chemical oxygen demand (COD) removal rates were 38% (I), 42% (H) and 48% (G), over a period of 168 h with COD reduction being highest at near neutral pH. PMID:27148718

  10. Production, characterization, and flocculation mechanism of cation independent, pH tolerant, and thermally stable bioflocculant from Enterobacter sp. ETH-2.

    PubMed

    Tang, Wei; Song, Liyan; Li, Dou; Qiao, Jing; Zhao, Tiantao; Zhao, Heping

    2014-01-01

    Synthetic high polymer flocculants, frequently utilized for flocculating efficiency and low cost, recently have been discovered as producing increased risk to human health and the environment. Development of a more efficient and environmentally sound alternative flocculant agent is investigated in this paper. Bioflocculants are produced by microorganisms and may exhibit a high rate of flocculation activity. The bioflocculant ETH-2, with high flocculating activity (2849 mg Kaolin particle/mg ETH-2), produced by strain Enterobacter sp. isolated from activated sludge, was systematically investigated with regard to its production, characterization, and flocculation mechanism. Analyses of microscopic observation, zeta potential and ETH-2 structure demonstrates the bridging mechanism, as opposed to charge neutralization, was responsible for flocculation of the ETH-2. ETH-2 retains high molecular weight (603 to 1820 kDa) and multi-functional groups (hydroxyl, amide and carboxyl) that contributed to flocculation. Polysaccharides mainly composed of mannose, glucose, and galactose, with a molar ratio of 1:2.9:9.8 were identified as the active constituents in bioflocculant. The structure of the long backbone with active sites of polysaccharides was determined as a primary basis for the high flocculation activity. Bioflocculant ETH-2 is cation independent, pH tolerant, and thermally stable, suggesting a potential fit for industrial application. PMID:25485629

  11. Structural and physiochemical characterization of rhamnolipids produced by Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa in single strain and mixed cultures.

    PubMed

    Hošková, Miriam; Ježdík, Richard; Schreiberová, Olga; Chudoba, Josef; Šír, Marek; Čejková, Alena; Masák, Jan; Jirků, Vladimír; Řezanka, Tomáš

    2015-01-10

    Rhamnolipids are naturally occurring biosurfactants with a wide range of potential commercial applications. As naturally derived products they present an ecological alternative to synthetic surfactants. The majority of described rhamnolipid productions are single strain Pseudomonas spp. cultivations. Here we report rhamnolipids producing bacteria Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa that were cultivated separately and as mixed populations. The ratio and composition of rhamnolipid congeners was determined by tandem mass spectrometry with negative electrospray ionization. Mono-rhamnolipid and di-rhamnolipid homologues containing one or two saturated or monounsaturated 3-hydroxy fatty acids were found in all strains. Physiochemical characterization of rhamnolipids was evaluated by the critical micelle concentration determination, the emulsification test, oil displacement test and phenanthrene solubilization. Critical micelle concentrations of rhamnolipids produced by both single strain and mixed cultures were found to be very low (10-63 mg/l) and to correspond with saturated/unsaturated fatty acid content of rhamnolipid homologues. The rhamnolipids produced by all strains effectively emulsified crude petroleum in comparison with synthetic surfactants Tween 80 and sodium dodecyl sulfate (SDS). Good performance of phenanthrene solubilization was exhibited by rhamnolipids from E. asburiae. The single strain and co-cultures cultivations were proposed as a possible way to produce rhamnolipid mixtures with a specific composition and different physiochemical properties, which could be exploited in bioremediation of various hydrophobic contaminants.

  12. Cost-Effective and Rapid Presumptive Identification of Gram-Negative Bacilli in Routine Urine, Pus, and Stool Cultures: Evaluation of the Use of CHROMagar Orientation Medium in Conjunction with Simple Biochemical Tests

    PubMed Central

    Ohkusu, Kiyofumi

    2000-01-01

    The algorithm for a new identification system was designed on the basis of colony color and morphology on CHROMagar Orientation medium in conjunction with simple biochemical tests such as indole (IND), lysine decarboxylase (LDC), and ornithine decarboxylase (ODC) utilization tests with gram-negative bacilli isolated from urine samples as well as pus, stool, and other clinical specimens by the following colony characteristics, biochemical reactions, and serological results: pinkish to red, IND positive (IND+), Escherichia coli; metallic blue, IND+, LDC+, and ODC negative (ODC−), Klebsiella oxytoca; IND+, LDC−, and ODC+, Citrobacter diversus; IND+ or IND−, LDC−, and ODC−, Citrobacter freundii; IND−, LDC+, and ODC+, Enterobacter aerogenes; IND−, LDC−, and ODC+, Enterobacter cloacae; IND−, LDC+, and ODC−, Klebsiella pneumoniae; diffuse brown and IND+, Morganella morganii; IND−, Proteus mirabilis; aqua blue, Serratia marcescens; bluish green and IND+, Proteus vulgaris; transparent yellow-green, serology positive, Pseudomonas aeruginosa; clear and serology positive, Salmonella sp.; other colors and reactions, the organism was identified by the full identification methods. The accuracy and cost-effectiveness of this new system were prospectively evaluated. During an 8-month period, a total of 345 specimens yielded one or more gram-negative bacilli. A total of 472 gram-negative bacillus isolates were detected on CHROMagar Orientation medium. For 466 of the isolates (98.7%), no discrepancies in the results were obtained on the basis of the identification algorithm. The cost of identification of gram-negative bacilli during this period was reduced by about 70%. The results of this trial for the differentiation of the most commonly encountered gram-negative pathogens in clinical specimens with the new algorithm were favourable in that it permitted reliable detection and presumptive identification. In addition, this rapid identification system not only

  13. [Utility of prolonged incubation and terminal subcultures of blood cultures from immunocompromised patients].

    PubMed

    Soloaga, R; Procopio, A; Manganello, S; Ivanovic, V; Romay, N; Pirosanto, Y; Fernández, A; Zudiker, R; Echeverría, A; Nagel, C; del Castillo, M; López, E; Gutfraind, Z; Tokumoto, M; Guelfand, L

    2001-01-01

    The value of blind terminal subcultures (7 and 30 days) and prolonged incubation (30 days) of blood cultures from immunosuppressed patients was analyzed in the Fundación Favaloro, the Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia and the Hospital de Niños Ricardo Gutiérrez. A total of 2707 blood cultures and 369 patients were included (transplantation of solid organs 154, oncohematologic disorders 106 and solid tumors 109). Bact-Alert bottles were incubated at 35 degrees C for 30 days in the Bact-Alert System. Bottles with positive signals were routinely removed, and aliquots of the broth were Gram stained and subcultured aerobically in chocolate agar and Sabouraud agar. A total of 136 bacteremic episodes were obtained. The positivization time of blood cultures was 81.6% at 24 h, 93.3% at 48 h, 94.5% at 72 h and 97.7% within 7 days. Only 3 (2.2%) episodes were positive by blind terminal subcultures and 1 (0.75%) by prolonged incubation (14 days). The median time and range of positivization in hours were 13.8 and 2.2-168, respectively. The microorganisms isolated were coagulase negative staphylococci (n = 24), Klebsiella pneumoniae (n = 22), Staphylococcus aureus (n = 21), Escherichia coli (n = 18), Acinetobacter spp (n = 9), Candida spp (n = 8), Pseudomonas aeruginosa (n = 6), Enterobacter cloacae (n = 5), Stenotrophomonas maltophilia (n = 5), Enterococcus faecalis, Salmonella spp and Capnocytophaga sputigena (n = 2), Enterobacter aerogenes, Enterococcus faecium, Citrobacter diversus, Candida albicans, Klebsiella oxytoca, Chryseomonas luteola, Serratia marcescens, Abiotrophia spp, Campylobacter jejuni, Moraxella catarrhalis, Moraxella urethralis, Neisseria sicca, beta hemolytic group G streptococci, Rhodococcus equi, Micrococcus spp, Cryptococcus neoformans and Streptococcus mitis (n = 1). In our experience, blind terminal subcultures and prolonged incubation of blood cultures from immunosuppressed patients are unnecessary and

  14. The tryptophan repressor sequence is highly conserved among the Enterobacteriaceae.

    PubMed Central

    Arvidson, D N; Arvidson, C G; Lawson, C L; Miner, J; Adams, C; Youderian, P

    1994-01-01

    Tryptophan biosynthesis in Escherichia coli is regulated by the product of the trpR gene, the tryptophan (Trp) repressor. Trp aporepressor binds the corepressor, L-tryptophan, to form a holorepressor complex, which binds trp operator DNA tightly, and inhibits transcription of the tryptophan biosynthetic operon. The conservation of trp operator sequences among enteric Gram-negative bacteria suggests that trpR genes from other bacterial species can be cloned by complementation in E. coli. To clone trpR homologues, a deletion of the E. coli trpR gene, delta trpR504, was made on a plasmid by site-directed mutagenesis, then crossed onto the E. coli genome. Plasmid clones of the trpR genes of Enterobacter aerogenes and Enterobacter cloacae were isolated by complementation of the delta trpR504 allele, scored as the ability to repress beta-galactosidase synthesis from a prophage-borne trpE-lacZ gene fusion. The predicted amino acid sequences of four enteric TrpR proteins show differences, clustered on the backside of the folded repressor, opposite the DNA-binding helix-turn-helix substructures. These differences are predicted to have little effect on the interactions of the aporepressor with tryptophan, holorepressor with operator DNA, or tandemly bound holorepressor dimers with one another. Although there is some variation observed at the dimer interface, interactions predicted to stabilize the interface are conserved. The phylogenetic relationships revealed by the TrpR amino acid sequence alignment agree with the results of others. PMID:8208606

  15. Rapid Identification of ESKAPE Bacterial Strains Using an Autonomous Microfluidic Device

    PubMed Central

    Ho, Jack Y.; Cira, Nate J.; Crooks, John A.; Baeza, Josue; Weibel, Douglas B.

    2012-01-01

    This article describes Bacteria ID Chips (‘BacChips’): an inexpensive, portable, and autonomous microfluidic platform for identifying pathogenic strains of bacteria. BacChips consist of a set of microchambers and channels molded in the elastomeric polymer, poly(dimethylsiloxane) (PDMS). Each microchamber is preloaded with mono-, di-, or trisaccharides and dried. Pressing the layer of PDMS into contact with a glass coverslip forms the device; the footprint of the device in this article is ∼6 cm2. After assembly, BacChips are degased under large negative pressure and are stored in vacuum-sealed plastic bags. To use the device, the bag is opened, a sample containing bacteria is introduced at the inlet of the device, and the degased PDMS draws the sample into the central channel and chambers. After the liquid at the inlet is consumed, air is drawn into the BacChip via the inlet and provides a physical barrier that separates the liquid samples in adjacent microchambers. A pH indicator is admixed with the samples prior to their loading, enabling the metabolism of the dissolved saccharides in the microchambers to be visualized. Importantly, BacChips operate without external equipment or instruments. By visually detecting the growth of bacteria using ambient light after ∼4 h, we demonstrate that BacChips with ten microchambers containing different saccharides can reproducibly detect the ESKAPE panel of pathogens, including strains of: Enterococcus faecalis, Enteroccocus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter aerogenes, and Enterobacter cloacae. This article describes a BacChip for point-of-care detection of ESKAPE pathogens and a starting point for designing multiplexed assays that identify bacterial strains from clinical samples and simultaneously determine their susceptibility to antibiotics. PMID:22848451

  16. Cost-effective and rapid presumptive identification of gram-negative bacilli in routine urine, pus, and stool cultures: evaluation of the use of CHROMagar orientation medium in conjunction with simple biochemical tests.

    PubMed

    Ohkusu, K

    2000-12-01

    The algorithm for a new identification system was designed on the basis of colony color and morphology on CHROMagar Orientation medium in conjunction with simple biochemical tests such as indole (IND), lysine decarboxylase (LDC), and ornithine decarboxylase (ODC) utilization tests with gram-negative bacilli isolated from urine samples as well as pus, stool, and other clinical specimens by the following colony characteristics, biochemical reactions, and serological results: pinkish to red, IND positive (IND(+)), Escherichia coli; metallic blue, IND(+), LDC(+), and ODC negative (ODC(-)), Klebsiella oxytoca; IND(+), LDC(-), and ODC(+), Citrobacter diversus; IND(+) or IND(-), LDC(-), and ODC(-), Citrobacter freundii; IND(-), LDC(+), and ODC(+), Enterobacter aerogenes; IND(-), LDC(-), and ODC(+), Enterobacter cloacae; IND(-), LDC(+), and ODC(-), Klebsiella pneumoniae; diffuse brown and IND(+), Morganella morganii; IND(-), Proteus mirabilis; aqua blue, Serratia marcescens; bluish green and IND(+), Proteus vulgaris; transparent yellow-green, serology positive, Pseudomonas aeruginosa; clear and serology positive, Salmonella sp.; other colors and reactions, the organism was identified by the full identification methods. The accuracy and cost-effectiveness of this new system were prospectively evaluated. During an 8-month period, a total of 345 specimens yielded one or more gram-negative bacilli. A total of 472 gram-negative bacillus isolates were detected on CHROMagar Orientation medium. For 466 of the isolates (98.7%), no discrepancies in the results were obtained on the basis of the identification algorithm. The cost of identification of gram-negative bacilli during this period was reduced by about 70%. The results of this trial for the differentiation of the most commonly encountered gram-negative pathogens in clinical specimens with the new algorithm were favourable in that it permitted reliable detection and presumptive identification. In addition, this rapid

  17. Chromosomally Encoded AmpC-Type β-Lactamase in a Clinical Isolate of Proteus mirabilis

    PubMed Central

    Bret, L.; Chanal-Claris, C.; Sirot, D.; Chaibi, E. B.; Labia, R.; Sirot, J.

    1998-01-01

    A clinical strain of Proteus mirabilis (CF09) isolated from urine specimens of a patient displayed resistance to amoxicillin (MIC >4,096 μg/ml), ticarcillin (4,096 μg/ml), cefoxitin (64 μg/ml), cefotaxime (256 μg/ml), and ceftazidime (128 μg/ml) and required an elevated MIC of aztreonam (4 μg/ml). Clavulanic acid did not act synergistically with cephalosporins. Two β-lactamases with apparent pIs of 5.6 and 9.0 were identified by isoelectric focusing on a gel. Substrate and inhibition profiles were characteristic of an AmpC-type β-lactamase with a pI of 9.0. Amplification by PCR with primers for ampC genes (Escherichia coli, Enterobacter cloacae, and Citrobacter freundii) of a 756-bp DNA fragment from strain CF09 was obtained only with C. freundii-specific primers. Hybridization results showed that the ampC gene is only chromosomally located while the TEM gene is plasmid located. After cloning of the gene, analysis of the complete nucleotide sequence (1,146 bp) showed that this ampC gene is close to blaCMY-2, from which it differs by three point mutations leading to amino acid substitutions Glu → Gly at position 22, Trp → Arg at position 201, and Ser → Asn at position 343. AmpC β-lactamases derived from that of C. freundii (LAT-1, LAT-2, BIL-1, and CMY-2) have been found in Klebsiella pneumoniae, E. coli, and Enterobacter aerogenes and have been reported to be plasmid borne. This is the first example of a chromosomally encoded AmpC-type β-lactamase observed in P. mirabilis. We suggest that it be designated CMY-3. PMID:9593136

  18. In vitro activity and beta-lactamase stability of LJC 10,627.

    PubMed Central

    Neu, H C; Gu, J W; Fang, W; Chin, N X

    1992-01-01

    The in vitro activity of LJC 10,627, a new carbapenem, was compared with those of imipenem, cefotaxime, ceftazidime, and gentamicin. LJC 10,627 inhibited 90% of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter agglomerans, Enterobacter cloacae, Hafnia alvei, Citrobacter freundii, Citrobacter diversus, Proteus mirabilis, Morganella morganii, Proteus rettgeri, Serratia marcescens, Pseudomonas cepacia, salmonellae, shigellae, aeromonas, and yersiniae at less than or equal to 2 micrograms/ml. Haemophilus influenzae was inhibited by 0.5 microgram/ml, and moraxellae were inhibited by 0.12 microgram/ml. LJC 10,627 was twofold more active than imipenem against aerobic gram-negative organisms and inhibited ceftazidime-, cefotaxime-, and gentamicin-resistant members of the genera Klebsiella, Enterobacter, Citrobacter, and Serratia at less than or equal to 2 micrograms/ml. Xanthomonas maltophilia strains were resistant to the drug. Imipenem was two- to fourfold more active than LJC 10,627 against Staphylococcus aureus and Staphylococcus epidermidis. LJC 10,627 did not inhibit most methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis strains. LJC 10,627 inhibited Streptococcus pyogenes and Streptococcus pneumoniae at 0.06 and 0.12 microgram/ml, respectively. Bacteroides fragilis and other Bacteroides spp. were inhibited by 0.5 microgram of LJC 10,627 per ml. Serum (50%) did not affect the MICs. LJC 10,627 was not hydrolyzed by plasmid-mediated beta-lactamases of Bush types 2b, 2b', TEM-1, TEM-2, TEM-3, TEM-5, TEM-7, TEM-9, and SHV-1; the chromosomal beta-lactamases of Bush type 1; P-99; a Morganella enzyme; or a Citrobacter freundii enzyme. The Bush type 2c and 2d enzymes OXA-1, OXA-2, PSE-1, PSE-2, and PSE-4 did not hydrolyze LJC 10,627, nor did the beta-lactamases of Staphylococcus aureus, Moraxella spp., Bacteroides fragilis, and Proteus vulgaris. The beta-lactamase of Xanthomonas

  19. Partial hydrolysis of dieldrin by aerobacter aerogenes

    USGS Publications Warehouse

    Wedemeyer, G.

    1968-01-01

    Although dieldrin (1 , 2, 3 , 4, 10, 10-hexachloro-6, 7-epoxy-1 ,4 ,4a ,5 ,6, 7,8, 8a-octahydro-1 ,4-endo, exo-5, 8-dirnethanonaphthalene) metabolism by mammals (F. Korte and H. Arent, Life Sci. 4:2017, 1965) and insects (D. F. Heath and M. Vanderkar, Brit. J. Ind. Med. 21:269, 1964) has been reported, little is known about the degradation of this important pesticide by microorganisms.

  20. Effects of extended dry storage of powdered infant milk formula on susceptibility of Enterobacter sakazakii to hot water and ionizing radiation.

    PubMed

    Osaili, Tareq M; Al-Nabulsi, Anas A; Shaker, Reyad R; Ayyash, Mutamed M; Olaimat, Amin N; Al-Hasan, Ashraf S Abu; Kadora, Khaled M; Holley, Richard A

    2008-05-01

    Infant milk formula has been identified as a potential source of Enterobacter sakazakii, which has been implicated in neonatal meningitis and necrotizing enterocolitis. This study was undertaken to determine whether the length of E. sakazakii storage in powdered infant milk formula (PIMF) affected the ability of the pathogen to survive subsequent reconstitution of the powder with hot water or treatment with gamma radiation. Five E. sakazakii strains were mixed individually with PIMF and kept for up to 12 months at 25 degrees C. After storage PIMF was reconstituted with water at 60 to 100 degrees C or was exposed to < or = 5 kGy of gamma radiation. Without any treatment secondary to drying, E. sakazakii counts decreased < 1 log/g after 1 month but decreased about 4 log/g during storage for 8 to 12 months. Dry storage decreased thermal resistance but increased resistance of E. sakazakii to ionizing radiation in PIMF. Reconstitution of contaminated powder with water at 70 degrees C after 1 month of dry storage reduced E. sakazakii viability slightly, > 2 log/g, and after powder was stored for 12 months all E. sakazakii strains were eliminated. In contrast, desiccation substantially increased the resistance of E. sakazakii strains to ionizing radiation. Although the D-value for E. sakazakii IMF1 following overnight storage in PIMF was 0.98 kGy, > 4 kGy was required to kill 1.5 log/g of the same strain that had survived 12 months in dry PIMF. Results suggested that low-dose irradiation will more effectively eliminate E. sakazakii from PIMF if the treatment is applied shortly after PIMF manufacture.

  1. A comparative study between overlay method and selective-differential media for recovery of stressed Enterobacter sakazakii cells from infant formula.

    PubMed

    Al-Holy, Murad A; Lin, Mengshi; Al-Qadiri, Hamzah M; Rasco, Barbara A

    2008-02-01

    This study compares the performance of different selective-differential media with the overlay method for recovery of stressed cells of Enterobacter sakazakii from infant formula milk (IFM). Five different selective-differential media were used in this study: OK medium, violet red bile agar (VRBA), Druggan-Forsythe-Iversen agar (DFI), Enterobacteriaceae enrichment (EE) agar, and fecal coliform agar (FCA). Tryptic soy agar supplemented with 0.1% sodium pyruvate (TSAP) was used as a control. The overlay method involved applying a thin layer (8ml) of each of the selective media onto TSAP after spreading a sample onto TSAP. Reconstituted IFM was inoculated by ca 1x10(7)CFU/ml of a mixture of four strains of E. sakazakii and subjected to different stress conditions: heat (55 degrees C for 10min), a freeze-thaw cycle (-20 degrees C for 24h, thawed at room temperature, frozen again at -20 degrees C, and thawed), acidic pH (pH 3.56 for 15min), alkaline pH (pH 11.04 for 15min), and desiccation (E. sakazakii was inoculated onto powdered IFM at a level of ca 1x10(6)CFU/g, held at 21 degrees C, water activity of the inoculated product was 0.29 and examined at 0, 15, and 30d). No major differences were noticed between the control (TSAP) and the overlay methods. However, the overlay method recovered significantly higher numbers of stressed E. sakazakii cells compared to selective-differential media. Also, the selective-differential media exhibited some variability in terms of their capabilities to recover stressed cells of E. sakazakii. Among all the examined selective-differential media, DFI performed better for recovering stressed E. sakazakii cells. This study suggests that the overlay method may serve as a potential alternative to direct selective plating for best recovery of E. sakazakii from IFM.

  2. Prediction of a Required Log Reduction with Probability for Enterobacter sakazakii during High-Pressure Processing, Using a Survival/Death Interface Model▿

    PubMed Central

    Koseki, Shige; Matsubara, Maki; Yamamoto, Kazutaka

    2009-01-01

    A probabilistic model for predicting Enterobacter sakazakii inactivation in trypticase soy broth (TSB) and infant formula (IF) by high-pressure processing was developed. The modeling procedure is based on a previous model (S. Koseki and K. Yamamoto, Int. J. Food Microbiol. 116:136-143, 2007) that describes the probability of death of bacteria. The model developed in this study consists of a total of 300 combinations of pressure (400, 450, 500, 550, or 600 MPa), pressure-holding time (1, 3, 5, 10, or 20 min), temperature (25 or 40°C), inoculum level (3, 5, or 7 log10 CFU/ml), and medium (TSB or IF), with each combination tested in triplicate. For each replicate response of E. sakazakii, survival and death were scored with values of 0 and 1, respectively. Data were fitted to a logistic regression model in which the medium was treated as a dummy variable. The model predicted that the required pressure-holding times at 500 MPa for a 5-log reduction in IF with 90% achievement probability were 26.3 and 7.9 min at 25 and 40°C, respectively. The probabilities of achieving 5-log reductions in TSB and IF by treatment with 400 MPa at 25°C for 10 min were 92 and 3%, respectively. The model enabled the identification of a minimum processing condition for a required log reduction, regardless of the underlying inactivation kinetics pattern. Simultaneously, the probability of an inactivation effect under the predicted processing condition was also provided by taking into account the environmental factors mentioned above. PMID:19201951

  3. Prediction of a required log reduction with probability for Enterobacter sakazakii during high-pressure processing, using a survival/death interface model.

    PubMed

    Koseki, Shige; Matsubara, Maki; Yamamoto, Kazutaka

    2009-04-01

    A probabilistic model for predicting Enterobacter sakazakii inactivation in trypticase soy broth (TSB) and infant formula (IF) by high-pressure processing was developed. The modeling procedure is based on a previous model (S. Koseki and K. Yamamoto, Int. J. Food Microbiol. 116:136-143, 2007) that describes the probability of death of bacteria. The model developed in this study consists of a total of 300 combinations of pressure (400, 450, 500, 550, or 600 MPa), pressure-holding time (1, 3, 5, 10, or 20 min), temperature (25 or 40 degrees C), inoculum level (3, 5, or 7 log(10) CFU/ml), and medium (TSB or IF), with each combination tested in triplicate. For each replicate response of E. sakazakii, survival and death were scored with values of 0 and 1, respectively. Data were fitted to a logistic regression model in which the medium was treated as a dummy variable. The model predicted that the required pressure-holding times at 500 MPa for a 5-log reduction in IF with 90% achievement probability were 26.3 and 7.9 min at 25 and 40 degrees C, respectively. The probabilities of achieving 5-log reductions in TSB and IF by treatment with 400 MPa at 25 degrees C for 10 min were 92 and 3%, respectively. The model enabled the identification of a minimum processing condition for a required log reduction, regardless of the underlying inactivation kinetics pattern. Simultaneously, the probability of an inactivation effect under the predicted processing condition was also provided by taking into account the environmental factors mentioned above.

  4. Atomic resolution structure of EhpR: phenazine resistance in Enterobacter agglomerans Eh1087 follows principles of bleomycin/mitomycin C resistance in other bacteria

    PubMed Central

    2011-01-01

    Background The phenazines are redox-active secondary metabolites that a large number of bacterial strains produce and excrete into the environment. They possess antibiotic activity owing to the fact that they can reduce molecular oxygen to toxic reactive oxygen species. In order to take advantage of this activity, phenazine producers need to protect themselves against phenazine toxicity. Whereas it is believed that phenazine-producing pseudomonads possess highly active superoxide dismutases and catalases, it has recently been found that the plant-colonizing bacterium Enterobacter agglomerans expresses a small gene ehpR to render itself resistant towards D-alanyl-griseoluteic acid, the phenazine antibiotic produced by this strain. Results To understand the resistance mechanism installed by EhpR we have determined its crystal structure in the apo form at 2.15 Å resolution and in complex with griseoluteic acid at 1.01 Å, respectively. While EhpR shares a common fold with glyoxalase-I/bleomycin resistance proteins, the ligand binding site does not contain residues that some related proteins employ to chemically alter their substrates. Binding of the antibiotic is mediated by π-stacking interactions of the aromatic moiety with the side chains of aromatic amino acids and by a few polar interactions. The dissociation constant KD between EhpR and griseoluteic acid was quantified as 244 ± 45 μM by microscale thermophoresis measurements. Conclusions The data accumulated here suggest that EhpR confers resistance by binding D-alanyl-griseoluteic acid and acting as a chaperone involved in exporting the antibiotic rather than by altering it chemically. It is tempting to speculate that EhpR acts in concert with EhpJ, a transport protein of the major facilitator superfamily that is also encoded in the phenazine biosynthesis operon of E. agglomerans. The low affinity of EhpR for griseoluteic acid may be required for its physiological function. PMID:21849072

  5. Comparison of three chromogenic media and evaluation of two molecular-based identification systems for the detection of Enterobacter sakazakii from environmental samples from infant formulae factories.

    PubMed

    Derzelle, Sylviane; Dilasser, Françoise; Maladen, Véronique; Soudrie, Nicole; Leclercq, Alexandre; Lombard, Bertrand; Lafarge, Veŕonique

    2007-07-01

    Enterobacter sakazakii is an occasional contaminant of powdered infant formula that can cause rare but severe foodborne infections in infants. To determine optimal methods for the detection and identification of E. sakazakii, 38 naturally contaminated samples from infant formulae factories were analyzed by two PCR-based methods and by a method (TS 22964/RM 210) developed by the International Organization for Standardization and the International Dairy Federation (ISO-IDF) using three different commercial chromogenic agars. The ISO-IDF method includes two enrichment steps, plating of the second enrichment broth on E. sakazakii isolation agar (a chromogenic selective agar), picking of five typical colonies for transfer onto tryptone soy agar, and subsequent confirmation of yellow-pigmented colonies by biochemical characterization. Twenty-two of the 38 samples were positive by the culture method. E. sakazakii isolation agar (ESIA; AES Laboratoires), COMPASS agar (Biokar Diagnostics), and Druggan-Forsythe-Iversen agar (Oxoid) compared favorably with violet red bile glucose agar (VRBG, a selective medium for Enterobacteriaceae), with positive predictive values of 86.96, 88, and 74.07%, respectively, in contrast to 47.83% for VRBG. One additional positive sample was detected using the nonpatented real-time PCR method evaluated, and those results were in 97.3% concordance with the ISO-IDF results. Some discrepancies between the results of the DuPont Qualicon BAX system and those of the ISO-IDF method could be explained by heterogeneity of contamination and sampling. Thus, both PCR-based systems were suitable for detecting and specifically identifying E. sakazakii within 1 to 2 days, and COMPASS agar and ESIA could be used interchangeably as a first-step medium to isolate presumptive E. sakazakii colonies.

  6. A comparison of polymerase chain reaction and international organization for standardization methods for determination of Enterobacter sakazakii contamination of infant formulas from Chinese mainland markets.

    PubMed

    Ye, Yingwang; Wu, Qingping; Yao, Lin; Dong, Xiaohui; Wu, Kui; Zhang, Jumei

    2009-12-01

    Enterobacter sakazakii is an emerging foodborne pathogen associated with meningitis, necrotizing enterocolitis, and sepsis in infants. One of the main transmission vehicles is the commercially available infant formulas. To provide efficient options and direction for detecting E. sakazakii in infant formulas, evaluation of different polymerase chain reaction (PCR) assays targeting the 16S-23S rDNA internal transcribed spacer (ITS), the ompA gene, and the alpha-1,4-glucosidase gene (gluA) of this organism, were compared to the International Organization for Standardization (ISO) method for detecting E. sakazakii in the 243 commercial infant formula samples. Twelve samples were found to be positive for E. sakazakii by all the PCR assays used, followed by sequencing of PCR products. Ten samples were found to be positive by the ISO method, and all 10 gave positive signals for all the PCR amplifications. In contrast, four false-positive results were generated by single-PCR of the ITS region and one false-positive result targeting the ompA gene, while two false-negative results occurred with the ISO method. Combined with selective enrichment step(s), duplex-PCR targeting ITS and ompA and targeting ompA and gluA genes or single-PCR of the gluA gene can be used to test for contamination by E. sakazakii in infant formulas before they enter the market. PCR techniques will be helpful for routine monitoring and risk assessment for large-scale screenings. PMID:19743923

  7. Carbapenem-resistant Enterobacteriaceae: Prevalence and Risk Factors in a Single Community-Based Hospital in Korea

    PubMed Central

    Choi, Jae-Ki; Kim, Si-Hyun; Park, Sun Hee; Choi, Jung-Hyun

    2016-01-01

    Background Carbapenemase-producing Enterobacteriaceae (CPE) are Gram-negative bacteria with increasing prevalence of infection worldwide. In Korea, 25 cases of CPE isolates were reported by the Korea Centers for Disease Control and Prevention in 2011. Most CPE cases were detected mainly at tertiary referral hospitals. We analyzed the prevalence and risk factors for carbapenem-resistant Enterobacteriaceae (CRE) in a mid-sized community-based hospital in Korea. Materials and Methods We retrospectively analyzed all consecutive episodes of Enterobacteriaceae in a mid-sized community-based hospital from January 2013 to February 2014. CRE was defined as organisms of Enterobacteriaceae showing decreased susceptibility to carbapenems. Risk factors for CRE were evaluated by a case–double control design. Carbapenemase was confirmed for CRE using a combined disc test. Results During 229,710 patient-days, 2,510 Enterobacteriaceae isolates were obtained. A total of 41 (1.6%) CRE isolates were enrolled in the study period. Thirteen species (31.7%) were Enterobacter aerogenes, 8 (19.5%) Klebsiella pneumoniae, 5 (12.2%) Enterobacter cloacae, and 15 other species of Enterobacteriaceae, respectively. Among the 41 isolates, only one (2.4%) E. aerogenes isolate belonged to CPE. For evaluation of risk factors, a total of 111 patients were enrolled and this included 37 patients in the CRE group, 37 in control group I (identical species), and 37 in control group II (different species). Based on multivariate analysis, regularly visiting the outpatient clinic was a risk factor for CRE acquisition in the control group I (P = 0.003), while vascular catheter and Charlson comorbidity index score ≥ 3 were risk factors in control group II (P = 0.010 and 0.011, each). Patients with CRE were more likely to experience a reduced level of consciousness, use a vasopressor, be under intensive care, and suffer from acute kidney injury. However, CRE was not an independent predictor of mortality

  8. Geraniol Restores Antibiotic Activities against Multidrug-Resistant Isolates from Gram-Negative Species▿ †

    PubMed Central

    Lorenzi, Vannina; Muselli, Alain; Bernardini, Antoine François; Berti, Liliane; Pagès, Jean-Marie; Amaral, Leonard; Bolla, Jean-Michel

    2009-01-01

    The essential oil of Helichrysum italicum significantly reduces the multidrug resistance of Enterobacter aerogenes, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii. Combinations of the two most active fractions of the essential oil with each other or with phenylalanine arginine β-naphthylamide yield synergistic activity. Geraniol, a component of one fraction, significantly increased the efficacy of β-lactams, quinolones, and chloramphenicol. PMID:19258278

  9. A Simple Alternative to the IMViC Test in Microbiology.

    ERIC Educational Resources Information Center

    Benathen, Isaiah A.

    1992-01-01

    Presents a singular alternative to the Indole Methyl-red Voges-Proskauer Citrate (IMViC) test that uses bile-esculin agar to distinguish between the Escherichia coli and Enterobacter aerogenes bacteria. Includes materials and methods, results, and conclusions for the test. (MDH)

  10. Identification and characterization of a novel incompatibility group X3 plasmid carrying blaNDM-1 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China

    PubMed Central

    Ho, Pak-Leung; Li, Zhen; Lo, Wai-U; Cheung, Yuk-Yam; Lin, Chi-Ho; Sham, Pak-Chung; Chi-Chung Cheng, Vincent; Ng, Tak-Keung; Que, Tak-Lun; Chow, Kin-Hung

    2012-01-01

    The New Delhi metallo-β-lactamase (NDM-1) is one of the most important resistance traits in Enterobacteriaceae. We characterized nine blaNDM-1 producing Enterobacteriaceae recovered from seven patients who have recently travelled or been treated in India (n=1) or mainland China (n=6) during December 2010–May 2012. All the China-linked patients had no links to the Indian subcontinent. The blaNDM-1 carrying plasmids belonged to the novel IncX3 (∼50 kb, in seven isolates including two Escherichia coli, two Klebsiella pneumoniae, one Citrobacter freundii, one Enterobacter aerogenes and one E. cloacae), IncA/C2 (∼140 kb, in one E. coli) or FII-F1B groups (∼110 kb, in one E. coli). Restriction fragment length polymorphism analysis of the seven IncX3 plasmids revealed identical pattern in six and two bands difference in the remaining one. The IncX3 plasmids carrying blaNDM-1 were epidemiologically linked to Guangzhou (n=1), Hunan (n=4), Haifeng (n=1) and Dongguan (n=1) in mainland China. Complete sequencing of the IncX3 plasmid pNDM-HN380 revealed that it was 54 035 bp long and encoded 52 open reading frames. The blaNDM-1 gene was found in a transposon-like structure flanked by ISAba125 and IS26, inserted into the plasmid genetic load region. The sequences of the blaNDM-1 containing module within the two IS elements were identical to those previously described for blaNDM-1-positive Tn125 in the plasmids or chromosome of Acinetobacter isolates. In summary, this is the first description of IncX3 plasmids carrying blaNDM-1. The findings indicate the worrisome involvement of an epidemic plasmid in the dissemination of NDM-1 in China. PMID:26038408

  11. Spread of NDM-1-Producing Enterobacteriaceae in a Neonatal Intensive Care Unit in Istanbul, Turkey

    PubMed Central

    Poirel, Laurent; Yilmaz, Mesut; Istanbullu, Ayse; Arslan, Ferhat; Mert, Ali; Bernabeu, Sandrine

    2014-01-01

    Twenty-two consecutive carbapenem-resistant enterobacterial isolates were recovered from patients hospitalized between January and April 2013 in different units at a university hospital in Istanbul, Turkey. These were Klebsiella pneumoniae isolates producing the carbapenemases OXA-48, NDM-1, and KPC-2, Enterobacter cloacae isolates producing NDM-1, and Escherichia coli isolates producing OXA-48. Most of the OXA-48-producing K. pneumoniae and all the NDM-1-producing E. cloacae were clonally related. The NDM-1-producing E. cloacae isolates recovered from a single neonatal intensive care unit corresponded to a single cluster, highlighting the spread of that clone in that setting. PMID:24550328

  12. Significance of bacterial flora in abdominal irradiation-induced inhibition of lung metastases

    SciTech Connect

    Matsumoto, T.; Ando, K.; Koike, S.

    1988-06-01

    We have previously reported that abdominal irradiation prior to i.v. injection of syngeneic tumor cells reduced metastases in lung. Our report described an investigation of the significance of intestinal organisms in the radiation effect. We found that eliminating intestinal organisms with antibiotics totally abolished the radiation effect. Monoassociation of germ-free mice revealed that the radiation effect was observable only for Enterobacter cloacae, never for Streptococcus faecium, Bifidobacterium adlesentis, or Escherichia coli. After abdominal irradiation of regular mice, E. cloacae multiplied in cecal contents, adhered to mucous membranes, invaded the cecal wall, and translocated to mesenteric lymph nodes. Intravenous administration of E. cloacae in place of abdominal irradiation inhibited metastases. E. cloacae-monoassociated mice developed fewer metastases than germ-free mice, and the reduction was further enhanced by abdominal irradiation. We concluded that abdominal irradiation caused the invasion of E. cloacae from the mucous membrane of the intestine and inhibited formation of lung metastases.

  13. Localization and physical mapping of a plasmid-borne 23-kb nif gene cluster from Enterobacter agglomerans showing homology to the entire nif gene cluster of Klebsiella pneumoniae M5a1.

    PubMed

    Singh, M; Kreutzer, R; Acker, G; Klingmüller, W

    1988-01-01

    A physical and genetical map of the plasmid pEA3 indigenous to Enterobacter agglomerans is presented. pEA3 is a 111-kb large plasmid containing a 23-kb large cluster of nif genes which shows extensive homology (Southern hybridization and heteroduplex analysis) to the entire nif gene cluster of Klebsiella pneumoniae (Kp) M5a1. All the nif genes on pEA3 are organized in the same manner as in K. pneumoniae, except nifJ, which is located on the left end of pEA3 nif gene cluster (near nifQB). A BamHI restriction map of pEA3 and a detailed restriction map of the 23-kb nif region on pEA3 is also presented. The nif genes of pEA3 showed a low level of acetylene reduction in Escherichia coli, demonstrating that these genes are functional and contain the whole genetic information required to fix nitrogen. The origin of vegetative replication (OriV) of pEA3 was localized about 5.5 kb from the right end of the nif gene cluster. In addition to pEA3, large plasmids from four other strains of E. agglomerans showed homology to all the Kp nif genes tested, indicating that in diazotrophic strains of E. agglomerans nif genes are usually located on plasmids. In contrast, in most of the free-living, nitrogen-fixing bacteria the nif genes are on chromosome.

  14. Multifarious beneficial traits and plant growth promoting potential of Serratia marcescens KiSII and Enterobacter sp. RNF 267 isolated from the rhizosphere of coconut palms (Cocos nucifera L.).

    PubMed

    George, Priya; Gupta, Alka; Gopal, Murali; Thomas, Litty; Thomas, George V

    2013-01-01

    Two plant growth promoting bacteria designated as KiSII and RNF 267 isolated from the rhizosphere of coconut palms were identified as Serratia marcescens and Enterobacter sp. based on their phenotypic features, BIOLOG studies and 16S rRNA gene sequence analysis. Both bacteria exhibited phosphate solubilization, ammonification, and production of indole acetic acid, β-1, 3 glucanase activities and 1-aminocyclopropane-1-carboxylate-deaminase activity. They could also tolerate a range of pH conditions, low temperature and salinity (NaCl). In addition, S. marcescens KiSII exhibited N- fixation potential, chitinase activity, siderophore production and antibiotics production. Seed bacterization with these bacteria increased the growth parameters of test plants such as paddy and cowpea over uninoculated control in green house assay. In coconut seedlings, significant increase in growth and nutrient uptake accompanied with higher populations of plant beneficial microorganisms in their rhizospheres were recorded on inoculation with both the PGPRs. The present study clearly revealed that PGPRs can aid in production of healthy and vigorous seedlings of coconut palm which are hardy perennial crops. They offer a scope to be developed into novel PGPR based bioinoculants for production of elite seedlings that can benefit the coconut farming community and the coconut based ecology. PMID:22948479

  15. Multifarious beneficial traits and plant growth promoting potential of Serratia marcescens KiSII and Enterobacter sp. RNF 267 isolated from the rhizosphere of coconut palms (Cocos nucifera L.).

    PubMed

    George, Priya; Gupta, Alka; Gopal, Murali; Thomas, Litty; Thomas, George V

    2013-01-01

    Two plant growth promoting bacteria designated as KiSII and RNF 267 isolated from the rhizosphere of coconut palms were identified as Serratia marcescens and Enterobacter sp. based on their phenotypic features, BIOLOG studies and 16S rRNA gene sequence analysis. Both bacteria exhibited phosphate solubilization, ammonification, and production of indole acetic acid, β-1, 3 glucanase activities and 1-aminocyclopropane-1-carboxylate-deaminase activity. They could also tolerate a range of pH conditions, low temperature and salinity (NaCl). In addition, S. marcescens KiSII exhibited N- fixation potential, chitinase activity, siderophore production and antibiotics production. Seed bacterization with these bacteria increased the growth parameters of test plants such as paddy and cowpea over uninoculated control in green house assay. In coconut seedlings, significant increase in growth and nutrient uptake accompanied with higher populations of plant beneficial microorganisms in their rhizospheres were recorded on inoculation with both the PGPRs. The present study clearly revealed that PGPRs can aid in production of healthy and vigorous seedlings of coconut palm which are hardy perennial crops. They offer a scope to be developed into novel PGPR based bioinoculants for production of elite seedlings that can benefit the coconut farming community and the coconut based ecology.

  16. Multiplex PCR and a chromogenic DNA macroarray for the detection of Listeria monocytogens, Staphylococcus aureus, Streptococcus agalactiae, Enterobacter sakazakii, Escherichia coli O157:H7, Vibrio parahaemolyticus, Salmonella spp. and Pseudomonas fluorescens in milk and meat samples.

    PubMed

    Chiang, Yu-Cheng; Tsen, Hau-Yang; Chen, Hsin-Yen; Chang, Yu-Hsin; Lin, Chien-Ku; Chen, Chih-Yuan; Pai, Wan-Yu

    2012-01-01

    Food products, such as milk and meat products including cheese, milk powder, fermented milk, sausage, etc. are susceptible to the contamination by pathogenic and deteriorative bacteria. These bacteria include Listeria monocytogens, Staphylococcus aureus, Enterobacter sakazakii, Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Streptococcus agalactiae and Pseudomonas fluorescens, etc. Traditional methods for the detection of these microorganisms are laborious and time consuming. Therefore, rapid and accurate diagnostic methods are needed. In this study, we designed the DNA probes and PCR primers for the detection of aforementioned microorganisms. By using two sets of multiplex PCR, followed by a chromogenic macroarray system, these organisms in milk or other food products could be simultaneously detected. When the system was used for the inspection of milk or meat homogenate containing 10(0) target cells per milliliter or gram of the sample, all these bacterial species could be identified after an 8h pre-enrichment step. The system consisting of a multiplex PCR step followed by macroarray allowed us to detect multiple target bacterial species simultaneously without the use of agarose gel electrophoresis. Compared to the commonly used multiplex PCR method, this approach has the additional advantage of detecting more bacterial strains because some bacterial strains generate PCR products with the same molecular sizes which can be differentiated by macroarray but not by electrophoresis. PMID:22101309

  17. Molecular characteristics of extended-spectrum β-lactamases in clinical isolates of Enterobacteriaceae from the Philippines.

    PubMed

    Kanamori, Hajime; Navarro, Rizalina B; Yano, Hisakazu; Sombrero, Lydia T; Capeding, Ma Rosario Z; Lupisan, Socorro P; Olveda, Remigio M; Arai, Kazuaki; Kunishima, Hiroyuki; Hirakata, Yoichi; Kaku, Mitsuo

    2011-01-01

    β-Lactamases, including extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases, are major resistance mechanisms of Enterobacteriaceae. Emergence of plasmid-mediated quinolone resistance (PMQR) determinants in ESBL-producing isolates poses a global threat. The molecular characterisitcs of ESBL and PMQR determinants in the Philippines are not well characterized. In this study, we investigated ESBLs and AmpC β-lactamases in clinical isolates of Enterobacteriaceae from the Philippines, and analyzed the association between ESBL and PMQR genes. A total of 91 amoxicilin non-susceptible Enterobacteriaceae were collected at the Research Institute for Tropical Medicine of the Philippines from 2006 to 2008. AmpC- or ESBL-producing isolates were screened by detecting a zone diameter for cefoxitin ≤ 14 mm or cefpodoxime ≤ 20 mm, respectively. Possible ESBL-producing strains were assessed by the ESBL confirmation test of the Clinical and Laboratory Standards Institute. PCR and sequencing were performed to detect the ESBL and PMQR genes. The number of ESBL-producers and AmpC-producers confirmed phenotypically was 17 (18.7%) and 61 (67.0%), respectively. Of 17 phenotypic ESBL-producers, 14 isolates had ESBL genes, including 6 of Escherichia coli, 3 of Enterobacter cloacae, 2 of Enterobacter aerogenes, 2 of Klebsiella pneumoniae, and 1 of Klebsiella ozaenae. Among these isolates, there were 13, 4, and 12 with bla(CTX-M), bla(SHV), and bla(TEM), respectively. Of the bla(CTX-M)-positive isolates, bla(CTX-M-15) shows the highest prevalence, followed by bla(CTX-M-3) and bla(CTX-M-14). Of 14 ESBL-producers identified by PCR, 4, 6, and 7 isolates were positive for qnrB, qnrS, and aac(6')-Ib-cr, respectively. The frequency of aac(6')-Ib-cr positivity was significantly higher among CTX-M-15-producing isolates. Thus, we identified bla(CTX-M), aac(6')-Ib-cr, and qnr in ESBL-producing Enterobacteriaceae from the Philippines, and revealed a significant association between bla

  18. Molecular characteristics of extended-spectrum β-lactamases in clinical isolates of Enterobacteriaceae from the Philippines.

    PubMed

    Kanamori, Hajime; Navarro, Rizalina B; Yano, Hisakazu; Sombrero, Lydia T; Capeding, Ma Rosario Z; Lupisan, Socorro P; Olveda, Remigio M; Arai, Kazuaki; Kunishima, Hiroyuki; Hirakata, Yoichi; Kaku, Mitsuo

    2011-01-01

    β-Lactamases, including extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases, are major resistance mechanisms of Enterobacteriaceae. Emergence of plasmid-mediated quinolone resistance (PMQR) determinants in ESBL-producing isolates poses a global threat. The molecular characterisitcs of ESBL and PMQR determinants in the Philippines are not well characterized. In this study, we investigated ESBLs and AmpC β-lactamases in clinical isolates of Enterobacteriaceae from the Philippines, and analyzed the association between ESBL and PMQR genes. A total of 91 amoxicilin non-susceptible Enterobacteriaceae were collected at the Research Institute for Tropical Medicine of the Philippines from 2006 to 2008. AmpC- or ESBL-producing isolates were screened by detecting a zone diameter for cefoxitin ≤ 14 mm or cefpodoxime ≤ 20 mm, respectively. Possible ESBL-producing strains were assessed by the ESBL confirmation test of the Clinical and Laboratory Standards Institute. PCR and sequencing were performed to detect the ESBL and PMQR genes. The number of ESBL-producers and AmpC-producers confirmed phenotypically was 17 (18.7%) and 61 (67.0%), respectively. Of 17 phenotypic ESBL-producers, 14 isolates had ESBL genes, including 6 of Escherichia coli, 3 of Enterobacter cloacae, 2 of Enterobacter aerogenes, 2 of Klebsiella pneumoniae, and 1 of Klebsiella ozaenae. Among these isolates, there were 13, 4, and 12 with bla(CTX-M), bla(SHV), and bla(TEM), respectively. Of the bla(CTX-M)-positive isolates, bla(CTX-M-15) shows the highest prevalence, followed by bla(CTX-M-3) and bla(CTX-M-14). Of 14 ESBL-producers identified by PCR, 4, 6, and 7 isolates were positive for qnrB, qnrS, and aac(6')-Ib-cr, respectively. The frequency of aac(6')-Ib-cr positivity was significantly higher among CTX-M-15-producing isolates. Thus, we identified bla(CTX-M), aac(6')-Ib-cr, and qnr in ESBL-producing Enterobacteriaceae from the Philippines, and revealed a significant association between bla

  19. Molecular Characteristics of Extended-Spectrum Cephalosporin-Resistant Enterobacteriaceae from Humans in the Community

    PubMed Central

    van Hoek, Angela H. A. M.; Schouls, Leo; van Santen, Marga G.; Florijn, Alice; de Greeff, Sabine C.; van Duijkeren, Engeline

    2015-01-01

    Objective To investigate the molecular characteristics of extended-spectrum cephalosporin (ESC)-resistant Enterobacteriaceae collected during a cross-sectional study examining the prevalence and risk factors for faecal carriage of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in humans living in areas with high or low broiler density. Methods ESC-resistant Enterobacteriaceae were identified by combination disc-diffusion test. ESBL/AmpC/carbapenemase genes were analysed using PCR and sequencing. For E. coli, phylogenetic groups and MLST were determined. Plasmids were characterized by transformation and PCR-based replicon typing. Subtyping of plasmids was done by plasmid multilocus sequence typing. Results 175 ESC-resistant Enterobacteriaceae were cultured from 165/1,033 individuals. The isolates were Escherichia coli(n=65), Citrobacter freundii (n=52), Enterobacter cloacae (n=38), Morganella morganii (n=5), Enterobacter aerogenes (n=4), Klebsiella pneumoniae (n=3), Hafnia alvei (n=2), Shigella spp. (n=2), Citrobacter amalonaticus (n=1), Escherichia hermannii (n=1), Kluyvera cryocrescens (n=1), and Pantoea agglomerans (n=1). The following ESBL genes were recovered in 55 isolates originating from 49 of 1,033 (4.7 %) persons: blaCTX-M-1 (n=17), blaCTX-M-15 (n=16), blaCTX-M-14 (n=9), blaCTX-M-2 (n=3), blaCTX-M-3 (n=2), blaCTX-M-24 (n=2), blaCTX-M-27 (n=1), blaCTX-M-32 (n=1), blaSHV-12 (n=2), blaSHV-65 (n=1) and blaTEM-52 (n=1). Plasmidic AmpC (pAmpC) genes were discovered in 6 out of 1,033 (0.6 %) persons. One person carried two different E. coli isolates, one with blaCTX-M-1 and the other with blaCMY-2 and therefore the prevalence of persons carrying Enterobacteriaceae harboring ESBL and/or pAmpC genes was 5.2 %. In eight E. coli isolates the AmpC phenotype was caused by mutations in the AmpC promoter region. No carbapenemase genes were identified. A large variety of E. coli genotypes was found, ST131 and ST10 being most common. Conclusions ESBL

  20. Polymicrobial Ventriculitis Involving Pseudomonas fulva

    PubMed Central

    Rebolledo, Paulina A.; Vu, Catphuong Cathy L.; Carlson, Renee Donahue; Kraft, Colleen S.; Anderson, Evan J.

    2014-01-01

    Infections due to Pseudomonas fulva remain a rare but emerging concern. A case of ventriculitis due to Enterobacter cloacae and Pseudomonas fulva following placement of an external ventricular drain is described. Similar to other reports, the organism was initially misidentified as Pseudomonas putida. The infection was successfully treated with levofloxacin. PMID:24648556

  1. Professional Acquisition of M. bovis in Calabria Region (Southern Italy): A Challenging Case of Osteomyelitis in a Migrant Patient from Bulgaria

    PubMed Central

    Quirino, Angela; Torti, Carlo; Strazzulla, Alessio; Nisticò, Salvatore; Galati, Luisa; Barreca, Giorgio Settimo; Lamberti, Angelo Giuseppe; Berardelli, Giuseppina; Pacciarini, Maria; Gasparini, Giorgio; Pisani, Vincenzo; Gambardella, Antonio; Liberto, Maria Carla; Focà, Alfredo

    2015-01-01

    We report herein the first case of a coinfection with Brucella spp., M. bovis, and Enterobacter cloacae in a butcher who moved from Bulgaria to Italy. Molecular typing suggested professional acquisition of M. bovis in Italy. So, surveillance and preventive measures need to be implemented. PMID:26257970

  2. Multi-Strain Co-Cultures Surpass Blends for Broad Spectrum Biological Control of Maladies of Potatoes in Storage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens strains S11:P:12, P22:Y:05, and S22:T:04 and Enterobacter cloacae strain S11:T:07 have been documented to suppress four important storage potato maladies: dry rot, late blight, pink rot, and sprouting. This research investigates the efficacy and consistency of strain mixture...

  3. Papaya Varietal Resistance to Internal Yellowing: Reducing Food Safety Risk

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Internal yellowing (IY) is a bacterial disease of ripening papaya fruit that is caused by the enteric bacterium, Enterobacter cloacae. The disease is characterized by yellow discoloration of flesh, tissue softening and a foul or rotten odor that reduces the quality of fresh fruit and value-added pr...

  4. Hydrogen production from glucose by anaerobes.

    PubMed

    Ogino, Hiroyasu; Miura, Takashi; Ishimi, Kosaku; Seki, Minoru; Yoshida, Hiroyuki

    2005-01-01

    Various anaerobes were cultivated in media containing glucose. When 100 mL of thioglycollate medium containing 2.0% (w/v) glucose was used, Clostridium butyricum ATCC 859, NBRC 3315, and NBRC 13949 evolved 227-243 mL of biogas containing about 180 mL of hydrogen in 1 day. Although some strains had some resistance against oxygen, C. butyricum ATCC 859 and 860 did not have it. C. butyricum NBRC 3315 and Enterobacter aerogenes NBRC 13534 produced hydrogen in the presence of glucose or pyruvic acid, and E. aerogenes NBRC 13534 produced hydrogen by not only glucose and pyruvic acid but also dextrin, sucrose, maltose, galactose, fructose, mannose, and mannitol. When a medium containing 0.5% (w/v) yeast extract and 2.0% (w/v) glucose was used, E. aerogenes NBRC 13534 evolved more biogas and hydrogen than C. butyricum NBRC 3315 in the absence of reducing agent.

  5. Candida albicans blastoconidia in peripheral blood smears from non-neutropenic surgical patients.

    PubMed

    Berrouane, Y; Bisiau, H; Le Baron, F; Cattoen, C; Duthilleul, P; Dei Cas, E

    1998-07-01

    An 80 year old woman developed fever 11 days after volvulus surgery. A peripheral blood smear showed numerous yeast cells--both extraleucocytic and intraleucocytic--as well as leucoagglutination. The fungal elements included blastospores, pseudohyphae, and germ tubes. Two days later, blood cultures yielded Candida albicans, Enterobacter aerogenes, and Staphlococcus aureus. The patient had no medical history of immunodeficiency. Several reports indicate that fungal elements may be detected in peripheral blood smears from patients who have a severe intestinal disease.

  6. Stereoselective synthesis, spectral and antimicrobial studies of some cyanoacetyl hydrazones of 3-alkyl-2,6-diarylpiperidin-4-ones

    NASA Astrophysics Data System (ADS)

    Velayutham Pillai, M.; Rajeswari, K.; Vidhyasagar, T.

    2014-11-01

    A series of novel cyanoacetyl hydrazones of 3-alkyl-2,6-diarylpiperidin-4-ones were synthesized stereoselectively and characterized by IR, Mass, 1H NMR, 13C NMR, 1H-1H COSY and 1H-13C COSY spectra. The stereochemistry of the synthesized compounds was established using NMR spectra. Antimicrobial screening of the synthesized compounds revealed their antibacterial and antifungal potencies. Growth inhibition of Enterobacter Aerogenes by compound 15 was found to be superior to the standard drug.

  7. Nationwide study of the prevalence, characteristics, and molecular epidemiology of extended-spectrum-beta-lactamase-producing Enterobacteriaceae in France.

    PubMed

    Galas, Muriel; Decousser, Jean-Winoc; Breton, Nelly; Godard, Thierry; Allouch, Pierre Yves; Pina, Patrick

    2008-02-01

    Among 10,872 isolates of Enterobacteriaceae from a nationwide study of 88 French hospitals in 2005, 169 (1.7%) expressed an extended-spectrum beta-lactamase. The most prevalent species were Escherichia coli (48.5%), Enterobacter aerogenes (23.7%), and Klebsiella pneumoniae (14.8%). Molecular analysis underlined the polyclonal spread of CTX-M-expressing E. coli, primarily isolates of the CTX-M-1 subgroup.

  8. Polymicrobial abdominal wall necrotizing fasciitis after cesarean section.

    PubMed

    DeMuro, Jp; Hanna, Af; Chalas, E; Cunha, Ba

    2012-09-01

    We report a case of a previously healthy woman after an uneventful caesarean section who developed polymicrobial necrotizing fasciitis. She was given a non-steroidal anti-inflamatory drug (NSAID) after her delivery. Her post-delivery course was complicated by septic shock, and required multiple debridements before abdominal reconstruction. This case describes the increased risk of necrotizing fasciitis with NSAID use. Unusual were the organisms causing the polymicrobial necrotizing fasciitis: Staphylococcus aureus, Enterobacter agglomerans, Acinetobacter baumannii, and two strains of Enterobacter cloacae.

  9. Association of plasmid-mediated quinolone resistance with extended-spectrum beta-lactamase VEB-1.

    PubMed

    Poirel, Laurent; Van De Loo, Marc; Mammeri, Hedi; Nordmann, Patrice

    2005-07-01

    Association of the plasmid-mediated quinolone resistance determinant QnrA and the bla(VEB-1) gene was identified in a single Enterobacter cloacae isolate from K.-Bicêtre, France, and in 11 out of 23 bla(VEB-1)-positive enterobacterial isolates from Bangkok, Thailand. This result may explain in part the association between quinolone and extended-spectrum beta-lactam resistance.

  10. Determination of antimicrobial activity and resistance to oxidation of moringa peregrina seed oil.

    PubMed

    Lalas, Stavros; Gortzi, Olga; Athanasiadis, Vasilios; Tsaknis, John; Chinou, Ioanna

    2012-01-01

    The antimicrobial activity of the oil extracted with n-hexane from the seeds of Moringa peregrina was tested against Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Candida albicans, C. tropicalis and C. glabrata. The oil proved effective against all of the tested microorganisms. Standard antibiotics (netilmycin, 5-flucytocine, intraconazole and 7-amino-4-methylcoumarin-3-acetic acid) were used for comparison. The resistance to oxidation of the extracted seed oil was also determined. PMID:22367027

  11. Emergence of New Delhi Metallo-Beta-Lactamase (NDM-1) and Klebsiella pneumoniae Carbapenemase (KPC-2) in South Africa

    PubMed Central

    Coetzee, Jennifer; Clay, Cornelis G.; Sithole, Sindi; Richards, Guy A.; Poirel, Laurent; Nordmann, Patrice

    2012-01-01

    This report documents emergence of New Delhi metallo-beta-lactamase (NDM-1) and Klebsiella pneumoniae carbapenemase (KPC-2) in K. pneumoniae and Enterobacter cloacae in South Africa. NDM-1 producers have not been described in South Africa, and this is the first instance that KPC producers have been identified in Africa. The two patients infected with these carbapenemase-producing bacteria demised. PMID:22116157

  12. Determination of optimal dosage regimen for amikacin in healthy volunteers by study of pharmacokinetics and bactericidal activity.

    PubMed Central

    Garraffo, R; Drugeon, H B; Dellamonica, P; Bernard, E; Lapalus, P

    1990-01-01

    The pharmacokinetics and serum killing curves of amikacin, which was administered by a 30-minute intravenous infusion of single doses of 7.5 mg/kg and then 15 mg/kg, were investigated in six healthy volunteers who received the two doses in a crossover study with a washout period of 20 days. The serum killing curves were determined for four bacterial species: Escherichia coli, Serratia marcescens, Enterobacter cloacae, and Pseudomonas aeruginosa. All strains were serum resistant, and the bactericidal activity was analyzed by separating the early phase (first 5 h) and the late phase (24 h) of the killing curve. For the early phase, the bactericidal activity was evaluated by correlating an index of surviving bacteria with amikacin concentrations. This methodology allowed determination of two parameters: the maximal effective concentration and the lowest effective concentration. For the late phase, the threshold values separating bacteriostatic and bactericidal activities were lower than 10 mg/liter for each strain. The concentration dependence of amikacin bactericidal activity was confirmed for Escherichia coli and Enterobacter cloacae and, to a lesser extent, for Serratia marcescens and Pseudomonas aeruginosa. Correlation of these data with amikacin pharmacokinetic data in volunteers indicated that a daily dose of 15 mg/kg may be effective in the treatment of Escherichia coli and Enterobacter cloacae infections. For Pseudomonas aeruginosa and Serratia marcescens, the partially time-dependent activity probably necessitates two daily administrations and combination with another antibiotic. PMID:2111658

  13. Genetic Identification of an Enzymatic Se(VI) Reduction Pathway

    NASA Astrophysics Data System (ADS)

    Yee, N.; Kobayashi, D. Y.

    2006-12-01

    Enterobacter cloacae is a biofilm-forming organism that colonizes the subterranean portions of plants. Because of its ability to catalyze the reduction of selenium oxyanions, this bacterium plays an important role in Se(0) biomineralization and Se cycling in soils. Identification of the genes that regulate selenate reductase activity is needed to elucidate the mechanisms employed by this organism to reduce Se(VI). However, the genes in E. cloacae involved in selenium reduction are currently unknown. In this study, transposon mutagenesis and direct cloning techniques were used to identify genetic regions in E. cloacae SLD1a-1 associated with selenate reductase activity. The mini-Tn5 transposon system was used to produce mutants that have lost the ability to reduce selenate. E. cloacae mutants and genomic library clones heterologously expressed in E. coli S17-1 were screened for activity on LB agar supplemented with sodium selenate. The rate of selenate reduction by the clones was measured in liquid minimal media, and the Se(0) minerals formed by the clones were examined using EXAFS, TEM, and XRD. The transposon mutagenesis experiments revealed that mutation of menaquinone biosynthesis genes inhibits selenate reduction. The direct cloning experiments showed that heterologous expression of the global anaerobic regulatory gene fnr from Enterobacter cloacae in the non Se-reducing strain E. coli S17-1 activated selenate reductase activity and the ability to precipitate Se(0) particles. Se(VI) reduction by E. coli S17-1 containing the fnr gene occurred at similar rates as E. cloacae and produced elemental selenium particles with identical morphologies and short range atomic order. These findings indicate that Se(VI) reduction by facultative anaerobes is regulated by anaerobic electron carriers and oxygen sensing transcription factors.

  14. [Quantitative and qualitative characteristics of representatives of the enterobacteriaceae family in postradiation intestinal dysbacteriosis].

    PubMed

    Pinegin, B V; Korshunov, V M; Ikonnikova, T B; Kissina, E V

    1980-08-01

    The irradiation of CBA mice with gamma quanta in a dose of 700 C/kg resulted in the development of postradiation intestinal dysbacteriosis in the animals. The dysbacteriosis was characterized by a considerable increase in the number of Escherichia and Proteus mirabilis in the large intestine and by the insemination of the small intestine with these microbial associations. Pr. vulgaris, Pr. morganii, Ent. aerogenes, Ent. cloacae, Citrobacter appeared in great numbers in the intestinal tract of the irradiated mice, while none of these organisms were found in the intact mice.

  15. Development of a model for evaluation of microbial cross-contamination in the kitchen.

    PubMed

    Zhao, P; Zhao, T; Doyle, M P; Rubino, J R; Meng, J

    1998-08-01

    Foods can become contaminated with pathogenic microorganisms from hands, the cutting board, and knives during preparation in the kitchen. A laboratory model was developed to determine occurrence of cross-contamination and efficacy of decontamination procedures in kitchen food-handling practices. Enterobacter aerogenes B199A, an indicator bacterium with attachment characteristics similar to that of Salmonella spp., was used. Chicken meat with skin inoculated with 10(6) CFU of E. aerogenes B199A/g was cut into small pieces on a sterile cutting board. The extent of cross-contamination occurring from meat to the cutting board and from the cutting board to vegetables (lettuce and cucumbers) subsequently cut on the board was determined. Swab samples from the cutting board, hand washings, and lettuce and cucumber samples revealed that approximately 10(5) CFU of E. aerogenes/cm2 were transferred to the board and hands and approximately 10(3) to 10(4) CFU of E. aerogenes/g to the lettuce and cucumbers. The surfaces of the cutting board and hands were treated with antibacterial agents after cutting the meat, and counts of E. aerogenes on the cutting board and vegetables (lettuce and cucumbers) were determined. Results revealed that use of the disinfectant reduced the population of E. aerogenes to almost nondetectable levels on the cutting boards. The average counts after treatment were < 20 CFU/g of vegetable and ranged from < 20 to 200 CFU per cm2 or g on the cutting board and subsequently on the vegetables. These results indicate that bacteria with attachment characteristics similar to Salmonella spp. can be readily transferred to cutting boards during food preparation and then cross-contaminate fresh vegetables if the boards are not cleaned. Application of a kitchen disinfectant can greatly reduce bacterial contamination on cutting boards.

  16. Evolution of chemotactic-signal transducers in enteric bacteria.

    PubMed Central

    Dahl, M K; Boos, W; Manson, M D

    1989-01-01

    The methyl-accepting chemotactic-signal transducers of the enteric bacteria are transmembrane proteins that consist of a periplasmic receptor domain and a cytoplasmic signaling domain. To study their evolution, transducer genes from Enterobacter aerogenes and Klebsiella pneumoniae were compared with transducer genes from Escherichia coli and Salmonella typhimurium. There are at least two functional transducer genes in the nonmotile species K. pneumoniae, one of which complements the defect in serine taxis of an E. coli tsr mutant. The tse (taxis to serine) gene of E. aerogenes also complements an E. coli tsr mutant; the tas (taxis to aspartate) gene of E. aerogenes complements the defect in aspartate taxis, but not the defect in maltose taxis, of an E. coli tar mutant. The sequence was determined for 5 kilobases of E. aerogenes DNA containing a 3' fragment of the cheA gene, cheW, tse, tas, and a 5' fragment of the cheR gene. The tse and tas genes are in one operon, unlike tsr and tar. The cytoplasmic domains of Tse and Tas are very similar to those of E. coli and S. typhimurium transducers. The periplasmic domain of Tse is homologous to that of Tsr, but Tas and Tar are much less similar in this region. However, several short sequences are conserved in the periplasmic domains of Tsr, Tar, Tse, and Tas but not of Tap and Trg, transducers that do not bind amino acids. These conserved regions include residues implicated in amino-acid binding. Images PMID:2496104

  17. Volatiles produced by soil-borne endophytic bacteria increase plant pathogen resistance and affect tritrophic interactions

    PubMed Central

    Ton, Jurriaan; Brandenburg, Anna; Karlen, Danielle; Zopfi, Jakob; Turlings, Ted C. J.

    2014-01-01

    Volatile organic compounds (VOCs) released by soil microorganisms influence plant growth and pathogen resistance. Yet, very little is known about their influence on herbivores and higher trophic levels. We studied the origin and role of a major bacterial VOC, 2,3-butanediol (2,3-BD), on plant growth, pathogen and herbivore resistance, and the attraction of natural enemies in maize. One of the major contributors to 2,3-BD in the headspace of soil-grown maize seedlings was identified as Enterobacter aerogenes, an endophytic bacterium that colonizes the plants. The production of 2,3-BD by E. aerogenes rendered maize plants more resistant against the Northern corn leaf blight fungus Setosphaeria turcica. On the contrary, E. aerogenes-inoculated plants were less resistant against the caterpillar Spodoptera littoralis. The effect of 2,3-BD on the attraction of the parasitoid Cotesia marginiventris was more variable: 2,3-BD application to the headspace of the plants had no effect on the parasitoids, but application to the soil increased parasitoid attraction. Furthermore, inoculation of seeds with E. aerogenes decreased plant attractiveness, whereas inoculation of soil with a total extract of soil microbes increased parasitoid attraction, suggesting that the effect of 2,3-BD on the parasitoid is indirect and depends on the composition of the microbial community. PMID:24127750

  18. Two Novel Bacterial Biosensors for Detection of Nitrate Availability in the Rhizosphere

    PubMed Central

    DeAngelis, Kristen M.; Ji, Pingsheng; Firestone, Mary K.; Lindow, Steven E.

    2005-01-01

    The nitrate-regulated promoter of narG in Escherichia coli was fused to promoterless ice nucleation (inaZ) and green fluorescent protein (GFP) reporter genes to yield the nitrate-responsive gene fusions in plasmids pNice and pNgfp, respectively. While the promoter of narG is normally nitrate responsive only under anaerobic conditions, the L28H-fnr gene was provided in trans to enable nitrate-dependent expression of these reporter gene fusions even under aerobic conditions in both E. coli DH5α and Enterobacter cloacae EcCT501R. E. cloacae and E. coli cells containing the fusion plasmid pNice exhibited more than 100-fold-higher ice nucleation activity in cultures amended with 10 mM sodium nitrate than in nitrate-free media. The GFP fluorescence of E. cloacae cells harboring pNgfp was uniform at a given concentration of nitrate and increased about 1,000-fold when nitrate increased from 0 to 1 mM. Measurable induction of ice nucleation in E. cloacae EcCT501R harboring pNice occurred at nitrate concentrations of as low as 0.1 μM, while GFP fluorescence was detected in cells harboring pNgfp at about 10 μM. In the rhizosphere of wild oat (Avena fatua), the whole-cell bioreporter E.cloacae(pNgfp) or E. cloacae(pNice) expressed significantly higher GFP fluorescence or ice nucleation activity when the plants were grown in natural soils amended with nitrate than in unamended natural soils. Significantly lower nitrate abundance was detected by the E. cloacae(pNgfp) reporter in the A. fatua rhizosphere compared to in bulk soil, indicating plant competition for nitrate. Ice- and GFP-based bacterial sensors thus are useful for estimating nitrate availability in relevant microbial niches in natural environments. PMID:16332845

  19. Enzymatic transesterification of Jatropha oil

    PubMed Central

    Kumari, Annapurna; Mahapatra, Paramita; Garlapati, Vijay Kumar; Banerjee, Rintu

    2009-01-01

    Background Transesterification of Jatropha oil was carried out in t-butanol solvent using immobilized lipase from Enterobacter aerogenes. The presence of t-butanol significantly reduced the negative effects caused by both methanol and glycerol. The effects of various reaction parameters on transesterification of Jatropha oil were studied. Results The maximum yield of biodiesel was 94% (of which 68% conversion was achieved with respect to methyl oleate) with an oil:methanol molar ratio of 1:4, 50 U of immobilized lipase/g of oil, and a t-butanol:oil volume ratio of 0.8:1 at 55°C after 48 h of reaction time. There was negligible loss in lipase activity even after repeated use for seven cycles. Conclusion To the best of our knowledge this is the first report on biodiesel synthesis using immobilized E. aerogenes lipase. PMID:19144158

  20. Biological activity of alkaloids from Solanum dulcamara L.

    PubMed

    Kumar, Padma; Sharma, Bindu; Bakshi, Nidhi

    2009-01-01

    Alkaloids are well known for their antimicrobial activity. Though all natural alkaloids come from plants, not all plants produce alkaloids. Plants of the Solanaceae family are known for their high alkaloid content. Alkaloids are found in all plant parts like roots, stems, leaves, flowers, fruits and seeds. In the present study, those plant parts of Solanum dulcamara were selected which have been reported to produce a high content of a specific alkaloid: solanine (from unripe fruits), solasodine (from flowers) and beta-solamarine (from roots). These alkaloids were extracted from various parts of S. dulcamara by well-established methods and were screened for their antibacterial activity. Human pathogenic bacteria, viz., Enterobacter aerogenes, Escherichia coli, Staphylococcus aureus, were selected for the study. All three alkaloids inhibited the growth of E. coli and S. aureus. However, no significant activity was observed against E. aerogenes. Minimum inhibitory concentration and minimum bactericidal concentration were also evaluated.

  1. Biohydrogen production from sugarcane bagasse by integrating dark- and photo-fermentation.

    PubMed

    Rai, Pankaj K; Singh, S P; Asthana, R K; Singh, Shweta

    2014-01-01

    Hydrogen production from sugarcane bagasse (SCB) by integrating dark-fermentation by Enterobacter aerogenes MTCC 2822 and photo-fermentation by Rhodopseudomonas BHU 01 was investigated. The SCB was hydrolysed by sulphuric acid and the hydrolysate detoxified by passing through adsorbent resin column (Amberlite XAD-4) to remove the inhibitory furfural, and subjected to dark-fermentation. The cellulosic residue from acid hydrolysis was hydrolysed by the new isolate Cellulomonas fimi to release sugars for H2 production by E. aerogenes, through simultaneous saccharification, filtration and fermentation (SSFF). Cumulative H2 production during dark-fermentation and SSFF was 1000 and 613 ml/L, respectively. The spent media of dark-fermentation and SSFF were utilized for photo-fermentation by Rhodopseudomonas BHU 01. The cumulative H2 production was 755 ml/L for dark-fermentation and 351 ml/L for SSFF spent medium.

  2. Bacteriological evaluation of pre-cut fruits sold in Kano metropolis, Kano State, Nigeria.

    PubMed

    Chukwu, O O C; Olabode, O A; Chukwuedo, A A; Umoh, E G; Esiekpe, M K

    2009-04-01

    One hundred and fifty (150) pre-cut fruit samples comprising of Pineapples (50), Paw-paw (50) and Watermelon (50) at the point of stand retail outlets were tested by standard bacteriological methods to determine bacterial contamination of the fruits. Out of these 150 examined 136 (90.67%) were contaminated with bacteria. The bacterial distribution were; Escherichia coli 69 (46.00%), Staphylococcus aureus 29 (19.33%), Salmonella species 13 (8.67%), Proteus species 18 (12.00%), Enterobacter aerogenes 3 (2.00%), Klebsiella pneumoniae 2 (1.33%) and Pseudomonas aeruginosa 2 (1.33%). Among the 50 Pineapple pre-cuts, Escherichia coli 26 (17.33%), Staphylococcus aureus 6 (4.00%), Salmonella species 7 (4.67%), Proteus species 9 (6.00%), Pseudomonas aeruginosa 2 (1.33%); the 50 Watermelon had Escherchia coli 22 (14.67%), Staphylococcus aureus 13 (8.67%), Salmonella species 3 (2.00%), Proteus species 5 (3.33%), Enterobacter aerogenes 2 (1.33%), Klebsiella species 2 (1.33%). Of the 50 Paw-paw pre-cuts were: Escherichia coli 21 (14.00%), Staphylococcus aureus 10 (6.67%), Salmonella species 3 (2.00%), Proteus species 4 (2.67%), Enterobacter aerogenes 1 (0.67%) were isolated. The findings in this study have shown that the food vendors failed to adopt adequate hygiene for food handling and thus, suggest that the quality of all the pre-cut fruits sold at the retail outlets were not bacteriologically satisfactory. The public health risks associated with these pre-cut fruits may suggest that these fruits could serve as the vehicles for foodborne illnesses. This study has shown the need to educate the vendors on how to protect utensils and fruits to avoid contamination and spoilage.

  3. A new antimicrobial and radical-scavenging glycoside from Paullinia pinnata var. cameroonensis.

    PubMed

    Lunga, Paul-Keilah; Qin, Xu-Jie; Yang, Xing-Wei; Kuiate, Jules-Roger; Du, Zhi-Zhi; Gatsing, Donatien

    2015-01-01

    A new glycoside, pinnatoside A (1), together with two known compounds (2 and 3), were isolated from the stems of Paullinia pinnata. Their structures were elucidated on the basis of extensive spectroscopic analysis and chemical methods. Compound 1 showed significant antibacterial activity with a minimum inhibitory concentration (MIC) value of 1.56 μg/mL against Escherichia coli, and 2 displayed significant antibacterial activity with a MIC value of 1.56 μg/mL against Enterobacter aerogenes and E. coli. Equally, compound 1 exhibited the best radical-scavenging activity (RSa50 = 25.07 ± 0.49 μg/mL). PMID:25563339

  4. A new antimicrobial and radical-scavenging glycoside from Paullinia pinnata var. cameroonensis.

    PubMed

    Lunga, Paul-Keilah; Qin, Xu-Jie; Yang, Xing-Wei; Kuiate, Jules-Roger; Du, Zhi-Zhi; Gatsing, Donatien

    2015-01-01

    A new glycoside, pinnatoside A (1), together with two known compounds (2 and 3), were isolated from the stems of Paullinia pinnata. Their structures were elucidated on the basis of extensive spectroscopic analysis and chemical methods. Compound 1 showed significant antibacterial activity with a minimum inhibitory concentration (MIC) value of 1.56 μg/mL against Escherichia coli, and 2 displayed significant antibacterial activity with a MIC value of 1.56 μg/mL against Enterobacter aerogenes and E. coli. Equally, compound 1 exhibited the best radical-scavenging activity (RSa50 = 25.07 ± 0.49 μg/mL).

  5. Growth of Paramecium tetraurelia in bacterized, monoxenic cultures.

    PubMed

    Enright, W J; Hennessey, T M

    1987-05-01

    Wild type and mutant Paramecium tetraurelia were grown in monoxenic cultures by first growing Enterobacter aerogenes on a defined medium and then adding the Paramecium to the stationary phase bacterial culture. The bacterial growth was proportional to the concentration of the carbon source (citrate), and the Paramecium growth was dependent upon both the bacterial density and the starting density of Paramecium. The behavior, electrophysiological properties, ciliary lipid composition, and growth characteristics were similar to the commonly used bacterized medium (Cerophyl) except that 5-10 times greater Paramecium yields were reliably obtained.

  6. [Clinico-etiological characteristics of intestinal diseases in young children].

    PubMed

    Luvsandagva, E; Altantsétség, Zh; Suvdaa, M; Nortmaa, M

    1990-01-01

    Intestinal disorders in infants are determined in 96.9% of cases by the opportunistic flora with the predominance of Pr. mirabilis (25.5%), E. coli (19.1%), Enterobacter aerogenes (12.6%) and with the less frequent occurrence of Klebsiella (4.1%) and pathogenic staphylococci (5.8%). As a result of the unbased use of antibiotics, the majority of children demonstrate dysbacteriosis and the growth of the number of resistant hospital strains. It is suggested that in children with ARVI, the drugs containing lactic acid bacteria and lactose should be used on a wider basis to prevent dysbacteriosis and reduction of resistant strains.

  7. A 1998 Survey of Extended-Spectrum β-Lactamases in Enterobacteriaceae in France

    PubMed Central

    De Champs, C.; Sirot, D.; Chanal, C.; Bonnet, R.; Sirot, J.

    2000-01-01

    In a 3-month period in 1998, 79 consecutive isolates of Enterobacteriaceae producing an extended-spectrum β-lactamase (ESBL) were collected. ESBLs were predominantly TEM derivatives (74 of 79): TEM-24-like (40 isolates), TEM-3-like (29 isolates), TEM-21 (3 isolates), and TEM-4 and TEM-52 (1 isolate each). Four isolates produced SHV derivatives SHV-4 (three isolates) and SHV-5 (one isolate), and one strain produced a CTX-M-3 enzyme. The high proportion of TEM-24-like-producing Enterobacter aerogenes isolates (36 of 79) suggests the occurrence of an epidemic strain in France. PMID:11036046

  8. Bio-reduction of Cr(VI) by exopolysaccharides (EPS) from indigenous bacterial species of Sukinda chromite mine, India.

    PubMed

    Harish, R; Samuel, Jastin; Mishra, R; Chandrasekaran, N; Mukherjee, A

    2012-07-01

    Chrome mining activity has contributed intensively towards pollution of hexavalent chromium around Sukinda Valley, Orissa, India. In an attempt to study the specific contribution of exopolysaccharides (EPS) extracted from indigenous isolates towards Cr(VI) reduction, three chromium (VI) tolerant strains were isolated from the effluent mining sludge. Based on the tolerance towards Cr(VI) and EPS production capacity, one of them was selected for further work. The taxonomic identity of the selected strain was confirmed to be Enterobacter cloacae (showing 98% similarity in BLAST search to E. cloacae) through 16S rRNA analysis. The EPS production was observed to increase with increasing Cr(VI) concentration in the growth medium, highest being 0.078 at 100 mg/l Cr(VI). The extracted EPS from Enterobacter cloacae SUKCr1D was able to reduce 31.7% of Cr(VI) at 10 mg/l concentration, which was relevant to the prevailing natural concentrations at Sukinda mine effluent sludge. The FT-IR spectral studies confirmed the surface chemical interactions of hexavalent chromium with EPS.

  9. Analysis of bacterial diversity during the fermentation of inyu, a high-temperature fermented soy sauce, using nested PCR-denaturing gradient gel electrophoresis and the plate count method.

    PubMed

    Wei, Chia-Li; Chao, Shiou-Huei; Tsai, Wen-Bin; Lee, Pei-Shan; Tsau, Nai-Hung; Chen, Jhih-Shan; Lai, Wen-Lin; Tu, James Ching-Yueh; Tsai, Ying-Chieh

    2013-04-01

    The diversity of bacteria associated with the fermentation of inyu, also known as black soy sauce, was studied through the nested PCR-denaturing gradient gel electrophoresis (DGGE) of samples collected from the fermentation stages of the inyu production process. The DGGE profiles targeted the bacterial 16S rDNA and revealed the presence of Citrobacter farmeri, Enterobacter cloacae, Enterobacter hormaechei, Enterococcus faecium, Klebsiella pneumoniae, Pantoea agglomerans, Salmonella enterica, Serratia marcescens, Staphylococcus sciuri and Weissella confusa. The bacterial compositions of 4 fermented samples were further elucidated using the plate count method. The bacteria isolated from the koji-making stage exhibited the highest diversity; Brachybacterium rhamnosum, E. hormaechei, K. pneumoniae, Kurthia gibsonii, Pantoea dispersa, Staphylococcus gallinarum, Staphylococcus kloosii and S. sciuri were identified. Koji collected during the preincubation stage presented the largest cell counts, and E. hormaechei, K. pneumoniae, E. cloacae and Enterobacter pulveris were identified. In brine samples aged for 7 and 31 days, the majority of the bacteria isolated belonged to 4 Bacillus species, but 4 Staphylococcus species and Delftia tsuruhatensis were also detected. This study demonstrates the benefits of using a combined approach to obtain a more complete picture of microbial populations and provides useful information for the control or development of bacterial flora during inyu fermentation.

  10. Glufosinate aerogenic exposure induces glutamate and IL-1 receptor dependent lung inflammation.

    PubMed

    Maillet, Isabelle; Perche, Olivier; Pâris, Arnaud; Richard, Olivier; Gombault, Aurélie; Herzine, Ameziane; Pichon, Jacques; Huaux, Francois; Mortaud, Stéphane; Ryffel, Bernhard; Quesniaux, Valérie F J; Montécot-Dubourg, Céline

    2016-11-01

    Glufosinate-ammonium (GLA), the active component of an herbicide, is known to cause neurotoxicity. GLA shares structural analogy with glutamate. It is a powerful inhibitor of glutamine synthetase (GS) and may bind to glutamate receptors. Since these potentials targets of GLA are present in lung and immune cells, we asked whether airway exposure to GLA may cause lung inflammation in mice. A single GLA exposure (1 mg/kg) induced seizures and inflammatory cell recruitment in the broncho-alveolar space, and increased myeloperoxidase (MPO), inducible NO synthase (iNOS), interstitial inflammation and disruption of alveolar septae within 6-24 h. Interleukin 1β (IL-1β) was increased and lung inflammation depended on IL-1 receptor 1 (IL-1R1). We demonstrate that glutamate receptor pathway is central, since the N-methyl-D-aspartate (NMDA) receptor inhibitor MK-801 prevented GLA-induced lung inflammation. Chronic exposure (0.2 mg/kg 3× per week for 4 weeks) caused moderate lung inflammation and enhanced airway hyperreactivity with significant increased airway resistance. In conclusion, GLA aerosol exposure causes glutamate signalling and IL-1R-dependent pulmonary inflammation with airway hyperreactivity in mice.

  11. Single-molecule sequencing to track plasmid diversity of hospital-associated carbapenemase-producing Enterobacteriaceae.

    PubMed

    Conlan, Sean; Thomas, Pamela J; Deming, Clayton; Park, Morgan; Lau, Anna F; Dekker, John P; Snitkin, Evan S; Clark, Tyson A; Luong, Khai; Song, Yi; Tsai, Yu-Chih; Boitano, Matthew; Dayal, Jyoti; Brooks, Shelise Y; Schmidt, Brian; Young, Alice C; Thomas, James W; Bouffard, Gerard G; Blakesley, Robert W; Mullikin, James C; Korlach, Jonas; Henderson, David K; Frank, Karen M; Palmore, Tara N; Segre, Julia A

    2014-09-17

    Public health officials have raised concerns that plasmid transfer between Enterobacteriaceae species may spread resistance to carbapenems, an antibiotic class of last resort, thereby rendering common health care-associated infections nearly impossible to treat. To determine the diversity of carbapenemase-encoding plasmids and assess their mobility among bacterial species, we performed comprehensive surveillance and genomic sequencing of carbapenem-resistant Enterobacteriaceae in the National Institutes of Health (NIH) Clinical Center patient population and hospital environment. We isolated a repertoire of carbapenemase-encoding Enterobacteriaceae, including multiple strains of Klebsiella pneumoniae, Klebsiella oxytoca, Escherichia coli, Enterobacter cloacae, Citrobacter freundii, and Pantoea species. Long-read genome sequencing with full end-to-end assembly revealed that these organisms carry the carbapenem resistance genes on a wide array of plasmids. K. pneumoniae and E. cloacae isolated simultaneously from a single patient harbored two different carbapenemase-encoding plasmids, indicating that plasmid transfer between organisms was unlikely within this patient. We did, however, find evidence of horizontal transfer of carbapenemase-encoding plasmids between K. pneumoniae, E. cloacae, and C. freundii in the hospital environment. Our data, including full plasmid identification, challenge assumptions about horizontal gene transfer events within patients and identify possible connections between patients and the hospital environment. In addition, we identified a new carbapenemase-encoding plasmid of potentially high clinical impact carried by K. pneumoniae, E. coli, E. cloacae, and Pantoea species, in unrelated patients and in the hospital environment. PMID:25232178

  12. Selective Antibiofilm Effects of Lucilia sericata Larvae Secretions/Excretions against Wound Pathogens

    PubMed Central

    Bohova, Jana; Majtan, Viktor; Takac, Peter

    2014-01-01

    Background. Maggot debridement therapy (MDT), using Lucilia sericata larvae, represents efficient, simple, and low-cost therapy for the treatment of chronic wounds. Aim. The aim was to investigate the antibiofilm activity of maggot excretions/secretions (ES) against biofilm of wound isolates Staphylococcus aureus (S. aureus), Enterobacter cloacae (E. cloacae), and Proteus mirabilis (P. mirabilis). Methods. Quantification of biofilm formation, was carried out using a microtiter plate assay. Proteolytic activity of maggot ES was performed using skim milk agar plates. A solid phase extraction and reverse phase HPLC C18 chromatography were employed to the isolate of maggot ES antibiofilm compounds. Results. Maggot ES at 100 mg/mL concentration significantly reduced biofilm formation thus disrupting established biofilm of E. cloacae. Heat-treated ES did not show any antibiofilm activity towards E. cloacae. Similar results were obtained in the case of S. aureus; however, the heat-treatment of maggot ES did not affect its antibiofilm activity. Moreover, a compound with molecular weight of 25 kDa exhibiting antibiofilm activity was identified in maggot ES. On the other hand, maggot ES protected and even stimulated P. mirabilis biofilm formation. Conclusions. Our results suggest that maggot ES may act selectively against different bacterial strain. PMID:25013449

  13. Selective Antibiofilm Effects of Lucilia sericata Larvae Secretions/Excretions against Wound Pathogens.

    PubMed

    Bohova, Jana; Majtan, Juraj; Majtan, Viktor; Takac, Peter

    2014-01-01

    Background. Maggot debridement therapy (MDT), using Lucilia sericata larvae, represents efficient, simple, and low-cost therapy for the treatment of chronic wounds. Aim. The aim was to investigate the antibiofilm activity of maggot excretions/secretions (ES) against biofilm of wound isolates Staphylococcus aureus (S. aureus), Enterobacter cloacae (E. cloacae), and Proteus mirabilis (P. mirabilis). Methods. Quantification of biofilm formation, was carried out using a microtiter plate assay. Proteolytic activity of maggot ES was performed using skim milk agar plates. A solid phase extraction and reverse phase HPLC C18 chromatography were employed to the isolate of maggot ES antibiofilm compounds. Results. Maggot ES at 100 mg/mL concentration significantly reduced biofilm formation thus disrupting established biofilm of E. cloacae. Heat-treated ES did not show any antibiofilm activity towards E. cloacae. Similar results were obtained in the case of S. aureus; however, the heat-treatment of maggot ES did not affect its antibiofilm activity. Moreover, a compound with molecular weight of 25 kDa exhibiting antibiofilm activity was identified in maggot ES. On the other hand, maggot ES protected and even stimulated P. mirabilis biofilm formation. Conclusions. Our results suggest that maggot ES may act selectively against different bacterial strain.

  14. Cellulosic Ethanol Production by Recombinant Cellulolytic Bacteria Harbouring pdc and adh II Genes of Zymomonas mobilis

    PubMed Central

    Piriya, P. Sobana; Vasan, P. Thirumalai; Padma, V. S.; Vidhyadevi, U.; Archana, K.; Vennison, S. John

    2012-01-01

    The ethanol fermenting genes such as pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adh II) were cloned from Zymomonas mobilis and transformed into three different cellulolytic bacteria, namely Enterobacter cloacae JV, Proteus mirabilis JV and Erwinia chrysanthemi and their cellulosic ethanol production capability was studied. Recombinant E. cloacae JV was found to produce 4.5% and 3.5% (v/v) ethanol, respectively, when CMC and 4% NaOH pretreated bagasse were used as substrates, whereas recombinant P. mirabilis and E. chrysanthemi with the same substrates could only produce 4%, 3.5%, 1%, and 1.5 % of ethanol, respectively. The recombinant E. cloacae strain produced twofold higher percentage of ethanol than the wild type. The recombinant E. cloacae strain could be improved further by increasing its ethanol tolerance capability through media optimization and also by combining multigene cellulase expression for enhancing ethanol production from various types of lignocellulosic biomass so that it can be used for industrial level ethanol production. PMID:22919503

  15. Cellulosic Ethanol Production by Recombinant Cellulolytic Bacteria Harbouring pdc and adh II Genes of Zymomonas mobilis.

    PubMed

    Piriya, P Sobana; Vasan, P Thirumalai; Padma, V S; Vidhyadevi, U; Archana, K; Vennison, S John

    2012-01-01

    The ethanol fermenting genes such as pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adh II) were cloned from Zymomonas mobilis and transformed into three different cellulolytic bacteria, namely Enterobacter cloacae JV, Proteus mirabilis JV and Erwinia chrysanthemi and their cellulosic ethanol production capability was studied. Recombinant E. cloacae JV was found to produce 4.5% and 3.5% (v/v) ethanol, respectively, when CMC and 4% NaOH pretreated bagasse were used as substrates, whereas recombinant P. mirabilis and E. chrysanthemi with the same substrates could only produce 4%, 3.5%, 1%, and 1.5 % of ethanol, respectively. The recombinant E. cloacae strain produced twofold higher percentage of ethanol than the wild type. The recombinant E. cloacae strain could be improved further by increasing its ethanol tolerance capability through media optimization and also by combining multigene cellulase expression for enhancing ethanol production from various types of lignocellulosic biomass so that it can be used for industrial level ethanol production.

  16. Communal microaerophilic-aerobic biodegradation of Amaranth by novel NAR-2 bacterial consortium.

    PubMed

    Chan, Giek Far; Rashid, Noor Aini Abdul; Chua, Lee Suan; Ab llah, Norzarini; Nasiri, Rozita; Ikubar, Mohamed Roslan Mohamad

    2012-02-01

    A novel bacterial consortium, NAR-2 which consists of Citrobacter freundii A1, Enterococcus casseliflavus C1 and Enterobacter cloacae L17 was investigated for biodegradation of Amaranth azo dye under sequential microaerophilic-aerobic condition. The NAR-2 bacterial consortium with E. casseliflavus C1 as the dominant strain enhanced the decolorization process resulting in reduction of Amaranth in 30 min. Further aerobic biodegradation, which was dominated by C. freundii A1 and E. cloacae L17, allowed biotransformation of azo reduction intermediates and mineralization via metabolic pathways including benzoyl-CoA, protocatechuate, salicylate, gentisate, catechol and cinnamic acid. The presence of autoxidation products which could be metabolized to 2-oxopentenoate was elucidated. The biodegradation mechanism of Amaranth by NAR-2 bacterial consortium was predicted to follow the steps of azo reduction, deamination, desulfonation and aromatic ring cleavage. This is for the first time the comprehensive microaerophilic-aerobic biotransformation pathways of Amaranth dye intermediates by bacterial consortium are being proposed.

  17. Bioaugmentation of biogas production by a hydrogen-producing bacterium.

    PubMed

    Ács, Norbert; Bagi, Zoltán; Rákhely, Gábor; Minárovics, János; Nagy, Katalin; Kovács, Kornél L

    2015-06-01

    The rate-limiting nature of the hydrogen concentration prevailing in the anaerobic digester has been recognized, but the associated alterations in the microbial community are unknown. In response to the addition of Enterobacter cloacae cells in laboratory anaerobic digesters, the level of biogas production was augmented. Terminal restriction fragment length polymorphism (T-RFLP) and real-time polymerase chain reaction (Real-Time PCR) were used to study the survival of mesophilic hydrogen-producing bacteria and the effects of their presence on the composition of the other members of the bacterial community. E. cloacae proved to maintain a stable cell number and to influence the microbial composition of the system. Bioaugmentation by a single strain added to the natural biogas-producing microbial community was demonstrated. The community underwent pronounced changes as a result of the relatively slight initial shift in the microbiological system, responding sensitively to the alterations in local hydrogen concentration.

  18. The comparative effect of novel Pelargonium essential oils and their corresponding hydrosols as antimicrobial agents in a model food system.

    PubMed

    Lis-Balchin, M; Steyrl, H; Krenn, E

    2003-01-01

    Essential oils and their corresponding hydrosols, obtained after distillation of various scented Pelargonium (Geraniaceae) leaves were assessed for their antimicrobial activity in a model food system. Both the essential oils and hydrosols were used at 1000 ppm in broccoli soup, previously inoculated with Enterobacter aerogenes (at 10(5) cfu g(-1)) and Staphylococcus aureus (at 10(4) cfu g(-1)). The results showed a complete inhibition of S. aureus in the broccoli soup by the essential oils of 'Sweet Mimosa', 'Mabel Grey', P. graveolens, 'Atomic Snowflake', 'Royal Oak', 'Attar of Roses' and a lesser effect by 'Chocolate Peppermint' and 'Clorinda'; the hydrosols, however, had a potentiating effect on the bacterial population in the food. Both extracts showed a complete inhibition of S. aureus in the Maximum Recovery Diluent (MRD). Antibacterial activity against E. aerogenes in the broccoli soup was generally very much reduced: only the essential oil of 'Mabel Grey' showed complete inhibition and virtually no reductions in colonies were seen with the other essential oils; the hydrosols again caused an increase in bacterial colonies. All the essential oils, bar Chocolate Peppermint showed complete inhibition of E. aerogenes in MRD, but the hydrosols showed no effect. The results strongly suggest that the residual hydrosols from distillation of these plant essential oils have no potential as antibacterial agents in foods, in contrast to most of the essential oils, which show potential against some micro-organisms, but only in some food systems. The problem of food component interference and its possible management is discussed.

  19. Transposition of the carbenicillin-hydrolyzing beta-lactamase gene.

    PubMed Central

    Katsu, K; Inoue, M; Mitsuhashi, S

    1982-01-01

    We isolated a new transposon Tn2101, from plasmid Rms433 in Enterobacter cloacae. Tn2101 encoded the formation of type IV (carbenicillin-hydrolyzing) beta-lactamase and multiple resistance to streptomycin, sulfanilamide, spectinomycin, and mercury in addition to ampicillin. Tn2101 was transposable between conjugative (or nonconjugative) plasmids and the host chromosome. Transposition occurred independently of the general recombination ability of the host cell. Tn2101 had a molecular size of 9.5 x 10(6) and contained short inverted repeat terminal sequences. Images PMID:6279559

  20. Spread of Plasmids Carrying Multiple GES Variants.

    PubMed

    Cuzon, Gaelle; Bogaerts, Pierre; Bauraing, Caroline; Huang, Te-Din; Bonnin, Rémy A; Glupczynski, Youri; Naas, Thierry

    2016-08-01

    Five GES-producing Enterobacteriaceae isolates that displayed an extended-spectrum β-lactamase (ESBL) phenotype harbored two GES variants: GES-7 ESBL and GES-6 carbapenemase. In all isolates, the two GES alleles were located on the same integron that was inserted into an 80-kb IncM1 self-conjugative plasmid. Whole-genome sequencing suggested in vivo horizontal gene transfer of the plasmid along with clonal diffusion of Enterobacter cloacae To our knowledge, this is the first description in Europe of clustered Enterobacteriaceae isolates carrying two GES β-lactamases, of which one has extended activity toward carbapenems. PMID:27216071