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1

Rapid in situ hybridization technique using 16S rRNA segments for detecting and differentiating the closely related gram-positive organisms Bacillus polymyxa and Bacillus macerans  

NASA Technical Reports Server (NTRS)

A rapid, sensitive, inexpensive in situ hybridization technique, using 30-mer 16S rRNA probes, can specifically differentiate two closely related Bacillus spp., B. polymyxa and B. macerans. The 16S rRNA probes were labeled with a rhodamine derivative (Texas Red), and quantitative fluorescence measurements were made on individual bacterial cells. The microscopic fields analyzed were selected by phase-contrast microscopy, and the fluorescence imaging analyses were performed on 16 to 67 individual cells. The labeled 16S rRNA probe, POL, whose sequence was a 100% match with B. polymyxa 16S rRNA but only a 60% match with B. macerans 16S rRNA, gave quantitative fluorescence ratio measurements that were 34.8-fold higher for B. polymyxa cells than for B. macerans cells. Conversely, the labeled probe, MAC, which matched B. polymyxa 16S rRNA in 86.6% of its positions and B. macerans 16S rRNA in 100% of its positions, gave quantitative fluorescence measurements that were 59.3-fold higher in B. macerans cells than in B. polymyxa cells. Control probes, whose 16S rRNA sequence segment (P-M) was present in both B. polymyxa and B. macerans as well as a panprokaryotic probe (16S), having a 100% match with all known bacteria, hybridized equally well with both organisms. These latter hybridizations generated very high fluorescence signals, but their comparative fluorescence ratios (the differences between two organisms) were low. The control paneukaryotic probe (28S), which had less than 30% identity for both B. macerans and B. polymyxa, did not hybridize with either organism.

Jurtshuk, R. J.; Blick, M.; Bresser, J.; Fox, G. E.; Jurtshuk, P. Jr

1992-01-01

2

The complete genome sequence of the gram-positive bacterium Bacillus subtilis  

Microsoft Academic Search

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large

F. Kunst; N. Ogasawara; I. Moszer; A. M. Albertini; G. Alloni; V. Azevedo; M. G. Bertero; P. Bessières; A. Bolotin; S. Borchert; R. Borriss; L. Boursier; A. Brans; M. Braun; S. C. Brignell; S. Bron; S. Brouillet; C. V. Bruschi; B. Caldwell; V. Capuano; N. M. Carter; S.-K. Choi; J.-J. Codani; I. F. Connerton; A. Danchin

1997-01-01

3

The complete genome sequence of the Gram-positive bacterium Bacillus subtilis  

Microsoft Academic Search

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large

F. Kunst; N. Ogasawara; I. Moszer; A. M. Albertini; G. Alloni; V. Azevedo; M. G. Bertero; P. Bessières; A. Bolotin; S. Borchert; R. Borriss; L. Boursier; A. Brans; M. Braun; S. C. Brignell; S. Bron; S. Brouillet; C. V. Bruschi; B. Caldwell; V. Capuano; N. M. Carter; S.-K. Choi; J.-J. Codani; I. F. Connerton; N. J. Cummings; R. A. Daniel; F. Denizot; K. M. Devine; A. Düsterhöft; S. D. Ehrlich; P. T. Emmerson; K. D. Entian; J. Errington; C. Fabret; E. Ferrari; D. Foulger; C. Fritz; M. Fujita; Y. Fujita; S. Fuma; A. Galizzi; N. Galleron; S.-Y. Ghim; P. Glaser; A. Goffeau; E. J. Golightly; G. Grandi; G. Guiseppi; B. J. Guy; K. Haga; J. Haiech; C. R. Harwood; A. Hénaut; H. Hilbert; S. Holsappel; S. Hosono; M.-F. Hullo; M. Itaya; L. Jones; B. Joris; D. Karamata; Y. Kasahara; M. Klaerr-Blanchard; C. Klein; Y. Kobayashi; P. Koetter; G. Koningstein; S. Krogh; M. Kumano; K. Kurita; A. Lapidus; S. Lardinois; J. Lauber; V. Lazarevic; S.-M. Lee; A. Levine; H. Liu; S. Masuda; C. Mauël; C. Médigue; N. Medina; R. P. Mellado; M. Mizuno; D. Moestl; S. Nakai; M. Noback; D. Noone; M. O'Reilly; K. Ogawa; A. Ogiwara; B. Oudega; S.-H. Park; V. Parro; T. M. Pohl; D. Portetelle; S. Porwollik; A. M. Prescott; E. Presecan; P. Pujic; B. Purnelle; G. Rapoport; M. Rieger; S. Reynolds; C. Rivolta; E. Rocha; B. Roche; M. Rose; Y. Sadaie; T. Sato; E. Scanlan; S. Schleich; R. Schroeter; F. Scoffone; J. Sekiguchi; A. Sekowska; S. J. Seror; P. Serror; B.-S. Shin; B. Soldo; A. Sorokin; E. Tacconi; T. Takagi; H. Takahashi; K. Takemaru; M. Takeuchi; A. Tamakoshi; T. Tanaka; P. Terpstra; A. Tognoni; V. Tosato; S. Uchiyama; M. Vandenbol; F. Vannier; A. Vassarotti; A. Viari; R. Wambutt; E. Wedler; H. Wedler; T. Weitzenegger; P. Winters; A. Wipat; H. Yamamoto; K. Yamane; K. Yasumoto; K. Yata; K. Yoshida; H.-F. Yoshikawa; E. Zumstein; H. Yoshikawa; A. Danchin

1997-01-01

4

Transformation of gram positive bacteria by sonoporation  

DOEpatents

The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

Yang, Yunfeng; Li, Yongchao

2014-03-11

5

Studies on the O3-initiated disinfection from Gram-positive bacteria Bacillus subtilis in aquatic systems  

Microsoft Academic Search

The kinetics of inactivation of Gram-positive strain, Bacillus subtilis in aquatic systems was investigated as function ozone aeration duration under varied conditions. Oxygen flow was in situ enriched with ozone using ozoniser, with [O3] ranging from (0.3 – 9.8) × 10 moles per liter of oxygen. The inactivation kinetics of B. subtilis followed pseudo–first-order kinetics with respect to microbe, under

Favourite N. Zuma; S. B. Jonnalagadda

2010-01-01

6

Extracellular vesicles produced by the Gram-positive bacterium Bacillus subtilis are disrupted by the lipopeptide surfactin.  

PubMed

Previously, extracellular vesicle production in Gram-positive bacteria was dismissed due to the absence of an outer membrane, where Gram-negative vesicles originate, and the difficulty in envisioning how such a process could occur through the cell wall. However, recent work has shown that Gram-positive bacteria produce extracellular vesicles and that the vesicles are biologically active. In this study, we show that Bacillus subtilis produces extracellular vesicles similar in size and morphology to other bacteria, characterized vesicles using a variety of techniques, provide evidence that these vesicles are actively produced by cells, show differences in vesicle production between strains, and identified a mechanism for such differences based on vesicle disruption. We found that in wild strains of B. subtilis, surfactin disrupted vesicles while in laboratory strains harbouring a mutation in the gene sfp, vesicles accumulated in the culture supernatant. Surfactin not only lysed B. subtilis vesicles, but also vesicles from Bacillus anthracis, indicating a mechanism that crossed species boundaries. To our knowledge, this is the first time a gene and a mechanism has been identified in the active disruption of extracellular vesicles and subsequent release of vesicular cargo in Gram-positive bacteria. We also identify a new mechanism of action for surfactin. PMID:24826903

Brown, Lisa; Kessler, Anne; Cabezas-Sanchez, Pablo; Luque-Garcia, Jose L; Casadevall, Arturo

2014-07-01

7

Daptomycin Dose-Effect Relationship against Resistant Gram-Positive Organisms  

PubMed Central

Daptomycin exhibits in vitro bactericidal activity against clinically significant gram-positive bacteria. We employed pharmacodynamic modeling to determine a once-daily dosing regimen of daptomycin that correlates to pharmacodynamic endpoints for different resistant gram-positive clinical strains. An in vitro pharmacodynamic model with an initial inoculum of 6 log10 CFU/ml was used to simulate daptomycin regimens ranging in dose from 0 to 9 mg/kg of body weight/day, with corresponding exposures reflecting free-daptomycin concentrations in serum. Bacterial density was profiled over 48 h for two methicillin-resistant Staphylococcus aureus (MRSA-67 and -R515), two glycopeptide intermediate-resistant S. aureus (GISA-992 and -147398), and two vancomycin-resistant Enterococcus faecium (VREF-12366 and -SF12047) strains. A sigmoid dose-response model was used to estimate the effective dose required to achieve 50% (ED50) and 80% (ED80) bacterial density reduction at 48 h. Daptomycin MICs for study isolates ranged from 0.125 to 4 ?g/ml. Model fitting resulted in an r2 of >0.80 for all tested isolates. Control growths at 48 h ranged from 7.3 to 8.5 log10 CFU/ml. Sigmoid relationships were not superimposable between categorical resistant species: ED50 and ED80 values were 1.9 and 3.1, 4.2 and 5.6, and 5.4 and 6.8 mg/kg for MRSA, GISA, and VREF isolates, respectively. Doses required to achieve ED50 and ED80 values correlated with MIC differences between tested organisms. Corresponding area under the concentration-time curve from 0 to 24 h/MIC exposure ratios demonstrated a wide range of ED80 values among the tested isolates. Doses ranging between 3 and 7 mg/kg produced significant bactericidal activity (ED80) against these multidrug-resistant S. aureus and E. faecium isolates. PMID:12709328

Cha, Raymond; Grucz Jr., Richard G.; Rybak, Michael J.

2003-01-01

8

A Pathway Closely Related to the d-Tagatose Pathway of Gram-Negative Enterobacteria Identified in the Gram-Positive Bacterium Bacillus licheniformis  

PubMed Central

We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus. PMID:23524682

Van der Heiden, Edwige; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M.; Galleni, Moreno; Joris, Bernard

2013-01-01

9

In vitro activity of the trinem sanfetrinem (GV104326) against gram-positive organisms.  

PubMed Central

The in vitro activity of the trinem sanfetrinem (formerly GV104326) (GV) was compared with that of vancomycin, ampicillin, and/or nafcillin against 287 gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and multiresistant enterococci, by the agar and microbroth dilution methods. GV demonstrated 2 to 16 times more activity than ampicillin and nafcillin against the majority of these organisms. The MIC range of GV was 16 to 64 micrograms/ml for 19 Enterococcus faecium strains that were highly resistant to ampicillin (ampicillin MIC range, 64 to 512 micrograms/ml) and vancomycin resistant and 0.25 to 32 micrograms/ml for resistant Rhodococcus spp. Similar activities (+/-1 dilution) were observed by either the agar or the broth microdilution method. GV demonstrated bactericidal activity against a beta-lactamase-producing Enterococcus faecalis strain and against two methicillin-susceptible Staphylococcus aureus strains in 10(5)-CFU/ml inocula. Synergy between GV and gentamicin was observed against an E. faecalis strain that lacked high-level gentamicin resistance. The activity of GV suggests this compound warrants further study. PMID:8878596

Singh, K V; Coque, T M; Murray, B E

1996-01-01

10

High osmolarity improves the electro-transformation efficiency of the gram-positive bacteria Bacillus subtilis and Bacillus licheniformis  

Microsoft Academic Search

A high osmolarity electroporation method has been developed for the efficient transformation of Bacillus subtilis and B. licheniformis. The presence of high concentrations of the osmoticums, sorbitol and mannitol, in the electroporation, growth and recovery media resulted in an approximately 5000-fold increase in the transformation efficiency of B. subtilis, with a maximum value of 1.4×106 transformants per ?g DNA. The

Gang-Ping Xue; Jennifer S Johnson; Brian P Dalrymple

1999-01-01

11

Identification of the sigmaB regulon of Bacillus cereus and conservation of sigmaB-regulated genes in low-GC-content gram-positive bacteria  

Microsoft Academic Search

The alternative sigma factor B has an important role in the acquisition of stress resistance in many gram-positive bacteria, including the food-borne pathogen Bacillus cereus. Here, we describe the identification of the set of B-regulated genes in B. cereus by DNA microarray analysis of the transcriptome upon a mild heat shock. Twenty-four genes could be identified as being B dependent

Willem van Schaik; Menno van der Voort; Douwe Molenaar; Roy Moezelaar; Vos de W. M; Tjakko Abee

2007-01-01

12

Novel Fastidious, Partially Acid-Fast, Anaerobic Gram-Positive Bacillus Associated with Abscess Formation and Recovered from Multiple Medical Centers  

PubMed Central

We report a novel anaerobe causing abscess in four patients at three hospitals. In the clinical specimen, bacilli were branching, Gram positive, and acid fast. The organism grew slowly and was not identified by 16S rRNA sequencing. Our findings support the description of a new genus and species of the suborder Corynebacterineae. PMID:24025902

Bell, M.; Bernard, K.; Lagacé-Wiens, P.; Schuetz, A. N.; Hartman, B.; McQuiston, J. R.; Wilson, D.; LaSalvia, M.; Ng, B.; Richter, S.; Taege, A.

2013-01-01

13

Expanding the Use of a Fluorogenic Method to Determine Activity and Mode of Action of Bacillus thuringiensis Bacteriocins Against Gram-Positive and Gram-Negative Bacteria  

PubMed Central

Previously we described a rapid fluorogenic method to measure the activity of five bacteriocins produced by Mexican strains of Bacillus thuringiensis against B. cereus 183. Here we standardize this method to efficiently determine the activity of bacteriocins against both Gram-positive and Gram-negative bacteria. It was determined that the crucial parameter required to obtain reproducible results was the number of cells used in the assay, that is, ~4?×?108?cell/mL and ~7?×?108?cell/mL, respectively, for target Gram-positive and Gram-negative bacteria. Comparative analyses of the fluorogenic and traditional well-diffusion assays showed correlation coefficients of 0.88 to 0.99 and 0.83 to 0.99, respectively, for Gram-positive and Gram-negative bacteria. The fluorogenic method demonstrated that the five bacteriocins of B. thuringiensis have bacteriolytic and bacteriostatic activities against all microorganisms tested, including clinically significant bacteria such as Listeria monocytogenes, Proteus vulgaris, and Shigella flexneri reported previously to be resistant to the antimicrobials as determined using the well-diffusion protocol. These results demonstrate that the fluorogenic assay is a more sensitive, reliable, and rapid method when compared with the well-diffusion method and can easily be adapted in screening protocols for bacteriocin production by other microorganisms. PMID:22919330

de la Fuente-Salcido, Norma M.; Barboza-Corona, J. Eleazar; Espino Monzón, A. N.; Pacheco Cano, R. D.; Balagurusamy, N.; Bideshi, Dennis K.; Salcedo-Hernández, Rubén

2012-01-01

14

Investigation of calcium-binding sites on the surfaces of selected gram-positive oral organisms.  

PubMed

Dental plaque is rich in anionic groups with a high calcium-binding capacity which may affect mineral dynamics at the tooth surface. The two major calcium-binding sites on Gram-positive cell surfaces are carboxylate groups (in proteins and peptidoglycan cross-links) and phosphate groups (in lipoteichoic and teichoic acid). Equilibrium dialysis was used to measure calcium-binding capacities of whole cells and purified cell-wall material (CWM) from Streptococcus mutans R9, Strep. oralis EF186, Strep. gordonii NCTC 7865, Strep. downei NCTC 11391, Actinomyces naeslundii WVU627 and Lactobacillus casei AC413. This material was stripped of phosphate (PS-CWM) and treated to mask carboxylate groups (CM-CWM). Whole-cell calcium-binding capacities ranged from 240 (Strep. downei) to 50 (L. casei) mu mol/g (dry wt). Differences in CWM, PS-CWM and CM-CWM calcium-binding capacities demonstrated the greater importance of phosphate in comparison with carboxylate groups in cell calcium binding. These data indicate that, in streptococci, calcium binding is predominantly phosphate group-based, especially in the teichoic acid-containing Strep. oralis. In the other species tested, calcium binding is predominantly carboxylate group-based. PMID:9403113

Rose, R K; Matthews, S P; Hall, R C

1997-09-01

15

Accentuate the (Gram) positive Victor Nizet  

E-print Network

EDITORIAL Accentuate the (Gram) positive Victor Nizet Received: 19 January 2010 /Accepted: 19 January 2010 # Springer-Verlag 2010 Keywords Gram-positive bacteria . Streptococcus . Special issue In the last two decades, Gram-positive bacteria have become the most common organisms associated

Nizet, Victor

16

Gram-positive siderophore-shuttle with iron-exchange from Fe-siderophore to apo-siderophore by Bacillus cereus YxeB  

PubMed Central

Small molecule iron-chelators, siderophores, are very important in facilitating the acquisition of Fe(III), an essential element for pathogenic bacteria. Many Gram-negative outer-membrane transporters and Gram-positive lipoprotein siderophore-binding proteins have been characterized, and the binding ability of outer-membrane transporters and siderophore-binding proteins for Fe-siderophores has been determined. However, there is little information regarding the binding ability of these proteins for apo-siderophores, the iron-free chelators. Here we report that Bacillus cereus YxeB facilitates iron-exchange from Fe-siderophore to apo-siderophore bound to the protein, the first Gram-positive siderophore-shuttle system. YxeB binds ferrioxamine B (FO, Fe-siderophore)/desferrioxamine B (DFO, apo-siderophore) in vitro. Disc-diffusion assays and growth assays using the yxeB mutant reveal that YxeB is responsible for importing the FO. Cr-DFO (a FO analog) is bound by YxeB in vitro and B. cereus imports or binds Cr-DFO in vivo. In vivo uptake assays using Cr-DFO and FO and growth assays using DFO and Cr-DFO show that B. cereus selectively imports and uses FO when DFO is present. Moreover, in vitro competition assays using Cr-DFO and FO clearly demonstrate that YxeB binds only FO, not Cr-DFO, when DFO is bound to the protein. Iron-exchange from FO to DFO bound to YxeB must occur when DFO is initially bound by YxeB. Because the metal exchange rate is generally first order in replacement ligand concentration, protein binding of the apo-siderophore acts to dramatically enhance the iron exchange rate, a key component of the Gram-positive siderophore-shuttle mechanism. PMID:23924612

Fukushima, Tatsuya; Allred, Benjamin E.; Sia, Allyson K.; Nichiporuk, Rita; Andersen, Ulla N.; Raymond, Kenneth N.

2013-01-01

17

Gram-positive siderophore-shuttle with iron-exchange from Fe-siderophore to apo-siderophore by Bacillus cereus YxeB.  

PubMed

Small molecule iron-chelators, siderophores, are very important in facilitating the acquisition of Fe(III), an essential element for pathogenic bacteria. Many Gram-negative outer-membrane transporters and Gram-positive lipoprotein siderophore-binding proteins have been characterized, and the binding ability of outer-membrane transporters and siderophore-binding proteins for Fe-siderophores has been determined. However, there is little information regarding the binding ability of these proteins for apo-siderophores, the iron-free chelators. Here we report that Bacillus cereus YxeB facilitates iron-exchange from Fe-siderophore to apo-siderophore bound to the protein, the first Gram-positive siderophore-shuttle system. YxeB binds ferrioxamine B (FO, Fe-siderophore)/desferrioxamine B (DFO, apo-siderophore) in vitro. Disc-diffusion assays and growth assays using the yxeB mutant reveal that YxeB is responsible for importing the FO. Cr-DFO (a FO analog) is bound by YxeB in vitro and B. cereus imports or binds Cr-DFO in vivo. In vivo uptake assays using Cr-DFO and FO and growth assays using DFO and Cr-DFO show that B. cereus selectively imports and uses FO when DFO is present. Moreover, in vitro competition assays using Cr-DFO and FO clearly demonstrate that YxeB binds only FO, not Cr-DFO, when DFO is bound to the protein. Iron-exchange from FO to DFO bound to YxeB must occur when DFO is initially bound by YxeB. Because the metal exchange rate is generally first order in replacement ligand concentration, protein binding of the apo-siderophore acts to dramatically enhance the iron exchange rate, a key component of the Gram-positive siderophore-shuttle mechanism. PMID:23924612

Fukushima, Tatsuya; Allred, Benjamin E; Sia, Allyson K; Nichiporuk, Rita; Andersen, Ulla N; Raymond, Kenneth N

2013-08-20

18

[Microbiological synthesis of [2H]-inosine with a high degree of isotopic enrichment by the gram-positive chemoheterotrophic bacterium Bacillus subtilis].  

PubMed

A 2H-labeled purine ribonucleoside inosine was microbiologically synthesized (yield, 3.9 g/L of culture liquid) using a deuterium-adapted strain ofthe gram-positive chemoheterotrophic bacterium Bacillus subtilis, cultivated in a heavy water medium with a high degree of deuteration (99.8 at % 2H) containing 2% hydrolysate of deuterated biomass of the methylotrophic bacterium Brevibacterium methylicum as a source of 2H-labeled growth substrate produced in an M9 minimal medium with 98% 2H20 and 2% [2H]-methanol. The inosine extracted from the culture liquid of the producer strain was fractionated by adsorption (desorption) on an activated carbon surface, extraction with 0.3 M ammonium-formate buffer (pH 8.9), subsequent crystallization in 80% ethanol, and ion exchange chromatography on a column with AG50WX 4 cation exchange resin equilibrated with 0.3 M ammonium-formate buffer containing 0.045 M NH4Cl. Fast atom bombardment (FAB) mass spectrometry demonstrated incorporation of five deuterium atoms in the inosine molecule (62.5% 2H), three of which were contained in the ribose moiety and two in the hypoxanthine moiety. PMID:23882944

Mosin, O V; Shvets, V I; Skladnev, D A; Ignatov, I

2013-01-01

19

Activity of Linezolid against 3,251 Strains of Uncommonly Isolated Gram-Positive Organisms: Report from the SENTRY Antimicrobial Surveillance Program?  

PubMed Central

Linezolid was tested against 32 species of uncommonly isolated gram-positive organisms (3,251 strains) by reference MIC methods and found to be highly active (MIC50 range, 0.25 to 2 ?g/ml; MIC90 range, 0.25 to 2 ?g/ml). Only one isolate (viridans group streptococcus; 0.03% of tested strains) was resistant to linezolid. PMID:17210770

Jones, Ronald N.; Stilwell, Matthew G.; Hogan, Patricia A.; Sheehan, Daniel J.

2007-01-01

20

Activity of Linezolid against 3,251 Strains of Uncommonly Isolated Gram-Positive Organisms: Report from the SENTRY Antimicrobial Surveillance Program  

Microsoft Academic Search

Linezolid was tested against 32 species of uncommonly isolated gram-positive organisms (3,251 strains) by reference MIC methods and found to be highly active (MIC50 range, 0.25 to 2 g\\/ml; MIC90 range, 0.25 to 2 g\\/ml). Only one isolate (viridans group streptococcus; 0.03% of tested strains) was resistant to linezolid.

Ronald N. Jones; Matthew G. Stilwell; Patricia A. Hogan; Daniel J. Sheehan

2007-01-01

21

Evaluation of a Microarray-Based Assay for Rapid Identification of Gram-Positive Organisms and Resistance Markers in Positive Blood Cultures  

PubMed Central

Rapid identification of pathogens directly from positive blood cultures can play a major role in reducing patient mortality rates. We evaluated the performance of the Verigene Gram-Positive Blood Culture (BC-GP) assay (Nanosphere Inc., Northbrook, IL) for detection of commonly isolated Gram-positive organisms as well as associated resistance markers from positive blood cultures. Positive blood cultures (VersaTREK; Trek Diagnostic Systems, Independence, OH) from 203 patients with Gram-positive organism infections were analyzed using the BC-GP assay within 12 h for the detection of 12 different organisms, including staphylococci, streptococci, and enterococci, as well as for the presence of 3 resistance markers (mecA, vanA, and vanB). Results were compared to those of routine laboratory methods for identification and susceptibility testing. For identification of organisms and detection of resistance markers in 178 monomicrobial positive blood cultures, the BC-GP assay showed 94% and 97% concordance, respectively, with routine methods. After 25 polymicrobial cultures were included, the results showed 92% and 96% agreement for identification and resistance markers, respectively, for a total of 203 positive cultures. In 6/25 polymicrobial cultures, at least 1 isolate was not detected. Concordance levels for detection of major pathogens such Staphylococcus aureus (n = 45) and enterococci (n = 19) were 98% and 95%, respectively. Agreement levels for detection of resistance markers such as mecA and vanA/B were 92% and 100%, respectively. The BC-GP assay is capable of providing rapid identification of Gram-positive cocci as well as detection of resistance markers directly from positive blood cultures at least 24 to 48 h earlier than conventional methods. PMID:23363838

Tibbetts, Robert J.; Agotesku, Adam; Fey, Margaret; Hensley, Rhonda; Meier, Frederick A.

2013-01-01

22

Optimizing Identification of Clinically Relevant Gram-Positive Organisms by Use of the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) can be used as a method for the rapid identification of microorganisms. This study evaluated the Bruker Biotyper (MALDI-TOF MS) system for the identification of clinically relevant Gram-positive organisms. We tested 239 aerobic Gram-positive organisms isolated from clinical specimens. We evaluated 4 direct-smear methods, including “heavy” (H) and “light” (L) smears, with and without a 1-?l direct formic acid (FA) overlay. The quality measure assigned to a MALDI-TOF MS identification is a numerical value or “score.” We found that a heavy smear with a formic acid overlay (H+FA) produced optimal MALDI-TOF MS identification scores and the highest percentage of correctly identified organisms. Using a score of ?2.0, we identified 183 of the 239 isolates (76.6%) to the genus level, and of the 181 isolates resolved to the species level, 141 isolates (77.9%) were correctly identified. To maximize the number of correct identifications while minimizing misidentifications, the data were analyzed using a score of ?1.7 for genus- and species-level identification. Using this score, 220 of the 239 isolates (92.1%) were identified to the genus level, and of the 181 isolates resolved to the species level, 167 isolates (92.2%) could be assigned an accurate species identification. We also evaluated a subset of isolates for preanalytic factors that might influence MALDI-TOF MS identification. Frequent subcultures increased the number of unidentified isolates. Incubation temperatures and subcultures of the media did not alter the rate of identification. These data define the ideal bacterial preparation, identification score, and medium conditions for optimal identification of Gram-positive bacteria by use of MALDI-TOF MS. PMID:23426925

McElvania TeKippe, Erin; Shuey, Sunni; Winkler, David W.; Butler, Meghan A.

2013-01-01

23

New insights into regulation of the tryptophan biosynthetic operon in Gram-positive bacteria.  

PubMed

The tryptophan operon of Bacillus subtilis serves as an excellent model for investigating transcription regulation in Gram-positive bacteria. In this article, we extend this knowledge by analyzing the predicted regulatory regions in the trp operons of other fully sequenced Gram-positive bacteria. Interestingly, it appears that in eight of the organisms examined, transcription of the trp operon appears to be regulated by tandem T-box elements. These regulatory elements have recently been described in the trp operons of two bacterial species. Single T-box elements are commonly found in Gram-positive bacteria in operons encoding aminoacyl tRNA synthetases and proteins performing other functions. Different regulatory mechanisms appear to be associated with variations of trp gene organization within the trp operon. PMID:15953653

Gutierrez-Preciado, A; Jensen, R A; Yanofsky, C; Merino, E

2005-08-01

24

Biosynthesis of Peptide Signals in Gram-Positive Bacteria  

Microsoft Academic Search

Gram-positive bacteria coordinate social behavior by sensing the extracellular level of peptide signals. These signals are biosynthesized through divergent pathways and some possess unusual functional chemistry as a result of posttranslational modifications. In this chapter, the biosynthetic pathways of Bacillus intracellular signaling peptides, Enterococcus pheromones, Bacillus subtilis competence pheromones, and cyclic peptide signals from Staphylococcus and other bacteria are covered.

Matthew Thoendel; Alexander R. Horswill

2010-01-01

25

Antimicrobial Activity of the Investigational Pleuromutilin Compound BC-3781 Tested against Gram-Positive Organisms Commonly Associated with Acute Bacterial Skin and Skin Structure Infections  

PubMed Central

BC-3781 is a novel semisynthetic pleuromutilin antimicrobial agent developed as an intravenous and oral therapy for acute bacterial skin and skin structure infections (ABSSSI) and respiratory tract infections (RTI). BC-3781 and comparator agents were tested by the broth microdilution method against 1,893 clinical Gram-positive organisms predominantly causing ABSSSI. BC-3781 exhibited potent activity against methicillin-resistant Staphylococcus aureus (MIC50/90, 0.12/0.25 ?g/ml), coagulase-negative staphylococci (MIC50/90, 0.06/0.12 ?g/ml), ?-hemolytic streptococci (MIC50/90, 0.03/0.06 ?g/ml), viridans group streptococci (MIC50/90, 0.12/0.5 ?g/ml), and Enterococcus faecium (including vancomycin-nonsusceptible strains) (MIC50/90, 0.12/2 ?g/ml). Compared with other antibiotics in use for the treatment of ABSSSI, BC-3781 displayed the lowest MICs and only a minimal potential for cross-resistance with other antimicrobial classes. PMID:22232289

Biedenbach, Douglas J.; Paukner, Susanne; Ivezic-Schoenfeld, Zrinka; Jones, Ronald N.

2012-01-01

26

Rapid method for distinction of gram-negative from gram-positive bacteria  

Microsoft Academic Search

A rapid method for distinction between gram-negative and grampositive bacteria by means of a 3% solution of potassium hydroxide is tested on 71 gram-positive and 55 gram-negative bacterial strains. The method proved reliable with one exception only, a Bacillus macerans strain. That strain was definately gram-negative on staining. Other Bacillus strains were proved gram-positive by the test, even those being

T. Gregersen

1978-01-01

27

Comparison of tryptophan biosynthetic operon regulation in different Gram-positive bacterial species.  

PubMed

The tryptophan biosynthetic operon has been widely used as a model system for studying transcription regulation. In Bacillus subtilis, the trp operon is primarily regulated by a tryptophan-activated RNA-binding protein, TRAP. Here we show that in many other Gram-positive species the trp operon is regulated differently, by tRNA(Trp) sensing by the RNA-based T-box mechanism, with T-boxes arranged in tandem. Our analyses reveal an apparent relationship between trp operon organization and the specific regulatory mechanism(s) used. PMID:17555843

Gutiérrez-Preciado, Ana; Yanofsky, Charles; Merino, Enrique

2007-09-01

28

Gram-positive toxic shock syndromes.  

PubMed

Toxic shock syndrome (TSS) is an acute, multi-system, toxin-mediated illness, often resulting in multi-organ failure. It represents the most fulminant expression of a spectrum of diseases caused by toxin-producing strains of Staphylococcus aureus and Streptococcus pyogenes (group A streptococcus). The importance of Gram-positive organisms as pathogens is increasing, and TSS is likely to be underdiagnosed in patients with staphylococcal or group A streptococcal infection who present with shock. TSS results from the ability of bacterial toxins to act as superantigens, stimulating immune-cell expansion and rampant cytokine expression in a manner that bypasses normal MHC-restricted antigen processing. A repetitive cycle of cell stimulation and cytokine release results in a cytokine avalanche that causes tissue damage, disseminated intravascular coagulation, and organ dysfunction. Specific therapy focuses on early identification of the illness, source control, and administration on antimicrobial agents including drugs capable of suppressing toxin production (eg, clindamycin, linezolid). Intravenous immunoglobulin has the potential to neutralise superantigen and to mitigate subsequent tissue damage. PMID:19393958

Lappin, Emma; Ferguson, Andrew J

2009-05-01

29

Antimicrobial Resistance in Gram-Positive Bacteria  

Microsoft Academic Search

Gram-positive bacteria are common causes of bloodstream and other infections in hospitalized patients in the United States, and the percentage of nosocomial bloodstream infections caused by antibiotic-resistant gram-positive bacteria is increasing. Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are of particular concern. In the United States, approximately 60% of staphylococcal infections in the intensive care unit are now caused

Louis B. Rice

2006-01-01

30

Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria  

PubMed Central

Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis. PMID:25419466

McBride, Shonna M.

2014-01-01

31

Ethanol production in Gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

Ingram, L.O.; Barbosa-Alleyne, M.D.F.

1996-01-09

32

Ethanol production in gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

1999-01-01

33

Ethanol production in Gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

1996-01-01

34

Ethanol production in Gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

Ingram, L.O.; Barbosa-Alleyne, M.D.F.

1999-06-29

35

Mechanical consequences of cell-wall turnover in the elongation of a Gram-positive bacterium.  

PubMed

A common feature of walled organisms is their exposure to osmotic forces that challenge the mechanical integrity of cells while driving elongation. Most bacteria rely on their cell wall to bear osmotic stress and determine cell shape. Wall thickness can vary greatly among species, with Gram-positive bacteria having a thicker wall than Gram-negative bacteria. How wall dimensions and mechanical properties are regulated and how they affect growth have not yet been elucidated. To investigate the regulation of wall thickness in the rod-shaped Gram-positive bacterium Bacillus subtilis, we analyzed exponentially growing cells in different media. Using transmission electron and epifluorescence microscopy, we found that wall thickness and strain were maintained even between media that yielded a threefold change in growth rate. To probe mechanisms of elongation, we developed a biophysical model of the Gram-positive wall that balances the mechanical effects of synthesis of new material and removal of old material through hydrolysis. Our results suggest that cells can vary their growth rate without changing wall thickness or strain by maintaining a constant ratio of synthesis and hydrolysis rates. Our model also indicates that steady growth requires wall turnover on the same timescale as elongation, which can be driven primarily by hydrolysis rather than insertion. This perspective of turnover-driven elongation provides mechanistic insight into previous experiments involving mutants whose growth rate was accelerated by the addition of lysozyme or autolysin. Our approach provides a general framework for deconstructing shape maintenance in cells with thick walls by integrating wall mechanics with the kinetics and regulation of synthesis and turnover. PMID:23746506

Misra, Gaurav; Rojas, Enrique R; Gopinathan, Ajay; Huang, Kerwyn Casey

2013-06-01

36

Virulence Plasmids of Nonsporulating Gram-Positive Pathogens  

PubMed Central

SUMMARY Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and surgical wound infections among hospitalized patients. These infections have become particularly problematic because many of the species causing them have become highly resistant to antibiotics. The role of mobile genetic elements, such as plasmids, in the dissemination of antibiotic resistance among Gram-positive bacteria has been well studied; less well understood is the role of mobile elements in the evolution and spread of virulence traits among these pathogens. While these organisms are leading agents of infection, they are also prominent members of the human commensal ecology. It appears that these bacteria are able to take advantage of the intimate association between host and commensal, via virulence traits that exacerbate infection and cause disease. However, evolution into an obligate pathogen has not occurred, presumably because it would lead to rejection of pathogenic organisms from the host ecology. Instead, in organisms that exist as both commensal and pathogen, selection has favored the development of mechanisms for variability. As a result, many virulence traits are localized on mobile genetic elements, such as virulence plasmids and pathogenicity islands. Virulence traits may occur within a minority of isolates of a given species, but these minority populations have nonetheless emerged as a leading problem in infectious disease. This chapter reviews virulence plasmids in nonsporulating Gram-positive bacteria, and examines their contribution to disease pathogenesis. PMID:25544937

Van Tyne, Daria; Gilmore, Michael S.

2014-01-01

37

Bacteriocins of gram-positive bacteria.  

PubMed Central

In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following posttranslational modification and depending on the pH, the molecules may either be released into the environment or remain bound to the cell wall. The antibacterial action against a sensitive cell of a gram-positive strain is produced principally by destabilization of membrane functions. Under certain conditions, gram-negative bacterial cells can also be sensitive to some of these molecules. By application of site-specific mutagenesis, bacteriocin variants which may differ in their antimicrobial spectrum and physicochemical characteristics can be produced. Research activity in this field has grown remarkably but sometimes with an undisciplined regard for conformity in the definition, naming, and categorization of these molecules and their genetic effectors. Some suggestions for improved standardization of nomenclature are offered. PMID:7603408

Jack, R W; Tagg, J R; Ray, B

1995-01-01

38

In Vitro and In Vivo Activities of PD 0305970 and PD 0326448, New Bacterial Gyrase/Topoisomerase Inhibitors with Potent Antibacterial Activities versus Multidrug-Resistant Gram-Positive and Fastidious Organism Groups?  

PubMed Central

PD 0305970 and PD 0326448 are new bacterial gyrase and topoisomerase inhibitors (quinazoline-2,4-diones) that possess outstanding in vitro and in vivo activities against a wide spectrum of bacterial species including quinolone- and multidrug-resistant gram-positive and fastidious organism groups. The respective MICs (?g/ml) for PD 0305970 capable of inhibiting ?90% of bacterial strains tested ranged from 0.125 to 0.5 versus staphylococci, 0.03 to 0.06 versus streptococci, 0.25 to 2 versus enterococci, and 0.25 to 0.5 versus Moraxella catarrhalis, Haemophilus influenzae, Listeria monocytogenes, Legionella pneumophila, and Neisseria spp. PD 0326448 MIC90s were generally twofold higher versus these same organism groups. Comparative quinolone MIC90 values were 4- to 512-fold higher than those of PD 0305970. In testing for frequency of resistance, PD 0305970 and levofloxacin showed low levels of development of spontaneous resistant mutants versus both Staphylococcus aureus and Streptococcus pneumoniae. Unlike quinolones, which target primarily gyrA and parC, analysis of resistant mutants in S. pneumoniae indicates that the likely targets of PD 0305970 are gyrB and parE. PD 0305970 demonstrated rapid bactericidal activity by in vitro time-kill testing versus streptococci. This bactericidal activity carried over to in vivo testing, where PD 0305970 and PD 0326448 displayed outstanding Streptococcus pyogenes 50% protective doses (PD50s) (oral dosing) of 0.7 and 3.6 mg/kg, respectively (ciprofloxacin and levofloxacin PD50s were >100 and 17.7 mg/kg, respectively). PD 0305970 was also potent in a pneumococcal pneumonia mouse infection model (PD50 = 3.2 mg/kg) and was 22-fold more potent than levofloxacin. PMID:17261623

Huband, Michael D.; Cohen, Michael A.; Zurack, Margaret; Hanna, Debra L.; Skerlos, Laura A.; Sulavik, Mark C.; Gibson, Glenn W.; Gage, Jeffrey W.; Ellsworth, Edmund; Stier, Michael A.; Gracheck, Stephen J.

2007-01-01

39

Management of Gram-Positive Bacterial Disease: Staphylococcus aureus , Streptococcal, Pneumococcal and Enterococcal Infections  

Microsoft Academic Search

\\u000a Gram-positive bacteria are a diverse group of organisms that are a major source of morbidity and mortality in patients with\\u000a cancer. The increasing use of long-term indwelling central catheters and cytotoxic chemotherapies has contributed to the emergence\\u000a of Gram-positive bacteria as the leading cause of bacteremia in cancer patients. These organisms are also among the foremost\\u000a causes of pneumonia, skin

Samuel Shelburne; Daniel M. Musher

40

Lipoprotein biogenesis in Gram-positive bacteria: knowing when to  

E-print Network

Lipoprotein biogenesis in Gram- positive bacteria: knowing when to hold `em, knowing when to fold Tyne, NE1 8ST, UK Gram-positive bacterial lipoproteins are a functionally diverse and important class of these proteins, their role in virulence in Gram-positive bacteria and their potential as vaccine candidates

Palmer, Tracy

41

Type IV Pili in Gram-Positive Bacteria  

PubMed Central

SUMMARY Type IV pili (T4P) are surface-exposed fibers that mediate many functions in bacteria, including locomotion, adherence to host cells, DNA uptake (competence), and protein secretion and that can act as nanowires carrying electric current. T4P are composed of a polymerized protein, pilin, and their assembly apparatuses share protein homologs with type II secretion systems in eubacteria and the flagella of archaea. T4P are found throughout Gram-negative bacterial families and have been studied most extensively in certain model Gram-negative species. Recently, it was discovered that T4P systems are also widespread among Gram-positive species, in particular the clostridia. Since Gram-positive and Gram-negative bacteria have many differences in cell wall architecture and other features, it is remarkable how similar the T4P core proteins are between these organisms, yet there are many key and interesting differences to be found as well. In this review, we compare the two T4P systems and identify and discuss the features they have in common and where they differ to provide a very broad-based view of T4P systems across all eubacterial species. PMID:24006467

Craig, Lisa

2013-01-01

42

Classification of Bacteriocins from Gram-Positive Bacteria  

NASA Astrophysics Data System (ADS)

Bacteriocins are ribosomally synthesised antimicrobial peptides produced by bacteria, including many Gram-positive species. The classification of bacteriocins from Gram-positive bacteria is complicated by their heterogeneity and thus, as the number of Gram-positive bacteriocins identified has continued to increase, classification schemes have had to continuously evolve. Here, we review the various classification approaches, both historical and current, their underlying scientific basis and their relative merit, and suggest a rational scheme given the state of the art.

Rea, Mary C.; Ross, R. Paul; Cotter, Paul D.; Hill, Colin

43

Regulation of Apoptosis by Gram-Positive Bacteria  

PubMed Central

Apoptosis, or programmed cell death (PCD), is an important physiological mechanism, through which the human immune system regulates homeostasis and responds to diverse forms of cellular damage. PCD may also be involved in immune counteraction to microbial infection. Over the past decade, the amount of research on bacteria-induced PCD has grown tremendously, and the implications of this mechanism on immunity are being elucidated. Some pathogenic bacteria actively trigger the suicide response in critical lineages of leukocytes that orchestrate both the innate and adaptive immune responses; other bacteria proactively prevent PCD to benefit their own survival and persistence. Currently, the microbial virulence factors, which represent the keys to unlocking the suicide response in host cells, are a primary focus of this field. In this review, we discuss these bacterial “apoptosis regulatory molecules” and the apoptotic events they either trigger or prevent, the host target cells of this regulatory activity, and the possible ramifications for immunity to infection. Gram-positive pathogens including Staphylococcus, Streptococcus, Bacillus, Listeria, and Clostridia species are discussed as important agents of human infection that modulate PCD pathways in eukaryotic cells. PMID:19081777

Ulett, Glen C.; Adderson, Elisabeth E.

2008-01-01

44

Methods for targetted mutagenesis in gram-positive bacteria  

SciTech Connect

The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

Yang, Yunfeng

2014-05-27

45

Distinct localization of the complement C5b-9 complex on Gram-positive bacteria.  

PubMed

The plasma proteins of the complement system fulfil important immune defence functions, including opsonization of bacteria for phagocytosis, generation of chemo-attractants and direct bacterial killing via the Membrane Attack Complex (MAC or C5b-9). The MAC is comprised of C5b, C6, C7, C8, and multiple copies of C9 that generate lytic pores in cellular membranes. Gram-positive bacteria are protected from MAC-dependent lysis by their thick peptidoglycan layer. Paradoxically, several Gram-positive pathogens secrete small proteins that inhibit C5b-9 formation. In this study, we found that complement activation on Gram-positive bacteria in serum results in specific surface deposition of C5b-9 complexes. Immunoblotting revealed that C9 occurs in both monomeric and polymeric (SDS-stable) forms, indicating the presence of ring-structured C5b-9. Surprisingly, confocal microscopy demonstrated that C5b-9 deposition occurs at specialized regions on the bacterial cell. On Streptococcus pyogenes, C5b-9 deposits near the division septum whereas on Bacillus subtilis the complex is located at the poles. This is in contrast to C3b deposition, which occurs randomly on the bacterial surface. Altogether, these results show a previously unrecognized interaction between the C5b-9 complex and Gram-positive bacteria, which might ultimately lead to a new model of MAC assembly and functioning. PMID:23869880

Berends, Evelien T M; Dekkers, Johanna F; Nijland, Reindert; Kuipers, Annemarie; Soppe, Jasper A; van Strijp, Jos A G; Rooijakkers, Suzan H M

2013-12-01

46

Chocolate agar, a differential medium for gram-positive cocci.  

PubMed Central

Reactions incurred on chocolate agar by gram-positive cocci were correlated with species identity. Darkening and clearing of the medium was usually associated with the species Staphylococcus epidermidis, Staphylococcus aureus, Staphylococcus simulans, and Streptococcus faecalis. Yellowing of chocolate agar was associated with alpha-hemolytic species of Streptococcus. The study demonstrated that reactions occurring on chocolate agar are useful in identifying gram-positive cocci. PMID:6490866

Gunn, B A

1984-01-01

47

An identification scheme for rapidly and aerobically growing gram-positive rods.  

PubMed

An identification scheme for aerobically growing Gram-positive rods (genera Actinomyces, Arcanobacterium, Aureobacterium, Bacillus, Brevibacterium, Cellulomonas, Corynebacterium, Dermabacter, Erysipelothrix, Gardnerella, Lactobacillus, Listeria, Microbacterium, Oerskovia, Propionibacterium, Rhodococcus, Rothia, Turicella, as well as unnamed CDC groups, Clostridium tertium, and Mycobacterium fortuitum/chelonae) is presented. It is derived from the Hollis-Weaver scheme and uses catalase, oxidative/fermentative carbohydrate metabolism and motility as primary reactions. Tests for lipophilism, nitrate reduction, urease, esculin hydrolysis, the CAMP reaction, acid formation from five carbohydrates, as well as for some facultative reactions should lead to a correct diagnosis based on information available at the end of 1995. PMID:8837385

von Graevenitz, A; Funke, G

1996-07-01

48

Sequence characterization of 5S ribosomal RNA from eight gram positive procaryotes.  

PubMed

The available comparative data on procaryotic 5S rRNA was extended through sequencing studies of eight gram positive procaryotes. Complete nucleotide sequences were presented for 5S rRNA from Bacillus subtilis, B. firmus, B. pasteurii, B. brevis, Lactobacillus brevis and Streptococcus faecalis. In addition, 5S rRNA oligonucleotide catalogs and partial sequence data were provided for B. cereus and Sporosarcina ureae. These sequences and catalogs were discussed in terms of known features of procaryotic 5S rRNA architecture. PMID:823342

Woese, C R; Luehrsen, K R; Pribula, C D; Fox, G E

1976-08-01

49

Gram-positive bacterial resistance: future treatment options.  

PubMed

Gram-positive infections are a major burden on patients and healthcare systems globally, and the need to treat these infections correctly in an empirical manner has become paramount. Further complicating this changing etiology is the emergence of resistant strains which are no longer predictably susceptible to standard first-line antimicrobials such as oxacillin or vancomycin. Thus, new agents such as linezolid have been developed to alleviate the 'guesswork' of initial empirical prescribing in infections where Gram-positive pathogens may be present. Future agents also being developed for multiresistant Gram-positive infections include evernimicin antibiotics, daptomycin, oritavancin, glycylcyclines and novel broad-spectrum cephalosporins; however, these are still in the development phase. PMID:14508878

Bassetti, Matteo; Melica, Giovanna; Di Biagio, Antonio; Rosso, Raffaella; Gatti, Giorgio; Bassetti, Dante

2003-08-01

50

Wall Teichoic Acids of Gram-Positive Bacteria  

PubMed Central

The peptidoglycan layers of many gram-positive bacteria are densely functionalized with anionic glycopolymers called wall teichoic acids (WTAs). These polymers play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of gram-positive bacterial physiology. Additionally, WTAs are important in pathogenesis and play key roles in antibiotic resistance. We provide an overview of WTA structure and biosynthesis, review recent studies on the biological roles of these polymers, and highlight remaining questions. We also discuss prospects for exploiting WTA biosynthesis as a target for new therapies to overcome resistant infections. PMID:24024634

Brown, Stephanie; Santa Maria, John P.; Walker, Suzanne

2013-01-01

51

Screening genomes of Gram-positive bacteria for  

E-print Network

Screening genomes of Gram-positive bacteria for double-glycine-motif- containing peptides Secreted-positive bacteria, the double-glycine (GG) motif plays a key role in many peptide secretion systems involved Microbiology Comment #12;peptides and class II bacteriocins, produced by streptococci and lactic acid bacteria

52

Daptomycin: a novel lipopeptide antibiotic against Gram-positive pathogens  

PubMed Central

The aim of this review is to summarize the historical background of drug resistance of Gram-positive pathogens as well as to describe in detail the novel lipopeptide antibiotic daptomycin. Pharmacological and pharmacokinetic aspects are reviewed and the current clinical use of daptomycin is presented. Daptomycin seems to be a reliable drug in the treatment of complicated skin and skin structure infections, infective right-sided endocarditis, and bacteremia caused by Gram-positive agents. Its unique mechanism of action and its low resistance profile, together with its rapid bactericidal action make it a favorable alternative to vancomycin in multi-drug resistant cocci. The role of daptomycin in the treatment of prosthetic material infections, osteomyelitis, and urogenital infections needs to be evaluated in randomized clinical trials. PMID:21694898

Beiras-Fernandez, Andres; Vogt, Ferdinand; Sodian, Ralf; Weis, Florian

2010-01-01

53

Psychrophilicity of Bacillus psychrosaccharolyticus: a proteomic study.  

PubMed

Psychrophilicity of Gram-positive bacterium, Bacillus psychrosaccharolyticus was investigated in a proteomic approach. One hundred and thirty-one protein spots were analyzed by electrospray ionization-quadrupole-time of flight-tandem mass spectrometry and identified using an unpublished translated contig database as well as a nonredundant Gram-positive bacteria protein database from NCBI because of the lack of a genome sequence of this organism. Results focused on proteomic behavior of cold-response show that global up-regulation of metabolic functions and protective mechanism by stress responses might play a major role in psychrophilicity of B. psychrosaccharolyticus. PMID:15529406

Seo, Jong Bok; Kim, Hye Sook; Jung, Gyoo Yeol; Nam, Myung Hee; Chung, Joo Hee; Kim, Jin Young; Yoo, Jong Shin; Kim, Chan Wha; Kwon, Ohoak

2004-11-01

54

Complete Genome Sequence of Bacillus megaterium Myophage Mater  

PubMed Central

Bacillus megaterium is a ubiquitous, soil inhabiting Gram-positive bacterium that is a common model organism and is used in industrial applications for protein production. The following reports the complete sequencing and annotation of the genome of B. megaterium myophage Mater and describes the major features identified. PMID:25593262

Lancaster, Jacob C.; Hodde, Mary K.; Hernandez, Adriana C.

2015-01-01

55

Recognition of U-rich RNA by Hfq from the Gram-positive pathogen Listeria monocytogenes  

PubMed Central

Hfq is a post-transcriptional regulator that binds U- and A-rich regions of sRNAs and their target mRNAs to stimulate their annealing in order to effect translation regulation and, often, to alter their stability. The functional importance of Hfq and its RNA-binding properties are relatively well understood in Gram-negative bacteria, whereas less is known about the RNA-binding properties of this riboregulator in Gram-positive species. Here, we describe the structure of Hfq from the Gram-positive pathogen Listeria monocytogenes in its RNA-free form and in complex with a U6 oligoribonucleotide. As expected, the protein takes the canonical hexameric toroidal shape of all other known Hfq structures. The U6 RNA binds on the “proximal face” in a pocket formed by conserved residues Q9, N42, F43, and K58. Additionally residues G5 and Q6 are involved in protein-nucleic and inter-subunit contacts that promote uracil specificity. Unlike Staphylococcus aureus (Sa) Hfq, Lm Hfq requires magnesium to bind U6 with high affinity. In contrast, the longer oligo-uridine, U16, binds Lm Hfq tightly in the presence or absence of magnesium, thereby suggesting the importance of additional residues on the proximal face and possibly the lateral rim in RNA interaction. Intrinsic tryptophan fluorescence quenching (TFQ) studies reveal, surprisingly, that Lm Hfq can bind (GU)3G and U6 on its proximal and distal faces, indicating a less stringent adenine-nucleotide specificity site on the distal face as compared to the Gram-positive Hfq proteins from Sa and Bacillus subtilis and suggesting as yet uncharacterized RNA-binding modes on both faces. PMID:25150227

Kovach, Alexander R.; Hoff, Kirsten E.; Canty, John T.; Orans, Jillian

2014-01-01

56

Optimization of Fluorescent Tools for Cell Biology Studies in Gram-Positive Bacteria  

PubMed Central

The understanding of how Gram-positive bacteria divide and ensure the correct localization of different molecular machineries, such as those involved in the synthesis of the bacterial cell surface, is crucial to design strategies to fight bacterial infections. In order to determine the correct subcellular localization of fluorescent proteins in Streptococcus pneumoniae, we have previously described tools to express derivatives of four fluorescent proteins, mCherry, Citrine, CFP and GFP, to levels that allow visualization by fluorescence microscopy, by fusing the first ten amino acids of the S. pneumoniae protein Wze (the i-tag), upstream of the fluorescent protein. Here, we report that these tools can also be used in other Gram-positive bacteria, namely Lactococcus lactis, Staphylococcus aureus and Bacillus subtilis, possibly due to optimized translation rates. Additionally, we have optimized the i-tag by testing the effect of the first ten amino acids of other pneumococcal proteins in the increased expression of the fluorescent protein Citrine. We found that manipulating the structure and stability of the 5? end of the mRNA molecule, which may influence the accessibility of the ribosome, is determinant to ensure the expression of a strong fluorescent signal. PMID:25464377

Henriques, Mafalda X.; Gomes, João Paulo; Filipe, Sérgio R.

2014-01-01

57

Synthetic Teichoic Acid Conjugate Vaccine against Nosocomial Gram-Positive Bacteria  

PubMed Central

Lipoteichoic acids (LTA) are amphiphilic polymers that are important constituents of the cell wall of many Gram-positive bacteria. The chemical structures of LTA vary among organisms, albeit in the majority of Gram-positive bacteria the LTAs feature a common poly-1,3-(glycerolphosphate) backbone. Previously, the specificity of opsonic antibodies for this backbone present in some Gram-positive bacteria has been demonstrated, suggesting that this minimal structure may be sufficient for vaccine development. In the present work, we studied a well-defined synthetic LTA-fragment, which is able to inhibit opsonic killing of polyclonal rabbit sera raised against native LTA from Enterococcus faecalis 12030. This promising compound was conjugated with BSA and used to raise rabbit polyclonal antibodies. Subsequently, the opsonic activity of this serum was tested in an opsonophagocytic assay and specificity was confirmed by an opsonophagocytic inhibition assay. The conjugated LTA-fragment was able to induce specific opsonic antibodies that mediate killing of the clinical strains E. faecalis 12030, Enterococcus faecium E1162, and community-acquired Staphylococcus aureus strain MW2 (USA400). Prophylactic immunization with the teichoic acid conjugate and with the rabbit serum raised against this compound was evaluated in active and passive immunization studies in mice, and in an enterococcal endocarditis rat model. In all animal models, a statistically significant reduction of colony counts was observed indicating that the novel synthetic LTA-fragment conjugate is a promising vaccine candidate for active or passive immunotherapy against E. faecalis and other Gram-positive bacteria. PMID:25333799

Laverde, Diana; Wobser, Dominique; Romero-Saavedra, Felipe; Hogendorf, Wouter; van der Marel, Gijsbert; Berthold, Martin; Kropec, Andrea; Codee, Jeroen; Huebner, Johannes

2014-01-01

58

Acyl-sulfamates Target the Essential Glycerol-Phosphate Acyltransferase (PlsY) in Gram-Positive Bacteria  

PubMed Central

PlsY is the essential first step in membrane phospholipid synthesis of Gram-positive pathogens. PlsY catalyzes the transfer of the fatty acid from acyl-phosphate to the 1-position of glycerol-3-phosphate to form the first intermediate in membrane biogenesis. A series of non-metabolizable, acyl-sulfamate analogs of the acyl-phosphate PlsY substrate were prepared and evaluated as inhibitors of Staphylococcus aureus PlsY and for their Gram-positive antibacterial activities. From this series phenyl (8-phenyloctanoyl) sulfamate had the best overall profile, selectively inhibiting S. aureus phospholipid biosynthesis and causing the accumulation of both long-chain fatty acids and acyl-acyl carrier protein intermediates demonstrating that PlsY was the primary cellular target. Bacillus anthracis was unique in being more potently inhibited by long chain acyl-sulfamates than other bacterial species. However, it is shown that Bacillus anthracis PlsY is not more sensitive to the acyl-sulfamates than S. aureus PlsY. Metabolic profiling showed that B. anthracis growth inhibition by the acyl-sulfamates was not specific for lipid synthesis illustrating that the amphipathic acyl-sulfamates can also have off-target effects in Gram-positive bacteria. Nonetheless, this study further advances PlsY as a druggable target for the development of novel antibacterial therapeutics, through the discovery and validation of the probe compound phenyl (8-phenyloctanoyl) sulfamate as a S. aureus PlsY inhibitor. PMID:22795901

Cherian, Philip; Yao, Jiangwei; Leonardi, Roberta; Maddox, Marcus M.; Luna, Vicki A.; Rock, Charles O.; Lee, Richard E.

2012-01-01

59

Surviving the Acid Test: Responses of Gram-Positive Bacteria to Low pH  

PubMed Central

Gram-positive bacteria possess a myriad of acid resistance systems that can help them to overcome the challenge posed by different acidic environments. In this review the most common mechanisms are described: i.e., the use of proton pumps, the protection or repair of macromolecules, cell membrane changes, production of alkali, induction of pathways by transcriptional regulators, alteration of metabolism, and the role of cell density and cell signaling. We also discuss the reponses of Listeria monocytogenes, Rhodococcus, Mycobacterium, Clostridium perfringens, Staphylococcus aureus, Bacillus cereus, oral streptococci, and lactic acid bacteria to acidic environments and outline ways in which this knowledge has been or may be used to either aid or prevent bacterial survival in low-pH environments. PMID:12966143

Cotter, Paul D.; Hill, Colin

2003-01-01

60

Transformation of the Gram-positive honey bee pathogen, Paenibacillus larvae, by electroporation.  

PubMed

In this study we developed an electrotransformation method for use with the Gram-positive bacterium Paenibacillus larvae-a deadly pathogen of honey bees. Combining multiple Bacillus electrotransformation methods to generate an initial protocol, we then optimized the following parameters for use with P. larvae: cell density of culture at harvest time, contents of the washing/electroporation solution, field strength of the electrical pulse, recovery growth medium, and recovery time period. With the optimized method, we achieved an average transformation efficiency of 1.9x10(5) transformants/mug DNA. The method is substantially different from the only other electrotransformation method for a Paenibacillus species found in the literature. This work should facilitate the study of the several previously discovered natural plasmids of P. larvae, and is a step toward developing a genetic system for this species. PMID:18687369

Murray, K Daniel; Aronstein, Katherine A

2008-10-01

61

Oritavancin - a new semisynthetic lipoglycopeptide agent to tackle the challenge of resistant gram positive pathogens.  

PubMed

Natural glycopeptide antibiotics like vancomycin and teicoplanin have played a significant role in countering the threat posed by Gram-positive bacterial infections. The emergence of resistance to glycopeptides among enterococci and staphylococci has prompted the search for second-generation drugs of this class and semi-synthetic derivatives are currently under clinical trials. Antimicrobial resistance among Gram-positive organisms has been increasing steadily during the past several decades and the current development of antibiotics falls short of meeting the needs. Oritavancin (LY-333328 diphosphate), a promising novel second-generation semisynthetic lipoglycopeptide, has a mechanism of action similar to that of other glycopeptides. It has concentration-dependent activity against a variety of Gram-positive organisms specially methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate resistant Staphylococcus aureus (VISA), Streptococcus pneumoniae and vancomycin-resistant enterococcus. It is rapidly bactericidal against many species and in particular for enterococci where vancomycin and teicoplanin are only bacteriostatic even against susceptible strains. The pharmacokinetic profile of oritavancin has not been fully described; however, oritavancin has a long half-life of about 195.4 hours and is slowly eliminated by renal means. Oritavancin is not metabolized by the liver in animals. Oritavancin will most probably be prescribed as a once-daily dose and it demonstrates concentration-dependent bactericidal activity. Oritavancin has demonstrated preliminary safety and efficacy in Phase I and II clinical trials. In a Phase III clinical trial, oritavancin has achieved the primary efficacy end point in the treatment of complicated Gram-positive skin and skin-structure infections. To date, adverse events have been mild and limited; the most common being administration site complaints, headache, rhinitis, dry skin, pain, increases in liver transaminases and accumulation of free cholesterol and phospholipids in phagocytic (macrophages) and nonphagocytic (fibroblast) cells. Oritavancin appears to be a promising antimicrobial alternative to vancomycin (with additional activity against Staphylococcus and Enterococcus resistant to vancomycin) for the treatment of complicated Gram-positive skin and skin-structure infections. Additional clinical data are required to fully explore its use. PMID:24035967

Das, Biswadeep; Sarkar, Chayna; Schachter, Jeffrey

2013-09-01

62

Fate study of water-borne gram positive vegetative bacterial cells with Raman microscopy  

NASA Astrophysics Data System (ADS)

We present an initial bacterial fate study of Gram positive vegetative cells suspended in water and stored at ambient room temperature via Raman spectroscopy monitoring. Two types of cells were considered for this study: vegetative cells of Bacillus cereus, Bacillus thuringiensis which contain the polyhydroxybutyric acid (PHBA) as an energy storage compound and Bacillus subtlilis cells which do not. The cells were cultured specifically for this project. Immediately following the culturing phase, the bacteria were extracted, cleaned and at the onset of the study were suspended in de-ionized water and stored at room temperature. Aliquots of suspensions were deposited onto aluminum slides at different times and allowed to dry for Raman analysis. Spectra from multiple regions of each dried spot and each deposit time were acquired along with the bright-field and fluorescence images. Results were examined to investigate the effect of suspension time on the spectral signatures as well as the fate behavior of the three types of cells investigated. The cells were monitored daily for over a 14 period during which time the onset of starvation induced sporulation was observed.

Guicheteau, Jason; Tripathi, Ashish; Minter, Jennifer; Wilcox, Phillip; Christesen, Steven

2010-04-01

63

SubtiWiki—a comprehensive community resource for the model organism Bacillus subtilis  

PubMed Central

In the post-genomic era, most components of a cell are known and they can be quantified by large-scale functional genomics approaches. However, genome annotation is the bottleneck that hampers our understanding of living cells and organisms. Up-to-date functional annotation is of special importance for model organisms that provide a frame of reference for studies with other relevant organisms. We have generated a Wiki-type database for the Gram-positive model bacterium Bacillus subtilis, SubtiWiki (http://subtiwiki.uni-goettingen.de/). This Wiki is centered around the individual genes and gene products of B. subtilis and provides information on each aspect of gene function and expression as well as protein activity and its control. SubtiWiki is accompanied by two companion databases SubtiPathways and SubtInteract that provide graphical representations of B. subtilis metabolism and its regulation and of protein–protein interactions, respectively. The diagrams of both databases are easily navigatable using the popular Google maps API, and they are extensively linked with the SubtiWiki gene pages. Moreover, each gene/gene product was assigned to one or more functional categories and transcription factor regulons. Pages for the specific categories and regulons provide a rapid overview of functionally related genes/proteins. Today, SubtiWiki can be regarded as one of the most complete inventories of knowledge on a living organism in one single resource. PMID:22096228

Mäder, Ulrike; Schmeisky, Arne G.; Flórez, Lope A.; Stülke, Jörg

2012-01-01

64

Identification and analysis of DNA-binding transcription factors in Bacillus subtilis and other Firmicutes- a genomic approach  

Microsoft Academic Search

BACKGROUND: Bacillus subtilis is one of the best-characterized organisms in Gram-positive bacteria. It represents a paradigm of gene regulation in bacteria due its complex life style (which could involve a transition between stages as diverse as vegetative cell and spore formation). In order to gain insight into the organization and evolution of the B. subtilis regulatory network and to provide

Samadhi Moreno-Campuzano; Sarath Chandra Janga; Ernesto Pérez-Rueda

2006-01-01

65

Two Active Forms of UDP-N-Acetylglucosamine Enolpyruvyl Transferase in Gram-Positive Bacteria  

PubMed Central

Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts were made to construct a double-deletion strain, no mutants were obtained. This indicates that both genes encode active enzymes that can substitute for each other, but that the presence of a MurA function is essential to the organism. The two genes were further cloned and overexpressed, and the enzymes they encode were purified. Both enzymes catalyzed the transfer of enolpyruvate from phosphoenolpyruvate to UDP-N-acetylglucosamine, confirming they are both active UDP-N-acetylglucosamine enolpyruvyl transferases. The catalytic parameters of the two enzymes were similar, and they were both inhibited by the antibiotic fosfomycin. PMID:10894720

Du, Wensheng; Brown, James R.; Sylvester, Daniel R.; Huang, Jianzhong; Chalker, Alison F.; So, Chi Y.; Holmes, David J.; Payne, David J.; Wallis, Nicola G.

2000-01-01

66

Two active forms of UDP-N-acetylglucosamine enolpyruvyl transferase in gram-positive bacteria.  

PubMed

Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts were made to construct a double-deletion strain, no mutants were obtained. This indicates that both genes encode active enzymes that can substitute for each other, but that the presence of a MurA function is essential to the organism. The two genes were further cloned and overexpressed, and the enzymes they encode were purified. Both enzymes catalyzed the transfer of enolpyruvate from phosphoenolpyruvate to UDP-N-acetylglucosamine, confirming they are both active UDP-N-acetylglucosamine enolpyruvyl transferases. The catalytic parameters of the two enzymes were similar, and they were both inhibited by the antibiotic fosfomycin. PMID:10894720

Du, W; Brown, J R; Sylvester, D R; Huang, J; Chalker, A F; So, C Y; Holmes, D J; Payne, D J; Wallis, N G

2000-08-01

67

Characterization of a pyridine-degrading branched Gram-positive bacterium isolated from the anoxic zone of an oil shale column  

Microsoft Academic Search

From the anoxic zone of an oil shale leachate column three pyridine-degrading bacterial strains were isolated. Two strains were Gram-negative facultative anaerobic rods and one strain was a branched Gram-positive bacterium. The branched Gram-positive strain had the best pyridine-degrading ability. This organism was aerobic, non-motile, catalase positive, oxidase negative, and had no flagellum. The G+C content of the DNA was

Sung-Taik Lee; Seung-Bong Lee; Yong-Ha Park

1991-01-01

68

Relevance of GC content to the conservation of DNA polymerase III/mismatch repair system in Gram-positive bacteria  

PubMed Central

The mechanism of DNA replication is one of the driving forces of genome evolution. Bacterial DNA polymerase III, the primary complex of DNA replication, consists of PolC and DnaE. PolC is conserved in Gram-positive bacteria, especially in the Firmicutes with low GC content, whereas DnaE is widely conserved in most Gram-negative and Gram-positive bacteria. PolC contains two domains, the 3?-5?exonuclease domain and the polymerase domain, while DnaE only possesses the polymerase domain. Accordingly, DnaE does not have the proofreading function; in Escherichia coli, another enzyme DnaQ performs this function. In most bacteria, the fidelity of DNA replication is maintained by 3?-5? exonuclease and a mismatch repair (MMR) system. However, we found that most Actinobacteria (a group of Gram-positive bacteria with high GC content) appear to have lost the MMR system and chromosomes may be replicated by DnaE-type DNA polymerase III with DnaQ-like 3?-5? exonuclease. We tested the mutation bias of Bacillus subtilis, which belongs to the Firmicutes and found that the wild type strain is AT-biased while the mutS-deletant strain is remarkably GC-biased. If we presume that DnaE tends to make mistakes that increase GC content, these results can be explained by the mutS deletion (i.e., deletion of the MMR system). Thus, we propose that GC content is regulated by DNA polymerase and MMR system, and the absence of polC genes, which participate in the MMR system, may be the reason for the increase of GC content in Gram-positive bacteria such as Actinobacteria. PMID:24062730

Akashi, Motohiro; Yoshikawa, Hirofumi

2013-01-01

69

Vancomycin-resistant gram-positive cocci isolated from the saliva of wild songbirds.  

PubMed

We analyzed highly vancomycin-resistant Gram-positive bacteria isolated from the saliva of migratory songbirds captured, sampled, and released from a bird-banding station in western Kansas. Individual bacterial isolates were identified by partial 16S rRNA sequencing. Most of the bacteria in this study were shown to be Staphylococcus succinus with the majority being isolated from the American Robin. Some of these bacteria were shown to carry vanA, vanB, and vanC vancomycin-resistance genes and have the ability to form biofilms. One of the van gene-carrying isolates is also coagulase positive, which is normally considered a virulence factor. Other organisms isolated included Staphylococcus saprophyticus as well as Enterococcus gallinarum. Given the wide range of the American Robin and ease of horizontal gene transfer between Gram-positive cocci, we postulate that these organisms could serve as a reservoir of vancomycin-resistance genes capable of transferring to human pathogens. PMID:23224296

Ishihara, Shingo; Bitner, Jessica J; Farley, Greg H; Gillock, Eric T

2013-04-01

70

Effect of Azasteroids on Gram-Positive Bacteria  

PubMed Central

A group of nitrogen-containing steroids closely related in structure was screened for antibacterial activity, by use of Bacillus subtilis and Sarcina lutea as the test organisms. The most active compounds were cholesterol derivatives containing a tertiary or quaternary nitrogen in, or attached to, the A ring. Similar methyltestosterone or progesterone derivatives were inactive. All of the cholesterol derivatives that inhibited growth were surfactant, and, structurally, they would be classified as cationic detergents. Some of the inactive compounds were surfactant, but, structurally, they would be classified as nonionic detergents. Certain features of the antibacterial activity of one of the active steroids—ND 212 (4-dimethylaminoethyl-4-aza-5-cholesten-3-one methiodide)—were studied. Growth of a culture of B. subtilis containing 5 × 107 cells per milliliter was inhibited by 1 ?g/ml (1.7 × 10?6m) of ND 212. The amount of growth inhibition was directly related to both cell and steroid concentration. Loss of viability was rapid and irreversible. With B. subtilis, cell lysis was observed. With S. lutea grown in C14-glucose, ND 212 caused release into the media of up to 25% of the cellular radioactivity. Extensive leakage occurred before loss of viability was observed. At bacteriostatic azasteroid concentrations, there was little leakage. ND 212 was readily bound in large amounts to B. subtilis cells. Inactive azasteroids were bound poorly. C14-cholestanone was also bound, whereas C14-methyltestosterone and C14-progesterone were not bound in significant amounts. At least 50% of the bound C14-cholestanone was associated with the membrane fraction. PMID:4960181

Varricchio, Frederick; Doorenbos, Norman J.; Stevens, Audrey

1967-01-01

71

Photodynamic inactivation of Gram-positive bacteria employing natural resources.  

PubMed

The aim of this paper was to investigate a collection of plant extracts from Argentina as a source of new natural photosensitizers (PS) to be used in Photodynamic Inactivation (PDI) of bacteria. A collection of plants were screened for phototoxicity upon the Gram-positive species Staphylococcus epidermidis. Three extracts turned out to be photoactive: Solanum verbascifolium flower, Tecoma stans flower and Cissus verticillata root. Upon exposure to a light dose of 55J/cm(2), they induced 4, 2 and 3logs decrease in bacterial survival, respectively. Photochemical characterisation of S. verbascifolium extract was carried out. PDI reaction was dependent mainly on singlet oxygen and to a lesser extent, on hydroxyl radicals, through type II and I reactions. Photodegradation experiments revealed that the active principle of the extract was not particularly photolabile. It is noticeable that S. verbascifolium -PDI was more efficient under sunlight as compared to artificial light (total eradication vs. 4 logs decrease upon 120min of sunlight). The balance between oxidant and antioxidant compounds is likely to be masking or unmasking potential PS of plant extracts, but employing the crude extract, the level of photoactivity of S. verbascifolium is similar to some artificial PS upon exposure to sunlight, demonstrating that natural resources can be employed in PDI of bacteria. PMID:24705374

Mamone, L; Di Venosa, G; Gándara, L; Sáenz, D; Vallecorsa, P; Schickinger, S; Rossetti, M V; Batlle, A; Buzzola, F; Casas, A

2014-04-01

72

Low-Molecular-Weight Protein Tyrosine Phosphatases of Bacillus subtilis  

Microsoft Academic Search

In gram-negative organisms, enzymes belonging to the low-molecular-weight protein tyrosine phosphatase (LMPTP) family are involved in the regulation of important physiological functions, including stress resistance and synthesis of the polysaccharide capsule. LMPTPs have been identified also in gram-positive bacteria, but their functions in these organisms are presently unknown. We cloned two putative LMPTPs from Bacillus subtilis, YfkJ and YwlE, which

Lucia Musumeci; Cristina Bongiorni; Lutz Tautz; Robert A. Edwards; Andrei Osterman; Marta Perego; Tomas Mustelin; Nunzio Bottini

2005-01-01

73

Thermophilic Gram-Positive Biocatalysts for Biomass Conversion to Ethanol  

SciTech Connect

Production of energy from renewable sources is receiving increased attention due to the finite nature of fossil fuels and the environmental impact associated with the continued large scale use of fossil energy sources. Biomass, a CO2-neutral abundant resource, is an attractive alternate source of energy. Biomass-derived sugars, such as glucose, xylose, and other minor sugars, can be readily fermented to fuel ethanol and commodity chemicals. Extracellular cellulases produced by fungi are commercially developed for depolymerization of cellulose in biomass to glucose for fermentation by appropriate biocatalysts in a simultaneous saccharification and fermentation (SSF) process. Due to the differences in the optimum conditions for the activity of the fungal cellulases and the growth and fermentation characteristics of the current industrial biocatalysts, SSF of cellulose is envisioned at conditions that are not optimal for the fungal cellulase activity leading to higher than required cost of cellulase in SSF. We have isolated bacterial biocatalysts whose growth and fermentation requirements match the optimum conditions for commercial fungal cellulase activity (pH 5.0 and 50 deg. C). These isolates fermented both glucose and xylose, major components of cellulose and hemicellulose, respectively, to L(+)-lactic acid. Xylose was metabolized through the pentose-phosphate pathway by these organisms as evidenced by the fermentation profile and analysis of the fermentation products of 13C1-xylose by NMR. As expected for the metabolism of xylose by the pentose-phosphate pathway, 13C-lactate accounted for more than 90% of the total 13C-labeled products. All three strains fermented crystalline cellulose to lactic acid with the addition of fungal cellulase (Spezyme CE) (SSF) at an optimum of about 10 FPU/g cellulose. These isolates also fermented cellulose and sugar cane bagasse hemicellulose acid hydrolysate simultaneously. Based on fatty acid profile and 16S rRNA sequence, these isolates cluster with Bacillus coagulans although B. coagulans type strain, ATCC 7050, failed to utilize xylose as a carbon source. For successful production of ethanol from pyruvate, both pyruvate decarboxylase (PDC) and alcohol dehydrogenase (AHD) need to be produced at optimal levels in these biocatalysts. A plasmid containing the S. ventriculi pdc gene and the adh gene from geobacillus stearothermophilus was constructed using plasmid pWH1520 that was successfully used for expression of pdc in B. megaterium. The resulting portable ethanol (PET) plasmid, pJAM423, was transformed into B. megaterium. After xylose induction, a significant fraction of cell cytoplasm was composed of the S. ventriculi PDC and G. stearothermophilus ADH proteins. In preliminary experiments, the amount of ethanol produced by b. megaterium with plasmid pJAM423 was about twice (20 mM) of the bacterium without the plasmid. These results show that the PET operon is functional in B. megaterium but high level ethanol production needs further genetic and metabolic engineering. A genetic transfer system for the second generation biocatalysts needs to be developed for transferring the plasmid pJAM423 and its derivatives for engineering these organisms for ethanol production from biomass derived sugars and cellulose to ethanol. One of the new biocatalysts, strain P4-102B was found to be transformable with plasmids and the method for introducing plasmid pJAM423 into this strain and expression of the encoded DNA is being optimized. These new second generation biocatalysts have the potential to reduce the cost of SSF by minimizing the amount of fungal cellulases, a significant cost component in the use of biomass as a renewable resource for production of fuels and chemicals.

Shanmugam, K.T.; Ingram, L.O.; Maupin-Furlow, J.A.; Preston, J.F.; Aldrich, H.C.

2003-12-01

74

Production of plantaricin NC8 by Lactobacillus plantarum NC8 is induced in the presence of different types of gram-positive bacteria  

Microsoft Academic Search

Lactobacillus plantarum NC8 was shown to produce plantaricin NC8 (PLNC8), a recently purified and genetically characterized inducible class IIb bacteriocin, only when it was co-cultured with other gram-positive bacteria. Among 82 strains belonging to the genera Bacillus, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Listeria, Pediococcus, Staphylococcus, and Streptococcus, 41 were shown to induce PLNC8 production in L. plantarum NC8. There was apparently

Antonio Maldonado; JoséLuis Ruiz-Barba; Rufino Jiménez-Díaz

2004-01-01

75

Computational identification of the Spo0A-phosphate regulon that is essential for the cellular differentiation and development in Gram-positive spore-forming bacteria  

Microsoft Academic Search

Spo0A-phosphate is essential for the initiation of cellular differentiation and developmental pro- cesses in Gram-positive spore-forming bacteria. Here we combined comparative genomics with analyses of microarray expression profiles to iden- tify the Spo0A-phosphate regulon in Bacillus subti- lis. The consensus Spo0A-phosphate DNA-binding motif identified from the training set based on differ- ent computational algorithms is an 8 bp sequence, TTGTCGAA.

Jiajian Liu; Kai Tan; Gary D. Stormo

2003-01-01

76

[Isolation of Gram-positive bacteria from raw milk with antimicrobial residues].  

PubMed

Two hundred samples of raw milk were collected at the receiving plants located in three areas of high milk production in Zulia state, Venezuela. The CTT test and trial disk were used in order to detect the presence of antimicrobials. The positive samples were inoculated in tripticase soy broth, human blood agar and manitol salt agar in order to isolate Gram-positive bacteria. The identification of species was performed through biochemical tests. It was found that 45 samples (22.5%) of analyzed milk contained antimicrobials, and bacterial growth was obtained in 35 of them. 100 strains were isolated namely: 44 Staphylococcus, 19 Streptococcus, 17 Enterococcus, 9 Bacillus, 4 Micrococcus, 4 Corynebacterium and 3 Lactococcus. The most frequently isolated specie was S. aureus, the main producing agent of bovine mastitis in Zulia state, a microorganism frequently associated in the country to food-borne intoxications, associated to cheese processed from raw milk. It is recommended to apply control programs for the use of antibiotics. PMID:12214550

Faría Reyes, José; García Urdaneta, Aleida; Izquierdo Corser, Pedro; Allara Cagnasso, María; Valero Leal, Kutchynskaya

2002-03-01

77

Pharmacodynamics of Telavancin (TD-6424), a Novel Bactericidal Agent, against Gram-Positive Bacteria  

PubMed Central

Telavancin (TD-6424) is a novel lipoglycopeptide that produces rapid and concentration-dependent killing of clinically relevant gram-positive organisms in vitro. The present studies evaluated the in vivo pharmacodynamics of telavancin in the mouse neutropenic thigh (MNT) and mouse subcutaneous infection (MSI) animal models. Pharmacokinetic-pharmacodynamic studies in the MNT model demonstrated that the 24-h area under the concentration-time curve (AUC)/MIC ratio was the best predictor of efficacy. Telavancin produced dose-dependent reduction of thigh titers of several organisms, including methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA), penicillin-susceptible and -resistant strains of Streptococcus pneumoniae, and vancomycin-resistant Enterococcus faecalis. The 50% effective dose (ED50) estimates for telavancin ranged from 0.5 to 6.6 mg/kg of body weight (administered intravenously), and titers were reduced by up to 3 log10 CFU/g from pretreatment values. Against MRSA ATCC 33591, telavancin was 4- and 30-fold more potent (on an ED50 basis) than vancomycin and linezolid, respectively. Against MSSA ATCC 13709, telavancin was 16- and 40-fold more potent than vancomycin and nafcillin, respectively. Telavancin, vancomycin, and linezolid were all efficacious and more potent against MRSA ATCC 33591 in the MSI model compared to the MNT model. This deviation in potency was, however, disproportionately greater for vancomycin and linezolid than for telavancin, suggesting that activity of telavancin is less affected by the immune status. The findings of these studies collectively suggest that once-daily dosing of telavancin may provide an effective approach for the treatment of clinically relevant infections with gram-positive organisms. PMID:15273119

Hegde, Sharath S.; Reyes, Noe; Wiens, Tania; Vanasse, Nicole; Skinner, Robert; McCullough, Julia; Kaniga, Koné; Pace, John; Thomas, Roger; Shaw, Jeng-Pyng; Obedencio, Glen; Judice, J. Kevin

2004-01-01

78

Antioxidant activity via DPPH, gram-positive and gram-negative antimicrobial potential in edible mushrooms.  

PubMed

Edible mushrooms (EMs) are nutritionally rich source of proteins and essential amino acids. In the present study, the antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) and antimicrobial potential in EMs (Pleurotus ostreatus, Morchella esculenta, P. ostreatus (Black), P. ostreatus (Yellow) and Pleurotus sajor-caju) were investigated. The DPPH radical scavenging activity revealed that the significantly higher activity (66.47%) was observed in Morchella esculenta at a maximum concentration. Similarly, the dose-dependent concentrations (200, 400, 600, 800 and 1000 µg) were also used for other four EMs. Pleurotus ostreatus exhibited 36.13% activity, P. ostreatus (Black (B)) exhibited 30.64%, P. ostreatus (Yellow (Y)) exhibited 40.75% and Pleurotus sajor-caju exhibited 47.39% activity at higher concentrations. Furthermore, the antimicrobial potential were investigated for its toxicity against gram-negative bacterial strains (Escherichia coli, Pseudomonas aeroginosa, Salmonella typhi, Klebsiella pneumonia, Erwinia carotovora and Agrobacterium tumifaciens), gram-positive bacterial strains (Bacillus subtilis, Bacillus atrophaeus and Staphylococcus aureus) and a fungal strain (Candida albicans) in comparison with standard antibiotics. Antimicrobial screening revealed that the ethanol extract of P. ostreatus was active against all microorganism tested except E. coli. Maximum zone of inhibition (13 mm) was observed against fungus and A. tumifaciens. P. sajor-caju showed best activities (12.5 mm) against B. subtilis, B. atrophaeus and K. pneumonia. P. ostreatus (Y) showed best activities against P. aeroginosa (21.83 mm), B. atrophaeus (20 mm) and C. albicans (21 mm). P. ostreatus (B) exhibited best activities against C. albicans (16 mm) and slightly lower activities against all other microbes except S. typhi. M. esculenta possess maximum activities in terms of inhibition zone against all microorganisms tested except S. typhi. PMID:23095488

Ahmad, Nisar; Mahmood, Fazal; Khalil, Shahid Akbar; Zamir, Roshan; Fazal, Hina; Abbasi, Bilal Haider

2014-10-01

79

Aspects of eukaryotic-like signaling in Gram-positive cocci: a focus on virulence  

PubMed Central

Living organisms adapt to the dynamic external environment for their survival. Environmental adaptation in prokaryotes is thought to be primarily accomplished by signaling events mediated by two-component systems, consisting of histidine kinases and response regulators. However, eukaryotic-like serine/threonine kinases (STKs) have recently been described to regulate growth, antibiotic resistance and virulence of pathogenic bacteria. This article summarizes the role of STKs and their cognate phosphatases (STPs) in Gram-positive cocci that cause invasive infections in humans. Given that a large number of inhibitors to eukaryotic STKs are approved for use in humans, understanding how serine/threonine phosphorylation regulates virulence and antibiotic resistance will be beneficial for the development of novel therapeutic strategies against bacterial infections. PMID:21797690

Burnside, Kellie; Rajagopal, Lakshmi

2011-01-01

80

Identification of Surprisingly Diverse Type IV Pili, across a Broad Range of Gram-Positive Bacteria  

E-print Network

Identification of Surprisingly Diverse Type IV Pili, across a Broad Range of Gram-Positive Bacteria, Pennsylvania, United States of America Abstract Background: In Gram-negative bacteria, type IV pili (TFP) have apparent that Gram-positive bacteria also express type IV pili; however, little is known about

Plotkin, Joshua B.

81

The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium  

PubMed Central

Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators. PMID:24847070

Santos, Joana A.; Alonso-García, Noelia; Macedo-Ribeiro, Sandra; Pereira, Pedro José Barbosa

2014-01-01

82

Mechanism of Action of Recombinant Acc-Royalisin from Royal Jelly of Asian Honeybee against Gram-Positive Bacteria  

PubMed Central

The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees, has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Asian honeybee Apis cerana cerana, was expressed by fusing with glutathione S-transferase (GST) in Escherichia coli BL21, isolated and purified. The agar dilution assays with inhibition zone showed that RAcc-royalisin, similar to nisin, inhibits the growth of Gram-positive bacteria. The antibacterial activity of RAcc-royalisin was associated with its concentration, and was weakened by heat treatment ranging from 55°C to 85°C for 15 min. Both RAcc-royalisin and nisin exhibited the minimum inhibitory concentrations (MIC) of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml against Gram-positive bacterial strains, Bacillus subtilis and Micrococcus flavus and Staphyloccocus aureus in the microplate assay, respectively. However, RAcc-royalisin did not show antimicrobial activity against tested Gram-negative bacterial and fungal strains. The antibacterial activity of RAcc-royalisin agrees well with the decrease in bacterial cell hydrophobicity, the leakage of 260-nm absorbing materials, and the observation by transmission electron microscopy, all indicating that RAcc-royalisin induced the disruption and dysfunction of cell walls and membranes. This is the first report detailing the antibacterial mechanism of royalisin against Gram-positive bacteria, and provides insight into the application of recombinant royalisin in food and pharmaceutical industries as an antimicrobial agent. PMID:23056609

Shen, Lirong; Liu, Dandan; Li, Meilu; Jin, Feng; Din, Meihui; Parnell, Laurence D.; Lai, Chao-Qiang

2012-01-01

83

Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study  

PubMed Central

Background Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria. Methods and results Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3) were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Conclusion Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3. PMID:23233805

Azam, Ameer; Ahmed, Arham S; Oves, Mohammad; Khan, Mohammad S; Habib, Sami S; Memic, Adnan

2012-01-01

84

Ultrasound-Mediated DNA Transformation in Thermophilic Gram-Positive Anaerobes  

PubMed Central

Background Thermophilic, Gram-positive, anaerobic bacteria (TGPAs) are generally recalcitrant to chemical and electrotransformation due to their special cell-wall structure and the low intrinsic permeability of plasma membranes. Methodology/Principal Findings Here we established for any Gram-positive or thermophiles an ultrasound-based sonoporation as a simple, rapid, and minimally invasive method to genetically transform TGPAs. We showed that by applying a 40 kHz ultrasound frequency over a 20-second exposure, Texas red-conjugated dextran was delivered with 27% efficiency into Thermoanaerobacter sp. X514, a TGPA that can utilize both pentose and hexose for ethanol production. Experiments that delivered plasmids showed that host-cell viability and plasmid DNA integrity were not compromised. Via sonoporation, shuttle vectors pHL015 harboring a jellyfish gfp gene and pIKM2 encoding a Clostridium thermocellum ?-1,4-glucanase gene were delivered into X514 with an efficiency of 6×102 transformants/µg of methylated DNA. Delivery into X514 cells was confirmed via detecting the kanamycin-resistance gene for pIKM2, while confirmation of pHL015 was detected by visualization of fluorescence signals of secondary host-cells following a plasmid-rescue experiment. Furthermore, the foreign ?-1,4-glucanase gene was functionally expressed in X514, converting the host into a prototypic thermophilic consolidated bioprocessing organism that is not only ethanologenic but cellulolytic. Conclusions/Significance In this study, we developed an ultrasound-based sonoporation method in TGPAs. This new DNA-delivery method could significantly improve the throughput in developing genetic systems for TGPAs, many of which are of industrial interest yet remain difficult to manipulate genetically. PMID:20838444

Ji, Yuetong; He, Zhili; Pu, Yunting; Zhou, Jizhong; Xu, Jian

2010-01-01

85

Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria.  

PubMed

Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50? ? L leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3?mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0?mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Daniels, Dwayne; Yadav, Anand

2013-01-01

86

Caenorhabditis elegans Immune Conditioning with the Probiotic Bacterium Lactobacillus acidophilus Strain NCFM Enhances Gram-Positive Immune Responses  

PubMed Central

Although the immune response of Caenorhabditis elegans to microbial infections is well established, very little is known about the effects of health-promoting probiotic bacteria on evolutionarily conserved C. elegans host responses. We found that the probiotic Gram-positive bacterium Lactobacillus acidophilus NCFM is not harmful to C. elegans and that L. acidophilus NCFM is unable to colonize the C. elegans intestine. Conditioning with L. acidophilus NCFM significantly decreased the burden of a subsequent Enterococcus faecalis infection in the nematode intestine and prolonged the survival of nematodes exposed to pathogenic strains of E. faecalis and Staphylococcus aureus, including multidrug-resistant (MDR) isolates. Preexposure of nematodes to Bacillus subtilis did not provide any beneficial effects. Importantly, L. acidophilus NCFM activates key immune signaling pathways involved in C. elegans defenses against Gram-positive bacteria, including the p38 mitogen-activated protein kinase pathway (via TIR-1 and PMK-1) and the ?-catenin signaling pathway (via BAR-1). Interestingly, conditioning with L. acidophilus NCFM had a minimal effect on Gram-negative infection with Pseudomonas aeruginosa or Salmonella enterica serovar Typhimurium and had no or a negative effect on defense genes associated with Gram-negative pathogens or general stress. In conclusion, we describe a new system for the study of probiotic immune agents and our findings demonstrate that probiotic conditioning with L. acidophilus NCFM modulates specific C. elegans immunity traits. PMID:22585961

2012-01-01

87

Genomics of Bacillus Species  

NASA Astrophysics Data System (ADS)

Members of the genus Bacillus are rod-shaped spore-forming bacteria belonging to the Firmicutes, the low G+C gram-positive bacteria. The Bacillus genus was first described and classified by Ferdinand Cohn in Cohn (1872), and Bacillus subtilis was defined as the type species (Soule, 1932). Several Bacilli may be linked to opportunistic infections. However, pathogenicity among Bacillus spp. is mainly a feature of bacteria belonging to the Bacillus cereus group, including B. cereus, Bacillus anthracis, and Bacillus thuringiensis. Here we review the genomics of B. cereus group bacteria in relation to their roles as etiological agents of two food poisoning syndromes (emetic and diarrhoeal).

Økstad, Ole Andreas; Kolstø, Anne-Brit

88

Efficacy of telavancin, a lipoglycopeptide antibiotic, in experimental models of Gram-positive infection.  

PubMed

Telavancin is a parenteral lipoglycopeptide antibiotic with a dual mechanism of action contributing to bactericidal activity against multidrug-resistant Gram-positive pathogens. It has been approved for the treatment of complicated skin and skin structure infections due to susceptible Gram-positive bacteria and hospital-acquired/ventilator-associated bacterial pneumonia due to Staphylococcus aureus when other alternatives are unsuitable. Telavancin has been demonstrated to be efficacious in multiple animal models of soft tissue, cardiac, systemic, lung, bone, brain and device-associated infections involving clinically relevant Gram-positive pathogens, including methicillin-resistant S. aureus, glycopeptide-intermediate S. aureus, heterogeneous vancomycin-intermediate S. aureus and daptomycin non-susceptible methicillin-resistant S. aureus. The AUC0-24h/MIC ratio is the primary pharmacodynamically-linked pharmacokinetic parameter. The preclinical data for telavancin supports further investigative clinical evaluation of its efficacy in additional serious infections caused by susceptible Gram-positive pathogens. PMID:25382700

Hegde, Sharath S; Janc, James W

2014-12-01

89

Quorum sensing by peptide pheromones and two component signal transduction systems in Gram-positive bacteria  

Microsoft Academic Search

Cell-density-dependent gene expression appears to be widely spread in bacteria. This quorum-sensing phenomenon has been well established in Gram-negative bacteria, where N-acyl homoserine lactones are the diffusible communication molecules that modulate cell-density-dependent phenotypes. Similarly, a variety of processes are known to be regulated in a cell-density- or growth-phase-dependent manner in Gram-positive bacteria. Examples of such quorum-sensing modes in Gram-positive bacteria

Michiel Kleerebezem; Luis E. N. Quadri; Oscar P. Kuipers; Willem M. de Vos

1997-01-01

90

Non-contiguous finished genome sequence and description of Bacillus massilioalgeriensis sp. nov.  

PubMed Central

Strain EB01T sp. nov. is the type strain of Bacillus massilioalgeriensis, a new species within the genus Bacillus. This strain, whose genome is described here, was isolated from sediment sample of the hypersaline lake Ezzemoul sabkha in northeastern Algeria. B. massilioalgeriensis is a facultative anaerobic Gram-positive bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 5,269,577 bp long genome contains 5,098 protein-coding and 95 RNA genes, including 12 rRNA genes. PMID:25197482

Bendjama, Esma; Loucif, Lotfi; Diene, Seydina M.; Michelle, Caroline; Gacemi-Kirane, Djamila; Rolain, Jean-Marc

2014-01-01

91

Non-contiguous finished genome sequence and description of Bacillus massilioalgeriensis sp. nov.  

PubMed

Strain EB01(T) sp. nov. is the type strain of Bacillus massilioalgeriensis, a new species within the genus Bacillus. This strain, whose genome is described here, was isolated from sediment sample of the hypersaline lake Ezzemoul sabkha in northeastern Algeria. B. massilioalgeriensis is a facultative anaerobic Gram-positive bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 5,269,577 bp long genome contains 5,098 protein-coding and 95 RNA genes, including 12 rRNA genes. PMID:25197482

Bendjama, Esma; Loucif, Lotfi; Diene, Seydina M; Michelle, Caroline; Gacemi-Kirane, Djamila; Rolain, Jean-Marc

2014-06-15

92

On-Probe Sample Pretreatment for Direct Analysis of Lipids in Gram-Positive Bacterial Cells by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry  

PubMed Central

On-probe sample pretreatment using trifluoroacetic acid as an additional reagent enabled the direct detection of phospholipids in whole bacteria by means of matrix-assisted laser desorption ionization mass spectrometry for not only gram-negative organisms but also gram-positive ones with a thicker peptidoglycan layer. PMID:16269798

Ishida, Yasuyuki; Kitagawa, Kuniyuki; Nakayama, Akihito; Ohtani, Hajime

2005-01-01

93

Gene replacement of adenylate kinase in the gram-positive thermophile Geobacillus stearothermophilus disrupts adenine nucleotide homeostasis and reduces cell viability  

Microsoft Academic Search

Thermophilic bacteria are of great value for industry and research communities. Unfortunately, the cellular processes and mechanisms of these organisms remain largely understudied. In the present study, we investigate how the inactivation of adenylate kinase (AK) affects the adenine nucleotide homeostasis of a gram-positive moderate thermophile, Geobacillus stearothermophilus strain NUB3621-R. AK plays a major role in the adenine nucleotide homeostasis

Rafael Couñago; Yousif Shamoo

2005-01-01

94

Investigating lipoprotein biogenesis and function in the model Gram-positive bacterium Streptomyces coelicolormmi_7261 943..957  

E-print Network

Investigating lipoprotein biogenesis and function in the model Gram-positive bacterium Streptomyces the lipid- modified cysteine at the N-terminus of the mature lipoprotein. In all Gram-positive bacteria of the cyto- plasmic membrane. Here we identify lipoproteins in the model Gram-positive bacterium Streptomyces

Palmer, Tracy

95

Experimental fossilisation of the thermophilic Gram-positive bacterium Geobacillus SP7A: a long duration preservation study.  

E-print Network

Experimental fossilisation of the thermophilic Gram-positive bacterium Geobacillus SP7A: a long of fossilised microbes in recent and ancient rocks, we experimentally silicified a Gram-positive bacterium of Gram-positive bacteria was extremely rapid, thus allowing very good preservation of Geobacillus SP7A

Paris-Sud XI, Université de

96

Evaluation of the Verigene Gram-positive blood culture nucleic acid test for rapid detection of bacteria and resistance determinants.  

PubMed

Rapid identification of pathogens from blood cultures can decrease lengths of stay and improve patient outcomes. We evaluated the accuracy of the Verigene Gram-positive blood culture (BC-GP) nucleic acid test for investigational use only (Nanosphere, Inc., Northbrook, IL) for the identification of Gram-positive bacteria from blood cultures. The detection of resistance genes (mecA in Staphylococcus aureus and Staphylococcus epidermidis and vanA or vanB in Enterococcus faecium and Enterococcus faecalis) by the BC-GP assay also was assessed. A total of 186 positive blood cultures (in BacT/Alert FA bottles) with Gram-positive cocci observed with Gram staining were analyzed using the BC-GP assay. The BC-GP results were compared with the identification and susceptibility profiles obtained with routine methods in the clinical laboratory. Discordant results were arbitrated with additional biochemical, cefoxitin disk, and repeat BC-GP testing. The initial BC-GP organism identification was concordant with routine method results for 94.6% of the blood cultures. Only 40% of the Streptococcus pneumoniae identifications were correct. The detection of the mecA gene for 69 blood cultures with only S. aureus or S. epidermidis was concordant with susceptibility testing results. For 3 of 6 cultures with multiple Staphylococcus spp., mecA detection was reported but was correlated with oxacillin resistance in a species other than S. aureus or S. epidermidis. The detection of vanA agreed with susceptibility testing results for 45 of 46 cultures with E. faecalis or E. faecium. Comparison of the mean times to results for each organism group showed that BC-GP results were available 31 to 42 h earlier than phenotypic identifications and 41 to 50 h earlier than susceptibility results. PMID:23596240

Wojewoda, Christina M; Sercia, Linda; Navas, Maria; Tuohy, Marion; Wilson, Deborah; Hall, Geraldine S; Procop, Gary W; Richter, Sandra S

2013-07-01

97

Evaluation of the Verigene Gram-Positive Blood Culture Nucleic Acid Test for Rapid Detection of Bacteria and Resistance Determinants  

PubMed Central

Rapid identification of pathogens from blood cultures can decrease lengths of stay and improve patient outcomes. We evaluated the accuracy of the Verigene Gram-positive blood culture (BC-GP) nucleic acid test for investigational use only (Nanosphere, Inc., Northbrook, IL) for the identification of Gram-positive bacteria from blood cultures. The detection of resistance genes (mecA in Staphylococcus aureus and Staphylococcus epidermidis and vanA or vanB in Enterococcus faecium and Enterococcus faecalis) by the BC-GP assay also was assessed. A total of 186 positive blood cultures (in BacT/Alert FA bottles) with Gram-positive cocci observed with Gram staining were analyzed using the BC-GP assay. The BC-GP results were compared with the identification and susceptibility profiles obtained with routine methods in the clinical laboratory. Discordant results were arbitrated with additional biochemical, cefoxitin disk, and repeat BC-GP testing. The initial BC-GP organism identification was concordant with routine method results for 94.6% of the blood cultures. Only 40% of the Streptococcus pneumoniae identifications were correct. The detection of the mecA gene for 69 blood cultures with only S. aureus or S. epidermidis was concordant with susceptibility testing results. For 3 of 6 cultures with multiple Staphylococcus spp., mecA detection was reported but was correlated with oxacillin resistance in a species other than S. aureus or S. epidermidis. The detection of vanA agreed with susceptibility testing results for 45 of 46 cultures with E. faecalis or E. faecium. Comparison of the mean times to results for each organism group showed that BC-GP results were available 31 to 42 h earlier than phenotypic identifications and 41 to 50 h earlier than susceptibility results. PMID:23596240

Wojewoda, Christina M.; Sercia, Linda; Navas, Maria; Tuohy, Marion; Wilson, Deborah; Hall, Geraldine S.; Procop, Gary W.

2013-01-01

98

Clinical update on linezolid in the treatment of Gram-positive bacterial infections  

PubMed Central

Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs. PMID:22787406

Ager, Sally; Gould, Kate

2012-01-01

99

Contemporary tetracycline susceptibility testing: doxycycline MIC methods and interpretive criteria (CLSI and EUCAST) performance when testing Gram-positive pathogens.  

PubMed

International susceptibility testing breakpoint organizations and regulatory agencies have markedly differing interpretive criteria for the tetracycline class. Here we examined the magnitude of these differences for doxycycline and tetracycline hydrochloride (HCL) when tested against a collection of 13,176 Gram-positive cocci from a worldwide surveillance network (SENTRY Antimicrobial Surveillance Program, 2010). Clinical and Laboratory Standards Institute (CLSI) breakpoints are routinely higher, usually 4-fold, compared to those of the European Committee on Antimicrobial Susceptibility Testing (EUCAST); however, CLSI recently (2013) modified Streptococcus pneumoniae breakpoints (? 2 ?g/mL in 2012) to ? 0.25 and ? 1 ?g/mL for doxycycline and tetracycline HCL, respectively. We report that these changes are a promising step toward international breakpoint harmonization, but lack a comprehensive approach needed for testing tetracyclines against all Gram-positive cocci. Generally, EUCAST breakpoint criteria showed i) lower spectrums (reduced susceptibility rates) for the tetracyclines, but highest for doxycycline versus all species examined; ii) greater test accuracy (lower predictive categorical errors), especially for tetracycline to predict doxycycline susceptibility (99.91%); and iii) zone diameter correlate breakpoints which are generally available online. Molecular tests for tet resistance genes demonstrate that tet (K) and tet (M) containing strains can occur in the susceptible population of MIC results by both CLSI and EUCAST breakpoint criteria. In summary, doxycycline continues to show greater comparative potency versus tetracycline HCL against all monitored Gram-positive species and the international harmonization of tetracycline breakpoints should be a priority, as the most recent CLSI update only addressed 1 streptococcal species and 2 tetracycline agents. PMID:23490012

Jones, Ronald N; Stilwell, Matthew G; Wilson, Michael L; Mendes, Rodrigo E

2013-05-01

100

Distribution of multi-resistant Gram-negative versus Gram-positive bacteria in the hospital inanimate environment.  

PubMed

We prospectively studied the difference in detection rates of multi-resistant Gram-positive and multi-resistant Gram-negative bacteria in the inanimate environment of patients harbouring these organisms. Up to 20 different locations around 190 patients were surveyed. Fifty-four patients were infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) and 136 with multi-resistant Gram-negative bacteria. The environmental detection rate for MRSA or VRE was 24.7% (174/705 samples) compared with 4.9% (89/1827 samples) for multi-resistant Gram-negative bacteria (P<0.001). Gram-positive bacteria were isolated more frequently than Gram-negatives from the hands of patients (P<0.001) and hospital personnel (P=0.1145). Environmental contamination did not differ between the intensive care units (ICUs) and the general wards (GWs), which is noteworthy because our ICUs are routinely disinfected twice a day, whereas GWs are cleaned just once a day with detergent. Current guidelines for the prevention of spread of multi-resistant bacteria in the hospital setting do not distinguish between Gram-positive and Gram-negative isolates. Our results suggest that the inanimate environment serves as a secondary source for MRSA and VRE, but less so for Gram-negative bacteria. Thus, strict contact isolation in a single room with complete barrier precautions is recommended for MRSA or VRE; however, for multi-resistant Gram-negative bacteria, contact isolation with barrier precautions for close contact but without a single room seems sufficient. This benefits not only the patients, but also the hospital by removing some of the strain placed on already over-stretched resources. PMID:15003666

Lemmen, S W; Häfner, H; Zolldann, D; Stanzel, S; Lütticken, R

2004-03-01

101

Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria  

NASA Astrophysics Data System (ADS)

A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO2-NH2-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

2010-02-01

102

Pili in Gram-positive bacteria: assembly, involvement in colonization and biofilm development  

PubMed Central

Various cell-surface multisubunit protein polymers, known as pili or fimbriae, have a pivotal role in the colonization of specific host tissues by many pathogenic bacteria. In contrast to Gram-negative bacteria, Gram-positive bacteria assemble pili by a distinct mechanism involving a transpeptidase called sortase. Sortase crosslinks individual pilin monomers and ultimately joins the resulting covalent polymer to the cell-wall peptidoglycan. Here we review current knowledge of this mechanism and the roles of Gram-positive pili in the colonization of specific host tissues, modulation of host immune responses and the development of bacterial biofilms. PMID:18083568

Mandlik, Anjali; Swierczynski, Arlene; Das, Asis; Ton-That, Hung

2010-01-01

103

The use of lysozyme modified with fluorescein for the detection of Gram-positive bacteria.  

PubMed

Lysozyme (1,4-?-N-acetylmuramidase) is commonly applied in the food, medical, and pharmaceutical industries. In this study, we tested a novel application of fluorescein-modified lysozyme (using carboxyfluorescein with a triazine-based coupling reagent) as a new tool for the detection of Gram-positive soil bacteria. The results, obtained by cultivation methods, fluorescence analysis, and laser interferometry, showed that, after optimization, fluorescein-modified lysozyme could be used to evaluate the prevalence of Gram-positive bacteria essential in bioremediation of soils with low pH, such as those degraded by sulfur. PMID:24916601

Arabski, Micha?; Konieczna, Iwona; Tusi?ska, Ewa; W?sik, S?awomir; Relich, Inga; Zaj?c, Krzysztof; Kami?ski, Zbigniew J; Kaca, Wies?aw

2015-01-01

104

Comparative genome?wide analysis of small RNAs of major Gram?positive pathogens: from identification to application  

PubMed Central

Summary In the recent years, the number of drug? and multi?drug?resistant microbial strains has increased rapidly. Therefore, the need to identify innovative approaches for development of novel anti?infectives and new therapeutic targets is of high priority in global health care. The detection of small RNAs (sRNAs) in bacteria has attracted considerable attention as an emerging class of new gene expression regulators. Several experimental technologies to predict sRNA have been established for the Gram?negative model organism Escherichia coli. In many respects, sRNA screens in this model system have set a blueprint for the global and functional identification of sRNAs for Gram?positive microbes, but the functional role of sRNAs in colonization and pathogenicity for Listeria monocytogenes, Staphylococcus aureus, Streptococcus pyogenes, Enterococcus faecalis and Clostridium difficile is almost completely unknown. Here, we report the current knowledge about the sRNAs of these socioeconomically relevant Gram?positive pathogens, overview the state?of?the?art high?throughput sRNA screening methods and summarize bioinformatics approaches for genome?wide sRNA identification and target prediction. Finally, we discuss the use of modified peptide nucleic acids (PNAs) as a novel tool to inactivate potential sRNA and their applications in rapid and specific detection of pathogenic bacteria. PMID:21255362

Mraheil, Mobarak A.; Billion, André; Kuenne, Carsten; Pischimarov, Jordan; Kreikemeyer, Bernd; Engelmann, Susanne; Hartke, Axel; Giard, Jean?Christophe; Rupnik, Maja; Vorwerk, Sonja; Beier, Markus; Retey, Julia; Hartsch, Thomas; Jacob, Anette; Cemi?, Franz; Hemberger, Jürgen; Chakraborty, Trinad; Hain, Torsten

2010-01-01

105

Biosynthesis of auxin by the gram-positive phytopathogen Rhodococcus fascians is controlled by compounds specific to infected plant tissues.  

PubMed

The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. We show here for the first time that R. fascians produces and secretes the auxin indole-3-acetic acid. Interestingly, whereas noninfected-tobacco extracts have no effect, indole-3-acetic acid synthesis is highly induced in the presence of infected-tobacco extracts when tryptophan is not limiting. Indole-3-acetic acid production by a plasmid-free strain shows that the biosynthetic genes are located on the bacterial chromosome, although plasmid-encoded genes contribute to the kinetics and regulation of indole-3-acetic acid biosynthesis. The indole-3-acetic acid intermediates present in bacterial cells and secreted into the growth media show that the main biosynthetic route used by R. fascians is the indole-3-pyruvic acid pathway with a possible rate-limiting role for indole-3-ethanol. The relationship between indole-3-acetic acid production and the symptoms induced by R. fascians is discussed. PMID:15746315

Vandeputte, Olivier; Oden, Sevgi; Mol, Adeline; Vereecke, Danny; Goethals, Koen; El Jaziri, Mondher; Prinsen, Els

2005-03-01

106

Biosynthesis of Auxin by the Gram-Positive Phytopathogen Rhodococcus fascians Is Controlled by Compounds Specific to Infected Plant Tissues  

PubMed Central

The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. We show here for the first time that R. fascians produces and secretes the auxin indole-3-acetic acid. Interestingly, whereas noninfected-tobacco extracts have no effect, indole-3-acetic acid synthesis is highly induced in the presence of infected-tobacco extracts when tryptophan is not limiting. Indole-3-acetic acid production by a plasmid-free strain shows that the biosynthetic genes are located on the bacterial chromosome, although plasmid-encoded genes contribute to the kinetics and regulation of indole-3-acetic acid biosynthesis. The indole-3-acetic acid intermediates present in bacterial cells and secreted into the growth media show that the main biosynthetic route used by R. fascians is the indole-3-pyruvic acid pathway with a possible rate-limiting role for indole-3-ethanol. The relationship between indole-3-acetic acid production and the symptoms induced by R. fascians is discussed. PMID:15746315

Vandeputte, Olivier; Öden, Sevgi; Mol, Adeline; Vereecke, Danny; Goethals, Koen; El Jaziri, Mondher; Prinsen, Els

2005-01-01

107

The Role of the Strictly Conserved Positively Charged Residue Differs among the Gram-positive, Gram-negative, and Chloroplast YidC Homologs.  

PubMed

Recently, the structure of YidC2 from Bacillus halodurans revealed that the conserved positively charged residue within transmembrane segment one (at position 72) is located in a hydrophilic groove that is embedded in the inner leaflet of the lipid bilayer. The arginine residue was essential for the Bacillus subtilis SpoIIIJ (YidC1) to insert MifM and to complement a SpoIIIJ mutant strain. Here, we investigated the importance of the conserved positively charged residue for the function of the Escherichia coli YidC, Streptococcus mutans YidC2, and the chloroplast Arabidopsis thaliana Alb3. Like the Gram-positive B. subtilis SpoIIIJ, the conserved arginine was required for functioning of the Gram-positive S. mutans YidC2 and was necessary to complement the E. coli YidC depletion strain and to promote insertion of a YidC-dependent membrane protein synthesized with one but not two hydrophobic segments. In contrast, the conserved positively charged residue was not required for the E. coli YidC or the A. thaliana Alb3 to functionally complement the E. coli YidC depletion strain or to promote insertion of YidC-dependent membrane proteins. Our results also show that the C-terminal half of the helical hairpin structure in cytoplasmic loop C1 is important for the activity of YidC because various deletions in the region either eliminate or impair YidC function. The results here underscore the importance of the cytoplasmic hairpin region for YidC and show that the arginine is critical for the tested Gram-positive YidC homolog but is not essential for the tested Gram-negative and chloroplast YidC homologs. PMID:25359772

Chen, Yuanyuan; Soman, Raunak; Shanmugam, Sri Karthika; Kuhn, Andreas; Dalbey, Ross E

2014-12-19

108

Transcriptional Profiling of Murine Organ Genes in Response to Infection with Bacillus anthracis Ames Spores  

PubMed Central

Bacillus anthracis is the gram positive, spore-forming etiological agent of anthrax, an affliction studied because of its importance as a potential bioweapon. Although in vitro transcriptional responses of macrophages to either spore or anthrax toxins have been previously reported, little is known regarding the impact of infection on gene expression in host tissues. We infected Swiss-Webster mice intranasally with 5 LD50 of B. anthracis virulent Ames spores and observed the global transcriptional profiles of various tissues over a 48 hr time period. RNA was extracted from spleen, lung, and heart tissues of infected and control mice and examined by Affymetrix GeneChip analysis. Approximately 580 host genes were significantly over or under expressed among the lung, spleen, and heart tissues at 8 hr and 48 hr time points. Expression of genes encoding for surfactant and major histocompatibility complex (MHC) presentation was diminished during the early phase of infection in lungs. By 48 hr, a significant number of genes were modulated in the heart, including up-regulation of calcium-binding related gene expression, and down-regulation of multiple genes related to cell adhesion, formation of the extracellular matrix, and the cell cytoskeleton. Interestingly, the spleen 8 hr post-infection showed striking increases in the expression of genes that encode hydrolytic enzymes, and these levels remained elevated throughout infection. Further, genes involving antigen presentation and interferon responses were down-regulated in the spleen at 8 hr. In late stages of infection, splenic genes related to the inflammatory response were up-regulated. This study is the first to describe the in vivo global transcriptional response of multiple organs during inhalational anthrax. Although numerous genes related to the host immunological response and certain protection mechanisms were up-regulated in these organs, a vast list of genes important for fully developing and maintaining this response were decreased. Additionally, the lung, spleen, and heart showed differential responses to the infection, further validating the demand for a better understanding of anthrax pathogenesis in order to design therapies against novel targets. PMID:18037264

Moen, Scott T.; Yeager, Linsey A.; Lawrence, William S.; Ponce, Cindy; Galindo, Cristi L.; Garner, Harold R.; Baze, Wallace B.; Suarez, Giovanni; Peterson, Johnny W.; Chopra, Ashok K.

2008-01-01

109

Phylogenetic Diversity of Gram-Positive Bacteria Cultured from Marine Sediments? †  

PubMed Central

Major advances in our understanding of marine bacterial diversity have been gained through studies of bacterioplankton, the vast majority of which appear to be gram negative. Less effort has been devoted to studies of bacteria inhabiting marine sediments, yet there is evidence to suggest that gram-positive bacteria comprise a relatively large proportion of these communities. To further expand our understanding of the aerobic gram-positive bacteria present in tropical marine sediments, a culture-dependent approach was applied to sediments collected in the Republic of Palau from the intertidal zone to depths of 500 m. This investigation resulted in the isolation of 1,624 diverse gram-positive bacteria spanning 22 families, including many that appear to represent new taxa. Phylogenetic analysis of 189 representative isolates, based on 16S rRNA gene sequence data, indicated that 124 (65.6%) belonged to the class Actinobacteria while the remaining 65 (34.4%) were members of the class Bacilli. Using a sequence identity value of ?98%, the 189 isolates grouped into 78 operational taxonomic units, of which 29 (37.2%) are likely to represent new taxa. The high degree of phylogenetic novelty observed during this study highlights the fact that a great deal remains to be learned about the diversity of gram-positive bacteria in marine sediments. PMID:17400789

Gontang, Erin A.; Fenical, William; Jensen, Paul R.

2007-01-01

110

Isolation and characterization of four gram-positive nickel-tolerant microorganisms from contaminated sediments.  

PubMed

Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms. Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing gene probes for functions associated with biogeochemical cycling, metal homeostasis, and organic contaminant degradation showed little overlap among the four isolates. Fifteen of the genes were detected in all four isolates with only two of these related to metal resistance, specifically to tellurium. Each of the four isolates also displayed resistance to at least one of six antibiotics tested, with resistance to kanamycin, gentamycin, and ciprofloxacin observed in at least two of the isolates. Further characterization of S. aureofaciens NR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Ni tolerance constitutively. In addition, both were able to grow in higher concentrations of Ni at pH 6 as compared with pH 7 (42.6 and 8.5 mM Ni at pH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examined in these two isolates; a similar pH-dependent metal tolerance was observed when grown with Co and Zn. Neither isolate was tolerant to Cd. These findings suggest that Ni is exerting a selection pressure at this site for metal-resistant actinomycetes. PMID:17404787

Van Nostrand, Joy D; Khijniak, Tatiana V; Gentry, Terry J; Novak, Michelle T; Sowder, Andrew G; Zhou, Jizhong Z; Bertsch, Paul M; Morris, Pamela J

2007-05-01

111

Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments  

SciTech Connect

Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms. Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing gene probes for functions associated with biogeochemical cycling, metal homeostasis, and organic contaminant degradation showed little overlap among the four isolates. Fifteen of the genes were detected in all four isolates with only two of these related to metal resistance, specifically to tellurium. Each of the four isolates also displayed resistance to at least one of six antibiotics tested, with resistance to kanamycin, gentamycin, and ciprofloxacin observed in at least two of the isolates. Further characterization of S. aureofaciens NR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Ni tolerance constitutively. In addition, both were able to grow in higher concentrations of Ni at pH 6 as compared with pH 7 (42.6 and 8.5 mM Ni at pH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examined in these two isolates; a similar pH-dependent metal tolerance was observed when grown with Co and Zn. Neither isolate was tolerant to Cd. These findings suggest that Ni is exerting a selection pressure at this site for metal-resistant actinomycetes.

Van Nostrand, J. D.; Khijniak, T. V.; Gentry, T. J.; Novak, M. T.; Sowder, A. G.; Zhou, J. Z.; Bertsch, P. M.; Morris, P. J.

2007-01-01

112

The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for Gram-positive bacteria over erythrocytes  

NASA Astrophysics Data System (ADS)

Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects.Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34254a

Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

2013-04-01

113

Antimicrobial susceptibilities of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents.  

PubMed Central

The susceptibilities of 265 strains of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents were tested. Most strains were susceptible to vancomycin, doxycycline, and fusidic acid. Corynebacterium jeikeium and Corynebacterium urealyticum were the most resistant organisms tested. Resistance to beta-lactams, clindamycin, erythromycin, azythromycin, ciprofloxacin and gentamicin was common among strains of Corynebacterium xerosis and Corynebacterium minutissimum. Ampicillin resistance among Listeria monocytogenes was more prevalent than previously reported. Optochin, fosfomycin, and nitrofurantoin showed very little activity against most organisms tested, but the use of nitrofurantoin as a selective agent in culture medium may prevent the recovery of some isolates. Except for the unvarying activity of vancomycin against Corynebacterium species, the antimicrobial susceptibilities of the latter to other antibiotics are usually unpredictable, such that susceptibility tests are necessary for selecting the best antimicrobial treatment. PMID:7695308

Soriano, F; Zapardiel, J; Nieto, E

1995-01-01

114

Lifesaving liver transplantation for multi-organ failure caused by Bacillus cereus food poisoning.  

PubMed

Bacillus cereus is a spore-forming, gram-positive bacterium that causes food poisoning presenting with either emesis or diarrhea. Diarrhea is caused by proteinaceous enterotoxin complexes, mainly hemolysin BL, non-hemolytic enterotoxin (NHE), and cytotoxin K. In contrast, emesis is caused by the ingestion of the depsipeptide toxin cereulide, which is produced in B. cereus contaminated food, particularly in pasta or rice. In general, the illness is mild and self-limiting. However, due to cereulide intoxication, nine severe cases with rhabdomyolysis and/or liver failure, five of them lethal, are reported in literature. Here we report the first case of life-threatening liver failure and severe rhabdomyolysis in this context that could not be survived without emergency hepatectomy and consecutive liver transplantation. PMID:25323120

Tschiedel, Eva; Rath, Peter-Michael; Steinmann, Jörg; Becker, Heinz; Dietrich, Rudolf; Paul, Andreas; Felderhoff-Müser, Ursula; Dohna-Schwake, Christian

2015-02-01

115

Genomic and Enzymatic Results Show Bacillus cellulosilyticus Uses a Novel Set of LPXTA Carbohydrases to Hydrolyze Polysaccharides  

PubMed Central

Background Alkaliphilic Bacillus species are intrinsically interesting due to the bioenergetic problems posed by growth at high pH and high salt. Three alkaline cellulases have been cloned, sequenced and expressed from Bacillus cellulosilyticus N-4 (Bcell) making it an excellent target for genomic sequencing and mining of biomass-degrading enzymes. Methodology/Principal Findings The genome of Bcell is a single chromosome of 4.7 Mb with no plasmids present and three large phage insertions. The most unusual feature of the genome is the presence of 23 LPXTA membrane anchor proteins; 17 of these are annotated as involved in polysaccharide degradation. These two values are significantly higher than seen in any other Bacillus species. This high number of membrane anchor proteins is seen only in pathogenic Gram-positive organisms such as Listeria monocytogenes or Staphylococcus aureus. Bcell also possesses four sortase D subfamily 4 enzymes that incorporate LPXTA-bearing proteins into the cell wall; three of these are closely related to each other and unique to Bcell. Cell fractionation and enzymatic assay of Bcell cultures show that the majority of polysaccharide degradation is associated with the cell wall LPXTA-enzymes, an unusual feature in Gram-positive aerobes. Genomic analysis and growth studies both strongly argue against Bcell being a truly cellulolytic organism, in spite of its name. Preliminary results suggest that fungal mycelia may be the natural substrate for this organism. Conclusions/Significance Bacillus cellulosilyticus N-4, in spite of its name, does not possess any of the genes necessary for crystalline cellulose degradation, demonstrating the risk of classifying microorganisms without the benefit of genomic analysis. Bcell is the first Gram-positive aerobic organism shown to use predominantly cell-bound, non-cellulosomal enzymes for polysaccharide degradation. The LPXTA-sortase system utilized by Bcell may have applications both in anchoring cellulases and other biomass-degrading enzymes to Bcell itself and in anchoring proteins other Gram-positive organisms. PMID:23593409

Mead, David; Drinkwater, Colleen; Brumm, Phillip J.

2013-01-01

116

In Vitro Activities of the New Semisynthetic Glycopeptide Telavancin (TD6424), Vancomycin, Daptomycin, Linezolid, and Four Comparator Agents against Anaerobic Gram-Positive Species and Corynebacterium spp  

Microsoft Academic Search

Telavancin is a new semisynthetic glycopeptide anti-infective with multiple mechanisms of action, including inhibition of bacterial membrane phospholipid synthesis and inhibition of bacterial cell wall synthesis. We determined the in vitro activities of telavancin, vancomycin, daptomycin, linezolid, quinupristin-dalfopristin, imipenem, piperacillin-tazobactam, and ampicillin against 268 clinical isolates of anaerobic gram-positive organisms and 31 Corynebacterium strains using agar dilution methods according to

Ellie J. C. Goldstein; Diane M. Citron; C. Vreni Merriam; Yumi A. Warren; Kerin L. Tyrrell; Helen T. Fernandez

2004-01-01

117

Mechanism of Action of the Mannopeptimycins, a Novel Class of Glycopeptide Antibiotics Active against Vancomycin-Resistant Gram-Positive Bacteria  

Microsoft Academic Search

The naturally occurring mannopeptimycins (formerly AC98-1 through AC98-5) are a novel class of glyco- peptide antibiotics that are active against a wide variety of gram-positive bacteria. The structures of the mannopeptimycins suggested that they might act by targeting cell wall biosynthesis, similar to other known glycopeptide antibiotics; but the fact that the mannopeptimycins retain activity against vancomycin-resistant organisms suggested that

Alexey Ruzin; Guy Singh; Anatoly Severin; Youjun Yang; Russell G. Dushin; Alan G. Sutherland; Albert Minnick; Michael Greenstein; Michael K. May; David M. Shlaes; Patricia A. Bradford

2004-01-01

118

Efficient enzymatic systems for synthesis of novel ?-mangostin glycosides exhibiting antibacterial activity against Gram-positive bacteria.  

PubMed

Two enzymatic systems were developed for the efficient synthesis of glycoside products of ?-mangostin, a natural xanthonoid exhibiting anti-oxidant, antibacterial, anti-inflammatory, and anticancer activities. In these systems, one-pot reactions for the synthesis of UDP-?-D-glucose and UDP-?-D-2-deoxyglucose were modified and combined with a glycosyltransferase (GT) from Bacillus licheniformis DSM-13 to afford C-3 and C-6 position modified glucose and 2-deoxyglucose conjugated novel ?-mangostin derivatives. ?-Mangostin 3-O-?-D-glucopyranoside, ?-mangostin 6-O-?-D-glucopyranoside, ?-mangostin 3,6-di-O-?-D-glucopyranoside, ?-mangostin 3-O-?-D-2-deoxyglucopyranoside, ?-mangostin 6-O-?-D-2-deoxyglucopyranoside, and ?-mangostin 3,6-di-O-?-D-2-deoxyglucopyranoside were successfully produced in practical quantities and characterized by high-resolution quadruple time-of-flight electrospray ionization-mass spectrometry (HR-QTOF ESI/MS), (1)H and (13)C NMR analyses. In excess of the substrate, the maximum productions of three ?-mangostin glucopyranosides (4.8 mg/mL, 86.5 % overall conversion of ?-mangostin) and three ?-mangostin 2-deoxyglucopyronosides (4.0 mg/mL, 79 % overall conversion of ?-mangostin) were achieved at 4-h incubation period. All the ?-mangostin glycosides exhibited improved water solubility, and their antibacterial activity against three Gram-positive bacteria Micrococcus luteus, Bacillus subtilis, and Staphylococcus aureus was drastically enhanced by the glucosylation at C-3 position. In this study, diverse glycosylated ?-mangostin were produced in significant quantities by using inexpensive starting materials and recycling co-factors within a reaction vessel without use of expensive NDP-sugars in the glycosylation reactions. PMID:25038930

Le, Tuoi Thi; Pandey, Ramesh Prasad; Gurung, Rit Bahadur; Dhakal, Dipesh; Sohng, Jae Kyung

2014-10-01

119

Surface Proteins of Gram-Positive Pathogens: Using Crystallography to Uncover Novel Features in Drug and Vaccine Candidates  

NASA Astrophysics Data System (ADS)

Proteins displayed on the cell surfaces of pathogenic organisms are the front-line troops of bacterial attack, playing critical roles in colonization, infection and virulence. Although such proteins can often be recognized from genome sequence data, through characteristic sequence motifs, their functions are often unknown. One such group of surface proteins is attached to the cell surface of Gram-positive pathogens through the action of sortase enzymes. Some of these proteins are now known to form pili: long filamentous structures that mediate attachment to human cells. Crystallographic analyses of these and other cell surface proteins have uncovered novel features in their structure, assembly and stability, including the presence of inter- and intramolecular isopeptide crosslinks. This improved understanding of structures on the bacterial cell surface offers opportunities for the development of some new drug targets and for novel approaches to vaccine design.

Baker, Edward N.; Proft, Thomas; Kang, Haejoo

120

Biological Characterization of Novel Inhibitors of the Gram-Positive DNA Polymerase IIIC Enzyme  

PubMed Central

Novel N-3-alkylated 6-anilinouracils have been identified as potent and selective inhibitors of bacterial DNA polymerase IIIC, the enzyme essential for the replication of chromosomal DNA in gram-positive bacteria. A nonradioactive assay measuring the enzymatic activity of the DNA polymerase IIIC in gram-positive bacteria has been assembled. The 6-anilinouracils described inhibited the polymerase IIIC enzyme at concentrations in the nanomolar range in this assay and displayed good in vitro activity (according to their MICs) against staphylococci, streptococci, and enterococci. The MICs of the most potent derivatives were about 4 ?g/ml for this panel of bacteria. The 50% effective dose of the best compound (6-[(3-ethyl-4-methylphenyl)amino]-3-{[1-(isoxazol-5-ylcarbonyl)piperidin-4-yl]methyl}uracil) was 10 mg/kg of body weight after intravenous application in a staphylococcal sepsis model in mice, from which in vivo pharmacokinetic data were also acquired. PMID:15728893

Kuhl, Alexander; Svenstrup, Niels; Ladel, Christoph; Otteneder, Michael; Binas, Annegret; Schiffer, Guido; Brands, Michael; Lampe, Thomas; Ziegelbauer, Karl; Rübsamen-Waigmann, Helga; Haebich, Dieter; Ehlert, Kerstin

2005-01-01

121

Atmospheric growth requirements for Alloiococcus species and related gram-positive cocci.  

PubMed Central

The growth of Alloiococcus otitis under different atmospheres and nutritional conditions was studied. The growth rates of 25 strains of gram-positive cocci representing five genera on heart infusion agar plates containing 5% rabbit blood and on brucella agar plates with and without sheep blood under aerobic, increased CO2, and anaerobic atmospheres were compared. Eight strains of alloiococci plated on heart infusion agar with rabbit blood and on brucella sheep blood agar grew under aerobic and candle jar atmospheres. Two of these strains showed poor anaerobic growth after 7 days. Strains of Aerococcus viridans, Aerococcus urinae, Helcococci kunzi, Dolosigranulum pigrum, Gemella haemolysans, and Gemella morbillorum grew well under all three atmospheres and on the three types of media and in thioglycolate broth. These results confirm all the aerobic atmospheric requirements for Alloiococcus strains and show that aerobic growth characteristics help distinguish the alloiococci from the other gram-positive cocci that are facultatively anaerobic. PMID:8815077

Miller, P H; Facklam, R R; Miller, J M

1996-01-01

122

Atmospheric growth requirements for Alloiococcus species and related gram-positive cocci.  

PubMed

The growth of Alloiococcus otitis under different atmospheres and nutritional conditions was studied. The growth rates of 25 strains of gram-positive cocci representing five genera on heart infusion agar plates containing 5% rabbit blood and on brucella agar plates with and without sheep blood under aerobic, increased CO2, and anaerobic atmospheres were compared. Eight strains of alloiococci plated on heart infusion agar with rabbit blood and on brucella sheep blood agar grew under aerobic and candle jar atmospheres. Two of these strains showed poor anaerobic growth after 7 days. Strains of Aerococcus viridans, Aerococcus urinae, Helcococci kunzi, Dolosigranulum pigrum, Gemella haemolysans, and Gemella morbillorum grew well under all three atmospheres and on the three types of media and in thioglycolate broth. These results confirm all the aerobic atmospheric requirements for Alloiococcus strains and show that aerobic growth characteristics help distinguish the alloiococci from the other gram-positive cocci that are facultatively anaerobic. PMID:8815077

Miller, P H; Facklam, R R; Miller, J M

1996-04-01

123

Lipoteichoic Acids, Phosphate-Containing Polymers in the Envelope of Gram-Positive Bacteria  

PubMed Central

Lipoteichoic acids (LTA) are polymers of alternating units of a polyhydroxy alkane, including glycerol and ribitol, and phosphoric acid, joined to form phosphodiester units that are found in the envelope of Gram-positive bacteria. Here we review four different types of LTA that can be distinguished on the basis of their chemical structure and describe recent advances in the biosynthesis pathway for type I LTA, d-alanylated polyglycerol-phosphate linked to di-glucosyl-diacylglycerol. The physiological functions of type I LTA are discussed in the context of inhibitors that block their synthesis and of mutants with discrete synthesis defects. Research on LTA structure and function represents a large frontier that has been investigated in only few Gram-positive bacteria. PMID:24415723

Schneewind, Olaf

2014-01-01

124

Maturation pathway of nisin and other lantibiotics: post-translationally modified antimicrobial peptides exported by Gram-positive bacteria  

Microsoft Academic Search

Lantibiotics form a family of highly modified peptides which are secreted by several Gram-positive bacteria. They exhibit antimicrobial activity, mainly against other Gram-positive bacteria, by forming pores in the cellular membrane. These antimicrobial peptides are ribosomally synthesized and contain leader peptides which do not show the characteristics of signal sequences. Several amino acid residues of the precursor lantibiotic are enzymatically

Willem M. de Vos; Oscar P. Kuipers; Jan Roelof van der Meer; Roland J. Siezen

1995-01-01

125

Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments  

Microsoft Academic Search

Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms.\\u000a Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates\\u000a were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing

Joy D. Van Nostrand; Tatiana V. Khijniak; Terry J. Gentry; Michelle T. Novak; Andrew G. Sowder; Jizhong Z. Zhou; Paul M. Bertsch; Pamela J. Morris

2007-01-01

126

Inactivation of Gram-positive biofilms by low-temperature plasma jet at atmospheric pressure  

Microsoft Academic Search

This work is devoted to the evaluation of the efficiency of a new low-temperature plasma jet driven in ambient air by a dc-corona discharge to inactivate adherent cells and biofilms of Gram-positive bacteria. The selected microorganisms were lactic acid bacteria, a Weissella confusa strain which has the particularity to excrete a polysaccharide polymer (dextran) when sucrose is present. Both adherent

F Marchal; H Robert; N Merbahi; C Fontagné-Faucher; M Yousfi; C E Romain; O Eichwald; C Rondel; B Gabriel

2012-01-01

127

Genome Sequence of the Diazotrophic Gram-Positive Rhizobacterium Paenibacillus riograndensis SBR5T  

PubMed Central

Paenibacillus riograndensis SBR5T, a nitrogen-fixing Gram-positive rhizobacterium isolated from a wheat field in the south of Brazil, has a great potential for agricultural applications due to its plant growth promotion effects. Here we present the draft genome sequence of P. riograndensis SBR5T. Its 7.37-Mb genome encodes determinants of the diazotrophic lifestyle and plant growth promotion, such as nitrogen fixation, antibiotic resistance, nitrate utilization, and iron uptake. PMID:22038959

Beneduzi, Anelise; Campos, Samanta; Ambrosini, Adriana; de Souza, Rocheli; Granada, Camille; Costa, Pedro; Arruda, Letícia; Moreira, Fernanda; Vargas, Luciano K.; Weiss, Vinícius; Tieppo, Eduardo; Faoro, Helisson; de Souza, Emanuel M.; Pedrosa, Fábio O.; Passaglia, Luciane M. P.

2011-01-01

128

Drosophila Toll is activated by Gram-positive bacteria through a circulating peptidoglycan recognition protein  

Microsoft Academic Search

Microbial infection activates two distinct intracellular signalling cascades in the immune-responsive fat body of Drosophila. Gram-positive bacteria and fungi predominantly induce the Toll signalling pathway, whereas Gram-negative bacteria activate the Imd pathway. Loss-of-function mutants in either pathway reduce the resistance to corresponding infections. Genetic screens have identified a range of genes involved in these intracellular signalling cascades, but how they

Tatiana Michel; Jean-Marc Reichhart; Jules A. Hoffmann; Julien Royet

2001-01-01

129

Identification of Aerobic Gram-Positive Bacilli by Use of Vitek MS  

PubMed Central

The accuracy of Vitek MS mass spectrometric identifications was assessed for 206 clinically significant isolates of aerobic Gram-positive bacilli representing 20 genera and 38 species. The Vitek MS identifications were correct for 85% of the isolates (56.3% to the species level, 28.6% limited to the genus level), with misidentifications occurring for 7.3% of the isolates. PMID:24501030

Navas, Maria; Pincus, David H.; Wilkey, Kathy; Sercia, Linda; LaSalvia, Margaret; Wilson, Deborah; Procop, Gary W.

2014-01-01

130

Gram-positive bacterial resistance. A challenge for the next millennium.  

PubMed

Penicillin G was first used in 1941. Since then, the trend in bacterial infections has changed. New antibiotics have been developed and bacterial resistance has spread as a consequence. The spread of Gram positive resistant bacteria is related to an inappropriate use of antibiotics. Antibacterial agents are abused or overused in various fields: medicine itself, veterinary science and zootechnics. Now, at the beginning of the third millennium we have been forced to limit our therapeutic options in order to combat these insidious enemies. Selective antibiotic pressure on the microbial population, notably on enterococci and staphylococci, made these two pathogens recalcitrant to traditional chemotherapy. It is a matter of concern that today, vancomycin-resistant Enterococcus spp. (VRE) and vancomycin-intermediate and resistant Staphylococcus aureus (VISA and VRSA) are now being observed worldwide among emerging pathogens. Most pharmaceutical companies are today developing antimicrobial drugs that are active against Gram-positive bacteria. Quinupristin/dalfopristin and linezolid are the most promising drugs and are available only for serious infections; future agents being developed for multi-resistant Gram-positive infections include daptomycin and the glycyclines, although these are still in the development phase. Nevertheless, our group has had the opportunity to treat some serious infections with these drugs and the good results achieved are reported in this review. PMID:12094131

Bassetti, M; Melica, G; Cenderello, G; Rosso, R; Di Biagio, A; Bassetti, D

2002-09-01

131

Critical cell wall hole size for lysis in Gram-positive bacteria  

NASA Astrophysics Data System (ADS)

Gram-positive bacteria transport molecules necessary for their survival through holes in their cell wall. The holes in cell walls need to be large enough to let critical nutrients pass through. However, the cell wall must also function to prevent the bacteria's membrane from protruding through a large hole into the environment and lysing the cell. As such, we hypothesize that there exists a range of cell wall hole sizes that allow for molecule transport but prevent membrane protrusion. Here we develop and analyze a biophysical theory of the response of a Gram-positive cell's membrane to the formation of a hole in the cell wall. We predict a critical hole size in the range 15-24nm beyond which lysis occurs. To test our theory, we measured hole sizes in Streptococcus pyogenes cells undergoing enzymatic lysis via transmission electron microscopy. The measured hole sizes are in strong agreement with our theoretical prediction. Together, the theory and experiments provide a means to quantify the mechanisms of death of Gram-positive cells via enzymatically mediated lysis and provides insight into the range of cell wall hole sizes compatible with bacterial homeostasis.

Mitchell, Gabriel; Wiesenfeld, Kurt; Nelson, Daniel; Weitz, Joshua

2013-03-01

132

Structure-Activity Relationships of 3,3?-Phenylmethylene-bis-4-hydroxycoumarins: Selective and Potent Inhibitors of Gram-Positive Bacteria  

PubMed Central

Dicoumarols and coumarin derivatives have shown a variety of pharmaceutical activities and have been found to be potent inhibitor for the NAD(P)H-dependent flavoproteins. In this report, dicoumarol and its derivatives containing the substituted benzene ring at the methylenebis position were synthesized and evaluated for their antibacterial activity against gram-positive bacteria: Staphylococcus aureus and Bacillus subtilis, and gram-negative bacteria: Escherichia coli and Klebsiella sp. The results showed that the synthesized dicoumarols affect cell growth but are selective against gram-positive over gram-negative bacterial cells. However, for most derivatives, the substitution of steric bulky benzene group on the methylenebis position appears to decrease in the efficacy of antibacterial effect. This finding is roughly described by the predicted poorer docked structure of the derivatives to a homology model of S. aureus flavoprotein. 3D-QSAR study highlighted structural features around the substituted benzene ring of dicoumarols as the antibacterial activity. CoMFA and CoMSIA contour maps support the idea that steric repulsion at the para position could diminish the antibacterial activity. The results of this study provide a better understanding of the molecular basis for the antibacterial activity of dicoumarols. PMID:24459419

Chavasiri, Warinthorn

2013-01-01

133

DNA Repair and Genome Maintenance in Bacillus subtilis  

PubMed Central

Summary: From microbes to multicellular eukaryotic organisms, all cells contain pathways responsible for genome maintenance. DNA replication allows for the faithful duplication of the genome, whereas DNA repair pathways preserve DNA integrity in response to damage originating from endogenous and exogenous sources. The basic pathways important for DNA replication and repair are often conserved throughout biology. In bacteria, high-fidelity repair is balanced with low-fidelity repair and mutagenesis. Such a balance is important for maintaining viability while providing an opportunity for the advantageous selection of mutations when faced with a changing environment. Over the last decade, studies of DNA repair pathways in bacteria have demonstrated considerable differences between Gram-positive and Gram-negative organisms. Here we review and discuss the DNA repair, genome maintenance, and DNA damage checkpoint pathways of the Gram-positive bacterium Bacillus subtilis. We present their molecular mechanisms and compare the functions and regulation of several pathways with known information on other organisms. We also discuss DNA repair during different growth phases and the developmental program of sporulation. In summary, we present a review of the function, regulation, and molecular mechanisms of DNA repair and mutagenesis in Gram-positive bacteria, with a strong emphasis on B. subtilis. PMID:22933559

Lenhart, Justin S.; Schroeder, Jeremy W.; Walsh, Brian W.

2012-01-01

134

Sequence characterization of 5S ribosomal RNA from eight gram positive procaryotes  

NASA Technical Reports Server (NTRS)

Complete nucleotide sequences are presented for 5S rRNA from Bacillus subtilis, B. firmus, B. pasteurii, B. brevis, Lactobacillus brevis, and Streptococcus faecalis, and 5S rRNA oligonucleotide catalogs and partial sequence data are given for B. cereus and Sporosarcina ureae. These data demonstrate a striking consistency of 5S rRNA primary and secondary structure within a given bacterial grouping. An exception is B. brevis, in which the 5S rRNA sequence varies significantly from that of other bacilli in the tuned helix and the procaryotic loop. The localization of these variations suggests that B. brevis occupies an ecological niche that selects such changes. It is noted that this organism produces antibiotics which affect ribosome function.

Woese, C. R.; Luehrsen, K. R.; Pribula, C. D.; Fox, G. E.

1976-01-01

135

The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for gram-positive bacteria over erythrocytes.  

PubMed

Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (gram-positive Bacillus subtilis, gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects. PMID:23525222

Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

2013-05-01

136

Identification and Characterization of a Novel-type Ferric Siderophore Reductase from a Gram-positive Extremophile*  

PubMed Central

Iron limitation is one major constraint of microbial life, and a plethora of microbes use siderophores for high affinity iron acquisition. Because specific enzymes for reductive iron release in Gram-positives are not known, we searched Firmicute genomes and found a novel association pattern of putative ferric siderophore reductases and uptake genes. The reductase from the schizokinen-producing alkaliphile Bacillus halodurans was found to cluster with a ferric citrate-hydroxamate uptake system and to catalyze iron release efficiently from Fe[III]-dicitrate, Fe[III]-schizokinen, Fe[III]-aerobactin, and ferrichrome. The gene was hence named fchR for ferric citrate and hydroxamate reductase. The tightly bound [2Fe-2S] cofactor of FchR was identified by UV-visible, EPR, CD spectroscopy, and mass spectrometry. Iron release kinetics were determined with several substrates by using ferredoxin as electron donor. Catalytic efficiencies were strongly enhanced in the presence of an iron-sulfur scaffold protein scavenging the released ferrous iron. Competitive inhibition of FchR was observed with Ga(III)-charged siderophores with Ki values in the micromolar range. The principal catalytic mechanism was found to couple increasing Km and KD values of substrate binding with increasing kcat values, resulting in high catalytic efficiencies over a wide redox range. Physiologically, a chromosomal fchR deletion led to strongly impaired growth during iron limitation even in the presence of ferric siderophores. Inductively coupled plasma-MS analysis of ?fchR revealed intracellular iron accumulation, indicating that the ferric substrates were not efficiently metabolized. We further show that FchR can be efficiently inhibited by redox-inert siderophore mimics in vivo, suggesting that substrate-specific ferric siderophore reductases may present future targets for microbial pathogen control. PMID:21051545

Miethke, Marcus; Pierik, Antonio J.; Peuckert, Florian; Seubert, Andreas; Marahiel, Mohamed A.

2011-01-01

137

Identification and characterization of a novel-type ferric siderophore reductase from a gram-positive extremophile.  

PubMed

Iron limitation is one major constraint of microbial life, and a plethora of microbes use siderophores for high affinity iron acquisition. Because specific enzymes for reductive iron release in gram-positives are not known, we searched Firmicute genomes and found a novel association pattern of putative ferric siderophore reductases and uptake genes. The reductase from the schizokinen-producing alkaliphile Bacillus halodurans was found to cluster with a ferric citrate-hydroxamate uptake system and to catalyze iron release efficiently from Fe[III]-dicitrate, Fe[III]-schizokinen, Fe[III]-aerobactin, and ferrichrome. The gene was hence named fchR for ferric citrate and hydroxamate reductase. The tightly bound [2Fe-2S] cofactor of FchR was identified by UV-visible, EPR, CD spectroscopy, and mass spectrometry. Iron release kinetics were determined with several substrates by using ferredoxin as electron donor. Catalytic efficiencies were strongly enhanced in the presence of an iron-sulfur scaffold protein scavenging the released ferrous iron. Competitive inhibition of FchR was observed with Ga(III)-charged siderophores with K(i) values in the micromolar range. The principal catalytic mechanism was found to couple increasing K(m) and K(D) values of substrate binding with increasing k(cat) values, resulting in high catalytic efficiencies over a wide redox range. Physiologically, a chromosomal fchR deletion led to strongly impaired growth during iron limitation even in the presence of ferric siderophores. Inductively coupled plasma-MS analysis of ?fchR revealed intracellular iron accumulation, indicating that the ferric substrates were not efficiently metabolized. We further show that FchR can be efficiently inhibited by redox-inert siderophore mimics in vivo, suggesting that substrate-specific ferric siderophore reductases may present future targets for microbial pathogen control. PMID:21051545

Miethke, Marcus; Pierik, Antonio J; Peuckert, Florian; Seubert, Andreas; Marahiel, Mohamed A

2011-01-21

138

Melanin: a photoprotection for Bacillus thuringiensis based biopesticides.  

PubMed

Melanins are negatively-charged, hydrophobic, dark high molecular weight irregular biopolymers, composed of polymerized phenolic and/or indolic compounds. They are produced by most organisms. Bacillus thuringiensis is a Gram-positive, spore-forming, soil bacterium and the most successful biological control agent that produces distinctly shaped crystals during sporulation that have insecticidal activity. However, one of the main disadvantages is that the insecticidal activity of B. thuringiensis formulation is unstable and rapidly loses its activity under field conditions due to UV radiation. Melanin absorbs radiation; therefore photoprotection of B. thuringiensis based on melanin has been studied and is herewith reviewed. PMID:25381045

Sansinenea, Estibaliz; Ortiz, Aurelio

2014-11-01

139

Gram-Positive Nickel Resistant Bacteria Isolated from Riparian Sediments Contaminated with Ni and U on the Savannah River Site  

NASA Astrophysics Data System (ADS)

The natural attenuation of pollutants in riparian and wetland systems is driven in large part by the services provided by the diverse microbial communities that thrive in these nutritionally and chemically complex environments. For co-contaminated systems, the presence of heavy metals at excessive levels may alter the structure and function of microbial communities that are essential for the immobilization of inorganics and degradation of organic contaminants. We examined riparian sediments heavily contaminated with U and Ni (1000's of mg/kg) from a small stream on the U.S. Department of Energy's Savannah River Site that received metallurgical process effluents wastewater over a thirty-year period associated with the production of nuclear materials. Four gram positive bacteria were isolated that displayed marked resistance (5000 mg/kg) to Ni relative to organisms from uncontaminated control locations: Arthrobacter oxydans, Streptomyces galbus, Streptomyces aureofaciens, and Kitasatospora cystarginea. The metal resistance of S. aureofaciens and K. cystarginea was further characterized in growth experiments for resistance to other metals. Ongoing geochemical characterization of U and Ni in terms of solid phase partitioning and aqueous phase speciation and solubility indicate that Ni is more chemically labile and, by extension, bioavailable than U in these aged-contaminated sediments. Accordingly, the isolation of Ni resistant organisms is consistent with greater selective pressure from Ni as a result of its greater bioavailability. These results are placed in context of environmental management and remediation of co-contaminated, biogeochemically complex environments.

Sowder, A. G.; Khijniak, T. V.; van Nostrand, J.; Bertsch, P. M.; Morris, P. J.

2002-12-01

140

NClassG+: A classifier for non-classically secreted Gram-positive bacterial proteins  

PubMed Central

Background Most predictive methods currently available for the identification of protein secretion mechanisms have focused on classically secreted proteins. In fact, only two methods have been reported for predicting non-classically secreted proteins of Gram-positive bacteria. This study describes the implementation of a sequence-based classifier, denoted as NClassG+, for identifying non-classically secreted Gram-positive bacterial proteins. Results Several feature-based classifiers were trained using different sequence transformation vectors (frequencies, dipeptides, physicochemical factors and PSSM) and Support Vector Machines (SVMs) with Linear, Polynomial and Gaussian kernel functions. Nested k-fold cross-validation (CV) was applied to select the best models, using the inner CV loop to tune the model parameters and the outer CV group to compute the error. The parameters and Kernel functions and the combinations between all possible feature vectors were optimized using grid search. Conclusions The final model was tested against an independent set not previously seen by the model, obtaining better predictive performance compared to SecretomeP V2.0 and SecretPV2.0 for the identification of non-classically secreted proteins. NClassG+ is freely available on the web at http://www.biolisi.unal.edu.co/web-servers/nclassgpositive/ PMID:21235786

2011-01-01

141

Identification of gram-negative and gram-positive bacteria by fluorescence studies  

NASA Astrophysics Data System (ADS)

Several type strains of bacteria including Vibrio fischeri, Azotobacter vinelandii, Enterobacter cloacae, and Corynebacterium xerosis, were cultured in the laboratory following standard diagnostic protocol based on their individual metabolic strategies. The bacterial cultures were not further treated and they were studied in their pristine state (pure culture - axenic). The fluorescent studies were applied using a continuous wave and a pulsed excitation light sources. Emission and excitation spectra were recorded for the continuous wave excitation and they all show similar spectral features with the exception of the gram positive bacteria showing vibronic structures. The vibrational modes involved in these vibronic bands have energy typical for carbon-carbon vibrations. The fluorescence is quenched in addition of water, even a very thin layer, which confirms that the observed spectral features originate from the outer parts of the bacteria. These results allow to conclude that the fluorescence spectroscopy can be used as a method for studying the membranes of the bacteria and eventually to discriminate between gram positive and gram negative bacteria. The pulsed experiments show that the fluorescence lifetime is in the sub-microsecond range. The results indicate that the observed spectra are superposition of the emission with different lifetimes.

Demchak, Jonathan; Calabrese, Joseph; Tzolov, Marian

2011-03-01

142

Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens  

PubMed Central

Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria. PMID:23056510

Field, Des; Begley, Maire; O’Connor, Paula M.; Daly, Karen M.; Hugenholtz, Floor; Cotter, Paul D.; Hill, Colin; Ross, R. Paul

2012-01-01

143

Peptidoglycan architecture of Gram-positive bacteria by solid-state NMR.  

PubMed

Peptidoglycan is an essential component of cell wall in Gram-positive bacteria with unknown architecture. In this review, we summarize solid-state NMR approaches to address some of the unknowns in the Gram-positive bacteria peptidoglycan architecture: 1) peptidoglycan backbone conformation, 2) PG-lattice structure, 3) variations in the peptidoglycan architecture and composition, 4) the effects of peptidoglycan bridge-length on the peptidoglycan architecture in Fem mutants, 5) the orientation of glycan strands with respect to the membrane, and 6) the relationship between the peptidoglycan structure and the glycopeptide antibiotic mode of action. Solid-state NMR analyses of Staphylococcus aureus cell wall show that peptidoglycan chains are surprisingly ordered and densely packed. The peptidoglycan disaccharide backbone adopts 4-fold screw helical symmetry with the disaccharide unit periodicity of 40Å. Peptidoglycan lattice in the S. aureus cell wall is formed by cross-linked PG stems that have parallel orientations. The structural characterization of Fem-mutants of S. aureus with varying lengths of bridge structures suggests that the PG-bridge length is an important determining factor for the PG architecture. This article is part of a Special Issue entitled: NMR Spectroscopy for Atomistic Views of Biomembranes and Cell Surfaces. Guest Editors: Lynette Cegelski and David P. Weliky. PMID:24915020

Kim, Sung Joon; Chang, James; Singh, Manmilan

2015-01-01

144

Rapid method that aids in distinguishing Gram-positive from Gram-negative anaerobic bacteria.  

PubMed

Several species of anaerobic bacteria display variable Gram stain reactions which often make identification difficult. A simple, rapid method utilizing a 3% solution of potassium hydroxide to distinguish between gram-positive and gram-negative bacterial was tested on 213 strains of anaerobic bacteria representing 19 genera. The Gram stain reaction and KOH test results were compared with the antibiotic disk susceptibilities (vancomycin and colistin) the preliminary grouping of anaerobic bacteria. All three procedures were in agreement for the majority of strains examined. Some strains of clostridia, eubacteria, and bifidobacteria stained gram negative or gram variable; the KOH and antibiotic disk susceptibility tests correctly classified these strains as gram-positive. The KOH test incorrectly grouped some strains of Bacteroides sp., Fusobacterium sp., Leptotrichia buccalis, and Veillonella parvula, but all Gram stain results for these strains were consistent for gram-negative bacteria. The KOH test is a useful supplement to the Gram stain and antibiotic disk susceptibility testing for the initial classification of anaerobic bacteria. PMID:6165736

Halebian, S; Harris, B; Finegold, S M; Rolfe, R D

1981-03-01

145

Overview of resistant gram-positive pathogens in the surgical patient.  

PubMed

Staphylococci and enterococci are the most common pathogens in surgical-site and bloodstream infections. The emergence of drug resistance among these gram-positive bacteria thus poses a substantial threat to patients with surgical infections. Resistance to methicillin/oxacillin is frequently observed in Staphylococcus aureus isolates and is often accompanied by multidrug resistance. Vancomycin is usually the treatment of choice for infections caused by methicillin-resistant S. aureus (MRSA), so the recent appearance of S. aureus isolated with intermediate sensitivity to vancomycin is cause for concern. Vancomycin resistance has already appeared in most species of enterococci. Infections caused by vancomycin-resistant enterococci (VRE) are associated with increased mortality compared to infections caused by vancomycin-sensitive isolates. Measures for preventing vancomycin resistance include reducing the use of vancomycin and other agents that appear to be associated with VRE, including third-generation cephalosporins and anti-anaerobic drugs. Third-generation cephalosporins have also been implicated in the increased prevalence of MRSA infections. Prudent use of existing antibiotics is an essential strategy for combating the rising tide of drug-resistant gram-positive pathogens. PMID:12594908

Rapp, R P

2000-01-01

146

In Vitro Activities of Membrane-Active Peptides against Gram-Positive and Gram-Negative Aerobic Bacteria  

Microsoft Academic Search

Four peptides, cecropin P1, magainin II, indolicidin, and ranalexin, were evaluated against 202 clinical isolates of gram-positive and gram-negative aerobic bacteria by a microbroth dilution method. The gram- negative isolates were more susceptible to cecropin P1. Ranalexin was the most active compound against the gram-positive strains. The bactericidal activity of each peptide was equivalent to, or 1 dilution above, the

A. GIACOMETTI; O. CIRIONI; G. GREGANTI; M. QUARTA; G. SCALISE

1998-01-01

147

Prediction of Cell Wall Sorting Signals in Gram-Positive bacteria with a Hidden Markov Model: Application to Complete genomes  

Microsoft Academic Search

Surface proteins in Gram-positive bacteria are frequently implicated in virulence. We have focused on a group of extracellular cell wall-attached proteins (CWPs), contain- ing an LPXTG motif for cleavage and covalent coupling to peptidoglycan by sortase enzymes. A hidden Markov model (HMM) approach for predicting the LPXTG-anchored cell wall proteins of Gram-positive bacteria was developed and compared against existing methods.

Zoi I. Litou; Pantelis G. Bagos; Konstantinos D. Tsirigos; Theodore D. Liakopoulos; Stavros J. Hamodrakas

2008-01-01

148

In Vitro Activities of Dalbavancin and Nine Comparator Agents against Anaerobic Gram-Positive Species and Corynebacteria  

Microsoft Academic Search

Dalbavancin is a novel semisynthetic glycopeptide with enhanced activity against gram-positive species. Its comparative in vitro activities and those of nine comparator agents, including daptomycin, vancomycin, linezolid, and quinupristin-dalfopristin, against 290 recent gram-positive clinical isolates strains, as deter- mined by the NCCLS agar dilution method, were studied. The MICs of dalbavancin at which 90% of various isolates tested were inhibited

Ellie J. C. Goldstein; Diane M. Citron; C. Vreni Merriam; Yumi Warren; Kerin Tyrrell; Helen T. Fernandez

2003-01-01

149

Bacillus subtilis chromosome organization oscillates between two distinct patterns.  

PubMed

Bacterial chromosomes have been found to possess one of two distinct patterns of spatial organization. In the first, called "ori-ter" and exemplified by Caulobacter crescentus, the chromosome arms lie side-by-side, with the replication origin and terminus at opposite cell poles. In the second, observed in slow-growing Escherichia coli ("left-ori-right"), the two chromosome arms reside in separate cell halves, on either side of a centrally located origin. These two patterns, rotated 90° relative to each other, appear to result from different segregation mechanisms. Here, we show that the Bacillus subtilis chromosome alternates between them. For most of the cell cycle, newly replicated origins are maintained at opposite poles with chromosome arms adjacent to each other, in an ori-ter configuration. Shortly after replication initiation, the duplicated origins move as a unit to midcell and the two unreplicated arms resolve into opposite cell halves, generating a left-ori-right pattern. The origins are then actively segregated toward opposite poles, resetting the cycle. Our data suggest that the condensin complex and the parABS partitioning system are the principal driving forces underlying this oscillatory cycle. We propose that the distinct organization patterns observed for bacterial chromosomes reflect a common organization-segregation mechanism, and that simple modifications to it underlie the unique patterns observed in different species. PMID:25071173

Wang, Xindan; Montero Llopis, Paula; Rudner, David Z

2014-09-01

150

Comparative in vitro activity of gemifloxacin against gram-positive and gram-negative clinical isolates in Argentina.  

PubMed

The in vitro activity of gemifloxacin against 1,000 clinical isolates of 147 Streptococcus pneumoniae (115, penicilin susceptible; 26, intermediate penicillin-resistant and 6, penicillin-resistant), 127 Hemophilus influenzae (109, beta lactamasa non-producer; 18, beta lactamase producers), 95 Streptococcus pyogenes (6, azytromycin-resistant), 84 Moraxella catarrhalis (79, beta lactamase producers), 110 Staphilococcus aureus (89, methicillin-susceptible; 21, methicilin-resistant), 98 Eenterococcus faecalis and 339 Enterobacteriacea, (recovered from patients with respiratory tract infection; skin and soft tissue infection and urinary tract infection), was compared with the activities of four fluorquinolones and five other antimicrobial agents. Of the quinolones tested, gemifloxacin was the most potent against Streptococcus pneumoniae, including penicillin intermediate and resistant strains. Mic(90) values obtained for gemifloxacin, ciprofloxacin, ofloxacin, levofloxacin and trvafloxacin were 0.03, 2, 2, 1 and 0.25 mg/L respectively. Gemifloxacin was 16 fold more potent than ciprofloxacin against methicillin-susceptible Staphylococcus aureus and 32 fold more potent than ciprofloxacin against Streptococcus pyogenes. When tested against Hemophilus influenzae, Moraxella catarrhalis and Enterobacteriaceae, all the quinolones showed similar activity. Our results demonstrate that gemifloxacin has similar activity than the other quinolones tested against Gram-negative organisms and is considerably more potent against Gram-positive organisms. PMID:11576792

Lopez, H; Stepanik, D; Vilches, V; Scarano, S; Sarachian, B; Mikaelian, G; Finlay, J; Sucari, A

2001-08-01

151

Atopococcus tabaci gen. nov., sp. nov., a novel Gram-positive, catalase-negative, coccus-shaped bacterium isolated from tobacco.  

PubMed

A novel Gram-positive, aerobic, catalase-negative, coccus-shaped organism originating from tobacco was characterized using phenotypic and molecular taxonomic methods. The organism contained a cell wall murein based on L-lysine (variation A4alpha, type L-lysine-L-glutamic acid), synthesized long-chain cellular fatty acids of the straight-chain saturated and monounsaturated types (with C(16:1)omega9, C(16:0) and C(18:1)omega9 predominating) and possessed a DNA G+C content of 46 mol%. Based on morphological, biochemical and chemical characteristics, the coccus-shaped organism did not conform to any presently recognized taxon. Comparative 16S rRNA gene sequencing studies confirmed the distinctiveness of the unknown coccus, with the bacterium displaying sequence divergence values of greater than 7% with other recognized Gram-positive taxa. Treeing analysis reinforced its distinctiveness, with the unidentified organism forming a relatively long subline branching at the periphery of an rRNA gene sequence cluster which encompasses the genera Alloiococcus, Allofustis, Alkalibacterium, Atopostipes, Dolosigranulum and Marinilactibacillus. Based on phenotypic and molecular phylogenetic evidence, it is proposed that the unknown organism from tobacco be classified as a new genus and species, Atopococcus tabaci gen. nov., sp. nov. The type strain of Atopococcus tabaci is CCUG 48253(T) (=CIP 108502(T)). PMID:16014503

Collins, Matthew D; Wiernik, Anna; Falsen, Enevold; Lawson, Paul A

2005-07-01

152

Purification Techniques of Bacteriocins from Lactic Acid Bacteria and Other Gram-Positive Bacteria  

NASA Astrophysics Data System (ADS)

The search for new antimicrobial peptides produced by lactic acid ­bacteria and other Gram-positive microorganisms has become an interesting field of research in the past decades. The fact that bacteriocins are active against numerous foodborne and human pathogens, are produced by generally regarded as safe (GRAS) microorganisms, and are readily degraded by proteolytic host systems makes them attractive candidates for biotechnological applications. However, before suggesting or choosing a new bacteriocin for future technology developments, it is necessary to elucidate its biochemical structure and its mode of action, which may be carried out once the bacteriocin is purified to homogeneity. This chapter focuses on describing the main strategies used for the purification of numerous bacteriocins.

Saavedra, Lucila; Sesma, Fernando

153

Microcins from Enterobacteria: On the Edge Between Gram-Positive Bacteriocins and Colicins  

NASA Astrophysics Data System (ADS)

Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

Rebuffat, Sylvie

154

A Continuum of Anionic Charge: Structures and Functions of d-Alanyl-Teichoic Acids in Gram-Positive Bacteria†  

PubMed Central

Teichoic acids (TAs) are major wall and membrane components of most gram-positive bacteria. With few exceptions, they are polymers of glycerol-phosphate or ribitol-phosphate to which are attached glycosyl and d-alanyl ester residues. Wall TA is attached to peptidoglycan via a linkage unit, whereas lipoteichoic acid is attached to glycolipid intercalated in the membrane. Together with peptidoglycan, these polymers make up a polyanionic matrix that functions in (i) cation homeostasis; (ii) trafficking of ions, nutrients, proteins, and antibiotics; (iii) regulation of autolysins; and (iv) presentation of envelope proteins. The esterification of TAs with d-alanyl esters provides a means of modulating the net anionic charge, determining the cationic binding capacity, and displaying cations in the wall. This review addresses the structures and functions of d-alanyl-TAs, the d-alanylation system encoded by the dlt operon, and the roles of TAs in cell growth. The importance of dlt in the physiology of many organisms is illustrated by the variety of mutant phenotypes. In addition, advances in our understanding of d-alanyl ester function in virulence and host-mediated responses have been made possible through targeted mutagenesis of dlt. Studies of the mechanism of d-alanylation have identified two potential targets of antibacterial action and provided possible screening reactions for designing novel agents targeted to d-alanyl-TA synthesis. PMID:14665680

Neuhaus, Francis C.; Baddiley, James

2003-01-01

155

Biocompatible Fe3O4 increases the efficacy of amoxicillin delivery against Gram-positive and Gram-negative bacteria.  

PubMed

This paper reports the synthesis and characterization of amoxicillin- functionalized magnetite nanostructures (Fe3O4@AMO), revealing and discussing several biomedical applications of these nanomaterials. Our results proved that 10 nm Fe3O4@AMO nanoparticles does not alter the normal cell cycle progression of cultured diploid cells, and an in vivo murine model confirms that the nanostructures disperse through the host body and tend to localize in particular sites and organs. The nanoparticles were found clustered especially in the lungs, kidneys and spleen, next to the blood vessels at this level, while being totally absent in the brain and liver, suggesting that they are circulated through the blood flow and have low toxicity. Fe3O4@AMO has the ability to be easily circulated through the body and optimizations may be done so these nanostructures cluster to a specific target region. Functionalized magnetite nanostructures proved a great antimicrobial effect, being active against both the Gram positive pathogen S. aureus and the Gram negative pathogen E. coli. The fabricated nanostructures significantly reduced the minimum inhibitory concentration (MIC) of the active drug. This result has a great practical relevance, since the functionalized nanostructures may be used for decreasing the therapeutic doses which usually manifest great severe side effects, when administrated in high doses. Fe3O4@AMO represents also a suitable approach for the development of new alternative strategies for improving the activity of therapeutic agents by targeted delivery and controlled release. PMID:24759068

Grumezescu, Alexandru Mihai; Gestal, Monica Cartelle; Holban, Alina Maria; Grumezescu, Valentina; Vasile, Bogdan Stefan; Mogoant?, Lauren?iu; Iordache, Florin; Bleotu, Coralia; Mogo?anu, George Dan

2014-01-01

156

A Myeloid Hypoxia-inducible Factor 1?-Krüppel-like Factor 2 Pathway Regulates Gram-positive Endotoxin-mediated Sepsis*  

PubMed Central

Although Gram-positive infections account for the majority of cases of sepsis, the molecular mechanisms underlying their effects remains poorly understood. We investigated how cell wall components of Gram-positive bacteria contribute to the development of sepsis. Experimental observations derived from cultured primary macrophages and the cell line indicate that Gram-positive bacterial endotoxins induce hypoxia-inducible factor 1? (HIF-1?) mRNA and protein expression. Inoculation of live or heat-inactivated Gram-positive bacteria with macrophages induced HIF-1 transcriptional activity in macrophages. Concordant with these results, myeloid deficiency of HIF-1? attenuated Gram-positive bacterial endotoxin-induced cellular motility and proinflammatory gene expression in macrophages. Conversely, Gram-positive bacteria and their endotoxins reduced expression of the myeloid anti-inflammatory transcription factor Krüppel-like transcription factor 2 (KLF2). Sustained expression of KLF2 reduced and deficiency of KLF2 enhanced Gram-positive endotoxins induced HIF-1? mRNA and protein expression in macrophages. More importantly, KLF2 attenuated Gram-positive endotoxins induced cellular motility and proinflammatory gene expression in myeloid cells. Consistent with these results, mice deficient in myeloid HIF-1? were protected from Gram-positive endotoxin-induced sepsis mortality and clinical symptomatology. By contrast, myeloid KLF2-deficient mice were susceptible to Gram-positive sepsis induced mortality and clinical symptoms. Collectively, these observations identify HIF-1? and KLF2 as critical regulators of Gram-positive endotoxin-mediated sepsis. PMID:22110137

Mahabeleshwar, Ganapati H.; Qureshi, Muhammad Awais; Takami, Yoichi; Sharma, Nikunj; Lingrel, Jerry B.; Jain, Mukesh K.

2012-01-01

157

Lysis of gram-positive and gram-negative bacteria by antibacterial porous polymeric monolith formed in microfluidic biochips for sample preparation.  

PubMed

Bacterial cell lysis is demonstrated using polymeric microfluidic biochips operating via a hybrid mechanical shearing/contact killing mechanism. These biochips are fabricated from a cross-linked poly(methyl methacrylate) (X-PMMA) substrate by well-controlled, high-throughput laser micromachining. The unreacted double bonds at the surface of X-PMMA provide covalent bonding for the formation of a porous polymeric monolith (PPM), thus contributing to the mechanical stability of the biochip and eliminating the need for surface treatment. The lysis efficiency of these biochips was tested for gram-positive (Enterococcus saccharolyticus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas fluorescens) and confirmed by off-chip PCR without further purification. The influence of the flow rate when pumping the bacterial suspension through the PPM, and of the hydrophobic-hydrophilic balance on the cell lysis efficiency was investigated at a cell concentration of 10(5) CFU/mL. It was shown that the contribution of contact killing to cell lysis was more important than that of mechanical shearing in the PPM. The biochip showed better lysis efficiency than the off-chip chemical, mechanical, and thermal lysis techniques used in this work. The biochip also acts as a filter that isolates cell debris and allows PCR-amplifiable DNA to pass through. The system performs more efficient lysis for gram-negative than for gram-positive bacteria. The biochip does not require chemical/enzymatic reagents, power consumption, or complicated design and fabrication processes, which makes it an attractive on-chip lysis device that can be used in sample preparation for genetics and point-of-care diagnostics. The biochips were reused for 20 lysis cycles without any evidence of physical damage to the PPM, significant performance degradation, or DNA carryover when they were back-flushed between cycles. The biochips efficiently lysed both gram-positive and gram-negative bacteria in about 35 min per lysis and PPM regeneration cycle. PMID:25059724

Aly, Mohamed Aly Saad; Gauthier, Mario; Yeow, John

2014-09-01

158

A Complex Genetic Switch Involving Overlapping Divergent Promoters and DNA Looping Regulates Expression of Conjugation Genes of a Gram-positive Plasmid  

PubMed Central

Plasmid conjugation plays a significant role in the dissemination of antibiotic resistance and pathogenicity determinants. Understanding how conjugation is regulated is important to gain insights into these features. Little is known about regulation of conjugation systems present on plasmids from Gram-positive bacteria. pLS20 is a native conjugative plasmid from the Gram-positive bacterium Bacillus subtilis. Recently the key players that repress and activate pLS20 conjugation have been identified. Here we studied in detail the molecular mechanism regulating the pLS20 conjugation genes using both in vivo and in vitro approaches. Our results show that conjugation is subject to the control of a complex genetic switch where at least three levels of regulation are integrated. The first of the three layers involves overlapping divergent promoters of different strengths regulating expression of the conjugation genes and the key transcriptional regulator RcoLS20. The second layer involves a triple function of RcoLS20 being a repressor of the main conjugation promoter and an activator and repressor of its own promoter at low and high concentrations, respectively. The third level of regulation concerns formation of a DNA loop mediated by simultaneous binding of tetrameric RcoLS20 to two operators, one of which overlaps with the divergent promoters. The combination of these three layers of regulation in the same switch allows the main conjugation promoter to be tightly repressed during conditions unfavorable to conjugation while maintaining the sensitivity to accurately switch on the conjugation genes when appropriate conditions occur. The implications of the regulatory switch and comparison with other genetic switches involving DNA looping are discussed. PMID:25340403

Ramachandran, Gayetri; Singh, Praveen K.; Luque-Ortega, Juan Roman; Yuste, Luis; Alfonso, Carlos; Rojo, Fernando; Wu, Ling J.; Meijer, Wilfried J. J.

2014-01-01

159

Homologs of the Rml Enzymes from Salmonella enterica Are Responsible for dTDP-?-l-Rhamnose Biosynthesis in the Gram-Positive Thermophile Aneurinibacillus thermoaerophilus DSM 10155  

PubMed Central

The glycan chains of the surface layer (S-layer) glycoprotein from the gram-positive, thermophilic bacterium Aneurinibacillus (formerly Bacillus) thermoaerophilus strain DSM 10155 are composed of l-rhamnose- and d-glycero-d-manno-heptose-containing disaccharide repeating units which are linked to the S-layer polypeptide via core structures that have variable lengths and novel O-glycosidic linkages. In this work we investigated the enzymes involved in the biosynthesis of thymidine diphospho-l-rhamnose (dTDP-l-rhamnose) and their specific properties. Comparable to lipopolysaccharide O-antigen biosynthesis in gram-negative bacteria, dTDP-l-rhamnose is synthesized in a four-step reaction sequence from dTTP and glucose 1-phosphate by the enzymes glucose-1-phosphate thymidylyltransferase (RmlA), dTDP-d-glucose 4,6-dehydratase (RmlB), dTDP-4-dehydrorhamnose 3,5-epimerase (RmlC), and dTDP-4-dehydrorhamnose reductase (RmlD). The rhamnose biosynthesis operon from A. thermoaerophilus DSM 10155 was sequenced, and the genes were overexpressed in Escherichia coli. Compared to purified enterobacterial Rml enzymes, the enzymes from the gram-positive strain show remarkably increased thermostability, a property which is particularly interesting for high-throughput screening and enzymatic synthesis. The closely related strain A. thermoaerophilus L420-91T produces d-rhamnose- and 3-acetamido-3,6-dideoxy-d-galactose-containing S-layer glycan chains. Comparison of the enzyme activity patterns in A. thermoaerophilus strains DSM 10155 and L420-91T for l-rhamnose and d-rhamnose biosynthesis indicated that the enzymes are differentially expressed during S-layer glycan biosynthesis and that A. thermoaerophilus L420-91T is not able to synthesize dTDP-l-rhamnose. These findings confirm that in each strain the enzymes act specifically on S-layer glycoprotein glycan formation. PMID:12147463

Graninger, Michael; Kneidinger, Bernd; Bruno, Katharina; Scheberl, Andrea; Messner, Paul

2002-01-01

160

Homologs of the Rml enzymes from Salmonella enterica are responsible for dTDP-beta-L-rhamnose biosynthesis in the gram-positive thermophile Aneurinibacillus thermoaerophilus DSM 10155.  

PubMed

The glycan chains of the surface layer (S-layer) glycoprotein from the gram-positive, thermophilic bacterium Aneurinibacillus (formerly Bacillus) thermoaerophilus strain DSM 10155 are composed of L-rhamnose- and D-glycero-D-manno-heptose-containing disaccharide repeating units which are linked to the S-layer polypeptide via core structures that have variable lengths and novel O-glycosidic linkages. In this work we investigated the enzymes involved in the biosynthesis of thymidine diphospho-L-rhamnose (dTDP-L-rhamnose) and their specific properties. Comparable to lipopolysaccharide O-antigen biosynthesis in gram-negative bacteria, dTDP-L-rhamnose is synthesized in a four-step reaction sequence from dTTP and glucose 1-phosphate by the enzymes glucose-1-phosphate thymidylyltransferase (RmlA), dTDP-D-glucose 4,6-dehydratase (RmlB), dTDP-4-dehydrorhamnose 3,5-epimerase (RmlC), and dTDP-4-dehydrorhamnose reductase (RmlD). The rhamnose biosynthesis operon from A. thermoaerophilus DSM 10155 was sequenced, and the genes were overexpressed in Escherichia coli. Compared to purified enterobacterial Rml enzymes, the enzymes from the gram-positive strain show remarkably increased thermostability, a property which is particularly interesting for high-throughput screening and enzymatic synthesis. The closely related strain A. thermoaerophilus L420-91(T) produces D-rhamnose- and 3-acetamido-3,6-dideoxy-D-galactose-containing S-layer glycan chains. Comparison of the enzyme activity patterns in A. thermoaerophilus strains DSM 10155 and L420-91(T) for L-rhamnose and D-rhamnose biosynthesis indicated that the enzymes are differentially expressed during S-layer glycan biosynthesis and that A. thermoaerophilus L420-91(T) is not able to synthesize dTDP-L-rhamnose. These findings confirm that in each strain the enzymes act specifically on S-layer glycoprotein glycan formation. PMID:12147463

Graninger, Michael; Kneidinger, Bernd; Bruno, Katharina; Scheberl, Andrea; Messner, Paul

2002-08-01

161

Allofustis seminis gen. nov., sp. nov., a novel Gram-positive, catalase-negative, rod-shaped bacterium from pig semen.  

PubMed

An unknown Gram-positive, catalase-negative, facultatively anaerobic, non-spore-forming, rod-shaped bacterium originating from semen of a pig was characterized using phenotypic, molecular chemical and molecular phylogenetic methods. Chemical studies revealed the presence of a directly cross-linked cell wall murein based on L-lysine and a DNA G + C content of 39 mol%. Comparative 16S rRNA gene sequencing showed that the unidentified rod-shaped organism formed a hitherto unknown subline related, albeit loosely, to Alkalibacterium olivapovliticus, Alloiococcus otitis, Dolosigranulum pigrum and related organisms, in the low-G + C-content Gram-positive bacteria. However, sequence divergence values of > 11% from these recognized taxa clearly indicated that the novel bacterium represents a separate genus. Based on phenotypic and phylogenetic considerations, it is proposed that the unknown bacterium from pig semen be classified as a new genus and species, Allofustis seminis gen. nov., sp. nov. The type strain is strain 01-570-1(T) (= CCUG 45438(T) = CIP 107425(T)). PMID:12807205

Collins, Matthew D; Higgins, Robert; Messier, Serge; Fortin, Madeleine; Hutson, Roger A; Lawson, Paul A; Falsen, Enevold

2003-05-01

162

Bacillus marcorestinctum sp. nov., a Novel Soil Acylhomoserine Lactone Quorum-Sensing Signal Quenching Bacterium  

PubMed Central

A Gram-positive, facultatively anaerobic, endospore-forming and rod-shaped bacterium was isolated from soil samples and designated strain LQQ. This organism strongly quenches the acylhomoserine lactone quorum-sensing signal. The LQQ strain exhibits phenotypic characteristics consistent with its classification in the genus Bacillus. It is positive in catalase and no special growth factor is needed. It uses glucose as sole carbon source. The DNA G + C content is 39.8 mol %. The closest relatives based on the 16S rRNA gene sequence are Bacillus anthracis, Bacillus thuringiensis, and Brevibacillus brevis (syn. Bacillus brevis) with the similarity of 96.5%. The DNA–DNA hybridization data indicates a low level of genomic relatedness with the relative type strains of Bacillus thuringiensis (6.1%), Bacillus anthracis (10.5%) and Brevibacillus brevis (8.7%). On the basis of the phenotypic and phylogenetic data together with the genomic distinctiveness, the LQQ strain represents a novel species of the genus Bacillus, for which the name Bacillus marcorestinctum sp. nov. is proposed. The type strain is LQQT. PMID:20386651

Han, Yan; Chen, Fang; Li, Nuo; Zhu, Bo; Li, Xianzhen

2010-01-01

163

Cellular fatty acid composition as an adjunct to the identification of asporogenous, aerobic gram-positive rods.  

PubMed

Cellular fatty acid (CFA) compositions of 561 asporogenous, aerobic gram-positive rods were analyzed by gas-liquid chromatography as an adjunct to their identification when grown on blood agar at 35 degrees C. The organisms could be divided into two groups. In the first group (branched-chain type), which included coryneform CDC groups A-3, A-4, and A-5; some strains of B-1 and B-3; "Corynebacterium aquaticum"; Brevibacterium liquefaciens; Rothia dentocariosa; and Listeria spp., the rods had sizable quantities of antiesopentadecanoic (Ca15:0) and anteisoheptadecanoic (Ca17:0) acids. Other species with these types of CFA included B. acetylicum, which contained large amounts of isotridecanoic (Ci13:0) and anteisotridecanoic (Ca13:0) acids. CFAs useful for distinguishing among Jonesia denitrificans, Oerskovia spp., some strains of CDC groups B-1 and B-3, Kurthia spp., and Propionibacterium avidum were hexadecanoic (C 16:0) acid, isopentadecanoic (Ci15:0) acid, and Ca15:0). The second group (straight-chained type), which included Actinomyces pyogenes; Arcanobacterium haemolyticum; C. bovis; C. cystitidis; C. diphtheriae; C. flavescens, "C. gentalium"; C. jeikeium; C. kutscheri; C. matruchotii; C .minutissimum; C. mycetoides; C. pilosum; C. pseudodiphtheriticum; "C. pseudogenitalium"; C. pseudotuberculosis; C. renale; CDC groups 1, 2, ANF-1, D-2, E, F-1, F-2, G-1, G-2, and I-2; C. striatum; "C. tuberculostearicum"; C. ulcerans; C. vitarumen; C. xerosis; and Erysipelothrix rhusiopathiae, was typified by significant quantities of hexadecanoic (C16:0) and oleic acids (C18:cis9), with differences in the amounts of linoleic acid (C18:2), stearic acid (C18:0), an unnamed peak (equivalent chain length, 14.966), and small quantities of other known saturated and unsaturated fatty acids. CFA composition of these organisms was sufficiently discriminatory to assist in classification but could not be used as the sole means of identification. PMID:1899679

Bernard, K A; Bellefeuille, M; Ewan, E P

1991-01-01

164

Isolation and structural elucidation of armeniaspirols?A-C: potent antibiotics against gram-positive pathogens.  

PubMed

In an antibiotic lead discovery program, the known strain Streptomyces armeniacus DSM19369 has been found to produce three new natural products when cultivated on a malt-containing medium. The challenging structural elucidation of the isolated compounds was achieved by using three independent methods, that is, chemical degradation followed by NMR spectroscopy, a computer-assisted structure prediction algorithm, and X-ray crystallography. The compounds, named armeniaspirol?A-C (2-4), exhibit a compact, hitherto unprecedented chlorinated spiro[4.4]non-8-ene scaffold. Labeling experiments with [1-(13)C] acetate, [1,2-(13)C2] acetate, and [U-(13)C] proline suggest a biosynthesis through a rare two-chain mechanism. Armeniaspirols displayed moderate to high in vitro activities against gram-positive pathogens such as methicillin-resistant S. aureus (MRSA) or vancomycin resistant E. faecium (VRE). As analogue 2 was active in vivo in an MRSA sepsis model, and showed no development of resistance in a serial passaging experiment, it represents a new antibiotic lead structure. PMID:23143837

Dufour, Cosima; Wink, Joachim; Kurz, Michael; Kogler, Herbert; Olivan, Helene; Sablé, Serge; Heyse, Winfried; Gerlitz, Martin; Toti, Luigi; Nußer, Antje; Rey, Astrid; Couturier, Cedric; Bauer, Armin; Brönstrup, Mark

2012-12-01

165

?, a new subunit of RNA polymerase found in gram-positive bacteria.  

PubMed

RNA polymerase in bacteria is a multisubunit protein complex that is essential for gene expression. We have identified a new subunit of RNA polymerase present in the high-A+T Firmicutes phylum of Gram-positive bacteria and have named it ?. Previously ? had been identified as a small protein (?1) that copurified with RNA polymerase. We have solved the structure of ? by X-ray crystallography and show that it is not an ? subunit. Rather, ? bears remarkable similarity to the Gp2 family of phage proteins involved in the inhibition of host cell transcription following infection. Deletion of ? shows no phenotype and has no effect on the transcriptional profile of the cell. Determination of the location of ? within the assembly of RNA polymerase core by single-particle analysis suggests that it binds toward the downstream side of the DNA binding cleft. Due to the structural similarity of ? with Gp2 and the fact they bind similar regions of RNA polymerase, we hypothesize that ? may serve a role in protection from phage infection. PMID:25092033

Keller, Andrew N; Yang, Xiao; Wiedermannová, Jana; Delumeau, Olivier; Krásný, Libor; Lewis, Peter J

2014-10-01

166

[Resistance to "last resort" antibiotics in Gram-positive cocci: The post-vancomycin era].  

PubMed

New therapeutic alternatives have been developed in the last years for the treatment of multidrug-resistant Gram-positive infections. Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are considered a therapeutic challenge due to failures and lack of reliable antimicrobial options. Despite concerns related to the use of vancomycin in the treatment of severe MRSA infections in specific clinical scenarios, there is a paucity of solid clinical evidence that support the use of alternative agents (when compared to vancomycin). Linezolid, daptomycin and tigecycline are antibiotics approved in the last decade and newer cephalosporins (such as ceftaroline and ceftobiprole) and novel glycopeptides (dalvavancin, telavancin and oritavancin) have reached clinical approval or are in the late stages of clinical development. This review focuses on discussing these newer antibiotics used in the "post-vancomycin" era with emphasis on relevant chemical characteristics, spectrum of antimicrobial activity, mechanisms of action and resistance, as well as their clinical utility. PMID:24968051

Rincón, Sandra; Panesso, Diana; Díaz, Lorena; Carvajal, Lina P; Reyes, Jinnethe; Munita, José M; Arias, César A

2014-04-01

167

Sortases and the Art of Anchoring Proteins to the Envelopes of Gram-Positive Bacteria  

PubMed Central

The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis. PMID:16524923

Marraffini, Luciano A.; DeDent, Andrea C.; Schneewind, Olaf

2006-01-01

168

Gram-positive pathogenic bacteria induce a common early response in human monocytes  

PubMed Central

Background We infected freshly isolated human peripheral monocytes with live bacteria of three clinically important gram-positive bacterial species, Staphylococcus aureus, Streptococcus pneumoniae and Listeria monocytogenes and studied the ensuing early transcriptional response using expression microarrays. Thus the observed response was unbiased by signals originating from other helper and effector cells of the host and was not limited to induction by solitary bacterial constituents. Results Activation of monocytes was demonstrated by the upregulation of chemokine rather than interleukin genes except for the prominent expression of interleukin 23, marking it as the early lead cytokine. This activation was accompanied by cytoskeleton rearrangement signals and a general anti-oxidative stress and anti-apoptotic reaction. Remarkably, the expression profiles also provide evidence that monocytes participate in the regulation of angiogenesis and endothelial function in response to these pathogens. Conclusion Regardless of the invasion properties and survival mechanisms of the pathogens used, we found that the early response comprised of a consistent and common response. The common response was hallmarked by the upregulation of interleukin 23, a rather unexpected finding regarding Listeria infection, as this cytokine has been linked primarily to the control of extracellular bacterial dissemination. PMID:21044323

2010-01-01

169

Chitosan augments photodynamic inactivation of gram-positive and gram-negative bacteria.  

PubMed

Antimicrobial photodynamic inactivation (PDI) was shown to be a promising treatment modality for microbial infections. This study explores the effect of chitosan, a polycationic biopolymer, in increasing the PDI efficacy against Gram-positive bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and methicillin-resistant S. aureus (MRSA), as well as the Gram-negative bacteria Pseudomonas aeruginosa and Acinetobacter baumannii. Chitosan at <0.1% was included in the antibacterial process either by coincubation with hematoporphyrin (Hp) and subjection to light exposure to induce the PDI effect or by addition after PDI and further incubation for 30 min. Under conditions in which Hp-PDI killed the microbe on a 2- to 4-log scale, treatment with chitosan at concentrations of as low as 0.025% for a further 30 min completely eradicated the bacteria (which were originally at ?10(8) CFU/ml). Similar results were also found with toluidine blue O (TBO)-mediated PDI in planktonic and biofilm cells. However, without PDI treatment, chitosan alone did not exert significant antimicrobial activity with 30 min of incubation, suggesting that the potentiated effect of chitosan worked after the bacterial damage induced by PDI. Further studies indicated that the potentiated PDI effect of chitosan was related to the level of PDI damage and the deacetylation level of the chitosan. These results indicate that the combination of PDI and chitosan is quite promising for eradicating microbial infections. PMID:21282440

Tsai, Tsuimin; Chien, Hsiung-Fei; Wang, Tze-Hsien; Huang, Ching-Tsan; Ker, Yaw-Bee; Chen, Chin-Tin

2011-05-01

170

Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria.  

PubMed

The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO? solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5-50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis. PMID:23867968

Tamboli, Dhawal P; Lee, Dae Sung

2013-09-15

171

Non-contiguous finished genome sequence and description of Bacillus massilioanorexius sp. nov.  

PubMed Central

Bacillus massilioanorexius strain AP8T sp. nov. is the type strain of B. massilioanorexius sp. nov., a new species within the genus Bacillus. This strain, whose genome is described here, was isolated from the fecal flora of a 21-year-old Caucasian French female suffering from a severe form of anorexia nervosa since the age of 12 years. B. massilioanorexius is a Gram-positive aerobic bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 4,616,135 bp long genome (one chromosome but no plasmid) contains 4,432 protein-coding and 87 RNA genes, including 8 rRNA genes. PMID:24501631

Mishra, Ajay Kumar; Pfleiderer, Anne; Lagier, Jean-Christophe; Robert, Catherine; Raoult, Didier; Fournier, Pierre-Edouard

2013-01-01

172

Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes  

EPA Science Inventory

The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

173

Identification of a structural determinant for resistance to ?-lactam antibiotics in Gram-positive bacteria  

PubMed Central

Streptococcus pneumoniae is the main causal agent of pathologies that are increasingly resistant to antibiotic treatment. Clinical resistance of S. pneumoniae to ?-lactam antibiotics is linked to multiple mutations of high molecular mass penicillin-binding proteins (H-PBPs), essential enzymes involved in the final steps of bacterial cell wall synthesis. H-PBPs from resistant bacteria have a reduced affinity for ?-lactam and a decreased hydrolytic activity on substrate analogues. In S. pneumoniae, the gene coding for one of these H-PBPs, PBP2x, is located in the cell division cluster (DCW). We present here structural evidence linking multiple ?-lactam resistance to amino acid substitutions in PBP2x within a buried cavity near the catalytic site that contains a structural water molecule. Site-directed mutation of amino acids in contact with this water molecule in the “sensitive” form of PBP2x produces mutants similar, in terms of ?-lactam affinity and substrate hydrolysis, to altered PBP2x produced in resistant clinical isolates. A reverse mutation in a PBP2x variant from a clinically important resistant clone increases the acylation efficiency for ?-lactams and substrate analogues. Furthermore, amino acid residues in contact with the structural water molecule are conserved in the equivalent H-PBPs of pathogenic Gram-positive cocci. We suggest that, probably via a local structural modification, the partial or complete loss of this water molecule reduces the acylation efficiency of PBP2x substrates to a point at which cell wall synthesis still occurs, but the sensitivity to therapeutic concentrations of ?-lactam antibiotics is lost. PMID:9811812

Mouz, N.; Gordon, E.; Di Guilmi, A.-M.; Petit, I.; Pétillot, Y.; Dupont, Y.; Hakenbeck, R.; Vernet, T.; Dideberg, O.

1998-01-01

174

Quantification of Gram-positive bacteria: adaptation and evaluation of a preparation strategy using high amounts of clinical tissue  

PubMed Central

Background A preparation method for quantification of bacteria in tissues is obligatory to reduce tissue mass, concentrate the target, purify, remove inhibitory substances and to achieve constant target recovery rates. No preparation method has been available until now for a high mass of tissue applicable for routine use and analytical veterinary diagnostics. Results This study describes an easy-to-use tissue preparation protocol to quantify Gram-positive bacteria from a large volume of tissue matrix. A previously published sample preparation method (Matrix-Lysis) from food science was successfully adapted for clinical use on tissues from pigs, including cerebrum, spinal cord, lung, liver, ileum, colon, caecum, kidney and muscle tissue. This tissue preparation method now permits quantification of pathogens from 5 g of organic matrix, which is a 20–200 fold increase by weight compared to other methods. It is based on solubilization of the sample matrix with either a chaotrope plus detergent or divalent salts as solubilization agents. The method was designed as a modular system, offering the possibility to change lysis buffers, according to tissue solubilization characteristics and the intended detection method (molecular or culture). Using Listeria monocytogenes as model organism, viable cell quantification or DNA extraction and quantitative real-time PCR were performed after Matrix-Lysis to determine recovery rates and detection limit (LOD). The adapted Matrix-Lysis protocol resulted in high recovery rates (mean value: 76%?±?39%) for all tested organs, except kidney, and recovery was constant over 5 log scales for all tested buffer systems. The LOD for Matrix-Lysis with subsequent plate count method (PCM) was as low as 1 CFU/5 g, while for qPCR based detection the LOD was 102 bacterial cell equivalents (BCE)/5 g for two buffer systems. Conclusions This tissue preparation is inexpensive and can be easily used for routine and analytical veterinary diagnostics. Inoculation studies or hazard assessments can profit from this tissue preparation method and it is anticipated that this study will be a valuable source for further research on tissue preparation strategies. PMID:24589061

2014-01-01

175

Bacillus cereus and related species.  

PubMed Central

Bacillus cereus is a gram-positive aerobic or facultatively anaerobic spore-forming rod. It is a cause of food poisoning, which is frequently associated with the consumption of rice-based dishes. The organism produces an emetic or diarrheal syndrome induced by an emetic toxin and enterotoxin, respectively. Other toxins are produced during growth, including phospholipases, proteases, and hemolysins, one of which, cereolysin, is a thiol-activated hemolysin. These toxins may contribute to the pathogenicity of B. cereus in nongastrointestinal disease. B. cereus isolated from clinical material other than feces or vomitus was commonly dismissed as a contaminant, but increasingly it is being recognized as a species with pathogenic potential. It is now recognized as an infrequent cause of serious nongastrointestinal infection, particularly in drug addicts, the immunosuppressed, neonates, and postsurgical patients, especially when prosthetic implants such as ventricular shunts are inserted. Ocular infections are the commonest types of severe infection, including endophthalmitis, panophthalmitis, and keratitis, usually with the characteristic formation of corneal ring abscesses. Even with prompt surgical and antimicrobial agent treatment, enucleation of the eye and blindness are common sequelae. Septicemia, meningitis, endocarditis, osteomyelitis, and surgical and traumatic wound infections are other manifestations of severe disease. B. cereus produces beta-lactamases, unlike Bacillus anthracis, and so is resistant to beta-lactam antibiotics; it is usually susceptible to treatment with clindamycin, vancomycin, gentamicin, chloramphenicol, and erythromycin. Simultaneous therapy via multiple routes may be required. PMID:8269390

Drobniewski, F A

1993-01-01

176

Evaluation of the Andromas Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Aerobically Growing Gram-Positive Bacilli  

PubMed Central

Matrix-associated laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a rapid and simple microbial identification method. Previous reports using the Biotyper system suggested that this technique requires a preliminary extraction step to identify Gram-positive rods (GPRs), a technical issue that may limit the routine use of this technique to identify pathogenic GPRs in the clinical setting. We tested the accuracy of the MALDI-TOF MS Andromas strategy to identify a set of 659 GPR isolates representing 16 bacterial genera and 72 species by the direct colony method. This bacterial collection included 40 C. diphtheriae, 13 C. pseudotuberculosis, 19 C. ulcerans, and 270 other Corynebacterium isolates, 32 L. monocytogenes and 24 other Listeria isolates, 46 Nocardia, 75 Actinomyces, 18 Actinobaculum, 11 Propionibacterium acnes, 18 Propionibacterium avidum, 30 Lactobacillus, 21 Bacillus, 2 Rhodococcus equi, 2 Erysipelothrix rhusiopathiae, and 38 other GPR isolates, all identified by reference techniques. Totals of 98.5% and 1.2% of non-Listeria GPR isolates were identified to the species or genus level, respectively. Except for L. grayi isolates that were identified to the species level, all other Listeria isolates were identified to the genus level because of highly similar spectra. These data demonstrate that rapid identification of pathogenic GPRs can be obtained without an extraction step by MALDI-TOF mass spectrometry. PMID:22692743

Farfour, E.; Leto, J.; Barritault, M.; Barberis, C.; Meyer, J.; Dauphin, B.; Le Guern, A.-S.; Leflèche, A.; Badell, E.; Guiso, N.; Leclercq, A.; Le Monnier, A.; Lecuit, M.; Rodriguez-Nava, V.; Bergeron, E.; Raymond, J.; Vimont, S.; Bille, E.; Carbonnelle, E.; Guet-Revillet, H.; Lécuyer, H.; Beretti, J.-L.; Vay, C.; Berche, P.; Ferroni, A.; Nassif, X.

2012-01-01

177

Genome-wide gene order distances support clustering the gram-positive bacteria  

PubMed Central

Initially using 143 genomes, we developed a method for calculating the pair-wise distance between prokaryotic genomes using a Monte Carlo method to estimate the conservation of gene order. The method was based on repeatedly selecting five or six non-adjacent random orthologs from each of two genomes and determining if the chosen orthologs were in the same order. The raw distances were then corrected for gene order convergence using an adaptation of the Jukes-Cantor model, as well as using the common distance correction D? = ?ln(1-D). First, we compared the distances found via the order of six orthologs to distances found based on ortholog gene content and small subunit rRNA sequences. The Jukes-Cantor gene order distances are reasonably well correlated with the divergence of rRNA (R2 = 0.24), especially at rRNA Jukes-Cantor distances of less than 0.2 (R2 = 0.52). Gene content is only weakly correlated with rRNA divergence (R2 = 0.04) over all distances, however, it is especially strongly correlated at rRNA Jukes-Cantor distances of less than 0.1 (R2 = 0.67). This initial work suggests that gene order may be useful in conjunction with other methods to help understand the relatedness of genomes. Using the gene order distances in 143 genomes, the relations of prokaryotes were studied using neighbor joining and agreement subtrees. We then repeated our study of the relations of prokaryotes using gene order in 172 complete genomes better representing a wider-diversity of prokaryotes. Consistently, our trees show the Actinobacteria as a sister group to the bulk of the Firmicutes. In fact, the robustness of gene order support was found to be considerably greater for uniting these two phyla than for uniting any of the proteobacterial classes together. The results are supportive of the idea that Actinobacteria and Firmicutes are closely related, which in turn implies a single origin for the gram-positive cell. PMID:25653643

House, Christopher H.; Pellegrini, Matteo; Fitz-Gibbon, Sorel T.

2015-01-01

178

Complete Genome Sequences of Bacillus subtilis subsp. subtilis Laboratory Strains JH642 (AG174) and AG1839  

E-print Network

The Gram-positive bacterium Bacillus subtilis is widely used for studies of cellular and molecular processes. We announce the complete genomic sequences of strain AG174, our stock of the commonly used strain JH642, and ...

Smith, Janet L.

179

Novel polycarboxylate porphyrins: Synthesis, characterization, photophysical properties and preliminary antimicrobial study against Gram-positive bacteria.  

PubMed

We describe the synthesis, characterization and photophysical properties of two new polycarboxylic photosensitizers. Owing to their structural design, these two compounds show water solubilities larger than natural carboxylic photosensitizers (e.g., protoporphyrin IX, hematoporphyrin, etc.) and also good singlet oxygen quantum yields. These compounds were tested as photo-antimicrobial agents against Staphylococcus aureus and Bacillus cereus strains. Results reveal that their photocytotoxicities are strongly dependent on their amphiphilic character and more precisely the number and position of the carboxylic acid and mesityl substituents. PMID:25475206

Jiblaoui, Ahmad; Leroy-Lhez, Stéphanie; Ouk, Tan-Sothea; Grenier, Karine; Sol, Vincent

2015-01-15

180

Clinical relevance of a European collaborative study on comparative susceptibility of Gram-positive clinical isolates to teicoplanin and vancomycin  

Microsoft Academic Search

Seventy laboratories in nine European countries (Belgium, France, Germany, Italy, The Netherlands, Portugal, Spain, Switzerland and the UK) each collected 100 consecutive Gram-positive bacterial pathogens during 1995. MICs were determined by a co-ordinating laboratory in each country using an agar incorporation method with Mueller Hinton medium (NCCLS). Quality control was ensured by distribution of five test strains to the co-ordinating

R. N Grüneberg; W Hryniewicz

1998-01-01

181

Draft Genome Sequence of Bacillus oceanisediminis 2691  

PubMed Central

Bacillus oceanisediminis 2691 is an aerobic, Gram-positive, spore-forming, and moderately halophilic bacterium that was isolated from marine sediment of the Yellow Sea coast of South Korea. Here, we report the draft genome sequence of B. oceanisediminis 2691 that may have an important role in the bioremediation of marine sediment. PMID:23105082

Lee, Yong-Jik; Lee, Sang-Jae; Jeong, Haeyoung; Kim, Hyun Ju; Ryu, Naeun; Kim, Byoung-Chan; Lee, Han-Seung

2012-01-01

182

Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components  

NASA Technical Reports Server (NTRS)

Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

1984-01-01

183

In Vitro Activities of Dalbavancin and Nine Comparator Agents against Anaerobic Gram-Positive Species and Corynebacteria  

PubMed Central

Dalbavancin is a novel semisynthetic glycopeptide with enhanced activity against gram-positive species. Its comparative in vitro activities and those of nine comparator agents, including daptomycin, vancomycin, linezolid, and quinupristin-dalfopristin, against 290 recent gram-positive clinical isolates strains, as determined by the NCCLS agar dilution method, were studied. The MICs of dalbavancin at which 90% of various isolates tested were inhibited were as follows: Actinomyces spp., 0.5 ?g/ml; Clostridium clostridioforme, 8 ?g/ml; C. difficile, 0.25 ?g/ml; C. innocuum, 0.25 ?g/ml; C. perfringens, 0.125 ?g/ml; C. ramosum, 1 ?g/ml; Eubacterium spp., 1 ?g/ml; Lactobacillus spp., >32 ?g/ml, Propionibacterium spp., 0.5 ?g/ml; and Peptostreptococcus spp., 0.25 ?g/ml. Dalbavancin was 1 to 3 dilutions more active than vancomycin against most strains. Dalbavancin exhibited excellent activity against gram-positive strains tested and warrants clinical evaluation. PMID:12760876

Goldstein, Ellie J. C.; Citron, Diane M.; Merriam, C. Vreni; Warren, Yumi; Tyrrell, Kerin; Fernandez, Helen T.

2003-01-01

184

Ribosomal DNA Sequencing for Identification of Aerobic Gram-Positive Rods in the Clinical Laboratory (an 18-Month Evaluation)  

PubMed Central

We have evaluated over a period of 18 months the use of 16S ribosomal DNA (rDNA) sequence analysis as a means of identifying aerobic gram-positive rods in the clinical laboratory. Two collections of strains were studied: (i) 37 clinical strains of gram-positive rods well identified by phenotypic tests, and (ii) 136 clinical isolates difficult to identify by standard microbiological investigations, i.e., identification at the species level was impossible. Results of molecular analyses were compared with those of conventional phenotypic identification procedures. Good overall agreement between phenotypic and molecular identification procedures was found for the collection of 37 clinical strains well identified by conventional means. For the 136 clinical strains which were difficult to identify by standard microbiological investigations, phenotypic characterization identified 71 of 136 (52.2%) isolates at the genus level; 65 of 136 (47.8%) isolates could not be discriminated at any taxonomic level. In comparison, 16S rDNA sequencing identified 89 of 136 (65.4%) isolates at the species level, 43 of 136 (31.6%) isolates at the genus level, and 4 of 136 (2.9%) isolates at the family level. We conclude that (i) rDNA sequencing is an effective means for the identification of aerobic gram-positive rods which are difficult to identify by conventional techniques, and (ii) molecular identification procedures are not required for isolates well identified by phenotypic investigations. PMID:12958237

Bosshard, P. P.; Abels, S.; Zbinden, R.; Böttger, E. C.; Altwegg, M.

2003-01-01

185

[Evaluation of API Coryne System, version 2.0, for diphteroid gram-positive rods identification with clinical relevance].  

PubMed

The ability of the API Coryne system, version 2.0, to identify 178 strains of gram-positive rods was evaluated. Seventy eight isolates belonged to genus Corynebacterium and one hundred to related genera, all strains were isolated from clinical samples at the Laboratory of Bacteriology, Hospital de Clínicas José de San Martin (UBA) between 1995 and 2004. The isolates were identified according to von Graevenitz and Funke's scheme. One hundred and sixty two out of 178 strains (91%) were correctly identified at genus and species level (IC95 = 85.6-94.6), in 44 of them (24.7%) additional tests were needed to final identification. Sixteen strains (9%) were not correctly identified (IC95 = 5.4-14.4); none of the 178 strains remained unidentified. The API Coryne system, version 2.0, is useful to identify the majority of Cory-nebacterium species with clinical relevance: Corynebacterium jeikeium, Corynebacterium urealyticum, Corynebacterium striatum, Corynebacterium pseudodiphtheriticum, Corynebacterium amycolatum and related species such as Arcanobacterium haemolyticum, Dermabacter hominis, Listeria monocytogenes, among others. Nevertheless for yellow-pigmented diphteroid gram-positive rods (Aureobacterium spp., Leifsonia aquatica, Microbacterium spp. and Cellulomonas spp.) and for acid fast gram-positive rods (Rhodococcus, Gordonia, Tsukamurella and Nocardia) the identification usefulness the system is limited. PMID:17370571

Almuzara, M N; De Mier, C; Rodríguez, C R; Famiglietti, A M R; Vay, C A

2006-01-01

186

Evidence for Direct Electron Transfer by a Gram-Positive Bacterium Isolated from a Microbial Fuel Cell?†  

PubMed Central

Despite their importance in iron redox cycles and bioenergy production, the underlying physiological, genetic, and biochemical mechanisms of extracellular electron transfer by Gram-positive bacteria remain insufficiently understood. In this work, we investigated respiration by Thermincola potens strain JR, a Gram-positive isolate obtained from the anode surface of a microbial fuel cell, using insoluble electron acceptors. We found no evidence that soluble redox-active components were secreted into the surrounding medium on the basis of physiological experiments and cyclic voltammetry measurements. Confocal microscopy revealed highly stratified biofilms in which cells contacting the electrode surface were disproportionately viable relative to the rest of the biofilm. Furthermore, there was no correlation between biofilm thickness and power production, suggesting that cells in contact with the electrode were primarily responsible for current generation. These data, along with cryo-electron microscopy experiments, support contact-dependent electron transfer by T. potens strain JR from the cell membrane across the 37-nm cell envelope to the cell surface. Furthermore, we present physiological and genomic evidence that c-type cytochromes play a role in charge transfer across the Gram-positive bacterial cell envelope during metal reduction. PMID:21908627

Wrighton, K. C.; Thrash, J. C.; Melnyk, R. A.; Bigi, J. P.; Byrne-Bailey, K. G.; Remis, J. P.; Schichnes, D.; Auer, M.; Chang, C. J.; Coates, J. D.

2011-01-01

187

Multiple organ failure and granulomatous hepatitis following intravesical bacillus Calmette-Guérin instillation.  

PubMed

Intravesical instillations of Bacillus-Calmette Guérin are widely used in the treatment of superficial bladder carcinoma. Although relatively safe, it has potentially lethal systemic side effects. In this case report a 68 year old patient presented with septic shock and multiple organ failure three days after instillation with Bacillus Calmette-Guérin. After treatment with fluid, vasopressors, broad spectrum antibiotics and antimycobacterial drugs the patient's condition improved. Ten days after admission there was a dramatic increase in bilirubin levels. A liver biopsy revealed granulomatous hepatitis. After the initiation of methylprednisolone the overall condition of the patient improved and serum bilirubin levels returned to normal. PMID:23189546

Desmet, M; Moubax, K; Haerens, M

2012-01-01

188

Bioreduction of Cr(VI) by alkaliphilic Bacillus subtilis and interaction of the membrane groups  

PubMed Central

Detoxification of Cr(VI) under alkaline pH requires attention due to the alkaline nature of many effluents. An alkaliphilic gram-positive Bacillus subtilis isolated from tannery effluent contaminated soil was found to grow and reduce Cr(VI) up to 100% at an alkaline pH 9. Decrease in pH to acidic range with growth of the bacterium signified the role played by metabolites (organic acids) in chromium resistance and reduction mechanism. The XPS and FT-IR spectra confirmed the reduction of Cr(VI) by bacteria into +3 oxidation state. Chromate reductase assay indicated that the reduction was mediated by constitutive membrane bound enzymes. The kinetics of Cr(VI) reduction activity derived using the monod equation proved (Ks = 0.00032) high affinity of the organism to the metal. This study thus helped to localize the reduction activity at subcellular level in a chromium resistant alkaliphilic Bacillus sp. PMID:23961119

Mary Mangaiyarkarasi, M.S.; Vincent, S.; Janarthanan, S.; Subba Rao, T.; Tata, B.V.R.

2010-01-01

189

The presence of intragenically located REP-like elements in Bacillus sporothermodurans is sufficient for REP-PCR typing.  

PubMed

The technique of repetitive extragenic palindromic polymerase chain reaction (REP-PCR) enables the identification and discrimination of clonally related Bacillus sporothermodurans isolates from ultra-high temperature and sterilized milk. The aim of this study was to investigate the genetic basis for the generation of these highly informative REP-PCR patterns. The major 947-bp REP-PCR fragment of B. sporothermodurans was cloned, together with its 5' and 3' flanking sequences. Only partial homology with the REP consensus sequence was established at the borders of the REP-PCR fragment. Moreover, these border sequences were located within two distinct open reading frames, with great homology to the uvrA and uvrB genes of Escherichia coli. The presence of these REP-like elements in B. sporothermodurans was thus sufficient for high resolution REP-PCR typing of this Gram-positive organism. In some cases (and especially with Gram-positives), REP-PCR could thus be considered more as an arbitrary primed PCR, albeit at a somewhat higher annealing temperature and using conserved primers. The random priming effect at the less stringent annealing conditions of REP-PCR was also demonstrated for enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) on another Gram-positive organism, Listeria monocytogenes. PMID:10875282

Herman, L; Heyndrickx, M

2000-05-01

190

Competitive adsorption of metal cations onto two gram positive bacteria: testing the chemical equilibrium model  

NASA Astrophysics Data System (ADS)

In order to test the ability of a surface complexation approach to account for metal-bacteria interactions in near surface fluid-rock systems, we have conducted experiments that measure the extent of adsorption in mixed metal, mixed bacteria systems. This study tests the surface complexation approach by comparing estimated extents of adsorption based on surface complexation modeling to those we observed in the experimental systems. The batch adsorption experiments involved Ca, Cd, Cu, and Pb adsorption onto the surfaces of 2 g positive bacteria: Bacillus subtilis and Bacillus licheniformis. Three types of experiments were performed: 1. Single metal (Ca, Cu, Pb) adsorption onto a mixture of B. licheniformis and B. subtilis; 2. mixed metal (Cd, Cu, and Pb; Ca and Cd) adsorption onto either B. subtilis or B. licheniformis; and 3. mixed or single metal adsorption onto B. subtilis and B. licheniformis. %Independent of the experimental results, and based on the site specific stability constants for Ca, Cd, Cu, and Pb interactions with the carboxyl and phosphate sites on B. licheniformis and B. subtilis determined by Fein et al. (1997), by Daughney et al. (1998) and in this study, we estimate the extent of adsorption that is expected in the above experimental systems. Competitive cation adsorption experiments in both single and double bacteria systems exhibit little adsorption at pH values less than 4. With increasing pH above 4.0, the extent of Ca, Cu, Pb and Cd adsorption also increases due to the increased deprotonation of bacterial surface functional groups. In all cases studied, the estimated adsorption behavior is in excellent agreement with the observations, with only slight differences that were within the uncertainties of the estimation and experimental procedures. Therefore, the results indicate that the use of chemical equilibrium modeling of aqueous metal adsorption onto bacterial surfaces yields accurate predictions of the distribution of metals in complex multicomponent systems.

Fowle, David A.; Fein, Jeremy B.

1999-10-01

191

In vitro activities of daptomycin, vancomycin, quinupristin- dalfopristin, linezolid, and five other antimicrobials against 307 gram-positive anaerobic and 31 Corynebacterium clinical isolates.  

PubMed

The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The daptomycin MICs determined on Ca(2+)-supplemented (50 mg/liter) brucella agar plates were one- to fourfold lower than those determined in unsupplemented media. Daptomycin was highly active (MICs, 8 microg/ml were inhibited by <1 microg of daptomycin per ml. Daptomycin MICs were >or=4 microg/ml for most strains of Clostridium clostridioforme, Clostridium paraputrificum, Clostridium tertium, and Clostridium ramosum; the isolates were generally more resistant to other antimicrobials. Daptomycin was two- to fourfold less active against Actinomyces spp. than vancomycin, quinupristin-dalfopristin, or linezolid. Twenty-nine of 31 strains of Corynebacterium spp., including Corynebacterium jeikeium, Corynebacterium amycolatum, and Corynebacterium pseudodiphtheriticum, were inhibited by gram-positive organisms including vancomycin-resistant C. innocuum and lactobacillus strains and quinupristin-dalfopristin- and linezolid-resistant C. difficile strains. PMID:12499210

Goldstein, Ellie J C; Citron, Diane M; Merriam, C Vreni; Warren, Yumi A; Tyrrell, Kerrin L; Fernandez, Helen T

2003-01-01

192

In Vitro Activities of Daptomycin, Vancomycin, Quinupristin- Dalfopristin, Linezolid, and Five Other Antimicrobials against 307 Gram-Positive Anaerobic and 31 Corynebacterium Clinical Isolates  

PubMed Central

The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The daptomycin MICs determined on Ca2+-supplemented (50 mg/liter) brucella agar plates were one- to fourfold lower than those determined in unsupplemented media. Daptomycin was highly active (MICs, ?2 ?g/ml) against many strains including 36 of 37 peptostreptococci, 37 of 48 isolates of the Eubacterium group, and all strains of Propionibacterium spp., Clostridium perfringens, Clostridium difficile, and other Clostridium spp. It was fourfold or greater more active than vancomycin against Clostridium innocuum and 16 of 34 strains of vancomycin-resistant lactobacilli. Three strains of C. difficile for which quinupristin-dalfopristin and linezolid MICs were >8 ?g/ml were inhibited by <1 ?g of daptomycin per ml. Daptomycin MICs were ?4 ?g/ml for most strains of Clostridium clostridioforme, Clostridium paraputrificum, Clostridium tertium, and Clostridium ramosum; the isolates were generally more resistant to other antimicrobials. Daptomycin was two- to fourfold less active against Actinomyces spp. than vancomycin, quinupristin-dalfopristin, or linezolid. Twenty-nine of 31 strains of Corynebacterium spp., including Corynebacterium jeikeium, Corynebacterium amycolatum, and Corynebacterium pseudodiphtheriticum, were inhibited by ?0.25 ?g of daptomycin per ml. For two strains of “Corynebacterium aquaticum,” 8 ?g of daptomycin per ml was required for inhibition. Daptomycin demonstrated very good activities against a broad range of gram-positive organisms including vancomycin-resistant C. innocuum and lactobacillus strains and quinupristin-dalfopristin- and linezolid-resistant C. difficile strains. PMID:12499210

Goldstein, Ellie J. C.; Citron, Diane M.; Merriam, C. Vreni; Warren, Yumi A.; Tyrrell, Kerrin L.; Fernandez, Helen T.

2003-01-01

193

Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

2013-01-01

194

Results of the Surveillance of Tedizolid Activity and Resistance Program: in vitro susceptibility of Gram-positive pathogens collected in 2011 and 2012 from the United States and Europe.  

PubMed

The in vitro activity and spectrum of tedizolid and comparators were analyzed against 6884 Gram-positive clinical isolates collected from multiple US and European sites as part of the Surveillance of Tedizolid Activity and Resistance Program in 2011 and 2012. Organisms included 4499 Staphylococcus aureus, 537 coagulase-negative staphylococci (CoNS), 873 enterococci, and 975 ?-hemolytic streptococci. The MIC values that inhibited 90% of the isolates within each group (MIC90) were 0.25 ?g/mL for Staphylococcus epidermidis and ?-hemolytic streptococci and 0.5 ?g/mL for S. aureus, other CoNS, and enterococci. Of 16 isolates with elevated tedizolid or linezolid MIC values (intermediate or resistant isolates), 10 had mutations in the genes encoding 23S rRNA (primarily G2576T), 5 had mutations in the genes encoding ribosomal proteins L3 or L4, and 5 carried the cfr multidrug resistance gene. Overall, tedizolid showed excellent activity against Gram-positive bacteria and was at least 4-fold more potent than linezolid against wild-type and linezolid-resistant isolates. Given the low overall frequency of isolates that would be resistant to tedizolid at the proposed break point of 0.5 ?g/mL (0.19%) and potent activity against contemporary US and European isolates, tedizolid has the potential to serve as a valuable therapeutic option in the treatment of infections caused by Gram-positive pathogens. PMID:25488274

Sahm, Daniel F; Deane, Jennifer; Bien, Paul A; Locke, Jeffrey B; Zuill, Douglas E; Shaw, Karen J; Bartizal, Ken F

2015-02-01

195

[Suitability of Bacillus subtilis and Bacillus stearothermophilus spores as test organism bioindicators for detecting superheating of steam].  

PubMed

Biological indicators used to test sterilisation procedures for their efficacy consist of a so-called germ carrier to which the microorganisms used as test organisms adhere. In previous papers we demonstrated that carriers made of filter paper on contact with saturated steam show superheating while carriers made of glass fibre fleece as well as wetted filter paper do not. Using spores of Bacillus subtilis and Bacillus stearothermophilus as test organisms we have now investigated whether and to what extent carrier superheating affects the characteristic values (t50%) of these biological indicators. The indicators were exposed to saturated steam at 100 degrees C (B. subtilis) or 120 degrees C (B. stearothermophilus) under three different exposure conditions: 1. dry (i.e. conditioned to 45% relative humidity before introduction into the sterilising chamber), freely accessible; 2. dry with a substratum and a cover of filter card-board; 3. wet (moistened with twice distilled water before introduction into the sterilising chamber), freely accessible. For previously selected exposure periods, the incidence of indicators with surviving test organisms was determined. The reaction pattern of bioindicators with spores of B. stearothermophilus was different from that of bioindicators with spores of B. subtilis. For B. subtilis, the incidence of bioindicators exhibiting surviving test organisms depended on the nature of the carries as well as on the exposure conditions. On filter paper carriers, t50% increased in the order "wet, freely accessible", "dry, freely accessible", "dry, between filter card-board". On dry and wetted glass fibre fleece, resistance was approximately the same; when the indicators were sandwiched between layers of filter card-board, t50% increased. For B. stearothermophilus, t50% was largely dependent on the carrier material alone. The values obtained for filter paper were invariably much lower than those for glass fibre fleece. As the results show, using spores of B. subtilis it is possible to detect superheating, but the steam resistance of the spores is relatively low. Spores of B. stearothermophilus are of high steam resistance but they are practically unsuitable for detecting superheating. It is imperative to search for a test organism the resistance of which against steam is sufficiently high and which at the same time is capable of reacting to superheating (equivalent to reduced humidity) by a sufficiently large increase in resistance. PMID:9376061

Spicher, G; Peters, J

1997-02-01

196

Surface multiheme c-type cytochromes from Thermincola potens and implications for respiratory metal reduction by Gram-positive bacteria  

PubMed Central

Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium. PMID:22307634

Carlson, Hans K.; Iavarone, Anthony T.; Gorur, Amita; Yeo, Boon Siang; Tran, Rosalie; Melnyk, Ryan A.; Mathies, Richard A.; Auer, Manfred; Coates, John D.

2012-01-01

197

Identification, classification, and clinical relevance of catalase-negative, gram-positive cocci, excluding the streptococci and enterococci.  

PubMed Central

Several new genera and species of gram-positive, catalase-negative cocci that can cause infections in humans have been described. Although these bacteria were isolated in the clinical laboratory, they were considered nonpathogenic culture contaminants and were not thought to be the cause of any diseases. Isolation of pure cultures of these bacteria from normally sterile sites has led to the conclusion that these bacteria can be an infrequent cause of infection. This review describes the new bacteria and the procedures useful for clinical laboratories to aid in their identification. The clinical relevance and our experience with the various genera and species are reviewed and discussed. PMID:8665466

Facklam, R; Elliott, J A

1995-01-01

198

Antibiotic management of ventilator-associated pneumonia due to antibiotic-resistant gram-positive bacterial infection  

Microsoft Academic Search

Gram-positive cocci, in particular Staphylococcus aureus, account for as much as one-third of all cases of hospital-acquired pneumonia, and treatment has become increasingly complex\\u000a as the proportion of resistant isolates has increased. Methicillin-resistant S. aureus is of particular concern because this pathogen is now associated with hospital-acquired, ventilator-associated, community-acquired,\\u000a and healthcare-associated pneumonia. Antibiotic therapy for ventilator-associated pneumonia is challenging because

M. H. Kollef

2005-01-01

199

Identification of a Ligand on the Wip1 Bacteriophage Highly Specific for a Receptor on Bacillus anthracis  

PubMed Central

Tectiviridae is a family of tailless bacteriophages with Gram-negative and Gram-positive hosts. The family model PRD1 and its close relatives all infect a broad range of enterobacteria by recognizing a plasmid-encoded conjugal transfer complex as a receptor. In contrast, tectiviruses with Gram-positive hosts are highly specific to only a few hosts within the same bacterial species. The cellular determinants that account for the observed specificity remain unknown. Here we present the genome sequence of Wip1, a tectivirus that infects the pathogen Bacillus anthracis. The Wip1 genome is related to other tectiviruses with Gram-positive hosts, notably, AP50, but displays some interesting differences in its genome organization. We identified Wip1 candidate genes for the viral spike complex, the structure located at the capsid vertices and involved in host receptor binding. Phage adsorption and inhibition tests were combined with immunofluorescence microscopy to show that the Wip1 gene product p23 is a receptor binding protein. His-p23 also formed a stable complex with p24, a Wip1 protein of unknown function, suggesting that the latter is involved with p23 in host cell recognition. The narrow host range of phage Wip1 and the identification of p23 as a receptor binding protein offer a new range of suitable tools for the rapid identification of B. anthracis. PMID:23893110

Kan, Sherry; Fornelos, Nadine; Schuch, Raymond

2013-01-01

200

Production of a bacteriocin by a poultry derived Campylobacter jejuni isolate with antimicrobial activity against Clostridium perfringens and other Gram positive bacteria.  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have purified a bacteriocin peptide (termed CUV-3), produced by a poultry cecal isolate of Campylobacter jejuni (strain CUV-3) with inhibitory activity against Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staphylococcus epidermidis and Listeria mon...

201

Targeting agr- and agr-Like Quorum Sensing Systems for Development of Common Therapeutics to Treat Multiple Gram-Positive Bacterial Infections  

PubMed Central

Invasive infection by the Gram-positive pathogen Staphylococcus aureus is controlled by a four gene operon, agr that encodes a quorum sensing system for the regulation of virulence. While agr has been well studied in S. aureus, the contribution of agr homologues and analogues in other Gram-positive pathogens is just beginning to be understood. Intriguingly, other significant human pathogens, including Clostridium perfringens, Listeria monocytogenes, and Enterococcus faecalis contain agr or analogues linked to virulence. Moreover, other significant human Gram-positive pathogens use peptide based quorum sensing systems to establish or maintain infection. The potential for commonality in aspects of these signaling systems across different species raises the prospect of identifying therapeutics that could target multiple pathogens. Here, we review the status of research into these agr homologues, analogues, and other peptide based quorum sensing systems in Gram-positive pathogens as well as the potential for identifying common pathways and signaling mechanisms for therapeutic discovery. PMID:23598501

Gray, Brian; Hall, Pamela; Gresham, Hattie

2013-01-01

202

In vitro susceptibilities of aerobic and facultative non-spore-forming gram-positive bacilli to HMR 3647 (RU 66647) and 14 other antimicrobials.  

PubMed

The comparative in vitro activity of the ketolide HMR 3647 (RU 66647) and those of structurally related macrolide-lincosamide-streptogramin compounds (erythromycin, roxithromycin, azithromycin, clarithromycin, josamycin, lincomycin, pristinamycin, and quinupristin-dalfopristin) as well as those of benzylpenicillin, doxycycline, vancomycin, teicoplanin, levofloxacin, and rifapentine against 247 aerobic and facultative non-spore-forming gram-positive bacilli were determined by an agar dilution method. The ketolide was active against most organisms tested except Corynebacterium striatum, coryneform CDC group 12, and Oerskovia spp. The frequency of resistance to erythromycin and other macrolides as well as that to lincomycin was high. Pristinamycin and, to a lesser extent, quinupristin-dalfopristin were very active, but resistance to these agents was present in some strains of Rhodococcus equi, Listeria spp., C. striatum, Erysipelothrix rhusiopathiae, and Oerskovia spp. HMR 3647 was very active against all erythromycin-sensitive and many erythromycin-nonsusceptible strains, especially Corynebacterium minutissimum, Corynebacterium pseudodiphtheriticum, Corynebacterium amycolatum, and Corynebacterium jeikeium. In vitro resistance to benzylpenicillin was common, but doxycycline, vancomycin, and teicoplanin were very active against most organisms tested except E. rhusiopathiae, against which glycopeptide antibiotics were not active. The in vitro activity of levofloxacin was remarkable, but resistance to this agent was common for C. amycolatum, Corynebacterium urealyticum, C. jeikeium, and Oerskovia spp. strains. Rifapentine was also very active in vitro against many organisms, but resistance to this agent was always present in E. rhusiopathiae and was very common in C. striatum and C. urealyticum. PMID:9593121

Soriano, F; Fernández-Roblas, R; Calvo, R; García-Calvo, G

1998-05-01

203

Potential Role for Telavancin in Bacteremic Infections Due to Gram-Positive Pathogens: Focus on Staphylococcus aureus.  

PubMed

Staphylococcus aureus bacteremia (SAB) is one of the most common serious bacterial infections and the most frequent invasive infection due to methicillin-resistant S. aureus (MRSA). Treatment is challenging, particularly for MRSA, because of limited treatment options. Telavancin is a bactericidal lipoglycopeptide antibiotic that is active against a range of clinically relevant gram-positive pathogens including MRSA. In experimental animal models of sepsis telavancin was shown to be more effective than vancomycin. In clinically evaluable patients enrolled in a pilot study of uncomplicated SAB, cure rates were 88% for telavancin and 89% for standard therapy. Among patients with infection due to only gram-positive pathogens enrolled in the 2 phase 3 studies of telavancin for treatment of hospital-acquired pneumonia, cure rates for those with bacteremic S. aureus pneumonia were 41% (9/22, telavancin) and 40% (10/25, vancomycin) with identical mortality rates. These data support further evaluation of telavancin in larger, prospective studies of SAB. PMID:25472944

Corey, G Ralph; Rubinstein, Ethan; Stryjewski, Martin E; Bassetti, Matteo; Barriere, Steven L

2015-03-01

204

Identification and characterization of UDP-N-acetylenolpyruvylglucosamine reductase (MurB) from the Gram-positive pathogen Streptococcus pneumoniae.  

PubMed Central

The UDP-N-acetylenolpyruvylglucosamine reductase (MurB) from a Gram-positive pathogen, Streptococcus pneumoniae, was identified and characterized. The enzyme from S. pneumoniae shows 31% identity with the MurB protein from Escherichia coli, and contains the catalytic residues, substrate-binding residues and FAD-binding motif identified previously in the E. coli protein. The gene was cloned into the pET28a+ expression vector, and the 34.5 kDa protein that it encodes was overexpressed in E. coli strain BL21(DE3) to 30% of total cell protein. The majority of the protein was found to be insoluble. A variety of methods were used to increase the amount of soluble protein to 10%. This was then purified to near homogeneity in a two-step process. The absorption spectrum of the purified protein indicated it to be a flavoprotein, like its E. coli homologue, with a characteristic absorption at 463 nm. The enzyme was shown to be active, reducing UDP-N-acetylglucosamine enolpyruvate with the concomitant oxidation of NADPH, and was characterized kinetically with respect to its two substrates. The enzyme showed properties similar to those of its E. coli counterpart, being activated by univalent cations and being subject to substrate inhibition. The characterization of an important cell wall biosynthesis enzyme from a Gram-positive pathogen provides a good starting point for the discovery of antibacterial agents against MurB. PMID:11284731

Sylvester, D R; Alvarez, E; Patel, A; Ratnam, K; Kallender, H; Wallis, N G

2001-01-01

205

A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria  

PubMed Central

The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria. PMID:23771138

Quiles-Puchalt, Nuria; Tormo-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Íñigo; Novick, Richard P.; Christie, Gail E.; Penadés, José R.

2013-01-01

206

Complete genome sequence of Bacillus thuringiensis subsp. kurstaki strain HD73.  

PubMed

Bacillus thuringiensis is a Gram-positive bacterium that produces intracellular protein crystals toxic to a wide variety of insect larvae. We report the complete genome sequence of Bacillus thuringiensis subsp. kurstaki strain HD73 from the Centre OILB (Institut Pasteur, France), which belongs to serotype 3ab and is toxic to lepidopteran larvae. PMID:23516207

Liu, Guiming; Song, Lai; Shu, Changlong; Wang, Pinshu; Deng, Chao; Peng, Qi; Lereclus, Didier; Wang, Xumin; Huang, Dafang; Zhang, Jie; Song, Fuping

2013-01-01

207

[Studies on siderophore exchange properties between staphylococci and various species of gram-positive and gram-negative bacteria].  

PubMed

The ability of iron utilizing by means of staphylococcal siderophores by bacteria belonging to genera: Acinetobacter, Corynebacterium, Curtobacterium, Clavibacter, Bacillus and Mycobacterium was investigated. The staphylococcal donor strains (18 species) used in these experiments were characterized by the ability to utilize siderophores produced by various strains belonging to aforenamed genera. The utilization of staphylococcal siderophores was studied on agar media in which minimally effective concentrations of ethylenediaminedi-ortho-hydroxyphenylacetic acid (EDDA) were used to inhibit indicator strains. Test colonies (staphylococcal) were applied to the surface of the media to determine whether the indicator organisms could obtain the required iron for growth by utilizing chelators from the test colony. The growth inhibition by EDDA of most strains from the Acinetobacter rods and from the coryneform-organisms (plant pathogen) genera, and strains from the species: B. subtilis, M. phlei, M. smegmatis, M. fortuitum was reversed by staphylococcal siderophores. None of the staphylococcal strains investigated, had the ability to exchange siderophores with strains from the species: C. pseudodiphtheriticum, Corynebacterium ANF group, B. megaterium, M. vaccae, M. chitae and M. parafortuitum. PMID:10803251

Szarapi?ska-Kwaszewska, J; Mikucki, J

1999-01-01

208

A Newly Discovered Bacteroides Conjugative Transposon, CTnGERM1, Contains Genes Also Found in Gram-Positive Bacteria  

PubMed Central

Results of a recent study of antibiotic resistance genes in human colonic Bacteroides strains suggested that gene transfer events between members of this genus are fairly common. The identification of Bacteroides isolates that carried an erythromycin resistance gene, ermG, whose DNA sequence was 99% identical to that of an ermG gene found previously only in gram-positive bacteria raised the further possibility that conjugal elements were moving into Bacteroides species from other genera. Six of seven ermG-containing Bacteroides strains tested were able to transfer ermG by conjugation. One of these strains was chosen for further investigation. Results of pulsed-field gel electrophoresis experiments showed that the conjugal element carrying ermG in this strain is an integrated element about 75 kb in size. Thus, the element appears to be a conjugative transposon (CTn) and was designated CTnGERM1. CTnGERM1 proved to be unrelated to the predominant type of CTn found in Bacteroides isolates—CTns of the CTnERL/CTnDOT family—which sometimes carry another type of erm gene, ermF. A 19-kbp segment of DNA from CTnGERM1 was cloned and sequenced. A 10-kbp portion of this segment hybridized not only to DNA from all the ermG-containing strains but also to DNA from strains that did not carry ermG. Thus, CTnGERM1 seems to be part of a family of CTns, some of which have acquired ermG. The percentage of G+C content of the ermG region was significantly lower than that of the chromosome of Bacteroides species—an indication that CTnGERM1 may have entered Bacteroides strains from some other bacterial genus. A survey of strains isolated before 1970 and after 1990 suggests that the CTnGERM1 type of CTn entered Bacteroides species relatively recently. One of the genes located upstream of ermG encoded a protein that had 85% amino acid sequence identity with a macrolide efflux pump, MefA, from Streptococcus pyogenes. Our having found >90% sequence identity of two upstream genes, including mefA, and the remnants of two transposon-carried genes downstream of ermG with genes found previously only in gram-positive bacteria raises the possibility that gram-positive bacteria could have been the origin of CTnGERM1. PMID:12902247

Wang, Yanping; Wang, Gui-Rong; Shelby, Aikiesha; Shoemaker, Nadja B.; Salyers, Abigail A.

2003-01-01

209

Long-term fertilization of organic manure led to the succession of Bacillus community in an alluvial-aquic soil  

NASA Astrophysics Data System (ADS)

Long-term fertilization inevitably influences soil physic-chemical and biological properties. Our previous studies with a long-term fertilization experiment on an alluvial-aquic have revealed that specific Bacillus spp. was observed in organic manure-fertilized soils. The current study investigated the effects of long-term fertilization on the succession of Bacillus community in soils and their functions. The experiment included three fertilizer treatments: organic manure (OM), mineral fertilizers (NPK) and the control (without fertilizers). The results showed that long-term application of chemical fertilizers didn't increase the quantity of soil microbial population as much as organic fertilizers did, but it played an important role in maintaining the diversity and community structure of indigenous Bacilli. Correspondingly, long-term application of organic manure significantly increased the quantity while significantly decreased the diversity of Bacilli community. The ratio of Bacilli/bacteria was more constant in OM treatment than NPK indicating the stability of the response to long-term organic fertilizers. PCR-DGGE and clone library revealed the succession of Bacillus community after long-term application of organic manure and the dominant Bacillus spp occurred in the treatmen OM was Bacillus asahii. Our results also proved that Bacillus asahii was not derived from exogenous organic manure, but one of indigenous bacteria in the soil. Bacillus asahii was induced by the substrate after the application of organic manure, and gradually evolved into dominant Bacillus after 4 to 5 years. With an enzyme assay test of pure species and a soil incubation experiment, we came to a preliminary judgment, that the dominant Bacillus asahii didn't significantly influence the decomposition rate of cellulose and protein in the soil, but it promoted the decomposition of lipids, and could also improve the transformation process from fresh organic matter to humus. Applied organic manure led to the succession of soil microbial community, as a response, the changed microbial community and their activities influenced the turnover of exogenous and native soil organic matter, as well as the residuals of decomposition and microbial metabolisms.

Chen, Ruirui; Lin, Xiangui; Feng, Youzhi; Hu, Junli; Wang, Ruirui

2014-05-01

210

In Vitro Activities of the New Semisynthetic Glycopeptide Telavancin (TD-6424), Vancomycin, Daptomycin, Linezolid, and Four Comparator Agents against Anaerobic Gram-Positive Species and Corynebacterium spp.  

PubMed Central

Telavancin is a new semisynthetic glycopeptide anti-infective with multiple mechanisms of action, including inhibition of bacterial membrane phospholipid synthesis and inhibition of bacterial cell wall synthesis. We determined the in vitro activities of telavancin, vancomycin, daptomycin, linezolid, quinupristin-dalfopristin, imipenem, piperacillin-tazobactam, and ampicillin against 268 clinical isolates of anaerobic gram-positive organisms and 31 Corynebacterium strains using agar dilution methods according to National Committee for Clinical Laboratory Standards procedures. Plates with daptomycin were supplemented with Ca2+ to 50 mg/liter. The MICs at which 90% of isolates tested were inhibited (MIC90s) for telavancin and vancomycin were as follows: Actinomyces spp. (n = 45), 0.25 and 1 ?g/ml, respectively; Clostridium difficile (n = 14), 0.25 and 1 ?g/ml, respectively; Clostridium ramosum (n = 16), 1 and 4 ?g/ml, respectively; Clostridium innocuum (n = 15), 4 and 16 ?g/ml, respectively; Clostridium clostridioforme (n = 15), 8 and 1 ?g/ml, respectively; Eubacterium group (n = 33), 0.25 and 2 ?g/ml, respectively; Lactobacillus spp. (n = 26), 0.5 and 4 ?g/ml, respectively; Propionibacterium spp. (n = 34), 0.125 and 0.5 ?g/ml, respectively; Peptostreptococcus spp. (n = 52), 0.125 and 0.5 ?g/ml, respectively; and Corynebacterium spp. (n = 31), 0.03 and 0.5 ?g/ml, respectively. The activity of TD-6424 was similar to that of quinupristin-dalfopristin for most strains except C. clostridioforme and Lactobacillus casei, where quinupristin-dalfopristin was three- to fivefold more active. Daptomycin had decreased activity (MIC > 4 ?g/ml) against 14 strains of Actinomyces spp. and all C. ramosum, Eubacterium lentum, and Lactobacillus plantarum strains. Linezolid showed decreased activity (MIC > 4 ?g/ml) against C. ramosum, two strains of C. difficile, and 15 strains of Lactobacillus spp. Imipenem and piperacillin-tazobactam were active against >98% of strains. The MICs of ampicillin for eight Clostridium spp. and three strains of L. casei were >1 ?g/ml. The MIC90 of TD-6424 for all strains tested was ?2 ?g/ml. TD-6424 has potential for use against infections with gram-positive anaerobes and deserves further clinical evaluation. PMID:15155214

Goldstein, Ellie J. C.; Citron, Diane M.; Merriam, C. Vreni; Warren, Yumi A.; Tyrrell, Kerin L.; Fernandez, Helen T.

2004-01-01

211

Antimicrobial activity of daptomycin tested against Gram-positive pathogens collected in Europe, Latin America, and selected countries in the Asia-Pacific Region (2011).  

PubMed

We report the results of the international daptomycin surveillance programs for Europe, Latin America, and selected Asia-Pacific nations. A total of 7948 consecutive Gram-positive organisms of clinical significance were collected in 2011 and susceptibility tested against daptomycin and various comparator agents by Clinical and Laboratory Standards Institute (Clinical and Laboratory Standards Institute. M07-A9. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard: ninth edition Wayne, PA: CLSI. 2012.; Cubicin Package Insert 2012. Cubist Pharmaceuticals, Inc, Lexington, MA. Available at http://www.cubicin.com/pdf/PrescribingInformation.pdf. Accessed January 1, 2012.) broth microdilution methods. The test medium was adjusted to contain physiological levels of calcium (50 mg/L) when testing daptomycin. Daptomycin exhibited potent activity against methicillin-susceptible and -resistant Staphylococcus aureus overall and for each region (MIC(50/90), 0.25-0.5/0.5 ?g/mL), with susceptibility rates at 100.0% in Latin America, Australia/New Zealand, and India, and at 99.9% in Europe. The daptomycin MIC(50/90) for coagulase-negative staphylococci was also at 0.25-0.5/0.5 ?g/mL, and only 1 isolate was considered nonsusceptible with a MIC value at 2 ?g/mL. Daptomycin was also highly active against Enterococcus faecalis (MIC(50/90), 1/1-2 ?g/mL) and E. faecium (MIC(50/90), 2/2 ?g/mL for both vancomycin-susceptible and -resistant isolates). All enterococcal isolates were susceptible to daptomycin (MIC, ?4 ?g/mL) and tigecycline. Susceptibility to linezolid for E. faecalis was at 100.0%, while for E. faecium regional susceptibility rates were at 100.0% except in Europe (99.0%). Viridans group streptococci (MIC(50/90), 0.25/1 ?g/mL) and ?-haemolytic streptococci (MIC(50/90), ?0.06/0.25 ?g/mL) continue to be very susceptible to daptomycin. In summary, the results of this investigation document the high potency and wide spectrum of daptomycin when tested against a large resistance-surveillance collection of Gram-positive pathogens and indicate that daptomycin nonsusceptibility remains rare among indicated species after many years of clinical use worldwide. PMID:23514757

Sader, Helio S; Flamm, Robert K; Jones, Ronald N

2013-04-01

212

Protein(s) from the Gram-Positive Bacterium Clavibacter michiganensis subsp. michiganensis Induces a Hypersensitive Response in Plants.  

PubMed

ABSTRACT The gram-positive tomato pathogen Clavibacter michiganensis subsp. michiganensis induced a local necrotic response on four-o'clock (Mirabilis jalapa) and tobacco (Nicotiana tabacum) plants. This necrosis response was characteristic of the hypersensitive response (HR). The cell-free culture supernatant from strain CMM623 also induced a necrosis that was phenotypically similar to that induced by the bacteria. Inhibitors of plant metabolism suppressed the necrotic reaction of both M. jalapa and tobacco. The HR-inducing activity present in the supernatant was heat stable, sensitive to proteases, and had an apparent molecular mass in the range of 35 to 50 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The properties observed for the necrosis-inducing activity resembled harpin and PopA described from gram-negative phytopathogenic bacteria. PMID:18944953

Alarcón, C; Castro, J; Muñoz, F; Arce-Johnson, P; Delgado, J

1998-04-01

213

Evidence for high affinity binding-protein dependent transport systems in gram-positive bacteria and in Mycoplasma.  

PubMed Central

Gram-negative bacteria are surrounded by two membranes. In these bacteria, a class of high affinity transport systems for concentrating substrates from the medium into the cell, involves a binding protein located between the outer and inner membranes, in the periplasmic region. These 'periplasmic binding-proteins' are thought to bind the substrate in the vicinity of the inner membrane, and to transfer it to a complex of inner membrane proteins for concentration into the cytoplasm. We report evidence leading us to propose that a Gram-positive bacterium, Streptococcus pneumoniae, and a mycoplasma, Mycoplasma hyorhinis, which are surrounded by a single membrane and have therefore no periplasmic region, possess an equivalent to the high affinity periplasmic binding-protein dependent transport systems, i.e. extra-cytoplasmic binding lipoprotein dependent transport systems. The 'binding lipoproteins' would be maintained at proximity of the inner membrane by insertion of their N-terminal glyceride-cysteine into this membrane. Images PMID:3208757

Gilson, E; Alloing, G; Schmidt, T; Claverys, J P; Dudler, R; Hofnung, M

1988-01-01

214

Plants used in Guatemala for the treatment of respiratory diseases. 1. Screening of 68 plants against gram-positive bacteria.  

PubMed

Respiratory ailments are important causes of morbidity and mortality in developing countries. Ethnobotanical surveys and literature reviews conducted in Guatemala during 1986-88 showed that 234 plants from 75 families, most of them of American origin, have been used for the treatment of respiratory ailments. Three Gram-positive bacteria causing respiratory infections (Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes) were used to screen 68 of the most commonly used plants for activity. Twenty-eight of these (41.2%) inhibited the growth of one or more of the bacteria tested. Staphylococcus aureus was inhibited by 18 of the plant extracts, while 7 extracts were effective against Streptococcus pyogenes. Plants of American origin which exhibited antibacterial activity were: Gnaphalium viscosum, Lippia alba, Lippia dulcis, Physalis philadelphica, Satureja brownei, Solanum nigrescens and Tagetes lucida. These preliminary in vitro results provide scientific basis for the use of these plants against bacterial respiratory infections. PMID:2023428

Caceres, A; Alvarez, A V; Ovando, A E; Samayoa, B E

1991-02-01

215

The Transfer Origin for Bacteroides Mobilizable Transposon Tn4555 Is Related to a Plasmid Family from Gram-Positive Bacteria  

PubMed Central

Conjugal transfer of Bacteroides mobilizable transposon Tn4555 was examined with an Escherichia coli-based assay system. It was shown that mobilization required the cis-acting oriTTn region and that the Tn4555 mobATn gene and RK231 must be present in trans. With alkaline agarose gel electrophoresis and filter blot hybridizations, it was shown that at oriTTn there was a site- and strand-specific cleavage event that was dependent on mobATn. The 5? end of this cleavage site was mapped by primer extension, and the nucleotide sequence surrounding the site had homology to a family of oriT nick sites found in mobilizable plasmids of gram-positive bacteria. Removal of the nick site by deletion of 18 bp surrounding the site resulted in a significant loss of transfer activity. PMID:9440538

Smith, C. Jeffrey; Parker, Anita C.

1998-01-01

216

Induction of nitric oxide production by polyosides from the cell walls of Streptococcus mutans OMZ 175, a gram-positive bacterium, in the rat aorta.  

PubMed Central

The cardiovascular dysfunctions associated with septic shock induced by gram-negative or gram-positive bacteria (gram-positive or gram-negative septic shock) are comparable. In gram-negative septic shock, lipopolysaccharide (LPS) induces nitric oxide (NO) synthase, which contributes to the vascular hypotension and hyporeactivity to vasoconstrictors. The role of NO in gram-positive septic shock and the nature of the bacterial wall components responsible for the vascular effects of gram-positive bacteria are not well known. This study investigated the vascular effects of cell wall serotype polyosides, rhamnose glucose polymers (RGPs), from Streptococcus mutans, in comparison with lipoteichoic acid (LTA) from Staphylococcus aureus, on the induction of NO synthase activity in the rat aorta. We show that 10 microg of both RGPs and LTA per ml induced hyporeactivity to noradrenaline, L-arginine-induced relaxation, increases of 2.2- and 7.8-fold, respectively, of cyclic GMP production, and increases of 7- and 12-fold in nitrite release. All of these effects appeared after several hours of incubation and were inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase. Electron paramagnetic resonance spin trapping experiments demonstrated directly that RGPs and LTA induced NO overproduction (four- to eightfold, respectively) in rat aortic rings; this production was inhibited by L-NAME and prevented by dexamethasone. These results demonstrate directly the induction of NO production in vascular tissue by LTA and show that another, chemically different component of gram-positive bacteria can also have these properties. This result suggests that different components of the gram-positive bacterial wall could be implicated in the genesis of cardiovascular dysfunctions observed in gram-positive septic shock. PMID:9169734

Martin, V; Kleschyov, A L; Klein, J P; Beretz, A

1997-01-01

217

Functionalized magnetic iron oxide (Fe3O4) nanoparticles for capturing gram-positive and gram-negative bacteria.  

PubMed

The development of nanotechnology in biology and medicine has raised the need for conjugation of nanoparticles (NPs) to biomolecules. In this study, magnetic and functionalized magnetic iron oxide nanoparticles were synthesized and used as affinity probes to capture Gram-positive/negative bacteria. The morphology and properties of the magnetic NPs were examined by transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. Furthermore, this study investigated the interaction between functionalized magnetic nanoparticles and Gram positive/negative bacteria. The positively and negatively charged magnetic nanoparticles include functionalities of Fe3O4, SiO2, TiO2, ZrO2, poly ethyleneimine (PEI) and poly acrylic acid. Their capture efficiencies for bacteria were investigated based on factors such as zeta potential, concentration and pH value. PEI particles carry a positive charge over a range of pH values from 3 to 10, and the particles were found to be an excellent candidate for capturing bacteria over such pH range. Since the binding force is mainly electrostatic, the architecture and orientation of the functional groups on the NP surface are not critical. Finally the captured bacteria were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. The minimum detection limit was 10(4) CFU/mL and the analysis time was reduced to be less than 1 hour. In addition, the detection limit could be reduced to an extremely low concentration of 50 CFU/mL when captured bacteria were cultivated. PMID:25016643

Reddy, P Muralidhar; Chang, Kai-Chih; Liu, Zhen-Jun; Chen, Cheng-Tung; Ho, Yen-Peng

2014-08-01

218

Detection of Human Intestinal Catalase-Negative, Gram-Positive Cocci by rRNA-Targeted Reverse Transcription-PCR? †  

PubMed Central

An analytical system based on rRNA-targeted reverse transcription-quantitative PCR (RT-qPCR) for enumeration of catalase-negative, Gram-positive cocci was established. Subgroup- or species-specific primer sets targeting 16S or 23S rRNA from Enterococcus, Streptococcus, and Lactococcus were newly developed. The RT-qPCR method using these primers together with the previously reported primer sets specific for the Enterococcus genus, the Streptococcus genus, and several Streptococcus species was found to be able to quantify the target populations with detection limits of 103 to 104 cells per gram feces, which was more than 100 times as sensitive as the qPCR method (106 to 108 cells per gram feces). The RT-qPCR analysis of fecal samples from 24 healthy adult volunteers using the genus-specific primer sets revealed that Enterococcus and Streptococcus were present as intestinal commensals at population levels of log10 6.2 ± 1.4 and 7.5 ± 0.9 per gram feces (mean ± standard deviation [SD]), respectively. Detailed investigation using species- or subgroup-specific primer sets revealed that the volunteers harbored unique Enterococcus species, including the E. avium subgroup, the E. faecium subgroup, E. faecalis, the E. casseliflavus subgroup, and E. caccae, while the dominant human intestinal Streptococcus species was found to be S. salivarius. Various Lactococcus species, such as L. lactis subsp. lactis or L. lactis subsp. cremoris, L. garvieae, L. piscium, and L. plantarum, were also detected but at a lower population level (log10 4.6 ± 1.2 per gram feces) and prevalence (33%). These results suggest that the RT-qPCR method enables the accurate and sensitive enumeration of human intestinal subdominant but still important populations, such as Gram-positive cocci. PMID:20581195

Kubota, Hiroyuki; Tsuji, Hirokazu; Matsuda, Kazunori; Kurakawa, Takashi; Asahara, Takashi; Nomoto, Koji

2010-01-01

219

Activity of a New Oral Streptogramin, XRP2868, against Gram-Positive Cocci Harboring Various Mechanisms of Resistance to Streptogramins  

PubMed Central

The antibacterial activity of XRP2868, a new oral streptogramin composed of a combination of RPR132552 (streptogramin A) and RPR202868 (streptogramin B), was evaluated against a collection of clinical gram-positive isolates with characterized phenotypes and genotypes of streptogramin resistance. The effects of genes for resistance to streptogramin A or B on the activity of XRP2868 and its components were also tested by cloning these genes individually or in various combinations in gram-positive recipient strains susceptible to quinupristin-dalfopristin. The species tested included Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus faecalis, Enterococcus faecium, Streptococcus pneumoniae, and other species of streptococci. XRP2868 was generally fourfold more potent than quinupristin-dalfopristin against S. aureus, E. faecium, and streptococci and had activity against E. faecalis (MICs = 0.25 to 1 ?g/ml). XRP2868 appeared to be affected by the same mechanisms of resistance as those to quinupristin-dalfopristin. Nevertheless, the strong activity of factor A of the oral streptogramin enabled the combination to be very potent against streptogramin-susceptible staphylococci, streptococci, and E. faecium (MICs = 0.03 to 0.25 ?g/ml) and to retain low MICs against the strains harboring a mechanism of resistance to factor A or factor B of the streptogramin. However, the combination of mechanisms of resistance to factors A and B caused an increase in the MICs of XRP2868, which reached 1 to 4 ?g/ml. As with the other streptogramins, there was a reduction in the bactericidal effect of XRPR2868 when the staphylococcal strains acquired a constitutively expressed erm gene. PMID:16377692

Dupuis, Michel; Leclercq, Roland

2006-01-01

220

Size-dependent antimicrobial properties of CuO nanoparticles against Gram-positive and -negative bacterial strains  

PubMed Central

Background CuO is one of the most important transition metal oxides due to its captivating properties. It is used in various technological applications such as high critical temperature superconductors, gas sensors, in photoconductive applications, and so on. Recently, it has been used as an antimicrobial agent against various bacterial species. Here we synthesized different sized CuO nanoparticles and explored the size-dependent antibacterial activity of each CuO nanoparticles preparation. Methods CuO nanoparticles were synthesized using a gel combustion method. In this approach, cupric nitrate trihydrate and citric acid were dissolved in distilled water with a molar ratio of 1:1. The resulting solution was stirred at 100°C, until gel was formed. The gel was allowed to burn at 200°C to obtain amorphous powder, which was further annealed at different temperatures to obtain different size CuO nanoparticles. We then tested the antibacterial properties using well diffusion, minimum inhibitory concentration, and minimum bactericidal concentration methods. Results XRD spectra confirmed the formation of single phase CuO nanoparticles. Crystallite size was found to increase with an increase in annealing temperature due to atomic diffusion. A minimum crystallite size of 20 nm was observed in the case of CuO nanoparticles annealed at 400°C. Transmission electron microscopy results corroborate well with XRD results. All CuO nanoparticles exhibited inhibitory effects against both Gram-positive and -negative bacteria. The size of the particles was correlated with its antibacterial activity. Conclusion The antibacterial activity of CuO nanoparticles was found to be size-dependent. In addition, the highly stable minimum-sized monodispersed copper oxide nanoparticles synthesized during this study demonstrated a significant increase in antibacterial activities against both Gram-positive and -negative bacterial strains. PMID:22848176

Azam, Ameer; Ahmed, Arham S; Oves, M; Khan, MS; Memic, Adnan

2012-01-01

221

Sortase activity is controlled by a flexible lid in the pilus biogenesis mechanism of gram-positive pathogens.  

PubMed

Pili are surface-linked virulence factors that play key roles in infection establishment in a variety of pathogenic species. In Gram-positive pathogens, pilus formation requires the action of sortases, dedicated transpeptidases that covalently associate pilus building blocks. In Streptococcus pneumoniae, a major human pathogen, all genes required for pilus formation are harbored in a single pathogenicity islet which encodes three structural proteins (RrgA, RrgB, RrgC) and three sortases (SrtC-1, SrtC-2, SrtC-3). RrgB forms the backbone of the streptococcal pilus, to which minor pilins RrgA and RrgC are covalently associated. SrtC-1 is the main sortase involved in polymerization of the RrgB fiber and displays a lid which encapsulates the active site, a feature present in all pilus-related sortases. In this work, we show that catalysis by SrtC-1 proceeds through a catalytic triad constituted of His, Arg, and Cys and that lid instability affects protein fold and catalysis. In addition, we show by thermal shift analysis that lid flexibility can be stabilized by the addition of substrate-like peptides, a feature shared by other periplasmic transpeptidases. We also report the characterization of a trapped acyl-enzyme intermediate formed between SrtC-1 and RrgB. The presence of lid-encapsulated sortases in the pilus biogenesis systems in many Gram-positive pathogens points to a common mechanism of substrate recognition and catalysis that should be taken into consideration in the development of sortase inhibitors. PMID:19810750

Manzano, Clothilde; Izoré, Thierry; Job, Viviana; Di Guilmi, Anne Marie; Dessen, Andréa

2009-11-10

222

Gram-negative and gram-positive antibacterial properties of the whole plant extract of willow herb (Epilobium angustifolium).  

PubMed

The emergence of new pathogens and the increase in the number of multidrug-resistant strains in well-established pathogens during the past decade represent a growing public health concern globally. With the current lack of research and development of new antibiotics by large pharmaceutical companies due to poor financial returns, new alternatives need to be explored including natural herbal or plant-based extracts with reported antibacterial properties. Willow herb (Epilobium angustifolium) preparations have been used in traditional aboriginal and folk medicine preparations externally as an antiphlogistic to treat prostate and gastrointestinal disorders and as an antiseptic to treat infected wounds. The authors hypothesized that a whole plant extract of willow herb would exhibit antimicrobial properties on a variety of both Gram-positive and gram-negative bacteria in culture. The authors found that, in comparison to growth controls, willow herb extract significantly inhibited the growth of Micrococcus luteus (p < .01), Staphylococcus aureus (p < .05), Escherichia coli (p < .001), and Pseudomonas aeruginosa (p < .001). They also found that willow herb extract inhibited the growth of bacteria in culture more effectively than vancomycin (p < .05) or tetracycline (p < .004). These results provide preliminary support for the traditional folkloric claim that the plant willow herb possesses antibacterial properties against a variety of gram-positive and gram-negative bacteria. Given that whole plant extract was utilized for this study, further investigations are warranted to determine which specific part of the plant (i.e., leaves, stem, roots, and flowers) possess the antibacterial properties. PMID:21208973

Bartfay, Wally J; Bartfay, Emma; Johnson, Julia Green

2012-01-01

223

Isolation and Characterization of Four Gram-PositiveNickel-Tolerant Microorganisms from Contaminated Riparian Sediments  

SciTech Connect

Microbial communities from riparian sediments contaminatedwith high levels of Ni and U were examined for metal-tolerantmicroorganisms. Isolation of four aerobic Ni-tolerant, Gram-positiveheterotrophic bacteria indicated selection pressure from Ni. Theseisolates were identified as Arthrobacter oxydans NR-1, Streptomycesgalbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatosporacystarginea NR-4 based on partial 16S rDNA sequences. A functional genemicroarray containing gene probes for functions associated withbiogeochemical cycling, metal homeostasis, and organic contaminantdegradation showed little overlap among the four isolates. Fifteen of thegenes were detected in all four isolates with only two of these relatedto metal resistance, specifically to tellurium. Each of the four isolatesalso displayed resistance to at least one of six antibiotics tested, withresistance to kanamycin, gentamycin, and ciprofloxacin observed in atleast two of the isolates. Further characterization of S. aureofaciensNR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Nitolerance constitutively. In addition, both were able to grow in higherconcentrations of Ni at pH 6 as compared to pH 7 (42.6 and 8.5 mM Ni atpH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examinedin these two isolates; a similar pH-dependent metal tolerance wasobserved when grown with Co and Zn. Neither isolate was tolerant to Cd.These findings suggest that Ni is exerting a selection pressure at thissite for metal-resistant actinomycetes.

Van Nostrand, Joy D.; Khijniak, Tatiana V.; Gentry, Terry J.; Novak, Michelle T.; Sowder, Andrew G.; Zhou, Jizhong Z.; Bertsch, PaulM.; Morris, Pamela J.

2006-08-30

224

Prevalence of resistance phenotypes and genotypes to macrolide, lincosamide and streptogramin antibiotics in Gram-positive cocci isolated in Tunisian Bone Marrow Transplant Center.  

PubMed

To investigate the prevalence of resistance to macrolide, lincosamide and streptogramin (MLS) antibiotics in Gram-positive cocci isolated in a Bone Marrow Transplant Center of Tunisia, we tested the antibiotic susceptibility of 172 clinical isolates of Staphylococcus epidermidis, Streptococcus mitis and Enterococcus faecium to macrolide erythromycin and spiramycin, the lincosamide clindamycin and the streptogramin pristinamycin. These three groups of organisms were mostly resistant to macrolides and lincosamide, but were commonly susceptible to pristinamycin. The resistance phenotypes of erythromycin-resistant isolates were determined by the five-disc test with erythromycin, spiramycin, lincomycin, clindamycin and pristinamycin, which showed that most exhibited constitutive MLS resistance. In order to determine the prevalence of the resistance genotypes and the resistance mechanisms, the prevalence of the erythromycin resistance methylase (erm) (A), erm(B), erm(C), msr(A) and macrolide efflux (mef) (A) genes in the erythromycin-resistant isolates was identified by polymerase chain reaction (PCR) analysis. The resistance was due mainly to the presence of ermB in E. faecium (80%), ermC in S. epidermidis (53%) and mefA in S. mitis (65%). PMID:19481372

Bouchami, O; Achour, W; Ben Hassen, A

2011-08-01

225

Complete Genome Sequence of Bacillus megaterium Myophage Moonbeam  

PubMed Central

Moonbeam is a newly isolated myophage of Bacillus megaterium, a common Gram-positive bacterium that is routinely used for large-scale protein production. Bacteriophages have potential to be useful tools for industrial applications. Here, we describe the complete genome of Moonbeam and describe its features. PMID:25593264

Cadungog, Joshua N.; Khatemi, Brontee E.; Hernandez, Adriana C.

2015-01-01

226

Cytokine Response to Infection with Bacillus anthracis Spores  

Microsoft Academic Search

Bacillus anthracis, the etiological agent of anthrax, is a gram-positive, spore-forming bacterium. The inhala- tional form of anthrax is the most severe and is associated with rapid progression of the disease and the outcome is frequently fatal. Transfer from the respiratory epithelium to regional lymph nodes appears to be an essential early step in the establishment of infection. This transfer

Alison K. Pickering; Manuel Osorio; Gloria M. Lee; Vanessa K. Grippe; Mechelle Bray; Tod J. Merkel

2004-01-01

227

Unravelling a vicious circle: animal feed marketed in Costa Rica contains irregular concentrations of tetracyclines and abundant oxytetracycline-resistant Gram-positive bacteria.  

PubMed

Diverse tetracyclines are used to prevent and control bacterial infections in livestock and farmed fish. These drugs are administered through the diet, but farmers seldom check whether feed contains antibiotic-resistant bacteria that may colonise their crops or transfer their resistance traits to species of veterinary relevance. To examine whether antibiotic dosage defines the abundance of antibiotic-resistant bacteria in animal feed, we determined the concentration of parental compounds and epimers of oxytetracycline (OTC), doxycycline, tetracycline and chlortetracycline, as well as the abundance and resistance level of OTC-resistant bacteria in samples of fish (n = 21), poultry (n = 21), swine (n = 21), and shrimp feed (n = 21) marketed in Costa Rica. Fish feed contained the highest amounts of tetracyclines (119-8365 mg kg(-1)) and the largest proportion of bacteria resistant to 10 ?g ml(-1) (1.8-92.4%) or 100 ?g ml(-1) of OTC (12.5-63.8%). Poultry (78-438 mg kg(-1)) and swine (41-1076 mg kg(-1)) feed had intermediate concentrations of tetracyclines and OTC-resistant bacteria (0.2-66% and 0.3-49%, respectively), whereas shrimp feed showed the lowest amounts of tetracyclines (21.5-50.3 mg kg(-1)), no OTC and no culturable OTC-resistant bacteria. In line with these results, the MIC50 of OTC for 150 isolates from fish and poultry feed was > 256 µg ml(-1), while that of 150 bacteria isolated from swine feed was 192 µg ml(-1). Phenotypic tests, fatty acid profiles and proteotypic analyses by matrix-assisted laser desorption/ionisation-time of flight mass-spectroscopy revealed that most OTC-resistant isolates were Gram-positive bacteria of low G+C% content from the genera Staphylococcus and Bacillus. Clear correlations between OTC dosage and feed colonisation with OTC-resistant bacteria were seen in medicated feed for fish (r = 0.179-0.651). Nonetheless, some unmedicated feed for fish, swine and poultry contained large populations of OTC-resistant bacteria, suggesting that raw materials and manufacturing processes may also influence carriage of OTC-resistant bacteria in animal feed. PMID:24660748

Granados-Chinchilla, Fabio; Alfaro, Margarita; Chavarría, Guadalupe; Rodríguez, César

2014-01-01

228

Bacillus and Paenibacillus spp.: Potential PGPR for Sustainable Agriculture  

Microsoft Academic Search

\\u000a The Gram-positive aerobic endospore-forming bacteria (AEFB) belonging to the genus Bacillus and Paenibacillus are essentially ubiquitous and occur abundantly in most rhizospheric soils. In the rhizosphere, species of these two genera\\u000a are involved in atmospheric nitrogen fixation, solubilization of soil phosphorus and uptake of micronutrients, and production\\u000a of phytohormones and antimicrobial metabolites. Multiple species of Bacillus and Paenibacillus affect the

Venkadasamy Govindasamy; Murugesan Senthilkumar; Vellaichamy Magheshwaran; Upendra Kumar; Pranita Bose; Vikas Sharma; Kannepalli Annapurna

229

Changes of the Quinolones Resistance to Gram-positive Cocci Isolated during the Past 8 Years in the First Bethune Hospital  

NASA Astrophysics Data System (ADS)

This study was to investigate the quinolones resistance to gram-positive cocci isolated in the First Bethune Hospital during the past 8 years. 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). The rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococci (MRCNS) were 50.8%?83.3% and 79.4%?81.5%during the past 8 years, respectively. In recent 8 years, the quinolones resistance to gram-positive cocci had increased. Monitoring of the quinolones resistance to gram-positive cocci should be strengthened. The change of the antimicrobial resistance should be investigated in order to guide rational drug usage in the clinic and prevent bacterial strain of drug resistance from being transmitted.

Xu, Jiancheng; Chen, Qihui; Yao, Hanxin; Zhou, Qi

230

Efficacy of the New Lantibiotic NAI-107 in Experimental Infections Induced by Multidrug-Resistant Gram-Positive Pathogens?  

PubMed Central

NAI-107 is a novel lantibiotic active against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), glycopeptide-intermediate S. aureus (GISA), and vancomycin-resistant enterococci (VRE). The aim of this study was to evaluate the in vivo efficacy of NAI-107 in animal models of severe infection. In acute lethal infections induced with a penicillin-intermediate Streptococcus pneumoniae strain in immunocompetent mice, or with MRSA, GISA, and VRE strains in neutropenic mice, the 50% effective dose (ED50) values of NAI-107 were comparable or lower than those of reference compounds, irrespective of the strain and immune status (0.51 to 14.2 mg/kg of body weight for intravenous [i.v.] NAI-107, 5.1 to 22.4 for oral linezolid, and 22.4 for subcutaneous [s.c.] vancomycin). In the granuloma pouch model induced in rats with a MRSA strain, intravenous NAI-107 showed a dose-proportional bactericidal activity that, at a single 40-mg/kg dose, compared with 2 20-mg/kg doses at a 12-h or 24-h interval, caused a 3-log10-CFU/ml reduction of viable MRSA in exudates that persisted for more than 72 h. Rat endocarditis was induced with a MRSA strain and treated for five consecutive days. In a first experiment, using 5, 10, or 20 mg/kg/day, and in a second experiment, when 10 mg/kg at 12-h intervals was compared to 20 mg/kg/day, intravenous NAI-107 was effective in reducing the bacterial load in heart vegetations in a dose-proportional manner. Trough plasma levels, as determined on days 2 and 5, were several times higher than the NAI-107 minimal bactericidal concentration (MBC). NAI-107 binding to rat and human serum ranges between 93% and 98.6%. The rapid bactericidal activity of NAI-107 observed in vitro was thus confirmed by the efficacy in several models of experimental infection induced by Gram-positive pathogens, supporting further investigation of the compound. PMID:21220527

Jabés, Daniela; Brunati, Cristina; Candiani, GianPaolo; Riva, Simona; Romanó, Gabriella; Donadio, Stefano

2011-01-01

231

Bacillus arenosi sp. nov., Bacillus arvi sp. nov. and Bacillus humi sp. nov., isolated from soil.  

PubMed

A group of nine Gram-positive endospore-forming bacteria was isolated from soil of the Drentse A agricultural research area in The Netherlands. Using (GTG)5-PCR genomic fingerprinting and fatty acid analysis, the nine isolates were divided into three consistent groups. On the basis of 16S rRNA gene sequence similarity of representative strains, the nine isolates were shown to belong to the genus Bacillus. The first group of four isolates was most closely related to Bacillus carboniphilus (95.5 %) and Bacillus sporothermodurans (95.5 %). The second and third groups of three and two isolates, respectively, showed highest sequence similarity to Bacillus neidei (97.0 and 97.1 %, respectively) and Bacillus pycnus (both 96.7 %). A DNA-DNA relatedness study confirmed the consistency of the three groups delineated by (GTG)5-PCR and fatty acid analysis. A small number of phenotypic characters allowed differentiation of the three groups of isolates. The three groups therefore represent novel species, for which the names Bacillus humi, Bacillus arenosi and Bacillus arvi are proposed, with LMG 22167T (=DSM 16318T), LMG 22166T (=DSM 16319T) and LMG 22165T (=DSM 16317T) as the respective type strains. PMID:15653863

Heyrman, Jeroen; Rodríguez-Díaz, Marina; Devos, Joke; Felske, Andreas; Logan, Niall A; De Vos, Paul

2005-01-01

232

Usefulness of the MicroSeq 500 16S rDNA bacterial identification system for identification of anaerobic Gram positive bacilli isolated from blood cultures  

PubMed Central

Using full 16S ribosomal RNA (rRNA) gene sequencing as the gold standard, 20 non?duplicating anaerobic Gram positive bacilli isolated from blood cultures were analysed by the MicroSeq 500 16S rDNA bacterial identification system. The MicroSeq system successfully identified 13 of the 20 isolates. Four and three isolates were misidentified at the genus and species level, respectively. Although the MicroSeq 500 16S rDNA bacterial identification system is better than three commercially available identification systems also evaluated, its database needs to be expanded for accurate identification of anaerobic Gram positive bacilli. PMID:16443743

Lau, S K P; Ng, K H L; Woo, P C Y; Yip, K?t; Fung, A M Y; Woo, G K S; Chan, K?m; Que, T?l

2006-01-01

233

Antimicrobial photodynamic efficiency of novel cationic porphyrins towards periodontal Gram-positive and Gram-negative pathogenic bacteria.  

PubMed

The Gram-negative Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum are major causative agents of aggressive periodontal disease. Due to increase in the number of antibiotic-resistant bacteria, antimicrobial Photodynamic therapy (aPDT) seems to be a plausible alternative. In this work, photosensitization was performed on Gram-positive and Gram-negative bacteria in pure culture using new-age cationic porphyrins, namely mesoimidazolium-substituted porphyrin derivative (ImP) and pyridinium-substituted porphyrin derivative (PyP). The photophysical properties of both the sensitizers including absorption, fluorescence emission, quantum yields of the triplet excited states and singlet oxygen generation efficiencies were evaluated in the context of aPDT application. The studied porphyrins exhibited high ability to accumulate into bacterial cells with complete penetration into early stage biofilms. As compared with ImP, PyP was found to be more effective for photoinactivation of bacterial strains associated with periodontitis, without any signs of dark toxicity, owing to its high photocytotoxicity. PMID:24164211

Prasanth, Chandra Sekhar; Karunakaran, Suneesh C; Paul, Albish K; Kussovski, Vesselin; Mantareva, Vanya; Ramaiah, Danaboyina; Selvaraj, Leslie; Angelov, Ivan; Avramov, Latchezar; Nandakumar, Krishnankutty; Subhash, Narayanan

2014-01-01

234

ppGpp analogues inhibit synthetase activity of Rel proteins from Gram-negative and Gram-positive bacteria.  

PubMed

A prominent feature of the stringent response is the accumulation of two unusual phosphorylated derivatives of GTP and GDP (pppGpp: 5'-triphosphate-3'-diphosphate, and ppGpp: 5'-3'-bis-diphosphate), collectively called (p)ppGpp, within a few seconds after the onset of amino-acid starvation. The synthesis of these 'alarmone' compounds is catalyzed by RelA homologues. Other features of the stringent response include inhibition of stable RNA synthesis and modulation of transcription, replication, and translation. (p)ppGpp accumulation is important for virulence induction, differentiation and antibiotic resistance. We have synthesized a group of (p)ppGpp analogues and tested them as competitive inhibitors of Rel proteins in vitro. 2'-Deoxyguanosine-3'-5'-di(methylene bisphosphonate) [compound (10)] was found as an inhibitor that reduces ppGpp formation in both Gram-negative and Gram-positive bacteria. In silico docking together with competitive inhibition analysis suggests that compound (10) inhibits activity of Rel proteins by competing with GTP/GDP for its binding site. As Rel proteins are completely absent in mammalians, this appears to be a very attractive approach for the development of novel antibacterial agents. PMID:20483622

Wexselblatt, Ezequiel; Katzhendler, Jehoshua; Saleem-Batcha, Raspudin; Hansen, Guido; Hilgenfeld, Rolf; Glaser, Gad; Vidavski, Roee R

2010-06-15

235

Mobilizable Rolling-Circle Replicating Plasmids from Gram-Positive Bacteria: A Low-Cost Conjugative Transfer  

PubMed Central

Chapter summary Conjugation is a key mechanism for horizontal gene transfer in bacteria. Some plasmids are not self-transmissible but can be mobilized by functions encoded in trans provided by other auxiliary conjugative elements. Although the transfer efficiency of mobilizable plasmids is usually lower than that of conjugative elements, mobilizable plasmidsare more frequently found in nature. In this sense, replication and mobilization can be considered as important mechanisms influencing plasmid promiscuity. Here we review the present available information on two families of small mobilizable plasmids from Gram-positive bacteria that replicate via the rolling-circle mechanism. One of these families, represented by the streptococcal plasmid pMV158, is an interesting model since it contains a specific mobilization module (MOBV) that is widely distributed among mobilizable plasmids. We discuss a mechanism in which the promiscuity of the pMV158 replicon is based on the presence of two origins of lagging strand synthesis. The current strategies to assess plasmid transfer efficiency as well as to inhibit conjugative plasmid transfer are presented. Some applications of these plasmids as biotechnological tools are also reviewed. PMID:25606350

Fernández-López, Cris; Bravo, Alicia; Ruiz-Cruz, Sofía; Solano-Collado, Virtu; Garsin, Danielle A.; Lorenzo-Díaz, Fabián; Espinosa, Manuel

2014-01-01

236

Use of Enzyme Tests in Characterization and Identification of Aerobic and Facultatively Anaerobic Gram-Positive Cocci  

PubMed Central

The contribution of enzyme tests to the accurate and rapid routine identification of gram-positive cocci is introduced. The current taxonomy of the genera of aerobic and facultatively anaerobic cocci based on genotypic and phenotypic characterization is reviewed. The clinical and economic importance of members of these taxa is briefly summarized. Tables summarizing test schemes and kits available for the identification of staphylococci, enterococci, and streptococci on the basis of general requirements, number of tests, number of taxa, test classes, and completion times are discussed. Enzyme tests included in each scheme are compared on the basis of their synthetic moiety. The current understanding of the activity of enzymes important for classification and identification of the major groups, methods of testing, and relevance to the ease and speed of identification are reviewed. Publications describing the use of different identification kits are listed, and overall identification successes and problems are discussed. The relationships between the results of conventional biochemical and rapid enzyme tests are described and considered. The use of synthetic substrates for the detection of glycosidases and peptidases is reviewed, and the advantages of fluorogenic synthetic moieties are discussed. The relevance of enzyme tests to accurate and meaningful rapid routine identification is discussed. PMID:9564566

Bascomb, Shoshana; Manafi, Mammad

1998-01-01

237

Identification of Multiple Soluble Fe(III) Reductases in Gram-Positive Thermophilic Bacterium Thermoanaerobacter indiensis BSB-33  

PubMed Central

Thermoanaerobacter indiensis BSB-33 has been earlier shown to reduce Fe(III) and Cr(VI) anaerobically at 60°C optimally. Further, the Gram-positive thermophilic bacterium contains Cr(VI) reduction activity in both the membrane and cytoplasm. The soluble fraction prepared from T. indiensis cells grown at 60°C was found to contain the majority of Fe(III) reduction activity of the microorganism and produced four distinct bands in nondenaturing Fe(III) reductase activity gel. Proteins from each of these bands were partially purified by chromatography and identified by mass spectrometry (MS) with the help of T. indiensis proteome sequences. Two paralogous dihydrolipoamide dehydrogenases (LPDs), thioredoxin reductase (Trx), NADP(H)-nitrite reductase (Ntr), and thioredoxin disulfide reductase (Tdr) were determined to be responsible for Fe(III) reductase activity. Amino acid sequence and three-dimensional (3D) structural similarity analyses of the T. indiensis Fe(III) reductases were carried out with Cr(VI) reducing proteins from other bacteria. The two LPDs and Tdr showed very significant sequence and structural identity, respectively, with Cr(VI) reducing dihydrolipoamide dehydrogenase from Thermus scotoductus and thioredoxin disulfide reductase from Desulfovibrio desulfuricans. It appears that in addition to their iron reducing activity T. indiensis LPDs and Tdr are possibly involved in Cr(VI) reduction as well. PMID:25180173

Pal, Subrata

2014-01-01

238

Novel tetrahydropyran-based bacterial topoisomerase inhibitors with potent anti-gram positive activity and improved safety profile.  

PubMed

Novel antibacterial drugs that are effective against infections caused by multidrug resistant pathogens are urgently needed. In a previous report, we have shown that tetrahydropyran-based inhibitors of bacterial type II topoisomerases (DNA gyrase and topoisomerase IV) display potent antibacterial activity and exhibit no target-mediated cross-resistance with fluoroquinolones. During the course of our optimization program, lead compound 5 was deprioritized due to adverse findings in cardiovascular safety studies. In the effort of mitigating these findings and optimizing further the pharmacological profile of this class of compounds, we have identified a subseries of tetrahydropyran-based molecules that are potent DNA gyrase and topoisomerase IV inhibitors and display excellent antibacterial activity against Gram positive pathogens, including clinically relevant resistant isolates. One representative of this class, compound 32d, elicited only weak inhibition of hERG K(+) channels and hNaV1.5 Na(+) channels, and no effects were observed on cardiovascular parameters in anesthetized guinea pigs. In vivo efficacy in animal infection models has been demonstrated against Staphylococcus aureus and Streptococcus pneumoniae strains. PMID:25494934

Surivet, Jean-Philippe; Zumbrunn, Cornelia; Rueedi, Georg; Bur, Daniel; Bruyère, Thierry; Locher, Hans; Ritz, Daniel; Seiler, Peter; Kohl, Christopher; Ertel, Eric A; Hess, Patrick; Gauvin, Jean-Christophe; Mirre, Azely; Kaegi, Verena; Dos Santos, Marina; Kraemer, Stéphanie; Gaertner, Mika; Delers, Jonathan; Enderlin-Paput, Michel; Weiss, Maria; Sube, Romain; Hadana, Hakim; Keck, Wolfgang; Hubschwerlen, Christian

2015-01-22

239

Differential Targeting of the E-Cadherin/?-Catenin Complex by Gram-Positive Probiotic Lactobacilli Improves Epithelial Barrier Function  

PubMed Central

The intestinal ecosystem is balanced by dynamic interactions between resident and incoming microbes, the gastrointestinal barrier, and the mucosal immune system. However, in the context of inflammatory bowel diseases (IBD), where the integrity of the gastrointestinal barrier is compromised, resident microbes contribute to the development and perpetuation of inflammation and disease. Probiotic bacteria have been shown to exert beneficial effects, e.g., enhancing epithelial barrier integrity. However, the mechanisms underlying these beneficial effects are only poorly understood. Here, we comparatively investigated the effects of four probiotic lactobacilli, namely, Lactobacillus acidophilus, L. fermentum, L. gasseri, and L. rhamnosus, in a T84 cell epithelial barrier model. Results of DNA microarray experiments indicating that lactobacilli modulate the regulation of genes encoding in particular adherence junction proteins such as E-cadherin and ?-catenin were confirmed by quantitative reverse transcription-PCR (qRT-PCR). Furthermore, we show that epithelial barrier function is modulated by Gram-positive probiotic lactobacilli via their effect on adherence junction protein expression and complex formation. In addition, incubation with lactobacilli differentially influences the phosphorylation of adherence junction proteins and the abundance of protein kinase C (PKC) isoforms such as PKC? that thereby positively modulates epithelial barrier function. Further insight into the underlying molecular mechanisms triggered by these probiotics might also foster the development of novel strategies for the treatment of gastrointestinal diseases (e.g., IBD). PMID:22179242

Hummel, Stephanie; Veltman, Katharina; Cichon, Christoph; Sonnenborn, Ulrich

2012-01-01

240

Transcriptional profiling of Gram-positive Arthrobacter in the phyllosphere: induction of pollutant degradation genes by natural plant phenolic compounds.  

PubMed

Arthrobacter chlorophenolicus?A6 is a Gram-positive, 4-chlorophenol-degrading soil bacterium that was recently shown to be an effective colonizer of plant leaf surfaces. The genetic basis for this phyllosphere competency is unknown. In this paper, we describe the genome-wide expression profile of A.chlorophenolicus on leaves of common bean (Phaseolus vulgaris) compared with growth on agar surfaces. In phyllosphere-grown cells, we found elevated expression of several genes known to contribute to epiphytic fitness, for example those involved in nutrient acquisition, attachment, stress response and horizontal gene transfer. A surprising result was the leaf-induced expression of a subset of the so-called cph genes for the degradation of 4-chlorophenol. This subset encodes the conversion of the phenolic compound hydroquinone to 3-oxoadipate, and was shown to be induced not only by 4-chlorophenol but also hydroquinone, its glycosylated derivative arbutin, and phenol. Small amounts of hydroquinone, but not arbutin or phenol, were detected in leaf surface washes of P.vulgaris by gas chromatography-mass spectrometry. Our findings illustrate the utility of genomics approaches for exploration and improved understanding of a microbial habitat. Also, they highlight the potential for phyllosphere-based priming of bacteria to stimulate pollutant degradation, which holds promise for the application of phylloremediation. PMID:24373130

Scheublin, Tanja R; Deusch, Simon; Moreno-Forero, Silvia K; Müller, Jochen A; van der Meer, Jan Roelof; Leveau, Johan H J

2014-07-01

241

Stronger T Cell Immunogenicity of Ovalbumin Expressed Intracellularly in Gram-Negative than in Gram-Positive Bacteria  

PubMed Central

This study aimed to clarify whether Gram-positive (G+) and Gram-negative (G?) bacteria affect antigen-presenting cells differently and thereby influence the immunogenicity of proteins they express. Lactobacilli, lactococci and Escherichia coli strains were transformed with plasmids conferring intracellular ovalbumin (OVA) production. Murine splenic antigen presenting cells (APCs) were pulsed with washed and UV-inactivated OVA-producing bacteria, control bacteria, or soluble OVA. The ability of the APCs to activate OVA-specific DO11.10 CD4+ T cells was assessed by measurments of T cell proliferation and cytokine (IFN-?, IL-13, IL-17, IL-10) production. OVA expressed within E. coli was strongly immunogenic, since 500 times higher concentrations of soluble OVA were needed to achieve a similar level of OVA-specific T cell proliferation. Furthermore, T cells responding to soluble OVA produced mainly IL-13, while T cells responding to E. coli-expressed OVA produced high levels of both IFN-? and IL-13. Compared to E. coli, G+ lactobacilli and lactococci were poor inducers of OVA-specific T cell proliferation and cytokine production, despite efficient intracellular expression and production of OVA and despite being efficiently phagocytosed. These results demonstrate a pronounced difference in immunogenicity of intracellular antigens in G+ and G? bacteria and may be relevant for the use of bacterial carriers in vaccine development. PMID:23741469

Martner, Anna; Östman, Sofia; Lundin, Samuel; Rask, Carola; Björnsson, Viktor; Telemo, Esbjörn; Collins, L. Vincent; Axelsson, Lars; Wold, Agnes E.

2013-01-01

242

A new organic solvent tolerant protease from Bacillus pumilus 115b.  

PubMed

Five out of the nine benzene-toulene-ethylbenzene-xylene (BTEX) tolerant bacteria that demonstrated high protease activity on skim milk agar were isolated. Among them, isolate 115b identified as Bacillus pumilus exhibited the highest protease production. The protease produced was stable in 25% (v/v) benzene and toluene and it was activated 1.7 and 2.5- fold by n-dodecane and n-tetradecane, respectively. The gene encoding the organic solvent tolerant protease was cloned and its nucleotide sequence determined. Sequence analysis revealed an open reading frame (ORF) of 1,149 bp that encoded a polypeptide of 383 amino acid residues. The polypeptide composed of 29 residues of signal peptide, a propeptide of 79 residues and a mature protein of 275 amino acids with a calculated molecular mass of 27,846 Da. This is the only report available to date on organic solvent tolerant protease from B. pumilus. PMID:17492323

Rahman, Raja Noor Zaliha Raja Abd; Mahamad, Shalihah; Salleh, Abu Bakar; Basri, Mahiran

2007-07-01

243

Multi-organ failure with atypical liver granulomas following intravesical Bacillus Calmette-Guerin instillation  

PubMed Central

Bacillus Calmette-Guerin (BCG) intravesical instillation has been adopted in the treatment of patients with superficial bladder cancer. BCG-induced disseminated infection, though rare, has been associated with the histological finding of epithelioid granulomas in different organs, including the liver. We report the case of an adult patient with multi-organ failure, who developed sepsis, acute respiratory failure and acute hepatic failure with encephalopathy whose liver biopsy confirmed the presence of atypical, granulomatous-like lesions. Recovery was observed only after empirical therapy for Mycobacterium bovis with isoniazid, rifampicin, ethambutol and steroids was introduced. This case highlights the importance of a thorough patient assessment in order to exclude other more common causes of hepatic granulomas and to confirm diagnosis. Histological findings may be non-specific when the liver is involved in BCG-induced disseminated infection. PMID:21487539

Kaklamanos, Michail; Hardavella, Georgia; Trigidou, Rodoula; Dionellis, Georgios; Paissios, Nikolaos; Koulouris, Nikolaos; Goritsas, Constantin

2011-01-01

244

Protein secretion in Bacillus species.  

PubMed Central

Bacilli secrete numerous proteins into the environment. Many of the secretory proteins, their export signals, and their processing steps during secretion have been characterized in detail. In contrast, the molecular mechanisms of protein secretion have been relatively poorly characterized. However, several components of the protein secretion machinery have been identified and cloned recently, which is likely to lead to rapid expansion of the knowledge of the protein secretion mechanism in Bacillus species. Comparison of the presently known export components of Bacillus species with those of Escherichia coli suggests that the mechanism of protein translocation across the cytoplasmic membrane is conserved among gram-negative and gram-positive bacteria differences are found in steps preceding and following the translocation process. Many of the secretory proteins of bacilli are produced industrially, but several problems have been encountered in the production of Bacillus heterologous secretory proteins. In the final section we discuss these problems and point out some possibilities to overcome them. PMID:8464403

Simonen, M; Palva, I

1993-01-01

245

Lessons from the modular organization of the transcriptional regulatory network of Bacillus subtilis  

PubMed Central

Background The regulation of gene expression at the transcriptional level is a fundamental process in prokaryotes. Among the different kind of mechanisms modulating gene transcription, the one based on DNA binding transcription factors, is the most extensively studied and the results, for a great number of model organisms, have been compiled making it possible the in silico construction of their corresponding transcriptional regulatory networks and the analysis of the biological relationships of the components of these intricate networks, that allows to elucidate the significant aspects of their organization and evolution. Results We present a thorough review of each regulatory element that constitutes the transcriptional regulatory network of Bacillus subtilis. For facilitating the discussion, we organized the network in topological modules. Our study highlight the importance of ? factors, some of them acting as master regulators which characterize modules by inter- or intra-connecting them and play a key role in the cascades that define relevant cellular processes in this organism. We discussed that some particular functions were distributed in more than one module and that some modules contained more than one related function. We confirm that the presence of paralogous proteins confers advantages to B. subtilis to adapt and select strategies to successfully face the extreme and changing environmental conditions in which it lives. Conclusions The intricate organization is the product of a non-random network evolution that primarily follows a hierarchical organization based on the presence of transcription and ? factor, which is reflected in the connections that exist within and between modules. PMID:24237659

2013-01-01

246

AFM study of the differential inhibitory effects of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) against Gram-positive and Gram-negative bacteria.  

PubMed

(-)-Epigallocatechin-3-gallate (EGCG), a main constituent of tea catechins, affects Gram-positive and Gram-negative bacteria differently; however, the underlying mechanisms are not clearly understood. Atomic force microscopy (AFM) was used to compare morphological alterations in Gram-positive and Gram-negative bacteria induced by EGCG and by H(2)O(2) at sub-minimum inhibitory concentrations (MICs). EGCG initially induced aggregates in the cell envelopes of Staphylococcus aureus and eventually caused cell lysis, which was not observed in cells treated with H(2)O(2). It initially induced nanoscale perforations or microscale grooves in the cell envelopes of Escherichia coli O157:H7 which eventually disappeared, similar to E. coli cells treated with H(2)O(2). An E. coli O157:H7 tpx mutant, with a defect in thioredoxin-dependent thiol peroxidase (Tpx), was more severely damaged by EGCG when compared with its wild type. Similar differing effects were observed in other Gram-positive and Gram-negative bacteria when exposed to EGCG; it caused aggregated in Streptococcus mutans, while it caused grooves in Pseudomonas aeruginosa. AFM results suggest that the major morphological changes of Gram-negative bacterial cell walls induced by EGCG depend on H(2)O(2) release. This is not the case for Gram-positive bacteria. Oxidative stress in Gram-negative bacteria induced by EGCG was confirmed by flow cytometry. PMID:22029921

Cui, Y; Oh, Y J; Lim, J; Youn, M; Lee, I; Pak, H K; Park, W; Jo, W; Park, S

2012-02-01

247

Immediate and carryover effects of Gram-negative and Gram-positive toxin-induced mastitis on follicular function in dairy cows  

Microsoft Academic Search

This study compared immediate and carryover effects of mastitis induced by Gram-negative endotoxin (E. coli LPS) and Gram-positive exosecretions (Staph. aureus ex.) on preovulatory follicle function. Synchronized, uninfected cyclic lactating Holstein cows were treated with PGF2? on day 6 of the cycle and 36 h later, a dose of either E. coli LPS (n = 8), S. aureus ex. (n

Y. Lavon; G. Leitner; U. Moallem; E. Klipper; H. Voet; S. Jacoby; G. Glick; R. Meidan; D. Wolfenson

2011-01-01

248

Comparison of the Bruker MALDI-TOF Mass Spectrometry System and Conventional Phenotypic Methods for Identification of Gram-Positive Rods  

PubMed Central

In recent years, MALDI-TOF Mass Spectrometry (MS) method has emerged as a promising and a reliable tool for bacteria identification. In this study we compared Bruker MALDI-TOF MS and conventional phenotypic methods to identify a collection of 333 Gram-positive clinical isolates comprising 22 genera and 60 species. 16S rRNA sequencing was the reference molecular technique, and rpoB gene sequecing was used as a secondary gene target when 16Sr RNA did not allow species identification of Corynebacterium spp. We also investigate if score cut-offs values of ?1,5 and ?1,7 were accurate for genus and species-level identification using the Bruker system. Identification at species level was obtained for 92,49% of Gram-positive rods by MALDI-TOF MS compared to 85,89% by phenotypic method. Our data validates the score ?1,5 for genus level and ?1,7 for species-level identification in a large and diverse collection of Gram-positive rods. The present study has proved the accuracy of MALDI-TOF MS as an identification method in Gram-positive rods compared to currently used methods in routine laboratories. PMID:25184254

Barberis, Claudia; Almuzara, Marisa; Join-Lambert, Olivier; Ramírez, María Soledad; Famiglietti, Angela; Vay, Carlos

2014-01-01

249

Identification of a gene cluster encoding an arginine ATP-binding-cassette transporter in the genome of the thermophilic Gram-positive bacterium Geobacillus stearothermophilus strain DSMZ 13240  

Microsoft Academic Search

A single gene cluster encoding components of a putative ATP-binding cassette (ABC) transporter for basic amino acids was identified in the incomplete genome sequence of the thermophilic Gram-positive bacterium Geobacillus stearothermophilus by BLAST searches. The cluster comprises three genes, and these were amplified from chromosomal DNA of G. stearothermophilus, ligated into plasmid vectors and expressed in Escherichia coli. The purified

Rebecca Fleischer; Antje Wengner; Frank Scheffel; Heidi Landmesser; Erwin Schneider

2005-01-01

250

Prostaglandin H synthase isoenzyme distribution in the gingival tissue of patients with periodontitis: pronounced expression adjacent to gram-positive bacteria.  

PubMed

Prostaglandin (PGE(2)) is an inflammatory mediator that plays a critical role in the pathogenesis of periodontal disease. Prostaglandin H synthase (PGHS) a rate-limiting enzyme in PGE(2) biosynthesis exists as two separate isoforms (PGHS-1 and PGHS-2). We have previously demonstrated that both isoforms are generally present in the gingival tissue of periodontitis patients. This study explores in greater detail the variable distribution of each isoenzyme in both inflamed and non-inflamed gingival tissues of patients with periodontitis, and the relationship to adjacent bacteria. Although the positive staining for PGHS-1 was never as intense as for PGHS-2 in the same tissue specimen, either in inflamed or non-inflamed tissues, there was strong staining for both isoenzymes in the epithelium. The keratin layer did not stain. Non-keratinizing crevicular and junctional epithelium contained both isoenzymes through their full thickness in both inflamed and non-inflamed tissues. Pronounced staining of PGHS-2 was evident in the epithelia adjacent to Gram-positively stained organisms. In non-inflamed tissue, PGHS-1 and PGHS-2 were particularly evident in the spinous cell layer; however, fewer of the fibroblasts, endothelial cells, and resident mononuclear inflammatory cells stained positively for PGHS-1 as compared to PGHS-2, but this was less apparent in the inflamed tissues. The immunohistochemical staining patterns indicate that both crevicular and gingival epithelium are important sources of prostaglandin production in the gingival tissue of patients with periodontitis and that bacteria entrapped near to these sites may be important in promoting expression of inducible PGHS-2. PMID:17694359

McDonald, J S; Cavanaugh, P F; Pavelic, L J; Limardi, R J; Gluckman, J L; Pavelic, Z P

1997-01-01

251

Bacillus cereus infection outbreak in captive psittacines.  

PubMed

This study reports an uncommon epizootic outbreak of Bacillus cereus that caused the sudden death of 12 psittacines belonging to the species Anodorhynchus hyacinthinus (1 individual), Diopsittaca nobilis (1 individual), Ara severa (1 individual) and Ara ararauna (9 individuals) in a Brazilian zoo. Post-mortem examination of the animals reveled extensive areas of lung hemorrhage, hepatic congestion, hemorrhagic enteritis and cardiac congestion. Histopathological examination of the organs showed the presence of multiple foci of vegetative cells of Gram-positive bacilli associated with discrete and moderate mononuclear inflammatory cell infiltrate. Seventeen B. cereus strains isolated from blood and sterile organs of nine A. ararauna were analyzed in order to investigate the genetic diversity (assessed by Rep-PCR) and toxigenic profiles (presence of hblA, hblC and hblD; nheA, nheB and nheC as well as cytK, ces and entFM genes) of such strains. Amplification of genomic DNA by Rep-PCR of B. cereus strains generated two closely related profiles (Rep-PCR types A and B) with three bands of difference. All strains were classified as belonging to the toxigenic profile I which contained HBL and NHE gene complexes, entFM and cytK genes. Altogether, microbiological and histopathological findings and the evidence provided by the success of the antibiotic prophylaxis, corroborate that B. cereus was the causative agent of the infection that killed the birds. PMID:22902190

Godoy, S N; Matushima, E R; Chaves, J Q; Cavados, C F G; Rabinovitch, L; Teixeira, R H F; Nunes, A L V; Melville, P; Gattamorta, M A; Vivoni, A M

2012-12-28

252

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases.

Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

2014-07-01

253

Identification of a structural determinant for resistance to beta-lactam antibiotics in Gram-positive bacteria.  

PubMed

Streptococcus pneumoniae is the main causal agent of pathologies that are increasingly resistant to antibiotic treatment. Clinical resistance of S. pneumoniae to beta-lactam antibiotics is linked to multiple mutations of high molecular mass penicillin-binding proteins (H-PBPs), essential enzymes involved in the final steps of bacterial cell wall synthesis. H-PBPs from resistant bacteria have a reduced affinity for beta-lactam and a decreased hydrolytic activity on substrate analogues. In S. pneumoniae, the gene coding for one of these H-PBPs, PBP2x, is located in the cell division cluster (DCW). We present here structural evidence linking multiple beta-lactam resistance to amino acid substitutions in PBP2x within a buried cavity near the catalytic site that contains a structural water molecule. Site-directed mutation of amino acids in contact with this water molecule in the "sensitive" form of PBP2x produces mutants similar, in terms of beta-lactam affinity and substrate hydrolysis, to altered PBP2x produced in resistant clinical isolates. A reverse mutation in a PBP2x variant from a clinically important resistant clone increases the acylation efficiency for beta-lactams and substrate analogues. Furthermore, amino acid residues in contact with the structural water molecule are conserved in the equivalent H-PBPs of pathogenic Gram-positive cocci. We suggest that, probably via a local structural modification, the partial or complete loss of this water molecule reduces the acylation efficiency of PBP2x substrates to a point at which cell wall synthesis still occurs, but the sensitivity to therapeutic concentrations of beta-lactam antibiotics is lost. PMID:9811812

Mouz, N; Gordon, E; Di Guilmi, A M; Petit, I; Pétillot, Y; Dupont, Y; Hakenbeck, R; Vernet, T; Dideberg, O

1998-11-10

254

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria  

PubMed Central

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases. PMID:25136281

2014-01-01

255

Relative Roles of the Cellular and Humoral Responses in the Drosophila Host Defense against Three Gram-Positive Bacterial Infections  

PubMed Central

Background Two NF-kappaB signaling pathways, Toll and immune deficiency (imd), are required for survival to bacterial infections in Drosophila. In response to septic injury, these pathways mediate rapid transcriptional activation of distinct sets of effector molecules, including antimicrobial peptides, which are important components of a humoral defense response. However, it is less clear to what extent macrophage-like hemocytes contribute to host defense. Methodology/Principal Findings In order to dissect the relative importance of humoral and cellular defenses after septic injury with three different Gram-positive bacteria (Micrococcus luteus, Enterococcus faecalis, Staphylococcus aureus), we used latex bead pre-injection to ablate macrophage function in flies wildtype or mutant for various Toll and imd pathway components. We found that in all three infection models a compromised phagocytic system impaired fly survival – independently of concomitant Toll or imd pathway activation. Our data failed to confirm a role of the PGRP-SA and GNBP1 Pattern Recognition Receptors for phagocytosis of S. aureus. The Drosophila scavenger receptor Eater mediates the phagocytosis by hemocytes or S2 cells of E. faecalis and S. aureus, but not of M. luteus. In the case of M. luteus and E. faecalis, but not S. aureus, decreased survival due to defective phagocytosis could be compensated for by genetically enhancing the humoral immune response. Conclusions/Significance Our results underscore the fundamental importance of both cellular and humoral mechanisms in Drosophila immunity and shed light on the balance between these two arms of host defense depending on the invading pathogen. PMID:21390224

Cho, Ju Hyun; Lee, Janice; Lafarge, Marie-Céline; Kocks, Christine; Ferrandon, Dominique

2011-01-01

256

Comparison of antimicrobial pharmacokinetic/pharmacodynamic breakpoints with EUCAST and CLSI clinical breakpoints for Gram-positive bacteria.  

PubMed

This study compared the susceptibility breakpoints based on pharmacokinetic/pharmacodynamic (PK/PD) models and Monte Carlo simulation with those defined by the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for antibiotics used for the treatment of infections caused by Gram-positive bacteria. A secondary objective was to evaluate the probability of achieving the PK/PD target associated with the success of antimicrobial therapy. A 10,000-subject Monte Carlo simulation was executed to evaluate 13 antimicrobials (47 intravenous dosing regimens). Susceptibility data were extracted from the British Society for Antimicrobial Chemotherapy database for bacteraemia isolates. The probability of target attainment and the cumulative fraction of response (CFR) were calculated. No antibiotic was predicted to be effective (CFR?90%) against all microorganisms. The PK/PD susceptibility breakpoints were also estimated and were compared with CLSI and EUCAST breakpoints. The percentages of strains affected by breakpoint discrepancies were calculated. In the case of ?-lactams, breakpoint discrepancies affected <15% of strains. However, higher differences were detected for low doses of vancomycin, daptomycin and linezolid, with PK/PD breakpoints being lower than those defined by the CLSI and EUCAST. If this occurs, an isolate will be considered susceptible based on CLSI and EUCAST breakpoints although the PK/PD analysis predicts failure, which may explain treatment failures reported in the literature. This study reinforces the idea of considering not only the antimicrobial activity but also the dosing regimen to increase the probability of clinical success of an antimicrobial treatment. PMID:22921422

Asín, Eduardo; Isla, Arantxazu; Canut, Andrés; Rodríguez Gascón, Alicia

2012-10-01

257

Inhibition of biofilm formation in Bacillus subtilis by new halogenated furanones.  

PubMed

Gram-positive bacteria can cause various infections including hospital-acquired infections. While in the biofilm, the resistance of bacteria to both antibiotics and the human immune system is increased causing difficulties in the treatment. Bacillus subtilis, a non-pathogenic Gram-positive bacterium, is widely used as a model organism for studying biofilm formation. Here we investigated the effect of novel synthesized chloro- and bromo-containing 2(5H)-furanones on biofilm formation by B. subtilis. Mucobromic acid (3,4-dibromo-5-hydroxy-2(5H)-furanone) and the two derivatives of mucochloric acid (3,4-dichloro-5-hydroxy-2(5H)-furanone)-F8 and F12-were found to inhibit the growth and to efficiently prevent biofilm formation by B. subtilis. Along with the low production of polysaccharide matrix and repression of the eps operon, strong repression of biofilm-related yqxM also occurred in the presence of furanones. Therefore, our data confirm that furanones affect significantly the regulatory pathway(s) leading to biofilm formation. We propose that the global regulator, Spo0A, is one of the potential putative cellular targets for these compounds.The Journal of Antibiotics advance online publication, 22 October 2014; doi:10.1038/ja.2014.143. PMID:25335695

Kayumov, Airat R; Khakimullina, Elvina N; Sharafutdinov, Irshad S; Trizna, Elena Y; Latypova, Lilia Z; Thi Lien, Hoang; Margulis, Anna B; Bogachev, Mikhail I; Kurbangalieva, Almira R

2014-10-22

258

Identification, Evolution, and Essentiality of the Mevalonate Pathway for Isopentenyl Diphosphate Biosynthesis in Gram-Positive Cocci  

Microsoft Academic Search

The mevalonate pathway and the glyceraldehyde 3-phosphate (GAP)-pyruvate pathway are alternative routes for the biosynthesis of the central isoprenoid precursor, isopentenyl diphosphate. Genomic analysis revealed that the staphylococci, streptococci, and enterococci possess genes predicted to encode all of the enzymes of the mevalonate pathway and not the GAP-pyruvate pathway, unlike Bacillus subtilis and most gram-negative bacteria studied, which possess only

E. IMOGEN WILDING; JAMES R. BROWN; ALEXANDER P. BRYANT; ALISON F. CHALKER; DAVID J. HOLMES; KAREN A. INGRAHAM; SERBAN IORDANESCU; CHI Y. SO; MARTIN ROSENBERG; MICHAEL N. GWYNN

2000-01-01

259

Susceptibility of leafrollers (Lepidoptera: Tortricidae) from organic and conventional orchards to azinphosmethyl, spinosad, and Bacillus thuringiensis.  

PubMed

Populations of obliquebanded leafroller, Choristoneura rosaceana Harris, and three-lined leafroller, Pandemis limitata Robinson, were obtained from seven sites in the Okanagan and Similkameen Valleys of British Columbia and assayed for their responses to three insecticides using a leaf disk bioassay. Lethal concentration ratios (LCRs) were calculated for all populations compared with a susceptible laboratory colony of C. rosaceana; significant variation was detected in response to all three insecticides. LCRs were 0.86-15.52 for azinphosmethyl, 0.38-2.37 for spinosad (Success), and 0.58-4.89 for Bacillus thuringiensis (Foray). Correlation analysis indicated no cross-resistance among the three insecticides. Leafroller populations obtained from apple orchards managed with organic production practices were more susceptible to azinphosmethyl than leafrollers obtained from conventionally managed sites. Conversely, the highest levels of tolerance to B. thuringiensis were observed in the populations from organic sites, possibly reflecting usage patterns; B. thuringiensis is one of the few insecticides allowed under organic production guidelines. All populations were highly susceptible to spinosad, which may be a useful tool for resistance management programs if used judiciously. PMID:12852631

Smirle, Michael J; Lowery, D Thomas; Zurowski, Cheryl L

2003-06-01

260

Purification and characterization of organic solvent stable protease from Bacillus licheniformis RSP-09-37.  

PubMed

A protease was purified from the cell-free supernatant of Bacillus licheniformis RSP-09-37, a mutant from a thermophilic bacterial strain, B. licheniformis RSP-09, using affinity chromatography with alpha-casein agarose resin. The protease was purified 85-fold to electrophoretic homogeneity. The apparent molecular mass of purified protease was 55 kDa using gel filtration in high-performance liquid chromatography, which is in agreement with the results obtained from sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting a monomeric nature of the protein. The purified protease revealed temperature optima of 50 degrees C and pH optima of 10.0 and was classified as serine protease based on its complete inhibition with phenyl methyl sulfonyl fluoride. The purified protease exhibited tolerance to both detergents and organic solvent. The synthetic activity of the protease was tested using the transesterification reaction between N-acetyl-L-phenylalanine-ethyl ester and n-propanol in organic solvents varying in their log P values and the kinetic parameters of the enzyme in these organic solvents were studied. The enzyme has potential to be employed for synthetic reactions and in detergent formulations. PMID:18427806

Sareen, Ritu; Mishra, Prashant

2008-06-01

261

Prospective study using standardized methodology for antimicrobial susceptibility of gram-positive cocci isolated from the Puerto Rico Medical Center.  

PubMed

The Gram-positive cocci (GPC), Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis and Enterococcus faecium, have become important causes of community and nosocomial-acquired infections. The prevalence of multiple resistant isolates to standard antimicrobial drugs has significantly increased over the past decades. Few prospective studies have been performed in Puerto Rico (PR) concerning the GPC antimicrobial susceptibilities pattern. The purpose of this study was to evaluate the in vitro susceptibility of GPC clinical isolates from PR to selected standard antibiotics and to the new antimicrobial agents, linezolid (LZ), quinupristin/dalfopristin (Q/D) and gemifloxacin (GM). The in vitro susceptibility utilizing disk diffusion and Etest methods to selected antibiotics was determined for a total of 429 isolates obtained during a period of 5 months from the Puerto Rico Medical Center Bacteriology Laboratory. The distribution of GPC collected was as follows: 213 S. aureus isolates, 162 E. faecalis, 16 E. faecium and 38 S. pneumoniae. The results of the susceptibility test demonstrated: 1) that in S. aureus, 100% of the isolates were susceptible to vancomycin (VAN), LZ and Q/D; 93% to GM; and 61% to methicillin/oxacillin; 2) in S. pneumoniae, 100% were susceptible to LN and GM; 87% to Q/D; and 53% to penicillin; 3) in E. faecalis, 99% were susceptible to ampicillin; 93% to LZ; 79% to GM; 78.6% to VAN; and 0% to Q/D. Sixty eight and 66% of the E. faecalis isolates were susceptible to gentamicin and streptomycin respectively; and 4) in E. faecium, 100% were susceptible to LZ; 94% to Q/D; 69% to GM; 37.5% to VAN and 20% to ampicillin. In E. faecium isolates, 50% and 31% were susceptible to gentamicin and streptomycin, respectively. Of the vancomycin resistant enterococci, 88.9% and 21% of E. faecium and faecalis showed VanA phenotypic resistance, respectively. These results show that there is a significant degree of antimicrobial resistance in GPC, including 38% methicillin resistance in S. aureus, a near 50% penicillin resistant S. pneumoniae, and a significant resistance of enterococcal species to VAN. The new agents, LZ, Q/D and GM, proved to be effective against both, S. aureus and S. pneumoniae. For E. faecium, both, LZ and Q/D were active, while for E. faecalis, only LZ showed consistent activity. PMID:12572243

Rodríguez, Jorge L; Vázquez, Guillermo J; Bermúdez, Myriam; De Orbeta, Jessica; García, Yaira; Rivera, Yisel; Robledo, Iraida E

2002-12-01

262

Pharmacodynamics of TD-1792, a Novel Glycopeptide-Cephalosporin Heterodimer Antibiotic Used against Gram-Positive Bacteria, in a Neutropenic Murine Thigh Model  

PubMed Central

TD-1792 is a novel glycopeptide-cephalosporin heterodimer investigational antibiotic that displays potent bactericidal effects against clinically relevant Gram-positive organisms in vitro. The present studies evaluated the in vivo pharmacokinetics (PK) and pharmacodynamics (PD) of TD-1792 in the neutropenic murine thigh infection animal model. TD-1792, dosed subcutaneously (SC), produced dose-dependent reduction in the thigh bacterial burden of several organisms, including methicillin-susceptible and -resistant strains of Staphylococcus aureus and Staphylococcus epidermidis (MSSA, MRSA, MSSE, MRSE, respectively), penicillin-susceptible strains of Streptococcus pneumoniae (PSSP), Streptococcus pyogenes, and vancomycin-intermediate-susceptible Staphylococcus aureus (VISA). In single-dose efficacy studies, the 1-log10 CFU kill effective dose (ED1-log kill) estimates for TD-1792 ranged from 0.049 to 2.55 mg/kg of body weight administered SC, and the bacterial burden was reduced by up to 3 log10 CFU/g from pretreatment values. Against S. aureus ATCC 33591 (MRSA), the total 24-h log10 stasis dose (EDstasis) and ED1-logkill doses for TD-1792 were 0.53 and 1.11 mg/kg/24 h, respectively, compared to 23.4 and 54.6 mg/kg/24 h for vancomycin, indicating that TD-1762 is 44- to 49-fold more potent than vancomycin. PK-PD analysis of data from single-dose and dose-fractionation studies for MRSA (ATCC 33591) demonstrated that the total-drug 24-h area under the concentration-time curve-to-MIC ratio (AUC/MIC ratio) was the best predictor of efficacy (r2 = 0.826) compared to total-drug maximum plasma concentration of drug-to-MIC ratio (Cmax/MIC ratio; r2 = 0.715) and percent time that the total-drug plasma drug concentration remains above the MIC (%Time>MIC; r2 = 0.749). The magnitudes of the total-drug AUC/MIC ratios associated with net bacterial stasis, a 1-log10 CFU reduction from baseline and near maximal effect, were 21.1, 37.2, and 51.8, respectively. PK-PD targets based on such data represent useful inputs for analyses to support dose selection decisions for clinical studies of patients. PMID:22155835

Okusanya, Olanrewaju O.; Skinner, Robert; Shaw, Jeng-Pyng; Obedencio, Glenmar; Ambrose, Paul G.; Blais, Johanne; Bhavnani, Sujata M.

2012-01-01

263

Functional validation of putative toxin-antitoxin genes from the Gram-positive pathogen Streptococcus pneumoniae: phd-doc is the fourth bona-fide operon  

PubMed Central

Bacterial toxin-antitoxin (TAs) loci usually consist of two genes organized as an operon, where their products are bound together and inert under normal conditions. However, under stressful circumstances the antitoxin, which is more labile, will be degraded more rapidly, thereby unleashing its cognate toxin to act on the cell. This, in turn, causes cell stasis or cell death, depending on the type of TAs and/or time of toxin exposure. Previously based on in silico analyses, we proposed that Streptococcus pneumoniae, a pathogenic Gram-positive bacterium, may harbor between 4 and 10 putative TA loci depending on the strains. Here we have chosen the pneumococcal strain Hungary19A-6 which contains all possible 10 TA loci. In addition to the three well-characterized operons, namely relBE2, yefM-yoeB, and pezAT, we show here the functionality of a fourth operon that encodes the pneumococcal equivalent of the phd-doc TA. Transcriptional fusions with gene encoding Green Fluorescent Protein showed that the promoter was slightly repressed by the Phd antitoxin, and exhibited almost background values when both Phd-Doc were expressed together. These findings demonstrate that phd-doc shows the negative self-regulatory features typical for an authentic TA. Further, we also show that the previously proposed TAs XreA-Ant and Bro-XreB, although they exhibit a genetic organization resembling those of typical TAs, did not appear to confer a functional behavior corresponding to bona fide TAs. In addition, we have also discovered new interesting bioinformatics results for the known pneumococcal TAs RelBE2 and PezAT. A global analysis of the four identified toxins-antitoxins in the pneumococcal genomes (PezAT, RelBE2, YefM-YoeB, and Phd-Doc) showed that RelBE2 and Phd-Doc are the most conserved ones. Further, there was good correlation among TA types, clonal complexes and sequence types in the 48 pneumococcal strains analyzed. PMID:25538695

Chan, Wai Ting; Yeo, Chew Chieng; Sadowy, Ewa; Espinosa, Manuel

2014-01-01

264

The Arthromitus stage of Bacillus cereus: intestinal symbionts of animals  

NASA Technical Reports Server (NTRS)

In the guts of more than 25 species of arthropods we observed filaments containing refractile inclusions previously discovered and named "Arthromitus" in 1849 by Joseph Leidy [Leidy, J. (1849) Proc. Acad. Nat. Sci. Philadelphia 4, 225-233]. We cultivated these microbes from boiled intestines of 10 different species of surface-cleaned soil insects and isopod crustaceans. Literature review and these observations lead us to conclude that Arthromitus are spore-forming, variably motile, cultivable bacilli. As long rod-shaped bacteria, they lose their flagella, attach by fibers or fuzz to the intestinal epithelium, grow filamentously, and sporulate from their distal ends. When these organisms are incubated in culture, their life history stages are accelerated by light and inhibited by anoxia. Characterization of new Arthromitus isolates from digestive tracts of common sow bugs (Porcellio scaber), roaches (Gromphodorhina portentosa, Blaberus giganteus) and termites (Cryptotermes brevis, Kalotermes flavicollis) identifies these flagellated, spore-forming symbionts as a Bacillus sp. Complete sequencing of the 16S rRNA gene from four isolates (two sow bug, one hissing roach, one death's head roach) confirms these as the low-G+C Gram-positive eubacterium Bacillus cereus. We suggest that B. cereus and its close relatives, easily isolated from soil and grown on nutrient agar, enjoy filamentous growth in moist nutrient-rich intestines of healthy arthropods and similar habitats.

Margulis, L.; Jorgensen, J. Z.; Dolan, S.; Kolchinsky, R.; Rainey, F. A.; Lo, S. C.

1998-01-01

265

The Arthromitus stage of Bacillus cereus: intestinal symbionts of animals.  

PubMed

In the guts of more than 25 species of arthropods we observed filaments containing refractile inclusions previously discovered and named "Arthromitus" in 1849 by Joseph Leidy [Leidy, J. (1849) Proc. Acad. Nat. Sci. Philadelphia 4, 225-233]. We cultivated these microbes from boiled intestines of 10 different species of surface-cleaned soil insects and isopod crustaceans. Literature review and these observations lead us to conclude that Arthromitus are spore-forming, variably motile, cultivable bacilli. As long rod-shaped bacteria, they lose their flagella, attach by fibers or fuzz to the intestinal epithelium, grow filamentously, and sporulate from their distal ends. When these organisms are incubated in culture, their life history stages are accelerated by light and inhibited by anoxia. Characterization of new Arthromitus isolates from digestive tracts of common sow bugs (Porcellio scaber), roaches (Gromphodorhina portentosa, Blaberus giganteus) and termites (Cryptotermes brevis, Kalotermes flavicollis) identifies these flagellated, spore-forming symbionts as a Bacillus sp. Complete sequencing of the 16S rRNA gene from four isolates (two sow bug, one hissing roach, one death's head roach) confirms these as the low-G+C Gram-positive eubacterium Bacillus cereus. We suggest that B. cereus and its close relatives, easily isolated from soil and grown on nutrient agar, enjoy filamentous growth in moist nutrient-rich intestines of healthy arthropods and similar habitats. PMID:9448315

Margulis, L; Jorgensen, J Z; Dolan, S; Kolchinsky, R; Rainey, F A; Lo, S C

1998-02-01

266

[Consensus on antimicrobial sensitivity tests in gram-positive cocci. Subcommittee on Antimicrobials, SADEBAC (Argentinian Society of Clinical Bacteriology), Argentinian Association of Microbiology].  

PubMed

Antimicrobial susceptibility testing is mainly performed in Argentina by disk diffusion method, following National Committee for Clinical Laboratory Standards (NCCLS) recommendations. We worked out new recommendations for the reporting and interpretation of this test when dealing with gram-positive cocci, in accordance to local trends and epidemiology. General considerations for performing the diffusion assay, quality control, and an update on susceptibility testing for gram-positive cocci are reported in this first document. The present update should be considered as a group of recommendations summarized by Argentinean experts and as the result of a consensus meeting coordinated by the Subcomisión de Antimicrobianos of the Sociedad Argentina de Bacteriología Clínica (Asociación Argentina de Microbiología). Experts in antimicrobial agents were convened in order to prepare this final document. These recommendations take into account local needs, affordability and availability to be used in current practice, tending to contribute to the correct antimicrobial treatment election, according to the particular microorganism and the infection sites. PMID:12833678

Famiglietti, A; Quinteros, M; Predari, S C; Corso, A; Lopardo, H; Casellas, J M; Bantar, C; Couto, E; Galas, M; Goldberg, M; Gutkind, G; Kovensky Pupko, J; Marín, M; Nicola, F; Pasterán, F; Radice, M; Soloaga, R

2003-01-01

267

Adsorption on stainless steel surfaces of biosurfactants produced by gram-negative and gram-positive bacteria: Consequence on the bioadhesive behavior of Listeria monocytogenes  

Microsoft Academic Search

The ability of adsorbed biosurfactants (Pf and Lb) obtained from gram-negative bacterium (Pseudomonas fluorescens) or gram-positive bacterium (Lactobacillus helveticus) to inhibit adhesion of four listerial strains to stainless steel was investigated. These metallic surfaces were characterized using the following complementary analytical techniques: contact-angle measurements (CAM), atomic force microscopy (AFM), polarization modulation-infrared reflection-adsorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Contact-angles

Thierry Meylheuc; Christophe Methivier; Margareth Renault; Jean-Marie Herry; Claire-Marie Pradier; Marie Noëlle Bellon-Fontaine

2006-01-01

268

In situ probing of Gram-positive bacteria with high DNA G + C content using 23S rRNA-targeted oligonucleotides  

Microsoft Academic Search

235-rRNA-targeted oligonucleotide probes were designed for the phylogenetic group Gram-positive bacteria with high G + C content of DNA ' (GPBHGC). A sequence idiosyncrasy in two adjacent base pairs in the stem of helix 69 in domain IV of the 235 rRNA is present in all hitherto analysed strains of GPBHGC. An oligonucleotide probe targeted to this region hybridized only

Carsten Roller; Michael Wagner; Rudolf Amann; Wolfgang Ludwig; K.-H. Schleifer

1994-01-01

269

In Vitro Susceptibilities of Aerobic and Facultative Non-Spore- Forming Gram-Positive Bacilli to HMR 3647 (RU 66647) and 14 Other Antimicrobials  

Microsoft Academic Search

The comparative in vitro activity of the ketolide HMR 3647 (RU 66647) and those of structurally related macrolide-lincosamide-streptogramin compounds (erythromycin, roxithromycin, azithromycin, clarithromy- cin, josamycin, lincomycin, pristinamycin, and quinupristin-dalfopristin) as well as those of benzylpenicillin, doxycycline, vancomycin, teicoplanin, levofloxacin, and rifapentine against 247 aerobic and facultative non- spore-forming gram-positive bacilli were determined by an agar dilution method. The ketolide was

FRANCISCO SORIANO; RICARDO FERNANDEZ-ROBLAS; RAQUEL CALVO; GLORIA GARCIA-CALVO

1998-01-01

270

A Nonsynonymous Polymorphism of IRAK4 Associated with Increased Prevalence of Gram-Positive Infection and Decreased Response to Toll-Like Receptor Ligands  

PubMed Central

Mutations in IRAK4 have been associated with recurrent Gram-positive infections in children. Given the central role of IRAK4 in innate immunity signaling, we hypothesized that common genetic variants of IRAK4 may be associated with prevalence of Gram-positive infection in critically ill adults. Haplotype clade tag single nucleotide polymorphisms (SNPs) of the IRAK4 gene were selected and genotyped in a cohort of 1,029 critically ill patients with systemic inflammatory response syndrome (SIRS). We found that a haplotype clade tagged by the A allele of the htSNP G29429A (Ala428Thr) was associated with increased relative risk of Gram-positive infection at admission to ICU (RR = 1.2, p < 0.05). Furthermore, the 29429A allele was associated with decreased lymphoblastoid cell response to CpG (as measured by IL-6 production) (raw values ± 95% CI 40.3 ± 32.3 vs. 85.8 ± 29.4 pg/ml; log-transformed values ± 95% CI 1.13 ± 0.37 vs. 1.55 ± 0.18, p < 0.04). We also found that IRAK4-deficient fibroblasts transfected with an IRAK4 expression plasmid containing the 29429A allele produced less IL-6 in response to lipopolysaccharide (p = 0.07). Our data suggest that the IRAK4 haplotype clade marked by 29429A (428Thr) alters susceptibility to Gram-positive bacteria, by decreasing cellular response to TLR ligands. Copyright © 2011 S. Karger AG, Basel PMID:21576904

Sutherland, Ainsley M.; Walley, Keith R.; Nakada, Taka-aki; Sham, Andy H.P.; Wurfel, Mark M.; Russell, James A.

2011-01-01

271

Differential Roles of TLR2 and TLR4 in Recognition of Gram-Negative and Gram-Positive Bacterial Cell Wall Components  

Microsoft Academic Search

Toll-like receptor (TLR) 2 and TLR4 are implicated in the recognition of various bacterial cell wall components, such as lipopolysaccharide (LPS). To investigate in vivo roles of TLR2, we generated TLR2-deficient mice. In contrast to LPS unresponsiveness in TLR4-deficient mice, TLR2-deficient mice responded to LPS to the same extent as wild-type mice. TLR2-deficient macrophages were hyporesponsive to several Gram-positive bacterial

Osamu Takeuchi; Katsuaki Hoshino; Taro Kawai; Hideki Sanjo; Haruhiko Takada; Tomohiko Ogawa; Kiyoshi Takeda; Shizuo Akira

1999-01-01

272

In Vitro Activities of Daptomycin, Vancomycin, Quinupristin- Dalfopristin, Linezolid, and Five Other Antimicrobials against 307 Gram-Positive Anaerobic and 31 Corynebacterium Clinical Isolates  

Microsoft Academic Search

The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The dapto- mycin MICs determined on Ca2-supplemented (50 mg\\/liter) brucella agar plates were one- to fourfold lower than

Ellie J. C. Goldstein; Diane M. Citron; C. Vreni Merriam; Yumi A. Warren; Kerrin L. Tyrrell; Helen T. Fernandez

2003-01-01

273

Solvent tolerant marine bacterium Bacillus aquimaris secreting organic solvent stable alkaline cellulase.  

PubMed

The organic solvent tolerant bacteria with their physiological abilities to decontaminate the organic pollutants have potentials to secrete extracellular enzymes of commercial importance. Of the 19 marine bacterial isolates examined for their solvent tolerance at 10vol.% concentration, one had the significant tolerance and showed a relative growth yield of 86% for acetone, 71% for methanol, 52% for benzene, 35% for heptane, 24% for toluene and 19% for ethylacetate. The phylogenetic analysis of this strain using 16S rDNA sequence revealed 99% homology with Bacillus aquimaris. The cellulase enzyme secreted by this strain under normal conditions showed an optimum activity at pH 11 and 45°C. The enzyme did show functional stability even at higher pH (12) and temperature (75°C) with residual activity of 85% and 95% respectively. The enzyme activity in the presence of different additives were in the following order: Co(+2)>Fe(+2)>NaOCl(2)>CuSO(4)>KCl>NaCl. The enzyme stability in the presence of solvents at 20vol.% concentration was highest in benzene with 122% followed by methanol (85%), acetone (75%), toluene (73%) and heptane (42%). The pre-incubation of enzyme in ionic liquids such as 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium bromide increased its activity to 150% and 155% respectively. The change in fatty acid profile with different solvents further elucidated the physiological adaptations of the strain to tolerate such extreme conditions. PMID:21388656

Trivedi, Nitin; Gupta, Vishal; Kumar, Manoj; Kumari, Puja; Reddy, C R K; Jha, Bhavanath

2011-04-01

274

Organization and Evolution of the cotG and cotH Genes of Bacillus subtilis?†  

PubMed Central

The cotG and cotH genes of Bacillus subtilis encode two previously characterized spore coat proteins. The two genes are adjacent on the chromosome and divergently transcribed by ?K, a sporulation-specific ? factor of the RNA polymerase. We report evidence that the cotH promoter maps 812 bp upstream of the beginning of its coding region and that the divergent cotG gene is entirely contained between the promoter and the coding part of cotH. A bioinformatic analysis of all entirely sequenced prokaryotic genomes showed that such chromosomal organization is not common in spore-forming bacilli. Indeed, CotG is present only in B. subtilis, B. amyloliquefaciens, and B. atrophaeus and in two Geobacillus strains. When present, cotG always encodes a modular protein composed of tandem repeats and is always close to but divergently transcribed with respect to cotH. Bioinformatic and phylogenic data suggest that such genomic organizations have a common evolutionary origin and that the modular structure of the extant cotG genes is the outcome of multiple rounds of gene elongation events of an ancestral minigene. PMID:21984783

Giglio, Rosa; Fani, Renato; Isticato, Rachele; De Felice, Maurilio; Ricca, Ezio; Baccigalupi, Loredana

2011-01-01

275

Synthesis of well-dispersed silver nanorods of different aspect ratios and their antimicrobial properties against Gram positive and negative bacterial strains.  

PubMed

In the present contribution, we describe the synthesis of highly dispersed silver nanorods (NRs) of different aspect ratios using a chemical route. The shape and size of the synthesized NRs were characterized by Transmission Electron Microscopy (TEM) and UV-visible spectroscopy. Longitudinal and transverse absorptions bands confirm the rod type structure. The experimentally recorded UV-visible spectra of NRs solutions were fitted by using an expression of the extinction coefficient for rod like nano structures under the dipole approximation. Simulated and experimentally observed UV-visible spectra were compared to determine the aspect ratios (R) of NRs. The average values of R for NR1, NR2 and NR3 solutions are estimated to be 3.0 ± 0.1, 1.8 ± 0.1 and 1.2 ± 0.1, respectively. These values are in good agreement with those obtained by TEM micrographs. The silver NRs of known aspect ratios are used to study antimicrobial activities against B. subtilis (gram positive) and E. coli (gram negative) microbes. We observed that the NRs of intermediate aspect ratio (R = 1.8) have greater antimicrobial effect against both, B. subtilis (gram positive) and E. coli (gram negative). The NRs of aspect ratio, R = 3.0 has better antimicrobial activities against gram positive than on the gram negative. PMID:24358993

Ojha, Animesh K; Forster, Stefan; Kumar, Sumeet; Vats, Siddharth; Negi, Sangeeta; Fischer, Ingo

2013-01-01

276

Synthesis of well–dispersed silver nanorods of different aspect ratios and their antimicrobial properties against gram positive and negative bacterial strains  

PubMed Central

In the present contribution, we describe the synthesis of highly dispersed silver nanorods (NRs) of different aspect ratios using a chemical route. The shape and size of the synthesized NRs were characterized by Transmission Electron Microscopy (TEM) and UV-visible spectroscopy. Longitudinal and transverse absorptions bands confirm the rod type structure. The experimentally recorded UV-visible spectra of NRs solutions were fitted by using an expression of the extinction coefficient for rod like nano structures under the dipole approximation. Simulated and experimentally observed UV-visible spectra were compared to determine the aspect ratios (R) of NRs. The average values of R for NR1, NR2 and NR3 solutions are estimated to be 3.0?±?0.1, 1.8?±?0.1 and 1.2?±?0.1, respectively. These values are in good agreement with those obtained by TEM micrographs. The silver NRs of known aspect ratios are used to study antimicrobial activities against B. subtilis (gram positive) and E. coli (gram negative) microbes. We observed that the NRs of intermediate aspect ratio (R?=?1.8) have greater antimicrobial effect against both, B. subtilis (gram positive) and E. coli (gram negative). The NRs of aspect ratio, R?=?3.0 has better antimicrobial activities against gram positive than on the gram negative. PMID:24358993

2013-01-01

277

Organized cell swimming motions in Bacillus subtilis colonies: patterns of short-lived whirls and jets.  

PubMed

The swimming motions of cells within Bacillus subtilis colonies, as well as the associated fluid flows, were analyzed from video films produced during colony growth and expansion on wet agar surfaces. Individual cells in very wet dense populations moved at rates between 76 and 116 microm/s. Swimming cells were organized into patterns of whirls, each approximately 1,000 microm2, and jets of about 95 by 12 microm. Whirls and jets were short-lived, lasting only about 0.25 s. Patterns within given areas constantly repeated with a periodicity of approximately 1 s. Whirls of a given direction became disorganized and then re-formed, usually into whirls moving in the opposite direction. Pattern elements were also organized with respect to one another in the colony. Neighboring whirls usually turned in opposite directions. This correlation decreased as a function of distance between whirls. Fluid flows associated with whirls and jets were measured by observing the movement of marker latex spheres added to colonies. The average velocity of markers traveling in whirls was 19 microm/s, whereas those traveling in jets moved at 27 microm/s. The paths followed by markers were aligned with the direction of cell motion, suggesting that cells create flows moving with them into whirls and along jets. When colonies became dry, swimming motions ceased except in regions close to the periphery and in isolated islands where cells traveled in slow whirls at about 4 microm/s. The addition of water resulted in immediate though transient rapid swimming (> 80 microm/s) in characteristic whirl and jet patterns. The rate of swimming decreased to 13 microm/s within 2 min, however, as the water diffused into the agar. Organized swimming patterns were nevertheless preserved throughout this period. These findings show that cell swimming in colonies is highly organized. PMID:9882676

Mendelson, N H; Bourque, A; Wilkening, K; Anderson, K R; Watkins, J C

1999-01-01

278

Detergent Compatible, Organic Solvent Tolerant Alkaline Protease from Bacillus circulans MTCC 7942: Purification and Characterization.  

PubMed

Proteases are now recognised as most indispensable industrial biocatalyst owing to their diverse microbial sources and innovative applications. In the present investigation, a thermostable, organic solvent tolerant, alkaline serine protease from Bacillus circulans MTCC 7942 was purified and characterized. The protease was purified to 37-fold by three step purification scheme with 39% recovery. The optimum pH and temperature for protease was 10 and 60°C, respectively. The apparent molecular mass of purified enzyme was 43 kDa as revealed by SDS-PAGE. The Km and Vmax values using casein-substrate were 3.1 mg/mL and 1.8 µmol/min, respectively. The protease remained stable in the presence of organic solvents with higher (>3.2) log P value (cyclohexane, n-octane, n-hexadecane, n-decane and n-dodecane), as compared to organic solvents with lower (<3.2) log P value (acetone, butanol, benzene, chloroform, toluene). Remarkably, the protease showed profound stability even in the presence of organic solvents with less log P values (glycerol, DMSO, p-xylene), indicating the possibility for non-aqueous enzymatic applications. Besides, protease activity was improved in the presence of metal ions (Ca(2+), Mg(2+), Mn(2+)); enhanced by biosurfactants; hardly affected by bleaching-, oxidizing agents, chemical surfactants and stable in commercial detergents. In addition, protease-detergent formulation effectively washed the egg and blood stains as compared to detergent alone. The protease was suitable for various commercial applications like processing of gelatinous film and compatible additive of detergent formulation with its operative utility in hard water. PMID:25356983

Patil, Ulhas; Mokashe, Narendra; Chaudhari, Ambalal

2014-10-30

279

Draft Genome Sequence of Bacillus thuringiensis NBIN-866 with High Nematocidal Activity  

PubMed Central

Bacillus thuringiensis NBIN-866, a Gram-positive bacterium, was isolated from soil in China. We announce here the draft genome sequence of strain B. thuringiensis NBIN-866, which possesses highly nematocidal factors, such as proteins and small molecular peptides. PMID:24855295

Zhou, Ronghua; Fu, Guiping; Zhang, Wei; Min, Yong; Tian, Yuxi; Huang, Daye; Wang, Kaimei; Wan, Zhongyi; Yao, Jingwu; Yang, Ziwen

2014-01-01

280

Complete Genome Sequence of Bacillus anthracis HYU01, Isolated from Soil Samples in the Korean Peninsula.  

PubMed

Bacillus anthracis is a Gram-positive endospore-forming bacterium that causes the zoonotic disease anthrax. We report a complete genome sequence of B. anthracis strain HYU01, isolated from Changnyung, which belongs to the B branch (B.Br.) 001/002 canonical single nucleotide polymorphism (canSNP) group. PMID:25103761

Kim, Se Kye; Chung, Won-Hyong; Kim, Sang Hoon; Jung, Kyoung Hwa; Kim, Namshin; Chai, Young Gyu

2014-01-01

281

Draft Genome Sequence of Bacillus thuringiensis NBIN-866 with High Nematocidal Activity.  

PubMed

Bacillus thuringiensis NBIN-866, a Gram-positive bacterium, was isolated from soil in China. We announce here the draft genome sequence of strain B. thuringiensis NBIN-866, which possesses highly nematocidal factors, such as proteins and small molecular peptides. PMID:24855295

Liu, Xiaoyan; Zhou, Ronghua; Fu, Guiping; Zhang, Wei; Min, Yong; Tian, Yuxi; Huang, Daye; Wang, Kaimei; Wan, Zhongyi; Yao, Jingwu; Yang, Ziwen

2014-01-01

282

Crystal structure of 3-chlorocatechol 1,2-dioxygenase key enzyme of a new modified ortho-pathway from the Gram-positive Rhodococcus opacus 1CP grown on 2-chlorophenol.  

PubMed

The crystal structure of the 3-chlorocatechol 1,2-dioxygenase from the Gram-positive bacterium Rhodococcus opacus (erythropolis) 1CP, a Fe(III) ion-containing enzyme specialized in the aerobic biodegradation of 3-chloro- and methyl-substituted catechols, has been solved by molecular replacement techniques using the coordinates of 4-chlorocatechol 1,2-dioxygenase from the same organism (PDB code 1S9A) as a starting model and refined at 1.9 A resolution (R(free) 21.9%; R-factor 17.4%). The analysis of the structure and of the kinetic parameters for a series of different substrates, and the comparison with the corresponding data for the 4-chlorocatechol 1,2-dioxygenase isolated from the same bacterial strain, provides evidence of which active site residues are responsible for the observed differences in substrate specificity. Among the amino acid residues expected to interact with substrates, only three are altered Val53(Ala53), Tyr78(Phe78) and Ala221(Cys224) (3-chlorocatechol 1,2-dioxygenase(4-chlorocatechol 1,2-dioxygenase)), clearly identifying the substitutions influencing substrate selectivity in these enzymes. The crystallographic asymmetric unit contains eight subunits (corresponding to four dimers) that show heterogeneity in the conformation of a co-crystallized molecule bound to the catalytic non-heme iron(III) ion resembling a benzohydroxamate moiety, probably a result of the breakdown of recently discovered siderophores synthesized by Gram-positive bacteria. Several different modes of binding benzohydroxamate into the active site induce distinct conformations of the interacting protein ligands Tyr167 and Arg188, illustrating the plasticity of the active site origin of the more promiscuous substrate preferences of the present enzyme. PMID:16793061

Ferraroni, Marta; Kolomytseva, Marina P; Solyanikova, Inna P; Scozzafava, Andrea; Golovleva, Ludmila A; Briganti, Fabrizio

2006-07-21

283

Co-production of surfactin and a novel bacteriocin by Bacillus subtilis subsp. subtilis H4 isolated from Bikalga, an African alkaline Hibiscus sabdariffa seed fermented condiment.  

PubMed

Bikalga is a Hibiscus sabdariffa seed fermented condiment widely consumed in Burkina Faso and neighboring countries. The fermentation is dominated by Bacillus subtilis group species. Ten B. subtilis subsp. subtilis (six isolates) and Bacillus licheniformis (four isolates) isolated from traditional Bikalga were examined for their antimicrobial activity against a panel of 36 indicator organisms including Gram-positive and Gram-negative bacteria and yeasts. The Bacillus spp. isolates showed variable inhibitory abilities depending on the method used. Both Gram-positive and Gram-negative bacteria were inhibited in the agar spot assay while only Gram-positive pathogens were inhibited in the agar well diffusion assay. Cell free supernatants (CFS) of pure cultures of 3 B. subtilis subsp. subtilis (G2, H4 and F1) strains inhibited growth of Listeria monocytogenes, Micrococcus luteus, Staphylococcus aureus and Bacillus cereus, while CFS of 2 B. licheniformis (E3 and F9) strains only inhibited M. luteus. The antimicrobial substance(s) produced by B. subtilis subsp. subtilis H4 was further characterized. The antimicrobial substance(s) produced by H4 was detected from mid-exponential growth phase. The activity was sensitive to protease and trypsin, but resistant to the proteolytic action of proteinase K and papain. Treatment with ?-amylase and lipase II resulted in a complete loss of antimicrobial effect, indicating that a sugar moiety and lipid moiety are necessary for the activity. Treatment with mercapto-ethanol resulted in a significant loss, indicative of the presence of disulfide bridges. The antimicrobial activity of H4 was heat resistant and active at pH3-10. PCR detection of yiwB, sboA, spoX, albA and spaS, etnS genes and genes coding for surfactins and plipastatins (fengycins) indicated a potential for subtilosin, subtilin and lipopeptide production, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was carried out and a single band of approximately 4kDa had antimicrobial activity. Ultra high performance liquid chromatography-time of flight mass spectrometry (UHPLC-TOFMS) analysis of the 4kDa band allowed identification of surfactin and a protein with a monoisotopic mass of 3346.59Da, which is dissimilar in size to subtilosin and subtilin. Surfactin is a cyclic lipoheptapeptide, which contains a ?-hydroxy fatty acid, but no di-sulfide bridges or sugar residues. The complete loss of activity upon amylase treatment indicates that surfactin was not responsible for the observed antimicrobial effect. However, it cannot completely be ruled out that surfactin acts synergistically with the detected protein, though further investigations are needed to confirm this. PMID:23466466

Compaoré, Clarisse S; Nielsen, Dennis S; Ouoba, Labia I I; Berner, Torben S; Nielsen, Kristian F; Sawadogo-Lingani, Hagrétou; Diawara, Bréhima; Ouédraogo, Georges A; Jakobsen, Mogens; Thorsen, Line

2013-04-01

284

Systematic Review of Membrane Components of Gram-Positive Bacteria Responsible as Pyrogens for Inducing Human Monocyte/Macrophage Cytokine Release  

PubMed Central

Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its Gram-positive counterpart is still under debate. Pyrogen tests based on the human monocyte activation have been validated for LPS detection as an alternative to the rabbit test and, increasingly, the limulus amebocyte lysate test. For full replacement, international validations with non-endotoxin pyrogens are in preparation. Following evidence-based medicine approaches, a systematic review of existing evidence as to the structural nature of the Gram-positive pyrogen was undertaken. For the three major constituents suggested, i.e., peptidoglycan, lipoteichoic acids (LTA), and bacterial lipoproteins (LP), the questions to be answered and a search strategy for relevant literature was developed, starting in MedLine. The evaluation was based on the Koch–Dale criteria for a mediator of an effect. A total of 380 articles for peptidoglycan, 391 for LP, and 285 for LTA were retrieved of which 12, 8, and 24, respectively, fulfilled inclusion criteria. The compiled data suggest that for peptidoglycan two Koch–Dale criteria are fulfilled, four for LTA, and two for bacterial LP. In conclusion, based on the best currently available evidence, LTA is the only substance that fulfills all criteria. LTA has been isolated from a large number of bacteria, results in cytokine release patterns inducible also with synthetic LTA. Reduction in bacterial cytokine induction with an inhibitor for LTA was shown. However, this systematic review cannot exclude the possibility that other stimulatory compounds complement or substitute for LTA in being the counterpart to LPS in some Gram-positive bacteria. PMID:22529809

Rockel, Christoph; Hartung, Thomas

2012-01-01

285

Comparison of Three Commercial Rapid Identification Systems for the Unusual Gram-Positive Cocci Dolosigranulum pigrum, Ignavigranum ruoffiae, and Facklamia Species  

PubMed Central

We evaluated three rapid identification systems—The Biomerieux rapid ID 32 STREP (ID32), the BBL Crystal rapid gram-positive identification (Crystal), and the Remel IDS RapID STR (IDS) systems—for their ability to identify 7 strains of Alloiococcus otitidis, 27 strains of Dolosigranulum pigrum, 3 strains of Ignavigranum ruoffiae, and 18 strains of 4 different Facklamia species. Since none of these six species of gram-positive cocci are included in the identification databases for these systems, the correct identification for the strains tested should be “unacceptable ID” for the ID32 and Crystal systems or “no choice” for the IDS system. The ID32 system identified all 27 strains of D. pigrum, 6 of 18 Facklamia species, and 2 of 3 cultures of I. ruoffiae as “unacceptable ID.” The Crystal system identified 10 of 27 D. pigrum, 2 of 18 Facklamia species, and 2 of 3 I. ruoffiae strains as “unacceptable ID.” The IDS system identified only 1 culture of D. pigrum as “no choice,” but it also identified 2 cultures of D. pigrum as a “questionable microcode” and 19 cultures of D. pigrum as an “inadequate ID, E. faecalis 90%, S. intermedius 9%.” A total of 2 of the 18 cultures of Facklamia and all 3 of the I. ruoffiae cultures were correctly identified as “no choice.” The most common misidentifications of Facklamia species by the ID32 and IDS systems were as various Streptococcus species and as Gemella species. In the Crystal system, the most common erroneous identification was Micrococcus luteus. These data indicate the need for the commercial manufacturers of these products to update their databases to include newly described species of gram-positive cocci. PMID:10834950

LaClaire, Leslye L.; Facklam, Richard R.

2000-01-01

286

Comparison of three commercial rapid identification systems for the unusual gram-positive cocci Dolosigranulum pigrum, Ignavigranum ruoffiae, and Facklamia species.  

PubMed

We evaluated three rapid identification systems-The Biomerieux rapid ID 32 STREP (ID32), the BBL Crystal rapid gram-positive identification (Crystal), and the Remel IDS RapID STR (IDS) systems-for their ability to identify 7 strains of Alloiococcus otitidis, 27 strains of Dolosigranulum pigrum, 3 strains of Ignavigranum ruoffiae, and 18 strains of 4 different Facklamia species. Since none of these six species of gram-positive cocci are included in the identification databases for these systems, the correct identification for the strains tested should be "unacceptable ID" for the ID32 and Crystal systems or "no choice" for the IDS system. The ID32 system identified all 27 strains of D. pigrum, 6 of 18 Facklamia species, and 2 of 3 cultures of I. ruoffiae as "unacceptable ID." The Crystal system identified 10 of 27 D. pigrum, 2 of 18 Facklamia species, and 2 of 3 I. ruoffiae strains as "unacceptable ID." The IDS system identified only 1 culture of D. pigrum as "no choice," but it also identified 2 cultures of D. pigrum as a "questionable microcode" and 19 cultures of D. pigrum as an "inadequate ID, E. faecalis 90%, S. intermedius 9%." A total of 2 of the 18 cultures of Facklamia and all 3 of the I. ruoffiae cultures were correctly identified as "no choice." The most common misidentifications of Facklamia species by the ID32 and IDS systems were as various Streptococcus species and as Gemella species. In the Crystal system, the most common erroneous identification was Micrococcus luteus. These data indicate the need for the commercial manufacturers of these products to update their databases to include newly described species of gram-positive cocci. PMID:10834950

LaClaire, L L; Facklam, R R

2000-06-01

287

Physico-Chemical-Managed Killing of Penicillin-Resistant Static and Growing Gram-Positive and Gram-Negative Vegetative Bacteria  

NASA Technical Reports Server (NTRS)

Systems and methods for the use of compounds from the Hofmeister series coupled with specific pH and temperature to provide rapid physico-chemical-managed killing of penicillin-resistant static and growing Gram-positive and Gram-negative vegetative bacteria. The systems and methods represent the more general physico-chemical enhancement of susceptibility for a wide range of pathological macromolecular targets to clinical management by establishing the reactivity of those targets to topically applied drugs or anti-toxins.

Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor); Farris, III, Alex F. (Inventor)

2012-01-01

288

Silver nanoparticles synthesized by pulsed laser ablation: as a potent antibacterial agent for human enteropathogenic gram-positive and gram-negative bacterial strains.  

PubMed

Present investigation deals with the study, to quantify the antibacterial property of silver nanoparticles (SNPs), synthesized by pulsed laser ablation (PLA) in aqueous media, on some human enteropathogenic gram-positive and gram-negative bacterial strains. Antibacterial property was studied by measuring the zone of inhibition using agar cup double-diffusion method, minimum inhibitory concentration by serial dilution method, and growth curve for 24 h. The results clearly show the potency of antibacterial property of PLA-synthesized SNPs and suggest that it can be used as an effective growth inhibitor against various pathogenic bacterial strains in various medical devices and antibacterial control systems. PMID:24801405

Pandey, Jitendra Kumar; Swarnkar, R K; Soumya, K K; Dwivedi, Priyanka; Singh, Manish Kumar; Sundaram, Shanthy; Gopal, R

2014-10-01

289

Discovery of a New Class of Non-?-lactam Inhibitors of Penicillin-Binding Proteins with Gram-Positive Antibacterial Activity  

PubMed Central

Infections caused by hard-to-treat methicillin-resistant Staphylococcus aureus (MRSA) are a serious global public-health concern, as MRSA has become broadly resistant to many classes of antibiotics. We disclose herein the discovery of a new class of non-?-lactam antibiotics, the oxadiazoles, which inhibit penicillin-binding protein 2a (PBP2a) of MRSA. The oxadiazoles show bactericidal activity against vancomycin- and linezolid-resistant MRSA and other Gram-positive bacterial strains, in vivo efficacy in a mouse model of infection, and have 100% oral bioavailability. PMID:24517363

2015-01-01

290

Comparison of killing of gram-negative and gram-positive bacteria by pure singlet oxygen. [Salmonella typhimurium; Escherichia coli; Sarcina lutea; Staphylococcus aureus; Streptococcus lactis; Streptococcus faecalis  

SciTech Connect

Gram-negative and gram-positive bacteria were found to display different sensitivities to pure singlet oxygen generated outside of cells. Killing curves for Salmonella typhimurium and Escherichia coli strains were indicative of multihit killing, whereas curves for Sarcina lutea, Staphylococcus aureus, Streptococcus lactis, and Streptococcus faecalis exhibited single-hit kinetics. The S. typhimurium deep rough strain TA1975, which lacks nearly all of the cell wall lipopolysaccharide coat and manifests concomitant enhancement of penetration by some exogenous substances, responded to singlet oxygen with initially faster inactivation than did the S. typhimurium wild-type strain, although the maximum rates of killing appeared to be quite similar. The structure of the cell wall thus plays an important role in susceptibility to singlet oxygen. The outer membrane-lipopolysaccharide portion of the gram-negative cell wall initially protects the bacteria from extracellular singlet oxygen, although it may also serve as a source for secondary reaction products which accentuate the rates of cell killing. S. typhimurium and E. coli strains lacking the cellular antioxidant, glutathione, showed no difference from strains containing glutathione in response to the toxic effects of singlet oxygen. Strains of Sarcina lutea and Staphylococcus aureus that contained carotenoids, however, were far more resistant to singlet oxygen lethality than were both carotenoidless mutants of the same species and other gram-positive species lacking high levels of protective carotenoids.

Dahl, T.A.; Midden, W.R. (Bowling Green State Univ., OH (USA)); Hartman, P.E. (Johns Hopkins Univ., Baltimore, MD (USA))

1989-04-01

291

Functional synergy of ?-helical antimicrobial peptides and traditional antibiotics against Gram-negative and Gram-positive bacteria in vitro and in vivo.  

PubMed

In this study, the antimicrobial activities based on the synergistic effects of traditional antibiotics (imipenem, cefepime, levofloxacin hydrochloride and vancomycin) and antimicrobial peptides (AMPs; PL-5, PL-31, PL-32, PL-18, PL-29 and PL-26), alone or in combination, against three Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae and Staphylococcus epidermidis) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) were investigated. In addition, the antimicrobial activity that was based on the synergistic effects of levofloxacin hydrochloride and PL-5 against Staphylococcus aureus in vivo was explored in a mouse infection model. Traditional antibiotics and AMPs showed significant synergistic effects on the antibacterial activities against the different Gram-positive and Gram-negative bacteria in vitro. A strong synergistic effect in the PL-5 and levofloxacin hydrochloride combination against Staphylococcus aureus was observed in the mouse infection model in vivo. The mechanism of synergistic action was due to the different targets of AMPs and traditional antibiotics. The combination of AMPs and traditional antibiotics can dramatically enhance antimicrobial activity and may help prevent or delay the emergence of antibiotic resistance. Thus, this combination therapy could be a promising approach to treat bacterial infections, particularly mixed infections and multi-antibiotic-resistant infections, in the clinics. PMID:25169965

Feng, Q; Huang, Y; Chen, M; Li, G; Chen, Y

2015-01-01

292

Field detection of bacillus spore aerosols with stand-alone pyrolysis-gas chromatography and ion mobility spectrometry  

Microsoft Academic Search

A commercially available, hand-held chemical vapor detector was modified to detect Gram-positive Bacillus subtilis var. globigii spores (BG) in outdoor field scenarios. An Airborne Vapor Monitor (AVM) ion mobility spectrometry (IMS) vapor detector was interfaced to a biological sample processing and transfer introduction system. The biological sample processing was accomplished by quartz tube pyrolysis (Py), and the resultant vapor was

A. P. Snyder; Waleed M. Maswadeh; John A. Parsons; Ashish Tripathi; Henk L. Meuzelaar; Jacek P. Dworzanski; Man-Goo Kim

1999-01-01

293

Assessing the interactions of a natural antibacterial clay with model Gram-positive and Gram-negative human pathogens  

NASA Astrophysics Data System (ADS)

The emergence of antibiotic resistant bacteria and increasing accumulations of antibiotics in reclaimed water, drive the quest for new natural antimicrobials. We are studying the antibacterial mechanism(s) of clays that have shown an ability to destroy bacteria or significantly inhibit their growth. One possible mode of action is from soluble transition metal species, particularly reduced Fe, capable of generating deleterious oxygen radical species. Yet another possibility is related to membrane damage as a consequence of physical or electrostatic interaction between clay and bacteria. Both mechanisms could combine to produce cell death. This study addresses a natural antibacterial clay from the NW Amazon basin, South America (AMZ clay). Clay mineralogy is composed of disordered kaolinite (28.9%), halloysite (17.8%) illite (12%) and smectite (16.7%). Mean particle size is 1.6?m and total and specific surface area 278.82 and 51.23 m2/g respectively. The pH of a suspension (200mg/ml) is 4.1 and its Eh is 361mV after 24h of equilibration. The ionic strength of the water in equilibrium with the clay after 24 h. is 6 x10-4M. These conditions, affect the element solubility, speciation, and interactions between clay and bacteria. Standard microbiological methods were used to assess the viability of two model bacteria (Escherichia coli and Bacillus subtilis) after incubation with clay at 37 degC for 24 hrs. A threefold reduction in bacterial viability was observed upon treatment with AMZ clay. We separated the cells from the clay using Nycodenz gradient media and observed the mounts under the TEM and SEM. Results showed several membrane anomalies and structural changes that were not observed in the control cells. Additionally, clay minerals appeared in some places attached to cell walls. Experiments showed that exchanging AMZ clay with KCl caused loss of antibacterial property. Among the exchangeable -and potentially toxic- ions we measured Al+3, Cu+2, Zn+2, Ba+2 and Co+2. Besides being toxic at high concentrations, these species affect the electrophoretic interactions between clay and bacteria surfaces. Additionally, the cation exchange neutralizes the clay surface charge thus modifying further the behavior of particles in suspension. Therefore, we evaluated the clay and bacteria zeta potential (?) as an index for possible electrostatic forces and modeled the total interactions using DLVO theory. We suspended the particles in water equilibrated with clay (leachate). Results show that at pH 4, the ? of clays is -14 mV while it is -3mV for bacteria. The divalent ions and trivalent Aluminum, present in the AMZ leachate, compress the thickness of the double layer (hydration shell) thus decreasing electrostatic repulsion and allowing particles to come closer. The proximity of particles increases the probability of attractive forces to bind clays and cells. In summary, results indicate that a process other than simple chemical transfer from clay to bacteria is operating. The electrostatic attraction and physical proximity may enhance the toxic action of metals and interfere with the membrane properties or processes.

Londono, S. C.; Williams, L. B.

2013-12-01

294

Communication of ? phage lysin plyG enzymes binding toward SrtA for inhibition of Bacillus anthracis: protein-protein interaction and molecular dynamics study.  

PubMed

Bacillus anthracis is a pathogenic, Gram-positive bacterium which chiefly affects the livestock of animals and humans through acute disease anthrax. All around the globe this bio-threat organism damages millions of lives in every year and also most of the drugs were not responding properly in inhibition against this diseased pathogen. In recent development, phage therapy is considered as alternative solution to treat this serious infectious disease. In this study, we elucidated the binding of ? phage lysin plyG enzymes toward the SrtA along with its activator peptide LPXTG. Through protein-protein docking and molecular dynamics simulation studies, we showed the distinguished structure complementarity of SrtA and plyG complex. Especially, MD simulation relates strong and stable interaction occurs between the protein complex structures. These results suggest that additional experimental studies on our approach will lead to availability of better inhibitor against the SrtA. PMID:24978154

Selvaraj, Chandrabose; Bharathi Priya, Ramanathan; Singh, Sanjeev Kumar

2014-10-01

295

Isolation of a halophilic bacterium, Bacillus sp. strain NY-6 for organic contaminants removal in saline wastewater on ship  

NASA Astrophysics Data System (ADS)

The objective of this research was to examine if certain strains of Bacillus bacteria, could survive in dry powder products and if so, could the bacteria degrade organic contaminants in saline wastewater on a ship. As part of the study, we isolated 7 domesticated strains named NY1, NY2,..., and NY7, the strain NY6 showed to have the best performance for organic matter degradation and could survive in dry powder more than 3 months. NY6 was identified as Bacillus aerius, based on the morphological and physic-chemical properties. Its optimal growth conditions were as follows: salinity was 2%; temperature was 37°C; pH was in 6.5-7.0; best ratio of C: N: P was 100:5:1. The capability of its dry powder for Chemical Oxygen Demand (COD) removal was 800mg COD/g in synthesized marine wastewater with 2% salinity. The spores in the dry powder were 1.972×108 g -1.

Gao, Jie; Yu, Zhenjiang; Zhang, Xiaohui; Zhao, Dan; Zhao, Fangbo

2013-06-01

296

Crystallization and first data collection of the putative transfer protein TraN from the Gram-positive conjugative plasmid pIP501  

PubMed Central

Conjugative plasmid transfer is the most important route for the spread of resistance and virulence genes among bacteria. Consequently, bacteria carrying conjugative plasmids are a substantial threat to human health, especially hospitalized patients. Whilst detailed information about the process has been obtained for Gram-negative type-4 secretion systems, little is known about the corresponding mechanisms in Gram-positive (G+) bacteria. The successful purification and crystallization of the putative transfer protein TraN from the G+ conjugative model plasmid pIP501 of Enterococcus faecalis are presented. Native crystals diffracted to 1.8?Å resolution on a synchrotron beamline. The crystals belonged to space group P21, with unit-cell parameters a = 32.88, b = 54.94, c = 57.71?Å, ? = 91.89° and two molecules per asymmetric unit. PMID:23143259

Goessweiner-Mohr, Nikolaus; Fercher, Christian; Abajy, Mohammad Yaser; Grohmann, Elisabeth; Keller, Walter

2012-01-01

297

A novel universal DNA labeling and amplification system for rapid microarray-based detection of 117 antibiotic resistance genes in Gram-positive bacteria.  

PubMed

A rapid and simple DNA labeling system has been developed for disposable microarrays and has been validated for the detection of 117 antibiotic resistance genes abundant in Gram-positive bacteria. The DNA was fragmented and amplified using phi-29 polymerase and random primers with linkers. Labeling and further amplification were then performed by classic PCR amplification using biotinylated primers specific for the linkers. The microarray developed by Perreten et al. (Perreten, V., Vorlet-Fawer, L., Slickers, P., Ehricht, R., Kuhnert, P., Frey, J., 2005. Microarray-based detection of 90 antibiotic resistance genes of gram-positive bacteria. J.Clin.Microbiol. 43, 2291-2302.) was improved by additional oligonucleotides. A total of 244 oligonucleotides (26 to 37 nucleotide length and with similar melting temperatures) were spotted on the microarray, including genes conferring resistance to clinically important antibiotic classes like ?-lactams, macrolides, aminoglycosides, glycopeptides and tetracyclines. Each antibiotic resistance gene is represented by at least 2 oligonucleotides designed from consensus sequences of gene families. The specificity of the oligonucleotides and the quality of the amplification and labeling were verified by analysis of a collection of 65 strains belonging to 24 species. Association between genotype and phenotype was verified for 6 antibiotics using 77 Staphylococcus strains belonging to different species and revealed 95% test specificity and a 93% predictive value of a positive test. The DNA labeling and amplification is independent of the species and of the target genes and could be used for different types of microarrays. This system has also the advantage to detect several genes within one bacterium at once, like in Staphylococcus aureus strain BM3318, in which up to 15 genes were detected. This new microarray-based detection system offers a large potential for applications in clinical diagnostic, basic research, food safety and surveillance programs for antimicrobial resistance. PMID:25451460

Strauss, Christian; Endimiani, Andrea; Perreten, Vincent

2015-01-01

298

Infective Endocarditis: Identification of Catalase-Negative, Gram-Positive Cocci from Blood Cultures by Partial 16S rRNA Gene Analysis and by Vitek 2 Examination  

PubMed Central

Streptococci, enterococci and Streptococcus-like bacteria are frequent etiologic agents of infective endocarditis and correct species identification can be a laboratory challenge. Viridans streptococci (VS) not seldomly cause contamination of blood cultures. Vitek 2 and partial sequencing of the 16S rRNA gene were applied in order to compare the results of both methods. Strains originated from two groups of patients: 149 strains from patients with infective endocarditis and 181 strains assessed as blood culture contaminants. Of the 330 strains, based on partial 16S rRNA gene sequencing results, 251 (76%) were VS strains, 10 (3%) were pyogenic streptococcal strains, 54 (16%) were E. faecalis strains and 15 (5%) strains belonged to a group of miscellaneous catalase-negative, Gram-positive cocci. Among VS strains, respectively, 220 (87,6%) and 31 (12,3%) obtained agreeing and non-agreeing identifications with the two methods with respect to allocation to the same VS group. Non-agreeing species identification mostly occurred among strains in the contaminant group, while for endocarditis strains notably fewer disagreeing results were observed. Only 67 of 150 strains in the mitis group strains obtained identical species identifications by the two methods. Most VS strains belonging to the groups of salivarius, anginosus, and mutans obtained agreeing species identifications with the two methods, while this only was the case for 13 of the 21 bovis strains. Pyogenic strains (n=10), Enterococcus faecalis strains (n=54) and a miscellaneous group of catalase-negative, Gram-positive cocci (n=15) seemed well identified by both methods, except that disagreements in identifications in the miscellaneous group of strains occurred for 6 of 15 strains. PMID:21673976

Abdul-Redha, Rawaa Jalil; Kemp, Michael; Bangsborg, Jette M; Arpi, Magnus; Christensen, Jens Jørgen

2010-01-01

299

Lactococcus lactis TrxD represents a subgroup of thioredoxins prevalent in Gram-positive bacteria containing WCXDC active site motifs.  

PubMed

Three protein disulfide reductases of the thioredoxin superfamily from the industrially important Gram-positive Lactococcus lactis (LlTrxA, LlTrxD and LlNrdH) are compared to the "classical" thioredoxin from Escherichia coli (EcTrx1). LlTrxA resembles EcTrx1 with a WCGPC active site motif and other key residues conserved. By contrast, LlTrxD is more distantly related and contains a WCGDC motif. Bioinformatics analysis suggests that LlTrxD represents a subgroup of thioredoxins from Gram-positive bacteria. LlNrdH is a glutaredoxin-like electron donor for ribonucleotide reductase class Ib. Based on protein-protein equilibria LlTrxA (E°'=-259mV) and LlNrdH (E°'=-238mV) show approximately 10mV higher standard state redox potentials than the corresponding E. coli homologues, while E°' of LlTrxD is -243mV, more similar to glutaredoxin than "classical" thioredoxin. EcTrx1 and LlTrxA have high capacity to reduce insulin disulfides and their exposed active site thiol is alkylated at a similar rate at pH 7.0. LlTrxD on the other hand, is alkylated by iodoacetamide at almost 100 fold higher rate and shows no activity towards insulin disulfides. LlTrxA, LlTrxD and LlNrdH are all efficiently reduced by NADPH dependent thioredoxin reductase (TrxR) from L. lactis and good cross-reactivity towards E. coli TrxR was observed with LlTrxD as the notable exception. PMID:25255970

Björnberg, Olof; Efler, Petr; Ebong, Epie Denis; Svensson, Birte; Hägglund, Per

2014-12-15

300

A Systems Biological Approach Reveals Multiple Crosstalk Mechanism between Gram-Positive and Negative Bacterial Infections: An Insight into Core Mechanism and Unique Molecular Signatures  

PubMed Central

Background Bacterial infections remain a major threat and a leading cause of death worldwide. Most of the bacterial infections are caused by gram-positive and negative bacteria, which are recognized by Toll-like receptor (TLR) 2 and 4, respectively. Activation of these TLRs initiates multiple pathways that subsequently lead to effective immune response. Although, both the TLRs share common signaling mechanism yet they may exhibit specificity as well, resulting in the release of diverse range of inflammatory mediators which could be used as candidate biomolecules for bacterial infections. Results We adopted systems biological approach to identify signaling pathways mediated by TLRs to determine candidate molecules associated with bacterial infections. We used bioinformatics concepts, including literature mining to construct protein-protein interaction network, prioritization of TLRs specific nodes using microarray data and pathway analysis. Our constructed PPI network for TLR 2 (nodes: 4091 and edges: 66068) and TLR 4 (node: 4076 and edges: 67898) showed 3207 common nodes, indicating that both the TLRs might share similar signaling events that are attributed to cell migration, MAPK pathway and several inflammatory cascades. Our results propose the potential collaboration between the shared signaling pathways of both the receptors may enhance the immune response against invading pathogens. Further, to identify candidate molecules, the TLRs specific nodes were prioritized using microarray differential expressed genes. Of the top prioritized TLR 2 molecules, 70% were co-expressed. A similar trend was also observed within TLR 4 nodes. Further, most of these molecules were preferentially found in blood plasma for feasible diagnosis. Conclusions The analysis reveals the common and unique mechanism regulated by both the TLRs that provide a broad perspective of signaling events in bacterial infections. Further, the identified candidate biomolecules could potentially aid future research efforts concerning the possibility in differential diagnosis of gram-positive and negative bacterial infections. PMID:24587173

Thangam, Berla; Ahmed, Shiek S. S. J.

2014-01-01

301

Sequence and genetic organization of a Bacillus subtilis operon encoding 2,3-dihydroxybenzoate biosynthetic enzymes  

Microsoft Academic Search

Under iron-limiting conditions, Bacillus subtilis (Bs) produces the siderophore 2,3-dihydroxybenzoate (DHB) to acquire extracellular iron. In Escherichia coli (Ec), DHB is a precursor of the siderophore enterobactin, which suggested that Bs may possess similar biosynthetic enzymes. The sequences of two overlapping Bs clones capable of complementing Ec enterobactin mutants [Grossman, T.H., Tuckman, M., Ellestad, S. and Osburne, M.S. (1993) Isolation

Belinda M. Rowland; Trudy H. Grossman; Marcia S. Osburne; Harry W. Taber

1996-01-01

302

Toxin-Antitoxin Genes of the Gram-Positive Pathogen Streptococcus pneumoniae: So Few and Yet So Many  

PubMed Central

Summary: Pneumococcal infections cause up to 2 million deaths annually and raise a large economic burden and thus constitute an important threat to mankind. Because of the increase in the antibiotic resistance of Streptococcus pneumoniae clinical isolates, there is an urgent need to find new antimicrobial approaches to triumph over pneumococcal infections. Toxin-antitoxin (TA) systems (TAS), which are present in most living bacteria but not in eukaryotes, have been proposed as an effective strategy to combat bacterial infections. Type II TAS comprise a stable toxin and a labile antitoxin that form an innocuous TA complex under normal conditions. Under stress conditions, TA synthesis will be triggered, resulting in the degradation of the labile antitoxin and the release of the toxin protein, which would poison the host cells. The three functional chromosomal TAS from S. pneumoniae that have been studied as well as their molecular characteristics are discussed in detail in this review. Furthermore, a meticulous bioinformatics search has been performed for 48 pneumococcal genomes that are found in public databases, and more putative TAS, homologous to well-characterized ones, have been revealed. Strikingly, several unusual putative TAS, in terms of components and genetic organizations previously not envisaged, have been discovered and are further discussed. Previously, we reported a novel finding in which a unique pneumococcal DNA signature, the BOX element, affected the regulation of the pneumococcal yefM-yoeB TAS. This BOX element has also been found in some of the other pneumococcal TAS. In this review, we also discuss possible relationships between some of the pneumococcal TAS with pathogenicity, competence, biofilm formation, persistence, and an interesting phenomenon called bistability. PMID:23204366

Chan, Wai Ting; Moreno-Córdoba, Inma

2012-01-01

303

Mass and Density Measurements of Live and Dead Gram-Negative and Gram-Positive Bacterial Populations  

PubMed Central

Monitoring cell growth and measuring physical features of food-borne pathogenic bacteria are important for better understanding the conditions under which these organisms survive and proliferate. To address this challenge, buoyant masses of live and dead Escherichia coli O157:H7 and Listeria innocua were measured using Archimedes, a commercially available suspended microchannel resonator (SMR). Cell growth was monitored with Archimedes by observing increased cell concentration and buoyant mass values of live growing bacteria. These growth data were compared to optical density measurements obtained with a Bioscreen system. We observed buoyant mass measurements with Archimedes at cell concentrations between 105 and 108 cells/ml, while growth was not observed with optical density measurements until the concentration was 107 cells/ml. Buoyant mass measurements of live and dead cells with and without exposure to hydrogen peroxide stress were also compared; live cells generally had a larger buoyant mass than dead cells. Additionally, buoyant mass measurements were used to determine cell density and total mass for both live and dead cells. Dead E. coli cells were found to have a larger density and smaller total mass than live E. coli cells. In contrast, density was the same for both live and dead L. innocua cells, while the total mass was greater for live than for dead cells. These results contribute to the ongoing challenge to further develop existing technologies used to observe cell populations at low concentrations and to measure unique physical features of cells that may be useful for developing future diagnostics. PMID:24705320

Craig, Caelli C.; Senecal, Andre G.

2014-01-01

304

Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria  

NASA Astrophysics Data System (ADS)

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10- x Ag x (PO4)6(OH)2, x Ag = 0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a = b = 9.435 Å, c = 6.876 Å for x Ag = 0.05, a = b = 9.443 Å, c = 6.875 Å for x Ag = 0.2, and a = b = 9.445 Å, c = 6.877 Å for x Ag = 0.3 are in good agreement with the standard of a = b = 9.418 Å, c = 6.884 Å (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples ( x Ag = 0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of x Ag in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth ( P. stuartii).

Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

2012-06-01

305

Mass and density measurements of live and dead Gram-negative and Gram-positive bacterial populations.  

PubMed

Monitoring cell growth and measuring physical features of food-borne pathogenic bacteria are important for better understanding the conditions under which these organisms survive and proliferate. To address this challenge, buoyant masses of live and dead Escherichia coli O157:H7 and Listeria innocua were measured using Archimedes, a commercially available suspended microchannel resonator (SMR). Cell growth was monitored with Archimedes by observing increased cell concentration and buoyant mass values of live growing bacteria. These growth data were compared to optical density measurements obtained with a Bioscreen system. We observed buoyant mass measurements with Archimedes at cell concentrations between 10(5) and 10(8) cells/ml, while growth was not observed with optical density measurements until the concentration was 10(7) cells/ml. Buoyant mass measurements of live and dead cells with and without exposure to hydrogen peroxide stress were also compared; live cells generally had a larger buoyant mass than dead cells. Additionally, buoyant mass measurements were used to determine cell density and total mass for both live and dead cells. Dead E. coli cells were found to have a larger density and smaller total mass than live E. coli cells. In contrast, density was the same for both live and dead L. innocua cells, while the total mass was greater for live than for dead cells. These results contribute to the ongoing challenge to further develop existing technologies used to observe cell populations at low concentrations and to measure unique physical features of cells that may be useful for developing future diagnostics. PMID:24705320

Lewis, Christina L; Craig, Caelli C; Senecal, Andre G

2014-06-01

306

Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria  

PubMed Central

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-xAgx(PO4)6(OH)2, xAg?=?0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a?=?b?=?9.435 Å, c?=?6.876 Å for xAg?=?0.05, a?=?b?=?9.443 Å, c?=?6.875 Å for xAg?=?0.2, and a?=?b?=?9.445 Å, c?=?6.877 Å for xAg?=?0.3 are in good agreement with the standard of a?=?b?=?9.418 Å, c?=?6.884 Å (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (xAg?=?0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of xAg in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii). PMID:22721352

2012-01-01

307

Bacillus anthracis Physiology and Genetics  

PubMed Central

Bacillus anthracis is a member of the Bacillus cereus group species (also known as the “group 1 bacilli”), a collection of Gram-positive spore-forming soil bacteria that are non-fastidious facultative anaerobes with very similar growth characteristics and natural genetic exchange systems. Despite their close physiology and genetics, the Bacillus cereus group species exhibit certain species-specific phenotypes, some of which are related to pathogenicity. B. anthracis is the etiologic agent of anthrax. Vegetative cells of B. anthracis produce anthrax toxin proteins and a poly-D-glutamic acid capsule during infection of mammalian hosts and when cultured in conditions considered to mimic the host environment. The genes associated with toxin and capsule synthesis are located on the B. anthracis plasmids, pXO1 and pXO2, respectively. Although plasmid content is considered a defining feature of the species, pXO1- and pXO2-like plasmids have been identified in strains that more closely resemble other members of the B. cereus group. The developmental nature of B. anthracis and its pathogenic (mammalian host) and environmental (soil) lifestyles of make it an interesting model for study of niche-specific bacterial gene expression and physiology. PMID:19654018

Koehler, Theresa M.

2009-01-01

308

Purification and characterization of a thermo- and organic solvent-tolerant alkaline protease from Bacillus sp. JER02.  

PubMed

Bacillus sp. JER02 is a bacterial strain that can be grown in a medium containing organic solvents and produce a protease enzyme. JER02 protease was purified with a yield of 31.9% of total protein and 328.83-fold purification. Km and Vmax of this protease were established as 0.826 µM and 7.18 µmol/min, respectively. JER02 protease stability was stimulated about 80% by cyclohexane. It exhibited optimum temperature activity at 70°C. Furthermore, this enzyme was active in a wide range of pH (4-12) and showed maximum activity at pH 9.0. The nonionic detergents Tween-20 and Triton X-100 improved the protease activity by 30 and 20%, respectively. In addition, this enzyme was shown to be very stable in the presence of strong anionic surfactants and oxidizing agents, since it retained 77%, 93%, and 98% of its initial activity, after 1 hr of incubation at room temperature with sodium dodecyl sulfate (SDS), sodium perborate (1%, v/v) and H2O2 (1%, v/v), respectively. Overall, the unique properties of the Bacillus sp. JER02 protease suggested that this thermo- and detergent-stable, solvent-tolerant protease has great potential for industrial applications. PMID:24845261

Badoei-Dalfard, Arastoo; Karami, Zahra; Ravan, Hadi

2015-01-01

309

Transcriptomic profiling of Bacillus amyloliquefaciens FZB42 in response to maize root exudates  

PubMed Central

Background Plant root exudates have been shown to play an important role in mediating interactions between plant growth-promoting rhizobacteria (PGPR) and their host plants. Most investigations were performed on Gram-negative rhizobacteria, while much less is known about Gram-positive rhizobacteria. To elucidate early responses of PGPR to root exudates, we investigated changes in the transcriptome of a Gram-positive PGPR to plant root exudates. Results Bacillus amyloliquefaciens FZB42 is a well-studied Gram-positive PGPR. To obtain a comprehensive overview of FZB42 gene expression in response to maize root exudates, microarray experiments were performed. A total of 302 genes representing 8.2% of the FZB42 transcriptome showed significantly altered expression levels in the presence of root exudates. The majority of the genes (261) was up-regulated after incubation of FZB42 with root exudates, whereas only 41 genes were down-regulated. Several groups of the genes which were strongly induced by the root exudates are involved in metabolic pathways relating to nutrient utilization, bacterial chemotaxis and motility, and non-ribosomal synthesis of antimicrobial peptides and polyketides. Conclusions Here we present a transcriptome analysis of the root-colonizing bacterium Bacillus amyloliquefaciens FZB42 in response to maize root exudates. The 302 genes identified as being differentially transcribed are proposed to be involved in interactions of Gram-positive bacteria with plants. PMID:22720735

2012-01-01

310

Cryo-EM analysis of the organization of BclA and BxpB in the Bacillus anthracis exosporium.  

PubMed

Bacillus anthracis and other pathogenic Bacillus species form spores that are surrounded by an exosporium, a balloon-like layer that acts as the outer permeability barrier of the spore and contributes to spore survival and virulence. The exosporium consists of a hair-like nap and a paracrystalline basal layer. The filaments of the nap are comprised of trimers of the collagen-like glycoprotein BclA, while the basal layer contains approximately 20 different proteins. One of these proteins, BxpB, forms tight complexes with BclA and is required for attachment of essentially all BclA filaments to the basal layer. Another basal layer protein, ExsB, is required for the stable attachment of the exosporium to the spore. To determine the organization of BclA and BxpB within the exosporium, we used cryo-electron microscopy, cryo-sectioning and crystallographic analysis of negatively stained exosporium fragments to compare wildtype spores and mutant spores lacking BclA, BxpB or ExsB (?bclA, ?bxpB and ?exsB spores, respectively). The trimeric BclA filaments are attached to basal layer surface protrusions that appear to be trimers of BxpB. The protrusions interact with a crystalline layer of hexagonal subunits formed by other basal layer proteins. Although ?bxpB spores retain the hexagonal subunits, the basal layer is not organized with crystalline order and lacks basal layer protrusions and most BclA filaments, indicating a central role for BxpB in exosporium organization. PMID:24607412

Rodenburg, Cynthia M; McPherson, Sylvia A; Turnbough, Charles L; Dokland, Terje

2014-04-01

311

Influence of temperature and organic load on chemical disinfection of Geobacillus steareothermophilus spores, a surrogate for Bacillus anthracis  

PubMed Central

This study evaluated the influence of temperature and organic load on the effectiveness of domestic bleach (DB), Surface Decontamination Foam (SDF), and Virkon in inactivating Geobacillus stearothermophilus spores, which are a surrogate for Bacillus anthracis spores. The spores were suspended in light or heavy organic preparations and the suspension was applied to stainless steel carrier disks. The dried spore inoculum was covered with the disinfectants and the disks were then incubated at various temperatures. At ?20°C, the 3 disinfectants caused less than a 2.0 log10 reduction of spores in both organic preparations during a 24-h test period. At 4°C, the DB caused a 4.4 log10 reduction of spores in light organic preparations within 2 h, which was about 3 log10 higher than what was achieved with SDF or Virkon. In heavy organic preparations, after 24 h at 4°C the SDF had reduced the spore count by 4.5 log10, which was about 2 log10 higher than for DB or Virkon. In general, the disinfectants were most effective at 23°C but a 24-h contact time was required for SDF and Virkon to reduce spore counts in both organic preparations by at least 5.5 log10. Comparable disinfecting activity with DB only occurred with the light organic load. In summary, at temperatures as low as 4°C, DB was the most effective disinfectant, inactivating spores within 2 h on surfaces with a light organic load, whereas SDF produced the greatest reduction of spores within 24 h on surfaces with a heavy organic load. PMID:24082400

Guan, Jiewen; Chan, Maria; Brooks, Brian W.; Rohonczy, Liz

2013-01-01

312

Influence of temperature and organic load on chemical disinfection of Geobacillus steareothermophilus spores, a surrogate for Bacillus anthracis.  

PubMed

This study evaluated the influence of temperature and organic load on the effectiveness of domestic bleach (DB), Surface Decontamination Foam (SDF), and Virkon in inactivating Geobacillus stearothermophilus spores, which are a surrogate for Bacillus anthracis spores. The spores were suspended in light or heavy organic preparations and the suspension was applied to stainless steel carrier disks. The dried spore inoculum was covered with the disinfectants and the disks were then incubated at various temperatures. At -20°C, the 3 disinfectants caused less than a 2.0 log10 reduction of spores in both organic preparations during a 24-h test period. At 4°C, the DB caused a 4.4 log10 reduction of spores in light organic preparations within 2 h, which was about 3 log10 higher than what was achieved with SDF or Virkon. In heavy organic preparations, after 24 h at 4°C the SDF had reduced the spore count by 4.5 log10, which was about 2 log10 higher than for DB or Virkon. In general, the disinfectants were most effective at 23°C but a 24-h contact time was required for SDF and Virkon to reduce spore counts in both organic preparations by at least 5.5 log10. Comparable disinfecting activity with DB only occurred with the light organic load. In summary, at temperatures as low as 4°C, DB was the most effective disinfectant, inactivating spores within 2 h on surfaces with a light organic load, whereas SDF produced the greatest reduction of spores within 24 h on surfaces with a heavy organic load. PMID:24082400

Guan, Jiewen; Chan, Maria; Brooks, Brian W; Rohonczy, Liz

2013-04-01

313

Organization of Gene Function in Bacillus subtilis Bacteriophage SP82G 1  

PubMed Central

A generalized assessment of the functions of 26 genes of SP82G, a bacteriophage of Bacillus subtilis, has been made. The production of phage-specific deoxyribonucleic acid (DNA), DNA-filled phage heads, completed phage particles, phage-specific antigen, and developmental aberrations has been examined in lysates of temperature-sensitive mutants grown under selective conditions. The genes show a tendency to occur on the genome in three groups of related function: genes involved with DNA synthesis, with tail synthesis, and with head synthesis. Images PMID:4113884

Green, D. MacDonald; Laman, David

1972-01-01

314

Bacillus anthracis.  

PubMed

The events of 11 September 2001 and the subsequent anthrax outbreaks have shown that the West needs to be prepared for an increasing number of terrorist attacks, which may include the use of biological warfare. Bacillus anthracis has long been considered a potential biological warfare agent, and this review will discuss the history of its use as such. It will also cover the biology of this organism and the clinical features of the three disease forms that it can produce: cutaneous, gastrointestinal, and inhalation anthrax. In addition, treatment and vaccination strategies will be reviewed. PMID:12610093

Spencer, R C

2003-03-01

315

Immediate and carryover effects of Gram-negative and Gram-positive toxin-induced mastitis on follicular function in dairy cows.  

PubMed

This study compared immediate and carryover effects of mastitis induced by Gram-negative endotoxin (E. coli LPS) and Gram-positive exosecretions (Staph. aureus ex.) on preovulatory follicle function. Synchronized, uninfected cyclic lactating Holstein cows were treated with PGF(2?) on day 6 of the cycle and 36 h later, a dose of either E. coli LPS (n = 8), S. aureus ex. (n = 10), or saline (n = 9) was administered into the mammary gland. Follicular fluids and granulosa cells were aspirated 6 h later from the preovulatory follicles and cows were treated with GnRH. This (cycle 1; immediate effect) was repeated three times (excluding the mammary injections) to induce three 7 d cycles (cycles 2, 3, and 4; carryover effect). E. coli LPS increased body temperature, plasma cortisol concentration, and somatic cell count (SCC), whereas S. aureus ex. induced a minor, subclinical elevation of SCC and slight rise (NS) in body temperature and cortisol concentration. Follicular estradiol, androstenedione, and progesterone concentrations in the E. coli LPS group decreased (P < 0.05) in cycle 1 to about 40%, 13%, and 35%, respectively, of control levels, whereas in the S. aureus ex. group, only estradiol decreased (P < 0.05), to 56% of control concentrations. In cycles 3 and 4, follicular steroids in the E. coli LPS group returned to control concentrations, whereas in the S. aureus ex. group, follicular concentrations of estradiol and androstenedione were lower (P < 0.10) than in controls. In the control group, the concentrations of all follicular and circulating steroids remained stable (P > 0.05) throughout the study. Follicle size was similar in all groups, but the S. aureus ex. treatment caused a decrease (P < 0.02) in the number of follicles developed in cycles 3 and 4. The mRNA expression of steroidogenic genes and LHCGR in the granulosa cells was not affected (P > 0.05) by either treatment during the study, except for a tendency toward lower (P < 0.1) expression in cycle 1 and lower (P < 0.05) expression in cycle 4 of the latter in the S. aureus ex. group. Strain levels, such as SCC and body temperature, following toxin injection correlated well with the magnitude of the immediate decline in follicular steroids. As is typical for Gram-negative clinical events, E. coli LPS-induced acute mastitis caused immediate, short-term, but not long-term impairment of follicular responses, whereas the Gram-positive S. aureus ex.-induced subclinical mastitis exhibited both immediate and carryover disruptive effects on preovulatory follicle function. PMID:21705051

Lavon, Y; Leitner, G; Moallem, U; Klipper, E; Voet, H; Jacoby, S; Glick, G; Meidan, R; Wolfenson, D

2011-09-15

316

Contemporary potencies of minocycline and tetracycline HCL tested against Gram-positive pathogens: SENTRY Program results using CLSI and EUCAST breakpoint criteria.  

PubMed

Tetracycline class agents vary widely in their activity against emerging important antimicrobial-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter spp. Also, published susceptibility breakpoints are discordant between the Clinical and Laboratory Standards Institute (CLSI), the European Committee on Antimicrobial Susceptibility Testing (EUCAST), and regulatory-approved documents. We have assessed the impact of these differences for tetracycline HCL and minocycline when tested against contemporary Gram-positive pathogens. The SENTRY Antimicrobial Surveillance Program (2011) compared minocycline and tetracycline HCL activity via reference methods (M07-A9) using a worldwide collection of S. aureus (SA; 4917 strains with 1955 MRSA), Streptococcus pneumoniae (SPN; 1899), S. pyogenes (GRA; 246), and S. agalactiae (GRB; 217). Regardless of applied categorical breakpoints, minocycline exhibited wider coverage (% susceptible) than tetracycline HCL of 4.5-11.8/0.5-2.6/1.4-2.3/0.4-0.4% for MRSA/SPN/GRB/GRA, respectively. Lower EUCAST susceptible breakpoints produced reduced susceptibility rates for minocycline ranging from no difference (?0.5 ?g/mL) for GRA to -8.9% (?1 ?g/mL) for MRSA (97.2% susceptible by CLSI; 88.3% by EUCAST). Use of tetracycline HCL-susceptible results to predict minocycline susceptibility was very accurate (99.0-100.0%), with absolute categorical agreement rates ranging from 92.1% to 98.4% (CLSI) to 98.4% to 99.6% (EUCAST) for streptococci; greatest predictive error was noted using the CLSI breakpoints (14.7%) compared to EUCAST criteria (only 5.0%; acceptable), both for MRSA testing dominated by false-resistant results for minocycline. In conclusion, minocycline demonstrates continued superior in vitro activity compared to tetracycline HCL when testing SA (especially MRSA) and pathogenic streptococci. When testing tetracyclines, laboratories must recognize the expanded spectrum of minocycline against certain pathogens and utilize methods minimizing interpretive error. We conclude that EUCAST breakpoint criteria (?0.5 or ?1 ?g/mL) represent the most conservative (better recognize strains with tet resistance mechanisms) and accurate tetracycline breakpoint guidelines for testing contemporary isolates of Gram-positive cocci. PMID:23514756

Jones, Ronald N; Wilson, Michael L; Weinstein, Melvin P; Stilwell, Matthew G; Mendes, Rodrigo E

2013-04-01

317

Antibiotic susceptibility in gram-positive chronic joint arthroplasty infections: increased aminoglycoside resistance rate in patients with prior aminoglycoside-impregnated cement spacer use.  

PubMed

Two-stage revision using aminoglycoside-cement spacers (A-CSs) is widely used to manage chronic periprosthetic joint infection (PJI). However, aminoglycoside-resistance in gram-positive cocci (GPC) seems to be increasing. Moreover, the contribution of these A-CSs to select resistant mutants is a matter of concern. We study the antibiotic susceptibility profile of GPC after 113 chronic hip and knee PJIs. Aminoglycoside susceptibility-profiles were compared between cases where A-CSs had previously been used (n: 52), and cases of primary infection (n: 61). 32% of isolates were resistant to gentamicin and 40.6% to tobramycin. Gentamicin resistance after previous A-CS use was significantly higher (49.2% [30/61] vs. 19.3% [16/83]; P: 0.0001) as well as with tobramycin (52.7% [29/55] vs. 30.9% [21/66]; P: 0.014). A high rate of gentamicin-tobramycin resistance exists among the most common bacteria involved in chronic-PJI. The risk of selection for aminoglycoside-resistant mutants in cases of infection relapse is a concern following A-CS use. PMID:24798194

Corona, Pablo S; Espinal, Laia; Rodríguez-Pardo, Dolors; Pigrau, Carles; Larrosa, Nieves; Flores, Xavier

2014-08-01

318

Antimicrobial Effect of the Triterpene 3?,6?,16?-Trihydroxylup-20(29)-ene on Planktonic Cells and Biofilms from Gram Positive and Gram Negative Bacteria  

PubMed Central

This study evaluated the antimicrobial effect of 3?,6?,16?-trihydroxylup-20(29)-ene (CLF1), a triterpene isolated from Combretum leprosum Mart., in inhibiting the planktonic growth and biofilms of Gram positive bacteria Streptococcus mutans and S. mitis. The antimicrobial activity was assessed by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antibiofilm potential was determined by quantifying total biomass and enumerating biofilm-entrapped viable bacteria. In addition, the acute toxicity of CLF1 on Artemia sp. nauplii was also determined. The results showed that CLF1 was able in inhibiting the growth of S. mutans and S. mitis with MIC and MBC of 7.8??g/mL and 15.6??g/mL, respectively. CLF1 was highly effective on biofilms of both bacteria. Only 7.8??g/mL CLF1 was enough to inhibit by 97% and 90% biomass production of S. mutans and S. mitis, respectively. On the other hand, such effects were not evident on Gram negative Pseudomonas aeruginosa and Klebsiella oxytoca. The toxicity tests showed that the LC50 of CLF1 was 98.19??g/mL. Therefore, CLF1 isolated from C. leprosum may constitute an important natural agent for the development of new therapies for caries and other infectious diseases caused by S. mutans and S. mitis. PMID:25093179

Evaristo, Francisco Flávio Vasconcelos; Albuquerque, Maria Rose Jane R.; dos Santos, Hélcio Silva; Bandeira, Paulo Nogueira; Ávila, Fábio do Nascimento; da Silva, Bruno Rocha; Vasconcelos, Ariana Azevedo; Rabelo, Érica de Menezes; Nascimento-Neto, Luiz Gonzaga; Arruda, Francisco Vassiliepe Sousa; Vasconcelos, Mayron Alves; Carneiro, Victor Alves; Cavada, Benildo Sousa; Teixeira, Edson Holanda

2014-01-01

319

Antibacterial inhibitors of Gram-positive thymidylate kinase: structure-activity relationships and chiral preference of a new hydrophobic binding region.  

PubMed

Thymidylate kinase (TMK), an essential enzyme in bacterial DNA biosynthesis, is an attractive therapeutic target for the development of novel antibacterial agents, and we continue to explore TMK inhibitors with improved potency, protein binding, and pharmacokinetic potential. A structure-guided design approach was employed to exploit a previously unexplored region in Staphylococcus aureus TMK via novel interactions. These efforts produced compound 39, with 3 nM IC50 against S. aureus TMK and 2 ?g/mL MIC against methicillin-resistant S. aureus (MRSA). This compound exhibits a striking inverted chiral preference for binding relative to earlier compounds and also has improved physical properties and pharmacokinetics over previously published compounds. An example of this new series was efficacious in a murine S. aureus infection model, suggesting that compounds like 39 are options for further work toward a new Gram-positive antibiotic by maintaining a balance of microbiological potency, low clearance, and low protein binding that can result in lower efficacious doses. PMID:24828090

Kawatkar, Sameer P; Keating, Thomas A; Olivier, Nelson B; Breen, John N; Green, Oluyinka M; Guler, Satenig Y; Hentemann, Martin F; Loch, James T; McKenzie, Andrew R; Newman, Joseph V; Otterson, Linda G; Martínez-Botella, Gabriel

2014-06-12

320

In situ probing of gram-positive bacteria with high DNA G + C content using 23S rRNA-targeted oligonucleotides.  

PubMed

23S-rRNA-targeted oligonucleotide probes were designed for the phylogenetic group 'Gram-positive bacteria with high G + C content of DNA' (GPBHGC). A sequence idiosyncrasy in two adjacent base pairs in the stem of helix 69 in domain IV of the 23S rRNA is present in all hitherto analysed strains of GPBHGC. An oligonucleotide probe targeted to this region hybridized only with strains of GPBHGC and was successfully used for in situ monitoring of these cells in activated sludge. Another unique feature of the 23S rRNA molecules of GPBHGC is a large insertion in domain III. Fluorescent oligonucleotides targeted to the highly variable regions of the rRNA within the insertions of Corynebacterium glutamicum DSM 20300, Aureobacterium testaceum DSM 20166 and Brevibacterium sp. DSM 20165 hybridized specifically to their target strains, whereas probing with oligonucleotides complementary to the rRNA-coding strand of the 23S rDNA and to the spacer between 16S and 23S rRNA of C. glutamicum did not result in detectable fluorescence. This confirmed that the large 23S insertions are indeed present in 23S rRNAs of GPBHGC and provide potential target sites for highly specific nucleic acid probes. PMID:8000548

Roller, C; Wagner, M; Amann, R; Ludwig, W; Schleifer, K H

1994-10-01

321

Signatures of the ATP-binding pocket as a basis for structural classification of the serine/threonine protein kinases of gram-positive bacteria.  

PubMed

Eukaryotic-like serine/threonine protein kinases (ESTPKs) are widely spread throughout the bacterial genomes. These enzymes can be potential targets of new antibacterial drugs useful for the treatment of socially important diseases such as tuberculosis. In this study, ESTPKs of pathogenic, probiotic, and antibiotic-producing Gram-positive bacteria were classified according to the physicochemical properties of amino acid residues in the ATP-binding site of the enzyme. Nine residues were identified that line the surface of the adenine-binding pocket, and ESTPKs were classified based on these signatures. Twenty groups were discovered, five of them containing >10 representatives. The two most abundant groups contained >150 protein kinases that belong to the various branches of the phylogenetic tree, whereas certain groups are genus- or even species-specific. Homology modeling of the typical representatives of each group revealed that the classification is reliable, and the differences between the protein kinase ATP-binding pockets predicted based on their signatures are apparent in their structure. The classification is expected to be useful for the selection of targets for new anti-infective drugs. PMID:22275035

Zakharevich, Natalia V; Osolodkin, Dmitry I; Artamonova, Irena I; Palyulin, Vladimir A; Zefirov, Nikolay S; Danilenko, Valery N

2012-05-01

322

Amino Acid modified xanthone derivatives: novel, highly promising membrane-active antimicrobials for multidrug-resistant gram-positive bacterial infections.  

PubMed

Antibiotic resistance is a critical global health care crisis requiring urgent action to develop more effective antibiotics. Utilizing the hydrophobic scaffold of xanthone, we identified three components that mimicked the action of an antimicrobial cationic peptide to produce membrane-targeting antimicrobials. Compounds 5c and 6, which contain a hydrophobic xanthone core, lipophilic chains, and cationic amino acids, displayed very promising antimicrobial activity against multidrug-resistant Gram-positive bacteria, including MRSA and VRE, rapid time-kill, avoidance of antibiotic resistance, and low toxicity. The bacterial membrane selectivity of these molecules was comparable to that of several membrane-targeting antibiotics in clinical trials. 5c and 6 were effective in a mouse model of corneal infection by S. aureus and MRSA. Evidence is presented indicating that 5c and 6 target the negatively charged bacterial membrane via a combination of electrostatic and hydrophobic interactions. These results suggest that 5c and 6 have significant promise for combating life-threatening infections. PMID:25474410

Koh, Jun-Jie; Lin, Shuimu; Aung, Thet Tun; Lim, Fanghui; Zou, Hanxun; Bai, Yang; Li, Jianguo; Lin, Huifen; Pang, Li Mei; Koh, Wee Luan; Salleh, Shuhaida Mohamed; Lakshminarayanan, Rajamani; Zhou, Lei; Qiu, Shengxiang; Pervushin, Konstantin; Verma, Chandra; Tan, Donald T H; Cao, Derong; Liu, Shouping; Beuerman, Roger W

2015-01-22

323

WhiA, a Protein of Unknown Function Conserved among Gram-Positive Bacteria, Is Essential for Sporulation in Streptomyces coelicolor A3(2)  

PubMed Central

The whiA sporulation gene of Streptomyces coelicolor A3(2), which plays a key role in switching aerial hyphae away from continued extension growth and toward sporulation septation, was cloned by complementation of whiA mutants. DNA sequencing of the wild-type allele and five whiA mutations verified that whiA is a gene encoding a protein with homologues in all gram-positive bacteria whose genome sequence is known, whether of high or low G+C content. No function has been attributed to any of these WhiA-like proteins. In most cases, as in S. coelicolor, the whiA-like gene is downstream of other conserved genes in an operon-like cluster. Phenotypic analysis of a constructed disruption mutant confirmed that whiA is essential for sporulation. whiA is transcribed from at least two promoters, the most downstream of which is located within the preceding gene and is strongly up-regulated when colonies are undergoing sporulation. The up-regulation depends on a functional whiA gene, suggesting positive autoregulation, although it is not known whether this is direct or indirect. Unlike the promoters of some other sporulation-regulatory genes, the whiA promoter does not depend on the sporulation-specific ? factor encoded by whiG. PMID:10986251

Aínsa, J. A.; Ryding, N. J.; Hartley, N.; Findlay, K. C.; Bruton, C. J.; Chater, K. F.

2000-01-01

324

Efficient Photodynamic Therapy against Gram-Positive and Gram-Negative Bacteria Using THPTS, a Cationic Photosensitizer Excited by Infrared Wavelength  

PubMed Central

The worldwide rise in the rates of antibiotic resistance of bacteria underlines the need for alternative antibacterial agents. A promising approach to kill antibiotic-resistant bacteria uses light in combination with a photosensitizer to induce a phototoxic reaction. Concentrations of 1, 10 and 100µM of tetrahydroporphyrin-tetratosylat (THPTS) and different incubation times (30, 90 and 180min) were used to measure photodynamic efficiency against two Gram-positive strains of S.aureus (MSSA and MRSA), and two Gram-negative strains of E.coli and P.aeruginosa. We found that phototoxicity of the drug is independent of the antibiotic resistance pattern when incubated in PBS for the investigated strains. Also, an incubation with 100µM THPTS followed by illumination, yielded a 6lg (?99.999%) decrease in the viable numbers of all bacteria strains tested, indicating that the THPTS drug has a high degree of photodynamic inactivation. We then modulated incubation time, photosensitizer concentration and monitored the effect of serum on the THPTS activity. In doing so, we established the conditions to obtain the strongest bactericidal effect. Our results suggest that this new and highly pure synthetic compound should improve the efficiency of photodynamic therapy against multiresistant bacteria and has a significant potential for clinical applications in the treatment of nosocomial infections. PMID:20652031

Schastak, Stanislaw; Ziganshyna, Svitlana; Gitter, Burkhard; Wiedemann, Peter; Claudepierre, Thomas

2010-01-01

325

Diversity of Bacillus-like organisms isolated from deep-sea hypersaline anoxic sediments  

PubMed Central

Background The deep-sea, hypersaline anoxic brine lakes in the Mediterranean are among the most extreme environments on earth, and in one of them, the MgCl2-rich Discovery basin, the presence of active microbes is equivocal. However, thriving microbial communities have been detected especially in the chemocline between deep seawater and three NaCl-rich brine lakes, l'Atalante, Bannock and Urania. By contrast, the microbiota of these brine-lake sediments remains largely unexplored. Results Eighty nine isolates were obtained from the sediments of four deep-sea, hypersaline anoxic brine lakes in the Eastern Mediterranean Sea: l'Atalante, Bannock, Discovery and Urania basins. This culture collection was dominated by representatives of the genus Bacillus and close relatives (90% of all isolates) that were investigated further. Physiological characterization of representative strains revealed large versatility with respect to enzyme activities or substrate utilization. Two third of the isolates did not grow at in-situ salinities and were presumably present as endospores. This is supported by high numbers of endospores in Bannock, Discovery and Urania basins ranging from 3.8 × 105 to 1.2 × 106 g-1 dw sediment. However, the remaining isolates were highly halotolerant growing at salinities of up to 30% NaCl. Some of the novel isolates affiliating with the genus Pontibacillus grew well under anoxic conditions in sulfidic medium by fermentation or anaerobic respiration using dimethylsulfoxide or trimethylamine N-oxide as electron acceptor. Conclusion Some of the halophilic, facultatively anaerobic relatives of Bacillus appear well adapted to life in this hostile environment and suggest the presence of actively growing microbial communities in the NaCl-rich, deep-sea brine-lake sediments. PMID:18541011

Sass, Andrea M; McKew, Boyd A; Sass, Henrik; Fichtel, Jörg; Timmis, Kenneth N; McGenity, Terry J

2008-01-01

326

Efficacy of Bacillus thuringiensis, Paecilomyces marquandii,and Streptomyces costaricanus with and without Organic Amendments against Meloidogyne hapla Infecting Lettuce  

PubMed Central

Chitin, wheat mash, or brewery compost were incorporated into unfumigated and methyl bromide-fumigated organic soils placed in microplots formed from cylindrical drainage tiles (0.25 m-diam. clay tile). After 3 weeks, Meloidogyne hapla and cell or spore suspensions of Bacillus thuringiensis, Paecilomyces marquandii, and Streptomyces costaricanus were individually added to the soils of designated microplots. A B. thuringiensis + S. costaricanus combination was also tested. Lettuce seedlings, cv. Montello, were transplanted into the soils 3 to 4 days later. All the bacterial and fungal antagonists applied without a soil amendment, except the B. thuringiensis + S. costaricanus treatment, reduced root galling and increased lettuce head weight in the unfumigated organic soil, but not in the fumigated soil. All three amendments were also effective against M. hapla and reduced root galling in fumigated and unfumigated soils. Wheat mash amendment increased lettuce head weight in the unfumigated soil. In general, no antagonist × amendment interaction was detected. Soil populations of B. thuringiensis were maintained at ?4.0 log10 colony-forming units/g organic soil during the first 14 days after planting. However, viable cells of B. thuringiensis were not detected after 49 days. PMID:19270951

Chen, J.; Abawi, G. S.; Zuckerman, B. M.

2000-01-01

327

Biofilm formation by Bacillus subtilis: new insights into regulatory strategies and assembly mechanisms  

PubMed Central

Biofilm formation is a social behaviour that generates favourable conditions for sustained survival in the natural environment. For the Gram-positive bacterium Bacillus subtilis the process involves the differentiation of cell fate within an isogenic population and the production of communal goods that form the biofilm matrix. Here we review recent progress in understanding the regulatory pathways that control biofilm formation and highlight developments in understanding the composition, function and structure of the biofilm matrix. PMID:24988880

Cairns, Lynne S; Hobley, Laura; Stanley-Wall, Nicola R

2014-01-01

328

Biodegradation of feather waste by extracellular keratinases and gelatinases from Bacillus spp  

Microsoft Academic Search

In this study, three feather degrading bacterial strains were isolated from agroindustrial residues from a Brazilian poultry\\u000a farm. Three Gram-positive, spore-forming, rod-shaped bacteria and were identified as B. subtilis 1271, B. licheniformis 1269 and B. cereus 1268 using biochemical, physiologic and molecular methods. These Bacillus spp. strains grew and produced keratinases and peptidases using chicken feather as the sole source

Ana Maria Mazotto; Ana Cristina N. de Melo; Andrew Macrae; Alexandre Soares Rosado; Raquel Peixoto; Sabrina M. L. Cedrola; Sônia Couri; Russolina B. Zingali; Ana Lúcia V. Villa; Leon Rabinovitch; Jeane Q. Chaves; Alane B. Vermelho

2011-01-01

329

16S ribosomal RNA analysis of Filibacter limicola indicates a close relationship to the genus Bacillus.  

PubMed

The phylogenetic relationship of the Gram-negative, filamentous gliding bacterium Filibacter limicola was analysed by 16S rRNA oligonucleotide cataloguing. In contrast to the proposed membership of this asporogenous species in the Flexibacteriaceae, Filibacter limicola clusters phylogenetically with the Gram-positive eubacteria Bacillus pasteurii, Sporosarcina ureae and the asporogenous species Planococcus citreus. The genetic relationship is supported by several common phenotypic properties. PMID:2415672

Clausen, V; Jones, J G; Stackebrandt, E

1985-10-01

330

TraA and its N-terminal relaxase domain of the Gram-positive plasmid pIP501 show specific oriT binding and behave as dimers in solution  

PubMed Central

TraA is the DNA relaxase encoded by the broad-host-range Grampositive plasmid pIP501. It is the second relaxase to be characterized from plasmids originating from Gram-positive organisms. Full-length TraA (654 amino acids) and the N-terminal domain (246 amino acids), termed TraAN246, were expressed as 6×His-tagged fusions and purified. Small-angle X-ray scattering and chemical cross-linking proved that TraAN246 and TraA form dimers in solution. Both proteins revealed oriTpIP501 (origin of transfer of pIP501) cleavage activity on supercoiled plasmid DNA in vitro. oriT binding was demonstrated by electrophoretic mobility shift assays. Radiolabelled oligonucleotides covering different parts of oriTpIP501 were subjected to binding with TraA and TraAN246. The KD of the protein–DNA complex encompassing the inverted repeat, the nick site and an additional 7 bases was found to be 55 nM for TraA and 26 nM for TraAN246. The unfolding of both protein constructs was monitored by measuring the change in the CD signal at 220 nm upon temperature change. The unfolding transition of both proteins occurred at approx. 42 °C. CD spectra measured at 20 °C showed 30% ?-helix and 13% ?-sheet for TraA, and 27% ?-helix and 18% ?-sheet content for the truncated protein. Upon DNA binding, an enhanced secondary structure content and increased thermal stability were observed for the TraAN246 protein, suggesting an induced-fit mechanism for the formation of the specific relaxase–oriT complex. PMID:15554903

Kopec, Jolanta; Bergmann, Alexander; Fritz, Gerhard; Grohmann, Elisabeth; Keller, Walter

2004-01-01

331

Comparative Analysis of Antimicrobial Activities of Valinomycin and Cereulide, the Bacillus cereus Emetic Toxin?  

PubMed Central

Cereulide and valinomycin are highly similar cyclic dodecadepsipeptides with potassium ionophoric properties. Cereulide, produced by members of the Bacillus cereus group, is known mostly as emetic toxin, and no ecological function has been assigned. A comparative analysis of the antimicrobial activity of valinomycin produced by Streptomyces spp. and cereulide was performed at a pH range of pH 5.5 to pH 9.5, under anaerobic and aerobic conditions. Both compounds display pH-dependent activity against selected Gram-positive bacteria, including Staphylococcus aureus, Listeria innocua, Listeria monocytogenes, Bacillus subtilis, and Bacillus cereus ATCC 10987. Notably, B. cereus strain ATCC 14579 and the emetic B. cereus strains F4810/72 and A529 showed reduced sensitivity to both compounds, with the latter two strains displaying full resistance to cereulide. Both compounds showed no activity against the selected Gram-negative bacteria. Antimicrobial activity against Gram-positive bacteria was highest at alkaline pH values, where the membrane potential (??) is the main component of the proton motive force (PMF). Furthermore, inhibition of growth was observed in both aerobic and anaerobic conditions. Determination of the ??, using the membrane potential probe DiOC2(3) (in the presence of 50 mM KCl) in combination with flow cytometry, demonstrated for the first time the ability of cereulide to dissipate the ?? in sensitive Gram-positive bacteria. The putative role of cereulide production in the ecology of emetic B. cereus is discussed. PMID:21357430

Tempelaars, Marcel H.; Rodrigues, Susana; Abee, Tjakko

2011-01-01

332

Modelling the influence of pH and organic acid types on thermal inactivation of Bacillus cereus spores.  

PubMed

A model is proposed to describe the influence pH on the heat resistance of Bacillus cereus spores. In addition to the conventional z value, the effect of pH on the thermal resistance of spores is characterised by a z(pH) value (z(pH) is the distance of pH from a reference pH*, which leads to a 10-fold reduction of D value). The type of organic acid used for acidifying the heating medium, influences the z(pH) value. For nine organic acids, a linear relationship between the calculated z(pH) value and its lower acid pKa is observed. This relationship showed that the acid form (dissociated or undissociated) modifies the thermal spore resistance in addition to the H+ ion. The influence of acetic acid concentration on the D value at pH 7 shows the protective effect of the dissociated acid form on the heat resistance of spores. The acid concentration in the medium modified the heat resistance of spore and the z(pH) value. PMID:11205951

Leguerinel, I; Mafart, P

2001-01-22

333

Structural Basis for the De-N-acetylation of Poly-?-1,6-N-acetyl-d-glucosamine in Gram-positive Bacteria.  

PubMed

Exopolysaccharides are required for the development and integrity of biofilms produced by a wide variety of bacteria. In staphylococci, partial de-N-acetylation of the exopolysaccharide poly-?-1,6-N-acetyl-d-glucosamine (PNAG) by the extracellular protein IcaB is required for biofilm formation. To understand the molecular basis for PNAG de-N-acetylation, the structure of IcaB from Ammonifex degensii (IcaBAd) has been determined to 1.7 Å resolution. The structure of IcaBAd reveals a (?/?)7 barrel common to the family four carbohydrate esterases (CE4s) with the canonical motifs circularly permuted. The metal dependence of IcaBAd is similar to most CE4s showing the maximum rates of de-N-acetylation with Ni(2+), Co(2+), and Zn(2+). From docking studies with ?-1,6-GlcNAc oligomers and structural comparison to PgaB from Escherichia coli, the Gram-negative homologue of IcaB, we identify Arg-45, Tyr-67, and Trp-180 as key residues for PNAG binding during catalysis. The absence of these residues in PgaB provides a rationale for the requirement of a C-terminal domain for efficient deacetylation of PNAG in Gram-negative species. Mutational analysis of conserved active site residues suggests that IcaB uses an altered catalytic mechanism in comparison to other characterized CE4 members. Furthermore, we identified a conserved surface-exposed hydrophobic loop found only in Gram-positive homologues of IcaB. Our data suggest that this loop is required for membrane association and likely anchors IcaB to the membrane during polysaccharide biosynthesis. The work presented herein will help guide the design of IcaB inhibitors to combat biofilm formation by staphylococci. PMID:25359777

Little, Dustin J; Bamford, Natalie C; Pokrovskaya, Varvara; Robinson, Howard; Nitz, Mark; Howell, P Lynne

2014-12-26

334

Adsorption and Fenton regeneration of SBA-15 for di-(2-ethylhexyl) phthalate leached from PVC sheets by Gram-positive strains LHM1 and LHM2  

NASA Astrophysics Data System (ADS)

Bioleaching of Di-(2-ethylhexyl) phthalate (DEHP) from PVC sheets was studied with newly isolated, Gram-positive strains LHM1 and LHM2 capable of growing on DEHP as the sole carbon source. According to 16S rRNA gene analysis, strains LHM1 and LHM2 were closely related (more than 97% similarity) to Chryseomicrobium imtechense MW 10(T) and Lysinibacillus fusiformis NBRC 15717(T), respectively. The biodeteriorated PVC sheets by the strains LHM1 and LHM2 had thicker biofilm development. Despite their metabolic capability of degrading DEHP as the sole carbon source, the strains LHM1 and LHM2 did not metabolize all DEHP leached out of the PVC sheets. Thermogravimetric analysis (TGA) showed that the biodeterioration by strains LHM1 and LHM2 resulted in less amount of and weakly bonded DEHP present in PVC sheets, in comparison to the virgin PVC sheet. Therefore, PVC biodeterioration by strains LHM1 and LHM2 might play an important role in stability of PVC sheets and fate and effect of leached DEHP on the environmental receptors. In response to this, an advanced adsorption with SBA-15 was assessed as a potential alternative DEHP remediation with arsenic as a co-contaminant. SBA-15 had an excellent arsenic adsorption showing >90% arsenic removal when arsenic was present as a singular contaminant. Adsorption effectiveness was irrelevant to the solid/liquid (S/L) ratio. However, when arsenic was present together with DEHP, arsenic adsorption to bare SBA-15 was reduced by 10 - 40%, with lesser S/L ratio having greater arsenic removal. On the contrary, bare SBA-15 only adsorbed ~30% of DEHP on average. When DEHP was present as a co-solute with arsenic, DEHP adsorption to bare SBA-15 was increased. For SBA-15 regeneration, adsorbed arsenic was recovered with EDTA elution, whereas adsorbed DEHP was destructed with Fenton oxidation.

Hwang, S.; Latorre, I.; Caban, M.; Soto, B.; Montalvo-Rodríguez, R.; Hernández-Maldonado, A.

2012-12-01

335

3,5-Dioxopyrazolidines, Novel Inhibitors of UDP-N- Acetylenolpyruvylglucosamine Reductase (MurB) with Activity against Gram-Positive Bacteria  

PubMed Central

A series of 3,5-dioxopyrazolidines was identified as novel inhibitors of UDP-N-acetylenolpyruvylglucosamine reductase (MurB). Compounds 1 to 3, which are 1,2-bis(4-chlorophenyl)-3,5-dioxopyrazolidine-4-carboxamides, inhibited Escherichia coli MurB, Staphyloccocus aureus MurB, and E. coli MurA with 50% inhibitory concentrations (IC50s) in the range of 4.1 to 6.8 ?M, 4.3 to 10.3 ?M, and 6.8 to 29.4 ?M, respectively. Compound 4, a C-4-unsubstituted 1,2-bis(3,4-dichlorophenyl)-3,5-dioxopyrazolidine, showed moderate inhibitory activity against E. coli MurB, S. aureus MurB, and E. coli MurC (IC50s, 24.5 to 35 ?M). A fluorescence-binding assay indicated tight binding of compound 3 with E. coli MurB, giving a dissociation constant of 260 nM. Structural characterization of E. coli MurB was undertaken, and the crystal structure of a complex with compound 4 was obtained at 2.4 Å resolution. The crystal structure indicated the binding of a compound at the active site of MurB and specific interactions with active-site residues and the bound flavin adenine dinucleotide cofactor. Peptidoglycan biosynthesis studies using a strain of Staphylococcus epidermidis revealed reduced peptidoglycan biosynthesis upon incubation with 3,5-dioxopyrazolidines, with IC50s of 0.39 to 11.1 ?M. Antibacterial activity was observed for compounds 1 to 3 (MICs, 0.25 to 16 ?g/ml) and 4 (MICs, 4 to 8 ?g/ml) against gram-positive bacteria including methicillin-resistant S. aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae. PMID:16436710

Yang, Youjun; Severin, Anatoly; Chopra, Rajiv; Krishnamurthy, Girija; Singh, Guy; Hu, William; Keeney, David; Svenson, Kristine; Petersen, Peter J.; Labthavikul, Pornpen; Shlaes, David M.; Rasmussen, Beth A.; Failli, Amedeo A.; Shumsky, Jay S.; Kutterer, Kristina M. K.; Gilbert, Adam; Mansour, Tarek S.

2006-01-01

336

Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.  

PubMed

The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n?=?2), Oceanobacillus picturae (n?=?5), and Oceanobacillus iheyensis (n?=?15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological and/or industrial processes. PMID:25227686

D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

2014-12-01

337

Treatment of Amaranthus cruentus with chemical and biological inducers of resistance has contrasting effects on fitness and protection against compatible Gram positive and Gram negative bacterial pathogens.  

PubMed

Amaranthus cruentus (Ac) plants were treated with the synthetic systemic acquired resistance (SAR) inducer benzothiadiazole (BTH), methyl jasmonate (MeJA) and the incompatible pathogen, Pseudomonas syringae pv. syringae (Pss), under greenhouse conditions. The treatments induced a set of marker genes in the absence of pathogen infection: BTH and Pss similarly induced genes coding for pathogenesis-related and antioxidant proteins, whereas MeJA induced the arginase, LOX2 and amarandin 1 genes. BTH and Pss were effective when tested against the Gram negative pathogen Ps pv. tabaci (Pst), which was found to have a compatible interaction with grain amaranth. The resistance response appeared to be salicylic acid-independent. However, resistance against Clavibacter michiganensis subsp. michiganensis (Cmm), a Gram positive tomato pathogen also found to infect Ac, was only conferred by Pss, while BTH increased susceptibility. Conversely, MeJA was ineffective against both pathogens. Induced resistance against Pst correlated with the rapid and sustained stimulation of the above genes, including the AhPAL2 gene, which were expressed both locally and distally. The lack of protection against Cmm provided by BTH, coincided with a generalized down-regulation of defense gene expression and chitinase activity. On the other hand, Pss-treated Ac plants showed augmented expression levels of an anti-microbial peptide gene and, surprisingly, of AhACCO, an ethylene biosynthetic gene associated with susceptibility to Cmm in tomato, its main host. Pss treatment had no effect on productivity, but compromised growth, whereas MeJA reduced yield and harvest index. Conversely, BTH treatments led to smaller plants, but produced significantly increased yields. These results suggest essential differences in the mechanisms employed by biological and chemical agents to induce SAR in Ac against bacterial pathogens having different infection strategies. This may determine the outcome of a particular plant-pathogen interaction, leading to resistance or susceptibility, as in Cmm-challenged Ac plants previously induced with Pss or BTH, respectively. PMID:24913050

Casarrubias-Castillo, Kena; Martínez-Gallardo, Norma A; Délano-Frier, John P

2014-07-01

338

Transcriptome-Wide Analyses of 5?-Ends in RNase J Mutants of a Gram-Positive Pathogen Reveal a Role in RNA Maturation, Regulation and Degradation  

PubMed Central

RNA decay and maturation have in recent years been recognised as major regulatory mechanisms in bacteria. In contrast to Escherichia coli, the Firmicute (Gram-positive) bacteria often do not encode the well-studied endonuclease RNase E, but instead rely on the endonucleases RNase Y, RNase J1 and RNase J2, of which the latter two have additionally been shown to have 5? to 3? exonucleolytic activity. We have previously demonstrated that these RNases could be deleted individually in the pathogenic Firmicute Staphylococcus aureus; however, we here present that, outside a narrow permissive window of growth conditions, deleting one or both of the RNase J genes presents serious difficulties for the cell. Moreover, an active site mutant of RNase J1 behaved like a deletion, whereas no phenotypes were detected for the RNase J2 active site mutant. Furthermore, in order to study the in vivo enzymatic activity of RNase J1 and J2, a method was developed to map the exact 5?-ends of mature and processed RNA, on a global scale. An enrichment of 5? RNA ends could be seen in the RNase J mutants, suggesting that their exonucleolytic activity is crucial for normal degradation of bulk RNA. Using the data to examine specific RNAs, we demonstrated that RNase J activity is needed for correct 5? maturation of both the 16S rRNA and the RNase P ribozyme, and can also inactivate the latter, possibly as quality control. Additional examples show that RNase J perform initial cleavages, apparently competing with ribosomes for access to mRNAs. The novel 5? mapping assay offers an exceptionally detailed view of RNase activity, and reveals that the roles of RNase J proteins are diverse, ranging from maturation and post-transcriptional regulation to degradation. PMID:24586213

Linder, Patrick; Lemeille, Sylvain; Redder, Peter

2014-01-01

339

The Bacteroides mobilizable transposon Tn4555 integrates by a site-specific recombination mechanism similar to that of the gram-positive bacterial element Tn916.  

PubMed Central

The Bacteroides mobilizable transposon Tn4555 is a 12.2-kb molecule that encodes resistance to cefoxitin. Conjugal transposition is hypothesized to occur via a circular intermediate and is stimulated by coresident tetracycline resistance elements and low levels of tetracycline. In this work, the ends of the transposon were identified and found to consist of 12-bp imperfect inverted repeats, with an extra base at one end. In the circular form, the ends were separated by a 6-bp "coupling sequence" which was associated with either the left or the right transposon terminus when the transposon was inserted into the chromosome. Tn4555 does not duplicate its target site upon insertion. Using a conjugation-based transposition assay, we showed that the coupling sequence originated from 6 bases of genomic DNA flanking either side of the transposon prior to excision. Tn4555 preferentially transposed into a 589-bp genomic locus containing a 207-bp direct repeat. Integration occurred before or after the repeated sequence, with one integration site between the two repeats. These observations are consistent with a transposition model based on site-specific recombination. In the bacteriophage lambda model for site-specific recombination, the bacteriophage recombines with the Escherichia coli chromosome via a 7-bp "crossover" region. We propose that the coupling sequence of Tn4555 is analogous in function to the crossover region of lambda but that unlike the situation in lambda, recombination occurs between regions of nonhomologous DNA. This ability to recombine into divergent target sites is also a feature of the gram-positive bacterial transposon Tn916. PMID:9098073

Tribble, G D; Parker, A C; Smith, C J

1997-01-01

340

Functional organization of the riboflavin biosynthesis operon from Bacillus subtilis SHgw.  

PubMed

We have sequenced 6006 bp DNA of a region from the Bacillus subtilis SHgw chromosome known to contain riboflavin biosynthesis genes (rib gene cluster, 210 degrees on the B. subtilis genetic map). Five of the seven open reading frames found within the sequence are shown to represent the genes ribG, ribB, ribA, ribH and ribTD. The calculated molecular masses for the putative translation products are 39,305, 23,481, 44,121, 16,287 and 14,574 daltons respectively. The five rib genes are transcribed as a polycistronic 4277 nucleotide messenger RNA. The steady-state level of the transcript is negatively regulated by riboflavin. A cis-acting element necessary for regulation was mapped by analysis of constitutive mutations within the 5' untranslated region of the operon. The element is at least 48 bp in length and does not bear obvious similarity to well defined prokaryotic regulatory elements. The molecular mechanism of regulation remains unknown, but the data presented argue against regulation by attenuation. PMID:8159171

Mironov, V N; Kraev, A S; Chikindas, M L; Chernov, B K; Stepanov, A I; Skryabin, K G

1994-01-01

341

Mercury Resistance in Bacillus cereus RC607: Transcriptional Organization and Two New Open Reading Frames  

PubMed Central

The chromosomal mercury resistance determinant of Bacillus cereus RC607 confers resistance to inorganic mercury and to organomercurials. The order of genes in the completed mercury resistance determinant is operator-promoter 1 (O/P1) merR1 merT open reading frame 3 (ORF3) ORF4 merA O/P2 merR2 merB2 merB1. The previously undetermined 1-kb DNA sequence between the merA and merB1 genes includes two significant ORFs, whose predicted protein products are homologous with MerR (the transcriptional regulator) and MerB (the organomercurial lyase enzyme). Two transcriptional start sites (promoters), O/P1 at the beginning of the determinant and O/P2 immediately upstream of the sixth ORF, the newly identified merR2, were mapped by reverse transcriptase (RT) primer extension. A long 6.3-kb mRNA traversing all eight ORFs was shown by RT-PCR. Growth sensitivity measurements in liquid media and cellular mercury volatization assays characterized inducibility and differences in functional activity in B. cereus RC607 and after cloning of the mer determinant into plasmids in Escherichia coli. PMID:10559175

Gupta, Amit; Phung, Le T.; Chakravarty, Leena; Silver, Simon

1999-01-01

342

Bacillus lehensis sp. nov., an alkalitolerant bacterium isolated from soil.  

PubMed

A Gram-positive, endospore-forming, alkalitolerant bacterial strain, designated MLB2T, was isolated from soil from Leh, India, and was subjected to a polyphasic taxonomic study. The strain exhibited phenotypic properties that included chemotaxonomic characteristics consistent with its classification in the genus Bacillus. Growth was observed at pH 7.0-11.0, but not at pH 6.0. The DNA G+C content was 41.4 mol%. The highest level of 16S rRNA gene sequence similarity was with Bacillus oshimensis JCM 12663T (98.8 %). However, DNA-DNA hybridization experiments indicated low levels of genomic relatedness with the type strains of B. oshimensis (62 %), Bacillus patagoniensis (55 %), Bacillus clausii (51 %) and Bacillus gibsonii (34 %), the species with which strain MLB2T formed a coherent cluster (based on the results of the phylogenetic analysis). On the basis of the phenotypic characteristics and genotypic distinctiveness of strain MLB2T, it should be classified within a novel species of Bacillus, for which the name Bacillus lehensis sp. nov. is proposed. The type strain is MLB2T (=MTCC 7633T=JCM 13820T). PMID:17267957

Ghosh, A; Bhardwaj, M; Satyanarayana, T; Khurana, M; Mayilraj, S; Jain, R K

2007-02-01

343

Bacillus odysseyi sp. nov., a round-spore-forming bacillus isolated from the Mars Odyssey spacecraft  

NASA Technical Reports Server (NTRS)

A round-spore-forming Bacillus species that produces an exosporium was isolated from the surface of the Mars Odyssey spacecraft. This novel species has been characterized on the basis of phenotypic traits, 16S rDNA sequence analysis and DNA-DNA hybridization. According to the results of these analyses, this strain belongs to the genus Bacillus and is a Gram-positive, aerobic, rod-shaped, endospore-forming eubacterium. Ultrathin sections of the spores showed the presence of an exosporium, spore coat, cortex and core. 16S rDNA sequence similarities between this strain, Bacillus fusiformis and Bacillus silvestris were approximately 96% and DNA-DNA reassociation values with these two bacilli were 23 and 17%, respectively. Spores of the novel species were resistant to desiccation, H2O2 and UV and gamma radiation. Of all strains tested, the spores of this strain were the most consistently resistant and survived all of the challenges posed, i.e. exposure to conditions of desiccation (100% survival), H2O2 (26% survival), UV radiation (10% survival at 660 J m(-2)) and gamma radiation (0.4% survival). The name proposed for this novel bacterium is Bacillus odysseyi sp. nov.; the type strain is 34hs-1T (=ATCC PTA-4993T=NRRL B-30641T=NBRC 100172T).

La Duc, Myron T.; Satomi, Masataka; Venkateswaran, Kasthuri

2004-01-01

344

The nitrate-ammonifying and nosZ-carrying bacterium Bacillus vireti is a potent source and sink for nitric and nitrous oxide under high nitrate conditions.  

PubMed

Several Gram-positive bacteria carry genes for anaerobic reduction of NO3(-) via NO2(-) to NH4(+) or gaseous nitrogen compounds, but the processes are understudied for these organisms. Here, we present results from a whole-genome analysis of the soil bacterium Bacillus vireti and a phenotypic characterization of intermediate and end-products, formed under anoxic conditions in the presence of NO3(-). Bacillus vireti has a versatile metabolism. It produces acetate, formate, succinate and lactate from fermentation and performs dissimilatory nitrate reduction via NO2(-) to ammonium (DNRA) using NrfA, while NirB may detoxify NO2(-) in the cytoplasm. Moreover, it produces NO from an unknown source and reduces it via N2O to N2 using two enzymes connected to denitrification: an unusual NO reductase, qCuA Nor encoded by cbaA, and a z-type N2O reductase, encoded by nosZ. In batch cultures, B.?vireti reduced all NO3(-) to NO2(-) before the NO2(-) was reduced further. The quantities of all products varied with the initial NO3(-) concentration. With 5?mM NO3(-) , 90% was reduced to NH4 (+) while with ??20?mM NO3(-), 50% was reduced to NO, N2O and N2. This organism is thus an aggressive NO2(-) accumulator and may act as a net source and sink of NO and N2O. PMID:24708037

Mania, Daniel; Heylen, Kim; van Spanning, Rob J M; Frostegård, Asa

2014-10-01

345

Solvent tolerant marine bacterium Bacillus aquimaris secreting organic solvent stable alkaline cellulase  

Microsoft Academic Search

The organic solvent tolerant bacteria with their physiological abilities to decontaminate the organic pollutants have potentials to secrete extracellular enzymes of commercial importance. Of the 19 marine bacterial isolates examined for their solvent tolerance at 10vol.% concentration, one had the significant tolerance and showed a relative growth yield of 86% for acetone, 71% for methanol, 52% for benzene, 35% for

Nitin Trivedi; Vishal Gupta; Manoj Kumar; Puja Kumari; C. R. K. Reddy; Bhavanath Jha

2011-01-01

346

Production of the Novel Two-Peptide Lantibiotic Lichenicidin by Bacillus licheniformis DSM 13  

PubMed Central

Background Lantibiotics are small microbial peptide antibiotics that are characterized by the presence of the thioether amino acids lanthionine and methyllanthionine. Lantibiotics possess structural genes which encode inactive prepeptides. During maturation, the prepeptide undergoes posttranslational modifications including the introduction of rare amino acids as lanthionine and methyllanthione as well as the proteolytic removal of the leader. The structural gene (lanA) as well as the other genes which are involved in lantibiotic modification (lanM, lanB, lanC, lanP), regulation (lanR, lanK), export (lanT(P)) and immunity (lanEFG) are organized in biosynthetic gene clusters. Methodology/Principal Findings Sequence comparisons in the NCBI database showed that Bacillus licheniformis DSM 13 harbours a putative lantibiotic gene cluster which comprises two structural genes (licA1, licA2) and two modification enzymes (licM1, licM2) in addition to 10 ORFs that show sequence similarities to proteins involved in lantibiotic production. A heat labile antimicrobial activity was detected in the culture supernatant and a heat stabile activity was present in the isopropanol cell wash extract of this strain. In agar well diffusion assays both fractions exhibited slightly different activity spectra against Gram-positive bacteria. In order to demonstrate the connection between the lantibiotic gene cluster and one of the antibacterial activities, two Bacillus licheniformis DSM 13 mutant strains harbouring insertions in the structural genes of the modification enzymes licM1 and licM2 were constructed. These strains were characterized by a loss of activity in the isopropanol extract and substractive MALDI-TOF predicted masses of 3020.6 Da and 3250.6 Da for the active peptides. Conclusions/Significance In conclusion, B. licheniformis DSM 13 produces an antimicrobial substance that represents the two-peptide lantibiotic lichenicidin and that shows activity against a wide range of Gram-positive bacteria including methicillin resistant Staphylococcus aureus strains. PMID:19707558

Dischinger, Jasmin; Josten, Michaele; Szekat, Christiane; Sahl, Hans-Georg; Bierbaum, Gabriele

2009-01-01

347

Screening micro-organisms for cadmium absorption from aqueous solution and cadmium absorption properties of Arthrobacter nicotianae.  

PubMed

To obtain basic information on how microbial cells absorb cadmium from aqueous solution, we examined cadmium absorption in various micro-organisms. Of 51 micro-organism strains tested, we found that some Gram-positive bacteria, such as, Arthrobacter nicotianae and Bacillus subtilis, and some actinomycetes, such as, Streptomyces flavoviridis and S. levoris were highly capable of absorbing cadmium from an aqueous solution. A. nicotianae absorbed the largest amount of cadmium, over 800 ?mol cadmium per gram of dry wt. cells. However, cadmium absorption by A. nicotianae was affected by the solution pH, cadmium concentration, and cell density. The absorption of cadmium was very rapid. Some factors that affected cadmium absorption by A. nicotianae cells were also discussed. PMID:25273147

Tsuruta, Takehiko; Umenai, Daishi; Hatano, Tomonobu; Hirajima, Tsuyoshi; Sasaki, Keiko

2014-10-01

348

Bacillus subtilis Spore Display of Laccase for Evolution under Extreme Conditions of High Concentrations of Organic Solvent.  

PubMed

Protein libraries were displayed on the spore coat of Bacillus subtilis, and this method was demonstrated as a tool for directed evolution under extreme conditions. Escherichia coli, yeast, and phage display suffer from protein folding, and viability issues. On the other hand, spores avoid folding concerns by the natural sporulation process, and they remain viable under harsh chemical and physical environments. The naturally occurring B. subtilis spore coat protein, CotA, was evolved for improved activity under conditions of high organic solvent concentrations. CotA is a laccase, which is a copper-containing oxidase enzyme. A CotA library was expressed on the spore coat, and ?3000 clones were screened at 60% dimethyl sulfoxide (DMSO). A Thr480Ala variant (Thr480Ala-CotA) was identified that was 2.38-fold more active than the wild-type CotA. In addition, Thr480Ala-CotA was more active with different concentrations of DMSO ranging from 0 to 70%. The mutant was also found to be more active compared with the wild-type CotA in different concentrations of methanol, ethanol, and acetonitrile. PMID:25392937

Jia, Han; Lee, Frederick S; Farinas, Edgardo T

2014-12-01

349

Effect of pfkA chromosomal interruption on growth, sporulation, and production of organic acids in Bacillus subtilis.  

PubMed

Phosphofructokinase (Pfk) plays a key role in the regulation of carbohydrate metabolism. Its activity can be used as an indicator of glycolytic flux in a microorganism. We have cloned and characterized the pfkA gene from Bacillus subtilis, which encodes the enzyme phosphofructokinase. This gene was insertionally inactivated at the chromosomal level in a wild type strain and in strains lacking the PEP:sugar phosphotranferase system (PTS). Although the pykA gene is immediately downstream of the pfkA gene, forming a constitutive operon in B. subtilis, the pyruvate kinase activity was not altered in the pfkA mutant. The inactivation of the pfkA gene had a strong impact on the growth of the B. subtilis wild type strain and PTS mutants in Spizizen's minimal media and Schaeffer's sporulation media. Pfk inactivation was also reflected by the timing and percentage of sporulation of the wild type and PTS mutants in sporulation media as well as in the production of organic by-products (pyruvate, lactate, and acetate). PMID:20473954

Muñoz-Márquez, María-Enriqueta; Ponce-Rivas, Elizabeth

2010-06-01

350

Preparation, characterization, and antimicrobial activity of quaternized chitosan/organic montmorillonite nanocomposites.  

PubMed

Quaternized chitosan/layered silicate nanocomposite was prepared by simple solution-mixing in aqueous media. Montmorillonite (MMT) modified with cetyltrimethyl ammonium bromide was used as an organically modified layered silicate. XRD and TEM analyses respectively confirmed that silicate layers of MMT were intercalated and nicely distributed in quaternized chitosan matrix in despite of the high content of MMT (25-50 wt %). The interactions between the quaternized chitosan macromolecules and MMT in aqueous media were analyzed using FTIR, XRD, and zeta-potential measurements. Antimicrobial studies showed that the nanocomposites could strongly inhibit the growth of a wide variety of microorganisms, including Gram-positive bacteria, Gram-negative bacteria, and fungi; more importantly, they exhibited good antimicrobial capacity in whichever medium, in weak acid, water, or weak base. As the amount of MMT increased, the nanocomposites had better inhibitory effect on microorganisms, especially Gram-positive bacteria. The lowest minimum inhibition concentration (MIC) value of the nanocomposites against Staphylococcus aureus and Bacillus subtilis were less than 0.00313% (w/v) under all the conditions. The adsorption action of MMT on bacteria was simply discussed via SEM images. The results revealed that the strong antimicrobial of the nanocomposites may be attributed to the fine dispersion and the interaction between quaternized chitosan and MMT. PMID:17618481

Wang, Xiaoying; Du, Yumin; Yang, Jianhong; Tang, Yufeng; Luo, Jiwen

2008-02-01

351

Bacillus thuringiensis Conjugation in Simulated Microgravity  

NASA Astrophysics Data System (ADS)

Spaceflight experiments have suggested a possible effect of microgravity on the plasmid transfer among strains of the Gram-positive Bacillus thuringiensis, as opposed to no effect recorded for Gram-negative conjugation. To investigate these potential effects in a more affordable experimental setup, three ground-based microgravity simulators were tested: the Rotating Wall Vessel (RWV), the Random Positioning Machine (RPM), and a superconducting magnet. The bacterial conjugative system consisted in biparental matings between two B. thuringiensis strains, where the transfer frequencies of the conjugative plasmid pAW63 and its ability to mobilize the nonconjugative plasmid pUB110 were assessed. Specifically, potential plasmid transfers in a 0-g position (simulated microgravity) were compared to those obtained under 1-g (normal gravity) condition in each device. Statistical analyses revealed no significant difference in the conjugative and mobilizable transfer frequencies between the three different simulated microgravitational conditions and our standard laboratory condition. These important ground-based observations emphasize the fact that, though no stimulation of plasmid transfer was observed, no inhibition was observed either. In the case of Gram-positive bacteria, this ability to exchange plasmids in weightlessness, as occurs under Earth's conditions, should be seen as particularly relevant in the scope of spread of antibiotic resistances and bacterial virulence.

Beuls, Elise; van Houdt, Rob; Leys, Natalie; Dijkstra, Camelia; Larkin, Oliver; Mahillon, Jacques

2009-10-01

352

Association of RNAs with Bacillus subtilis Hfq  

PubMed Central

The prevalence and characteristics of small regulatory RNAs (sRNAs) have not been well characterized for Bacillus subtilis, an important model system for Gram-positive bacteria. However, B. subtilis was recently found to synthesize many candidate sRNAs during stationary phase. In the current study, we performed deep sequencing on Hfq-associated RNAs and found that a small subset of sRNAs associates with Hfq, an enigmatic RNA-binding protein that stabilizes sRNAs in Gram-negatives, but whose role is largely unknown in Gram-positive bacteria. We also found that Hfq associated with antisense RNAs, antitoxin transcripts, and many mRNA leaders. Several new candidate sRNAs and mRNA leader regions were also discovered by this analysis. Additionally, mRNA fragments overlapping with start or stop codons associated with Hfq, while, in contrast, relatively few full-length mRNAs were recovered. Deletion of hfq reduced the intracellular abundance of several representative sRNAs, suggesting that B. subtilis Hfq-sRNA interactions may be functionally significant in vivo. In general, we anticipate this catalog of Hfq-associated RNAs to serve as a resource in the functional characterization of Hfq in B. subtilis. PMID:23457461

Dambach, Michael; Irnov, Irnov; Winkler, Wade C.

2013-01-01

353

Optimization of physical factors affecting the production of thermo-stable organic solvent-tolerant protease from a newly isolated halo tolerant Bacillus subtilis strain Rand  

PubMed Central

Background Many researchers have reported on the optimization of protease production; nevertheless, only a few have reported on the optimization of the production of organic solvent-tolerant proteases. Ironically, none has reported on thermostable organic solvent-tolerant protease to date. The aim of this study was to isolate the thermostable organic solvent-tolerant protease and identify the culture conditions which support its production. The bacteria of genus Bacillus are active producers of extra-cellular proteases, and the thermostability of enzyme production by Bacillus species has been well-studied by a number of researchers. In the present study, the Bacillus subtilis strain Rand was isolated from the contaminated soil found in Port Dickson, Malaysia. Results A thermostable organic solvent-tolerant protease producer had been identified as Bacillus subtilis strain Rand, based on the 16S rRNA analysis conducted, as well as the morphological characteristics and biochemical properties. The production of the thermostable organic solvent-tolerant protease was optimized by varying various physical culture conditions. Inoculation with 5.0% (v/v) of (AB600 = 0.5) inoculum size, in a culture medium (pH 7.0) and incubated for 24 h at 37°C with 200 rpm shaking, was the best culture condition which resulted in the maximum growth and production of protease (444.7 U/ml; 4042.4 U/mg). The Rand protease was not only stable in the presence of organic solvents, but it also exhibited a higher activity than in the absence of organic solvent, except for pyridine which inhibited the protease activity. The enzyme retained 100, 99 and 80% of its initial activity, after the heat treatment for 30 min at 50, 55, and 60°C, respectively. Conclusion Strain Rand has been found to be able to secrete extra-cellular thermostable organic solvent-tolerant protease into the culture medium. The protease exhibited a remarkable stability towards temperature and organic solvent. This unique property makes it attractive and useful to be used in industrial applications. PMID:19356254

Abusham, Randa A; Rahman, Raja Noor Zaliha RA; Salleh, Abu Bakar; Basri, Mahiran

2009-01-01

354

Enzymatic Manganese(II) Oxidation by Metabolically Dormant Spores of Diverse Bacillus Species  

PubMed Central

Bacterial spores are renowned for their longevity, ubiquity, and resistance to environmental insults, but virtually nothing is known regarding whether these metabolically dormant structures impact their surrounding chemical environments. In the present study, a number of spore-forming bacteria that produce dormant spores which enzymatically oxidize soluble Mn(II) to insoluble Mn(IV) oxides were isolated from coastal marine sediments. The highly charged and reactive surfaces of biogenic metal oxides dramatically influence the oxidation and sorption of both trace metals and organics in the environment. Prior to this study, the only known Mn(II)-oxidizing sporeformer was the marine Bacillus sp. strain SG-1, an extensively studied bacterium in which Mn(II) oxidation is believed to be catalyzed by a multicopper oxidase, MnxG. Phylogenetic analysis based on 16S rRNA and mnxG sequences obtained from 15 different Mn(II)-oxidizing sporeformers (including SG-1) revealed extensive diversity within the genus Bacillus, with organisms falling into several distinct clusters and lineages. In addition, active Mn(II)-oxidizing proteins of various sizes, as observed in sodium dodecyl sulfate-polyacrylamide electrophoresis gels, were recovered from the outer layers of purified dormant spores of the isolates. These are the first active Mn(II)-oxidizing enzymes identified in spores or gram-positive bacteria. Although extremely resistant to denaturation, the activities of these enzymes were inhibited by azide and o-phenanthroline, consistent with the involvement of multicopper oxidases. Overall, these studies suggest that the commonly held view that bacterial spores are merely inactive structures in the environment should be revised. PMID:11823231

Francis, Chris A.; Tebo, Bradley M.

2002-01-01

355

Causative organisms of post-traumatic endophthalmitis: a 20-year retrospective study  

PubMed Central

Background A wide range of organisms that enter the eye following ocular trauma can cause endophthalmitis. This study was to investigate the spectrum of pathogens and antibiotic susceptibility of bacterial isolates from a large cohort of post-traumatic endophthalmitis cases. Methods A retrospective study of 912 post-traumatic endophthalmitis patients treated at a tertiary eye-care center in China was performed. The associations between risk factors and the most common isolated organisms were investigated by Chi square Test. The percent susceptibilities for the first 10 years (1990–1999) and the second 10 years (2000–2009) were compared by Chi square test. p < 0.05 was considered statistically significant. Results Three-hundred-forty-seven (38.1%) cases of endophthalmitis were culture-positive, and 11 (3.2%) showed mixed infections (Gram-negative bacilli and fungi), yielding a total of 358 microbial pathogens. Culture proven organisms included 150 (41.9%) Gram-positive cocci, 104 (29.1%) Gram-negative bacilli, 44 (12.3%) Gram-positive bacilli, and 60 (16.8%) fungi. The coagulase-negative staphylococcal (CNS) species S. epidermidis (21.8%) and S. saprophyticus (12.0%) were the predominant pathogens, followed by Bacillus subtilis (8.7%), Pseudomonas aeruginosa (7.8%), and Escherichia coli (6.4%). Delayed repair over 24 h (p < 0.001) and metallic injury (p < 0.01) were significantly associated with positive culture of CNS. The most frequent fungal species were Aspergillus (26/60), followed by yeast-like fungi (18/60). P. aeruginosa was relatively sensitive to ciprofloxacin (83.3%), cefoperazone (75%), tobramycin (75%), cefuroxime (75%), and ceftazidime (75%) during the second decade. Multi-drug resistance was observed in the predominant Gram-negative bacteria. Conclusion We identified a broad spectrum of microbes causing post-traumatic endophthalmitis, with Gram-positive cocci the most frequently identified causative organism, followed by Bacillus species, fungi, and mixed infections. CNS infection was statistically associated with delayed repair and metallic injury. Variation in antibiotic susceptibility was observed among isolated bacteria and between different periods. Ciprofloxacin and ceftazidime in the first and second decades of the study, respectively, showed the highest activity against bacterial post-traumatic endophthalmitis. For infections caused by P. aeruginosa, a combination therapy of ciprofloxacin, tobramycin, and one of the cephalosporins might provide optimal coverage according to data from the second decade. PMID:24661397

2014-01-01

356

Characterization of Bacillus Probiotics Available for Human Use  

Microsoft Academic Search

Bacillus species (Bacillus cereus, Bacillus clausii, Bacillus pumilus) carried in five commercial probiotic products consisting of bacterial spores were characterized for potential attributes (colonization, immuno- stimulation, and antimicrobial activity) that could account for their claimed probiotic properties. Three B. cereus strains were shown to persist in the mouse gastrointestinal tract for up to 18 days postadministration, demonstrating that these organisms

L. H. Duc; Huynh A. Hong; Teresa M. Barbosa; Adriano O. Henriques

2004-01-01

357

Comparison of the Vitek Gram-Positive Susceptibility 106 Card and the MRSA-Screen Latex Agglutination Test for Determining Oxacillin Resistance in Clinical Bloodstream Isolates of Staphylococcus aureus  

Microsoft Academic Search

The Vitek automated susceptibility testing system with a modified Gram-Positive Susceptibility (GPS) 106 Card (bioMerieux Vitek, Inc., Hazelwood, Mo.) and a rapid slide latex agglutination test (MRSA-Screen; Denka Seiken Co., Ltd., Tokyo, Japan) were evaluated for their ability to detect oxacillin resistance in Staphylococcus aureus. The oxacillin-salt agar screen (OS) test, the reference broth microdilution method, and the detection of

T. Yamazumi; S. A. Marshall; W. W. Wilke; D. J. Diekema; M. A. Pfaller; R. N. Jones

2001-01-01

358

Comparative In Vitro Activities of SMT19969, a New Antimicrobial Agent, against Clostridium difficile and 350 Gram-Positive and Gram-Negative Aerobic and Anaerobic Intestinal Flora Isolates  

PubMed Central

The comparative in vitro activity of SMT19969, a novel, narrow-spectrum, nonabsorbable agent, was studied against 50 ribotype-defined Clostridium difficile strains, 174 Gram-positive and 136 Gram-negative intestinal anaerobes, and 40 Gram-positive aerobes. SMT19969 was one dilution more active against C. difficile isolates (MIC range, 0.125 to 0.5 ?g/ml; MIC90, 0.25 ?g/ml), including ribotype 027 strains, than fidaxomicin (range, 0.06 to 1 ?g/ml; MIC90, 0.5 ?g/ml) and two to six dilutions lower than either vancomycin or metronidazole. SMT19969 and fidaxomicin were generally less active against Gram-negative anaerobes, especially the Bacteroides fragilis group species, than vancomycin and metronidazole, suggesting that SMT19969 has a lesser impact on the normal intestinal microbiota that maintain colonization resistance. SMT19969 showed limited activity against other Gram-positive anaerobes, including Bifidobacteria species, Eggerthella lenta, Finegoldia magna, and Peptostreptococcus anaerobius, with MIC90s of >512, >512, 64, and 64 ?g/ml, respectively. Clostridium species showed various levels of susceptibility, with C. innocuum being susceptible (MIC90, 1 ?g/ml) and C. ramosum and C. perfringens being nonsusceptible (MIC90, >512 ?g/ml). Activity against Lactobacillus spp. (range, 0.06 to >512 ?g/ml; MIC90, >512 ?g/ml) was comparable to that of fidaxomicin and varied by species and strain. Gram-positive aerobic cocci (Staphylococcus aureus, Enterococcus faecalis, E. faecium, and streptococci) showed high SMT19969 MIC90 values (128 to >512 ?g/ml). PMID:23877700

Citron, Diane M.; Tyrrell, Kerin L.; Merriam, C. Vreni

2013-01-01

359

Impact of Domestication in the Production of the Class II Lanthipeptide Lichenicidin by Bacillus licheniformis I89.  

PubMed

Investigation on lantibiotics biosynthesis constitutes an emergent field, since these molecules have demonstrated a great potential to replace the so-called "traditional antibiotics". The adaptation of bacteria to laboratory conditions (domestication) is an unpredictable phenomenon, which sometimes is associated with the loss of important biotechnological properties. In this study, the domestication of Bacillus licheniformis was associated with the production of the lantibiotic lichenicidin, a two-peptide lantibiotic with activity against several Gram-positive bacteria. PMID:25399299

Caetano, Tânia; Süssmuth, Roderich D; Mendo, Sónia

2015-03-01

360

Cloning and enhancing production of a detergent- and organic-solvent-resistant nattokinase from Bacillus subtilis VTCC-DVN-12-01 by using an eight-protease-gene-deficient Bacillus subtilis WB800  

PubMed Central

Background Nattokinases/Subtilisins (EC 3.4.21.62) belong to the second large family of serine proteases, which gain significant attention and play important role in many biotechnology processes. Thus, a number of nattokinases/subtilisins from various Bacillus species, especially from B. subtilis strains, extensively have been investigated to understand their biochemical and physical properties as well as to improve the production for industrial application. The purpose of this study was to clone a nattokinase gene from Bacillus subtilis strain VTCC-DVN-12-01, enhance its production in B. subtilis WB800, which is deficient in eight extracellular proteases and characterize its physicochemical properties for potential application in organic synthesis and detergent production. Results A gene coding for the nattokinase (Nk) from B. subtilis strain VTCC-DVN-12-01 consisted of an ORF of 1146 nucleotides, encoding a pre-pro-protein enzyme (30-aa pre-signal peptide, 76-aa pro-peptide and 275-aa mature protein with a predicted molecular mass of 27.7 kDa and pI 6.6). The nattokinase showed 98-99% identity with other nattokinases/subtilisins from B. subtilis strains in GenBank. Nk was expressed in B. subtilis WB800 under the control of acoA promoter at a high level of 600 mg protein per liter culture medium which is highest yield of proteins expressed in any extracellular-protease-deficient B. subtilis system till date. Nk was purified to homogeneity with 3.25 fold purification, a specific activity of 12.7 U/mg, and a recovery of 54.17%. The purified Nk was identified by MALDI-TOF mass spectrometry through three peptides, which showed 100% identity to corresponding peptides of the B. subtilis nattokinase (CAC41625). An optimal activity for Nk was observed at 65°C and pH 9. The nattokinase was stable at temperature up to 50°C and in pH range of 5–11 and retained more than 85% of its initial activity after incubation for 1 h. Mg2+ activated Nk up to 162% of its activity. The addition of Triton X-100, Tween 20, and Tween 80 showed an activation of Nk up to 141% of its initial activity but SDS strongly inhibited. The enzyme was highly resistant to organic solvents. Conclusions Our findings demonstrated that an eight-protease-gene-deficient Bacillus subtilis WB800 could overproduce the nattokinase from B. subtilis VTCC-DVN-12-01. Due to high resistance to detergents and organic solvents of this nattokinase, it could be potentially applied in organic synthesis and detergent production. PMID:24021098

2013-01-01

361

Diamide Triggers Mainly S Thiolations in the Cytoplasmic Proteomes of Bacillus subtilis and Staphylococcus aureus? †  

PubMed Central

Glutathione constitutes a key player in the thiol redox buffer in many organisms. However, the gram-positive bacteria Bacillus subtilis and Staphylococcus aureus lack this low-molecular-weight thiol. Recently, we identified S-cysteinylated proteins in B. subtilis after treatment of cells with the disulfide-generating electrophile diamide. S cysteinylation is thought to protect protein thiols against irreversible oxidation to sulfinic and sulfonic acids. Here we show that S thiolation occurs also in S. aureus proteins after exposure to diamide. We further analyzed the formation of inter- and intramolecular disulfide bonds in cytoplasmic proteins using diagonal nonreducing/reducing sodium dodecyl sulfate gel electrophoresis. However, only a few proteins were identified that form inter- or intramolecular disulfide bonds under control and diamide stress conditions in B. subtilis and S. aureus. Depletion of the cysteine pool was concomitantly measured in B. subtilis using a metabolomics approach. Thus, the majority of reversible thiol modifications that were previously detected by two-dimensional gel fluorescence-based thiol modification assay are most likely based on S thiolations. Finally, we found that a glutathione-producing B. subtilis strain which expresses the Listeria monocytogenes gshF gene did not show enhanced oxidative stress resistance compared to the wild type. PMID:19837798

Pöther, Dierk-Christoph; Liebeke, Manuel; Hochgräfe, Falko; Antelmann, Haike; Becher, Dörte; Lalk, Michael; Lindequist, Ulrike; Borovok, Ilya; Cohen, Gerald; Aharonowitz, Yair; Hecker, Michael

2009-01-01

362

Physical interactions between tricarboxylic acid cycle enzymes in Bacillus subtilis: evidence for a metabolon.  

PubMed

The majority of all proteins of a living cell is active in complexes rather than in an isolated way. These protein-protein interactions are of high relevance for many biological functions. In addition to many well established protein complexes an increasing number of protein-protein interactions, which form rather transient complexes has recently been discovered. The formation of such complexes seems to be a common feature especially for metabolic pathways. In the Gram-positive model organism Bacillus subtilis, we identified a protein complex of three citric acid cycle enzymes. This complex consists of the citrate synthase, the isocitrate dehydrogenase, and the malate dehydrogenase. Moreover, fumarase and aconitase interact with malate dehydrogenase and with each other. These five enzymes catalyze sequential reaction of the TCA cycle. Thus, this interaction might be important for a direct transfer of intermediates of the TCA cycle and thus for elevated metabolic fluxes via substrate channeling. In addition, we discovered a link between the TCA cycle and gluconeogenesis through a flexible interaction of two proteins: the association between the malate dehydrogenase and phosphoenolpyruvate carboxykinase is directly controlled by the metabolic flux. The phosphoenolpyruvate carboxykinase links the TCA cycle with gluconeogenesis and is essential for B. subtilis growing on gluconeogenic carbon sources. Only under gluconeogenic growth conditions an interaction of these two proteins is detectable and disappears under glycolytic growth conditions. PMID:20933603

Meyer, Frederik M; Gerwig, Jan; Hammer, Elke; Herzberg, Christina; Commichau, Fabian M; Völker, Uwe; Stülke, Jörg

2011-01-01

363

Three biotechnical processes using Ashbya gossypii, Candida famata, or Bacillus subtilis compete with chemical riboflavin production.  

PubMed

Chemical riboflavin production, successfully used for decades, is in the course of being replaced by microbial processes. These promise to save half the costs, reduce waste and energy requirements, and use renewable resources like sugar or plant oil. Three microorganisms are currently in use for industrial riboflavin production. The hemiascomycetes Ashbya gossypii, a filamentous fungus, and Candida famata, a yeast, are naturally occurring overproducers of this vitamin. To obtain riboflavin production with the gram-positive bacterium Bacillus subtilis requires at least the deregulation of purine synthesis and a mutation in a flavokinase/FAD-synthetase. It is common to all three organisms that riboflavin production is recognizable by the yellow color of the colonies. This is an important tool for the screening of improved mutants. Antimetabolites like itaconate, which inhibits the isocitrate lyase in A. gossypii, tubercidin, which inhibits purine biosynthesis in C. famata, or roseoflavin, a structural analog of riboflavin used for B. subtilis, have been applied successfully for mutant selections. The production of riboflavin by the two fungi seems to be limited by precursor supply, as was concluded from feeding and gene-overexpression experiments. Although flux studies in B. subtilis revealed an increase both in maintenance metabolism and in the oxidative part of the pentose phosphate pathway, the major limitation there seems to be the riboflavin pathway. Multiple copies of the rib genes and promoter replacements are necessary to achieve competitive productivity. PMID:10855708

Stahmann, K P; Revuelta, J L; Seulberger, H

2000-05-01

364

Use of titanium dioxide nanoparticles biosynthesized by Bacillus mycoides in quantum dot sensitized solar cells  

PubMed Central

Background One of the major challenges of nanotechnology during the last decade has been the development of new procedures to synthesize nanoparticles. In this context, biosynthetic methods have taken hold since they are simple, safe and eco-friendly. Results In this study, we report the biosynthesis of TiO2 nanoparticles by an environmental isolate of Bacillus mycoides, a poorly described Gram-positive bacterium able to form colonies with novel morphologies. This isolate was able to produce TiO2 nanoparticles at 37°C in the presence of titanyl hydroxide. Biosynthesized nanoparticles have anatase polymorphic structure, spherical morphology, polydisperse size (40–60 nm) and an organic shell as determined by UV–vis spectroscopy, TEM, DLS and FTIR, respectively. Also, conversely to chemically produced nanoparticles, biosynthesized TiO2 do not display phototoxicity. In order to design less expensive and greener solar cells, biosynthesized nanoparticles were evaluated in Quantum Dot Sensitized Solar Cells (QDSSCs) and compared with chemically produced TiO2 nanoparticles. Solar cell parameters such as short circuit current density (ISC) and open circuit voltage (VOC) revealed that biosynthesized TiO2 nanoparticles can mobilize electrons in QDSSCs similarly than chemically produced TiO2. Conclusions Our results indicate that bacterial extracellular production of TiO2 nanoparticles at low temperatures represents a novel alternative for the construction of green solar cells. PMID:25027643

2014-01-01

365

Molecular Approaches to Improve the Insecticidal Activity of Bacillus thuringiensis Cry Toxins  

PubMed Central

Bacillus thuringiensis (Bt) is a gram-positive spore-forming soil bacterium that is distributed worldwide. Originally recognized as a pathogen of the silkworm, several strains were found on epizootic events in insect pests. In the 1960s, Bt began to be successfully used to control insect pests in agriculture, particularly because of its specificity, which reflects directly on their lack of cytotoxicity to human health, non-target organisms and the environment. Since the introduction of transgenic plants expressing Bt genes in the mid-1980s, numerous methodologies have been used to search for and improve toxins derived from native Bt strains. These improvements directly influence the increase in productivity and the decreased use of chemical insecticides on Bt-crops. Recently, DNA shuffling and in silico evaluations are emerging as promising tools for the development and exploration of mutant Bt toxins with enhanced activity against target insect pests. In this report, we describe natural and in vitro evolution of Cry toxins, as well as their relevance in the mechanism of action for insect control. Moreover, the use of DNA shuffling to improve two Bt toxins will be discussed together with in silico analyses of the generated mutations to evaluate their potential effect on protein structure and cytotoxicity. PMID:25123558

Lucena, Wagner A.; Pelegrini, Patrícia B.; Martins-de-Sa, Diogo; Fonseca, Fernando C. A.; Gomes, Jose E.; de Macedo, Leonardo L. P.; da Silva, Maria Cristina M.; Oliveira, Raquel S.; Grossi-de-Sa, Maria F.

2014-01-01

366

DegU co-ordinates multicellular behaviour exhibited by Bacillus subtilis.  

PubMed

Unicellular organisms use a variety of mechanisms to co-ordinate activity within a community and accomplish complex multicellular processes. Because some of the processes that are exhibited by one species can be physiologically incompatible, it raises the question of how entry into these different pathways is regulated. In the Gram-positive bacterium Bacillus subtilis, genetic competence, swarming motility, biofilm formation, complex colony architecture and protease production are all regulated by the response regulator DegU. DegU appears to integrate environmental signals and co-ordinate multicellular behaviours that are subsequently manifested at different levels of DegU phosphorylation. Data are presented which indicate that: (i) swarming motility is activated by very low levels of DegU approximately P that can be generated independently from its cognate sensor kinase DegS; (ii) complex colony architecture is activated by low levels of DegU approximately P that are produced in a DegS-dependent manner to activate transcription of yvcA, a novel gene required for complex colony architecture; and (iii) high levels of DegU approximately P inhibit complex colony architecture and swarming motility but are required prior to the activation of exoprotease production. A model is proposed to explain why such a system may have evolved within B. subtilis to control these multicellular processes through a single regulator. PMID:17590234

Verhamme, Daniël T; Kiley, Taryn B; Stanley-Wall, Nicola R

2007-07-01

367

Divergence of protein-coding capacity and regulation in the Bacillus cereus sensu lato group  

PubMed Central

Background The Bacillus cereus sensu lato group contains ubiquitous facultative anaerobic soil-borne Gram-positive spore-forming bacilli. Molecular phylogeny and comparative genome sequencing have suggested that these organisms should be classified as a single species. While clonal in nature, there do not appear to be species-specific clonal lineages, excepting B. anthracis, in spite of the wide array of phenotypes displayed by these organisms. Results We compared the protein-coding content of 201 B. cereus sensu lato genomes to characterize differences and understand the consequences of these differences on biological function. From this larger group we selected a subset consisting of 25 whole genomes for deeper analysis. Cluster analysis of orthologous proteins grouped these genomes into five distinct clades. Each clade could be characterized by unique genes shared among the group, with consequences for the phenotype of each clade. Surprisingly, this population structure recapitulates our recent observations on the divergence of the generalized stress response (SigB) regulons in these organisms. Divergence of the SigB regulon among these organisms is primarily due to the placement of SigB-dependent promoters that bring genes from a common gene pool into/out of the SigB regulon. Conclusions Collectively, our observations suggest the hypothesis that the evolution of these closely related bacteria is a consequence of two distinct processes. Horizontal gene transfer, gene duplication/divergence and deletion dictate the underlying coding capacity in these genomes. Regulatory divergence overlays this protein coding reservoir and shapes the expression of both the unique and shared coding capacity of these organisms, resulting in phenotypic divergence. Data from other organisms suggests that this is likely a common pattern in prokaryotic evolution. PMID:25350501

2014-01-01

368

Complete nucleotide sequence of the S10-spc operon of phytoplasma: gene organization and genetic code resemble those of Bacillus subtilis.  

PubMed

An 11.4-kbp region of genomic DNA containing the complete S10-spc operon was constructed by an integrative mapping technique with eight plasmid vectors carrying ribosomal protein sequences from onion yellows phytoplasma. Southern hybridization analysis indicated that phytoplasmal S10-spc is a single-copy operon. This is the first complete S10-spc operon of a phytoplasma to be reported, although only a part of six serial genes of the S10 operon is reported previously. The operon has a context of 5'-rps10, rpl3, rpl4, rpl23, rpl2, rps19, rpl22, rps3, rpl16, rpl29, rps17, rpl14, rpl24, rpl5, rps14, rps8, rpl6, rpl18, rps5, rpl30, rpl15, SecY-3', and is composed of 21 ribosomal protein subunit genes and a SecY protein translocase subunit gene. Resembling Bacillus, this operon contains an rpl30 gene that other mollicutes (Mycoplasma genitalium, M. pneumoniae, and M. pulmonis) lack. A phylogenetic tree based on the rps3 sequence showed that phytoplasmas are phylogenetically closer to acholeplasmas and bacillus than to mycoplasmas. In the S10-spc operon, translation may start from either a GTG codon or an ATG codon, and stop at a TGA codon, as has been reported for acholeplasmas and bacillus. However, in mycoplasmas, GTG was found as a start codon, and TGA was found not as a stop codon, but instead as a tryptophan codon. These data derived from the gene organization, and the genetic code deviation support the hypothesis that phytoplasmal genes resemble those of acholeplasmas and Bacillus more than those of other mollicutes. PMID:12162807

Miyata, Shin-Ichi; Furuki, Ken-Ichiro; Oshima, Kenro; Sawayanagi, Toshimi; Nishigawa, Hisashi; Kakizawa, Shigeyuki; Jung, Hee-Young; Ugaki, Masashi; Namba, Shigetou

2002-07-01

369

Differential Gene Expression To Investigate the Effect of (5Z)-4-Bromo- 5-(Bromomethylene)-3-Butyl-2(5H)-Furanone on Bacillus subtilis  

PubMed Central

(5Z)-4-Bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone (furanone) from the red marine alga Delisea pulchra was found previously to inhibit the growth, swarming, and biofilm formation of gram-positive bacteria. Using the gram-positive bacterium Bacillus subtilis as a test organism, we observed cell killing by 20 ?g of furanone per ml, while 5 ?g of furanone per ml inhibited growth approximately twofold without killing the cells. To discover the mechanism of this inhibition on a genetic level and to investigate furanone as a novel antibiotic, full-genome DNA microarrays were used to analyze the gene expression profiles of B. subtilis grown with and without 5 ?g of furanone per ml. This agent induced 92 genes more than fivefold (P < 0.05) and repressed 15 genes more than fivefold (P < 0.05). The induced genes include genes involved in stress responses (such as the class III heat shock genes clpC, clpE, and ctsR and the class I heat shock genes groES, but no class II or IV heat shock genes), fatty acid biosynthesis, lichenan degradation, transport, and metabolism, as well as 59 genes with unknown functions. The microarray results for four genes were confirmed by RNA dot blotting. Mutation of a stress response gene, clpC, caused B. subtilis to be much more sensitive to 5 ?g of furanone per ml (there was no growth in 8 h, while the wild-type strain grew to the stationary phase in 8 h) and confirmed the importance of the induction of this gene as identified by the microarray analysis. PMID:15294834

Ren, Dacheng; Bedzyk, Laura A.; Setlow, Peter; England, Dacre F.; Kjelleberg, Staffan; Thomas, Stuart M.; Ye, Rick W.; Wood, Thomas K.

2004-01-01

370

Binary Bacterial Toxins: Biochemistry, Biology, and Applications of Common Clostridium and Bacillus Proteins  

PubMed Central

Certain pathogenic species of Bacillus and Clostridium have developed unique methods for intoxicating cells that employ the classic enzymatic “A-B” paradigm for protein toxins. The binary toxins produced by B. anthracis, B. cereus, C. botulinum, C. difficile, C. perfringens, and C. spiroforme consist of components not physically associated in solution that are linked to various diseases in humans, animals, or insects. The “B” components are synthesized as precursors that are subsequently activated by serine-type proteases on the targeted cell surface and/or in solution. Following release of a 20-kDa N-terminal peptide, the activated “B” components form homoheptameric rings that subsequently dock with an “A” component(s) on the cell surface. By following an acidified endosomal route and translocation into the cytosol, “A” molecules disable a cell (and host organism) via disruption of the actin cytoskeleton, increasing intracellular levels of cyclic AMP, or inactivation of signaling pathways linked to mitogen-activated protein kinase kinases. Recently, B. anthracis has gleaned much notoriety as a biowarfare/bioterrorism agent, and of primary interest has been the edema and lethal toxins, their role in anthrax, as well as the development of efficacious vaccines and therapeutics targeting these virulence factors and ultimately B. anthracis. This review comprehensively surveys the literature and discusses the similarities, as well as distinct differences, between each Clostridium and Bacillus binary toxin in terms of their biochemistry, biology, genetics, structure, and applications in science and medicine. The information may foster future studies that aid novel vaccine and drug development, as well as a better understanding of a conserved intoxication process utilized by various gram-positive, spore-forming bacteria. PMID:15353562

Barth, Holger; Aktories, Klaus; Popoff, Michel R.; Stiles, Bradley G.

2004-01-01

371

Essential Bacillus subtilis genes  

Microsoft Academic Search

To estimate the minimal gene set required to sustain bacterial life in nutritious conditions, we carried out a systematic inactivation of Bacillus subtilis genes. Among 4,100 genes of the organism, only 192 were shown to be indispensable by this or previous work. Another 79 genes were predicted to be essential. The vast majority of essential genes were categorized in relatively

K. Kobayashi; S. D. Ehrlichb; A. Albertini; G. Amati; K. Asaig Arnaudf; M. Arnaud; K. Asai; S. Ashikaga; S. Aymerich; P. Bessieres; F. Boland; S. C. Brignell; S. Bron; K. Bunai; J. Chapuis; L. C. Christiansen; A. Danchin; M. Débarbouillé; E. Dervyn; E. Deuerling; K. Devine; S. K. Devine; O. Dreesen; J. Errington; S. Fillinger; S. J. Foster; Y. Fujita; A. Galizzi; R. Gardan; C. Eschevins; T. Fukushima; K. Haga; C. R. Harwood; M. Hecker; D. Hosoya; M. F. Hullo; H. Kakeshita; D. Karamata; Y. Kasahara; F. Kawamura; K. Koga; P. Koski; R. Kuwana; D. Imamura; M. Ishimaru; S. Ishikawa; I. Ishio; D. Le Coq; A. Masson; C. Mauël; R. Meima; R. P. Mellado; A. Moir; S. Moriya; E. Nagakawa; H. Nanamiya; S. Nakai; P. Nygaard; M. Ogura; T. Ohanan; M. O'Reilly; M. O'Rourke; Z. Pragai; H. M. Pooley; G. Rapoport; J. P. Rawlins; L. A. Rivas; C. Rivolta; A. Sadaie; Y. Sadaie; M. Sarvas; T. Sato; H. H. Saxild; E. Scanlan; W. Schumann; J. F. Seegers; J. Sekiguchi; A. Sekowska; S. J. Seror; M. Simon; P. Stragier; R. Studer; H. Takamatsu; T. Tanaka; M. Takeuchi; H. B. Thomaides; V. Vagner; J. M. van Dijl; K. Watabe; A. Wipat; H. Yamamoto; M. Yamamoto; Y. Yamamoto; K. Yamane; K. Yata; K. Yoshida; H. Yoshikawa; U. Zuber; N. Ogasawara

2003-01-01

372

Efficient isolation and identification of Bacillus cereus group.  

PubMed

Bacillus cereus is a group of ubiquitous facultative anaerobic sporeforming Gram-positive rods commonly found in soil. The spores frequently contaminate a variety of foods, including produce, meat, eggs, and dairy products. Foodborne illnesses associated with toxins produced by B. cereus can result in self-limiting diarrhea or vomiting. Plate enumeration methods recommended by recognized food authorities to detect the presence of B. cereus in potentially contaminated food products do not inhibit other Gram-positive competitive bacteria. This study evaluated the use of Bacara, a new chromogenic agar, as an efficient method to identify and enumerate B. cereus group from food matrixes, even in the presence of background flora. Inclusivity and exclusivity testing was performed using four different selective and differential media for B. cereus, including Mannitol Egg Yolk Polymyxin (MYP), Polymyxin Pyruvate Egg-Yolk Mannitol Bromothymol Blue Agar, Bacillus Chromogenic Media, Brilliance, and Bacara. MYP and Bacara were also used in plate enumeration studies to isolate B. cereus from artificially contaminated foods. PMID:22649932

Tallent, Sandra M; Kotewicz, Kristin M; Strain, Errol A; Bennett, Reginald W

2012-01-01

373

Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Analysis of Gram-Positive, Catalase-Negative Cocci Not Belonging to the Streptococcus or Enterococcus Genus and Benefits of Database Extension  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry with a Bruker Daltonics microflex LT system was applied to 90 well-characterized catalase-negative, Gram-positive cocci not belonging to the streptococci or enterococci. Biotyper version 2.0.43.1 software was used singly or in combination with a database extension generated in this study with 51 collection strains from 16 genera. Most strains were identified by using both databases individually, and some were identified only by applying the combined database. Thus, the methodology is very useful and the generated database extension was helpful. PMID:22403420

Dargis, Rimtas; Hammer, Monja; Justesen, Ulrik Stenz; Nielsen, Xiaohui C.; Kemp, Michael

2012-01-01

374

Bacillus coagulans  

MedlinePLUS

... infection due to the ulcer-causing bacterium Helicobacter pylori. Some people use Bacillus coagulans to prevent respiratory ... difficile colitis. Fighting growth of unwanted bacteria. Helicobacter pylori infection, which causes stomach ulcers. Respiratory infections. Cancer ...

375

Bacillus arsenicoselenatis, sp. nov., and Bacillus selenitireducens, sp. nov.: Two haloalkaliphiles from Mono Lake, California that respire oxyanions of selenium and arsenic  

USGS Publications Warehouse

Two gram-positive anaerobic bacteria (strains E1H and MLS10) were isolated from the anoxic muds of Mono Lake, California, an alkaline, hypersaline, arsenic-rich water body. Both grew by dissimilatory reduction of As(V) to As(III) with the concomitant oxidation of lactate to acetate plus CO2. Bacillus arsenicoselenatis (strain E1H) is a spore-forming rod that also grew by dissimilatory reduction of Se(VI) to Se(IV). Bacillus selenitireducens (strain MLS 10) is a short, non-spore-forming rod that grew by dissimilatory reduction of Se(IV) to Se(0). When the two isolates were cocultured, a complete reduction of Se(VI) to Se(0) was achieved. Both isolates are alkaliphiles and had optimal specific growth rates in the pH range of 8.5-10. Strain E1H had a salinity optimum at 60 g 1-1 NaCl, while strain MLS10 had optimal growth at lower salinities (24-60 g 1-1 NaCl). Both strains have limited abilities to grow with electron donors and acceptors other than those given above. Strain MLS10 demonstrated weak growth as a microaerophile and was also capable of fermentative growth on glucose, while strain E1H is a strict anaerobe. Comparative 16S rRNA gene sequence analysis placed the two isolates with other Bacillus spp. in the low G+C gram-positive group of bacteria.

Switzer, Blum J.; Burns, Bindi A.; Buzzelli, J.; Stolz, J.F.; Oremland, R.S.

1998-01-01

376

Oil biodegradation by Bacillus strains isolated from the rock of an oil reservoir located in a deep-water production basin in Brazil  

Microsoft Academic Search

Sixteen spore forming Gram-positive bacteria were isolated from the rock of an oil reservoir located in a deep-water production basin in Brazil. These strains were identified as belonging to the genus Bacillus using classical biochemical techniques and API 50CH kits, and their identity was confirmed by sequencing of part of the 16S rRNA gene. All strains were tested for oil

Claudia Duarte da Cunha; Alexandre S. Rosado; Gina V. Sebastián; Lucy Seldin; Irene von der Weid

2006-01-01

377

Complex Systems: From Chemistry to Systems Biology Special Feature: Complexity in bacterial cell-cell communication: Quorum signal integration and subpopulation signaling in the Bacillus subtilis phosphorelay  

Microsoft Academic Search

A common form of quorum sensing in Gram-positive bacteria is mediated by peptides that act as phosphatase regulators (Phr) of receptor aspartyl phosphatases (Raps). In Bacillus subtilis, several Phr signals are integrated in sporulation phosphorelay signal transduction. We theoretically demonstrate that the phosphorelay can act as a computational machine performing a sensitive division operation of kinase-encoded signals by quorum-modulated Rap

Ilka B. Bischofs; Joshua A. Hug; Aiwen W. Liu; Denise M. Wolf; Adam P. Arkin

2009-01-01

378

Efficiency of Bacillus coagulans as P biofertilizer to mobilize native soil organic and poorly soluble phosphates and increase crop yield  

Microsoft Academic Search

Bacillus coagulans, a phosphatase- and phytase-producing bacterium was isolated and tested under greenhouse conditions and in the field in a loamy sand soil. Bacterial population build-up and efficiency was compared under sterilized and non-sterilized soil conditions. Exploitation of plant unavailable (poorly soluble) P was higher in sterilized soil, mainly due to an increased bacteria population. A gradual increase in microbial

Brijesh Kumar Yadav; Jagdish Chandra Tarafdar

2011-01-01

379

Aerobic biodegradation of odorous dimethyl disulfide in aqueous medium by isolated Bacillus cereus GIGAN2 and identification of transformation intermediates.  

PubMed

A novel, flagellated, rod-shape, Gram-positive facultative aerobe, was isolated and identified as Bacillus cereus GIGAN2. It can effectively remove model odorous organics dimethyl disulfide (DMDS) in aqueous solution under aerobic conditions. Initial concentration, pH value and temperature played important role in DMDS biodegradation, and up to 100% of 10mgL(-1) of DMDS could be removed within 96h under the optimum conditions (30°C, pH 7.0 and 200rpm) with a maximum biodegradation rate constant of 0.0330h(-1) and minimum half-life of 21.0h, respectively. Three main intermediates were identified using gas chromatography-mass spectrometry during this biodegradation process. Further, a reaction scheme is also proposed to explain the possible DMDS biodegradation mechanism by GIGAN2 based on the above-identified intermediates. Overall, this is the first report to demonstrate a newly isolated strain using high concentrated DMDS as the sole carbon and energy source with high efficiency. PMID:25459868

Liang, Zhishu; An, Taicheng; Li, Guiying; Zhang, Zhengyong

2014-11-01

380

Bacillus arsenicoselenatis, sp. nov., and Bacillus selenitireducens, sp. nov.: two haloalkaliphiles from Mono Lake, California that respire oxyanions of selenium and arsenic  

Microsoft Academic Search

Two gram-positive anaerobic bacteria (strains E1H and MLS10) were isolated from the anoxic muds of Mono Lake, California,\\u000a an alkaline, hypersaline, arsenic-rich water body. Both grew by dissimilatory reduction of As(V) to As(III) with the concomitant\\u000a oxidation of lactate to acetate plus CO2. Bacillus arsenicoselenatis (strain E1H) is a spore-forming rod that also grew by dissimilatory reduction of Se(VI) to

Jodi Switzer Blum; A. Burns Bindi; J. Buzzelli; John F. Stolz; R. S. Oremland

1998-01-01

381

Transcriptional and metabolic responses of Bacillus subtilis to the availability of organic acids: transcription regulation is important but not sufficient to account for metabolic adaptation.  

PubMed

The soil bacterium Bacillus subtilis can use sugars or organic acids as sources of carbon and energy. These nutrients are metabolized by glycolysis, the pentose phosphate pathway, and the Krebs citric acid cycle. While the response of B. subtilis to the availability of sugars is well understood, much less is known about the changes in metabolism if organic acids feeding into the Krebs cycle are provided. If B. subtilis is supplied with succinate and glutamate in addition to glucose, the cells readjust their metabolism as determined by transcriptome and metabolic flux analyses. The portion of glucose-6-phosphate that feeds into the pentose phosphate pathway is significantly increased in the presence of organic acids. Similarly, important changes were detected at the level of pyruvate and acetyl coenzyme A (acetyl-CoA). In the presence of organic acids, oxaloacetate formation is strongly reduced, whereas the formation of lactate is significantly increased. The alsSD operon required for acetoin formation is strongly induced in the presence of organic acids; however, no acetoin formation was observed. The recently discovered phosphorylation of acetolactate decarboxylase may provide an additional level of control of metabolism. In the presence of organic acids, both types of analyses suggest that acetyl-CoA was catabolized to acetate rather than used for feeding the Krebs cycle. Our results suggest that future work has to concentrate on the posttranslational mechanisms of metabolic regulation. PMID:17122393

Schilling, Oliver; Frick, Oliver; Herzberg, Christina; Ehrenreich, Armin; Heinzle, Elmar; Wittmann, Christoph; Stülke, Jörg

2007-01-01

382

Transcriptional and Metabolic Responses of Bacillus subtilis to the Availability of Organic Acids: Transcription Regulation Is Important but Not Sufficient To Account for Metabolic Adaptation? †  

PubMed Central

The soil bacterium Bacillus subtilis can use sugars or organic acids as sources of carbon and energy. These nutrients are metabolized by glycolysis, the pentose phosphate pathway, and the Krebs citric acid cycle. While the response of B. subtilis to the availability of sugars is well understood, much less is known about the changes in metabolism if organic acids feeding into the Krebs cycle are provided. If B. subtilis is supplied with succinate and glutamate in addition to glucose, the cells readjust their metabolism as determined by transcriptome and metabolic flux analyses. The portion of glucose-6-phosphate that feeds into the pentose phosphate pathway is significantly increased in the presence of organic acids. Similarly, important changes were detected at the level of pyruvate and acetyl coenzyme A (acetyl-CoA). In the presence of organic acids, oxaloacetate formation is strongly reduced, whereas the formation of lactate is significantly increased. The alsSD operon required for acetoin formation is strongly induced in the presence of organic acids; however, no acetoin formation was observed. The recently discovered phosphorylation of acetolactate decarboxylase may provide an additional level of control of metabolism. In the presence of organic acids, both types of analyses suggest that acetyl-CoA was catabolized to acetate rather than used for feeding the Krebs cycle. Our results suggest that future work has to concentrate on the posttranslational mechanisms of metabolic regulation. PMID:17122393

Schilling, Oliver; Frick, Oliver; Herzberg, Christina; Ehrenreich, Armin; Heinzle, Elmar; Wittmann, Christoph; Stülke, Jörg

2007-01-01

383

Specific Targeting of the Metallophosphoesterase YkuE to the Bacillus Cell Wall Requires the Twin-arginine Translocation System*  

PubMed Central

The twin-arginine translocation (Tat) pathway is dedicated to the transport of fully folded proteins across the cytoplasmic membranes of many bacteria and the chloroplast thylakoidal membrane. Accordingly, Tat-dependently translocated proteins are known to be delivered to the periplasm of Gram-negative bacteria, the growth medium of Gram-positive bacteria, and the thylakoid lumen. Here, we present the first example of a protein, YkuE of Bacillus subtilis, that is specifically targeted by the Tat pathway to the cell wall of a Gram-positive bacterium. The cell wall binding of YkuE is facilitated by electrostatic interactions. Interestingly, under particular conditions, YkuE can also be targeted to the cell wall in a Tat-independent manner. The biological function of YkuE was so far unknown. Our present studies show that YkuE is a metal-dependent phosphoesterase that preferentially binds manganese and zinc. PMID:22767609

Monteferrante, Carmine G.; Miethke, Marcus; van der Ploeg, René; Glasner, Corinna; van Dijl, Jan Maarten

2012-01-01

384

The Bacillus subtilis cannibalism toxin SDP collapses the proton motive force and induces autolysis  

PubMed Central

Summary Bacillus subtilis SDP is a peptide toxin that kills cells outside the biofilm to support continued growth. We show that purified SDP acts like endogenously produced SDP; it delays sporulation, and the SdpI immunity protein confers SDP resistance. SDP kills a variety of Gram-positive bacteria in the phylum Firmicutes, as well as E. coli with a compromised outer membrane, suggesting it participates in defense of the B. subtilis biofilm against Gram-positive bacteria as well as cannibalism. Fluorescence microscopy reveals that the effect of SDP on cells differs from that of nisin, nigericin, valinomycin and vancomycin-KCl, but resembles that of CCCP, DNP and azide. Indeed, SDP rapidly collapses the PMF as measured by fluorometry and flow cytometry, which triggers the slower process of autolysis. This secondary consequence of SDP treatment is not required for cell death since the autolysin-defective lytC, lytD, lytE, lytF strain fails to be lysed but is nevertheless killed by SDP. Collapsing the PMF is an ideal mechanism for a toxin involved in cannibalism and biofilm defense, since this would incapacitate neighboring cells by inhibiting motility and secretion of proteins and toxins. It would also induce autolysis in many Gram-positive species, thereby releasing nutrients that promote biofilm growth. PMID:22469514

Lamsa, Anne; Liu, Wei-Ting; Dorrestein, Pieter C.; Pogliano, Kit

2013-01-01

385

Antimicrobial susceptibility of gram-negative and gram-positive bacteria collected from countries in Eastern Europe: results from the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) 2004-2010.  

PubMed

The Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) commenced in 2004 to longitudinally monitor global changes in bacterial susceptibility to a suite of antimicrobial agents. The current study examined the activity of tigecycline and comparators against isolates collected across Eastern Europe between 2004 and 2010. Minimum inhibitory concentrations were determined using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methodologies. Antimicrobial susceptibility was determined using CLSI interpretive criteria, and tigecycline susceptibility was established using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. This study included 10 295 Gram-negative and 4611 Gram-positive isolates from 42 centres. Extended-spectrum ?-lactamases (ESBLs) were reported among 15.3% of Escherichia coli and 39.3% of Klebsiella pneumoniae isolates; the highest rates were observed in Turkey (30.9%) and Bulgaria (53.8%), respectively. Imipenem-non-susceptible K. pneumoniae were identified only in Turkey. ESBL-positive E. coli were highly susceptible to imipenem (95.1%), meropenem (98.0%) and tigecycline (98.5%). Most antimicrobials showed poor activity against Acinetobacter baumannii and Pseudomonas aeruginosa. Vancomycin resistance was noted among 0.9% of Enterococcus faecalis and 11.7% of Enterococcus faecium isolates. High rates of susceptibility were reported for linezolid (99.7%) and tigecycline (100%) against E. faecium. One-quarter of Staphylococcus aureus isolates were meticillin-resistant S. aureus (MRSA), with the highest rate in Romania (51.5%); all MRSA were susceptible to linezolid, tigecycline and vancomycin. Antimicrobial resistance is high in much of Eastern Europe, with considerable variation seen among countries. Tigecycline and the carbapenems retain excellent activity against many pathogens from Eastern Europe; linezolid and vancomycin are active against most Gram-positive pathogens. PMID:23590898

Balode, Arta; Punda-Poli?, Volga; Dowzicky, Michael J

2013-06-01

386

Draft Genome Sequence Analysis of a Pseudomonas putida W15Oct28 Strain with Antagonistic Activity to Gram-Positive and Pseudomonas sp. Pathogens  

PubMed Central

Pseudomonas putida is a member of the fluorescent pseudomonads known to produce the yellow-green fluorescent pyoverdine siderophore. P. putida W15Oct28, isolated from a stream in Brussels, was found to produce compound(s) with antimicrobial activity against the opportunistic pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and the plant pathogen Pseudomonas syringae, an unusual characteristic for P. putida. The active compound production only occurred in media with low iron content and without organic nitrogen sources. Transposon mutants which lost their antimicrobial activity had the majority of insertions in genes involved in the biosynthesis of pyoverdine, although purified pyoverdine was not responsible for the antagonism. Separation of compounds present in culture supernatants revealed the presence of two fractions containing highly hydrophobic molecules active against P. aeruginosa. Analysis of the draft genome confirmed the presence of putisolvin biosynthesis genes and the corresponding lipopeptides were found to contribute to the antimicrobial activity. One cluster of ten genes was detected, comprising a NAD-dependent epimerase, an acetylornithine aminotransferase, an acyl CoA dehydrogenase, a short chain dehydrogenase, a fatty acid desaturase and three genes for a RND efflux pump. P. putida W15Oct28 genome also contains 56 genes encoding TonB-dependent receptors, conferring a high capacity to utilize pyoverdines from other pseudomonads. One unique feature of W15Oct28 is also the presence of different secretion systems including a full set of genes for type IV secretion, and several genes for type VI secretion and their VgrG effectors. PMID:25369289

Ye, Lumeng; Hildebrand, Falk; Dingemans, Jozef; Ballet, Steven; Laus, George; Matthijs, Sandra; Berendsen, Roeland; Cornelis, Pierre

2014-01-01

387

Isolation of an organic solvent-tolerant bacterium Bacillus licheniformis PAL05 that is able to secrete solvent-stable lipase.  

PubMed

In this study, seven lipase-producing bacterial strains were isolated from salt-enriched and cattle farm soil samples after incubation in toluene- and benzene-enriched media. One strain (PAL05) showed significantly greater lipase activity on spirit blue agar medium and stability in organic solvents. The positive strain (PAL05) was identified as Bacillus licheniformis by 16S rRNA gene sequencing. Lipase production was optimized in a medium containing glycerol as the carbon source and Tween 80 as an inducer (0.5% glycerol+0.5% Tween 80) at pH 8.0 and a temperature of 30 °C. In addition, the enzyme was moderately halotolerant as it exhibited increased activity in the presence of 2.5% NaCl. Optimized conditions increased the lipase production threefold. Crude lipase retained its activity for 14 days of incubation in the presence of various organic solvents at a level of 25% and 50%. The enzyme was stable at 25% in most solvents; some of the solvents such as hexane, benzene, and ethanol actually stimulated enzyme activity. The organic solvent stability of the lipase produced by the strain PAL05 enables the enzyme to be used as a potential biocatalyst for ester synthesis and other applications in nonaqueous conditions. PMID:24397298

Anbu, Periasamy; Hur, Byung Ki

2014-01-01

388

Plant growth-promoting rhizobacteria strain Bacillus amyloliquefaciens NJN-6-enriched bio-organic fertilizer suppressed Fusarium wilt and promoted the growth of banana plants.  

PubMed

Bacillus amyloliquefaciens strain NJN-6 is an important plant growth-promoting rhizobacteria (PGPR) which can produce secondary metabolites antagonistic to several soil-borne pathogens. In this study, the ability of a bio-organic fertilizer (BIO) containing NJN-6 strain to promote the growth and suppress Fusarium wilt of banana plants was evaluated in a pot experiment. The results showed that the application of BIO significantly decreased the incidence of Fusarium wilt and promoted the growth of banana plants compared to that for the organic fertilizer (OF). To determine the beneficial mechanism of the strain, the colonization of NJN-6 strain on banana roots was evaluated using scanning electron microscopy (SEM). The plant growth-promoting hormones indole-3-acetic acid (IAA) and gibberellin A3 (GA3), along with antifungal lipopeptides iturin A, were detected when the NJN-6 strain was incubated in both Landy medium with additional l-tryptophan and in root exudates of banana plants. In addition, some antifungal volatile organic compounds and iturin A were also detected in BIO. In summary, strain NJN-6 could colonize the roots of banana plants after the application of BIO and produced active compounds which were beneficial for the growth of banana plants. PMID:23541032

Yuan, Jun; Ruan, Yunze; Wang, Beibei; Zhang, Jian; Waseem, Raza; Huang, Qiwei; Shen, Qirong

2013-04-24

389

The respiratory arsenate reductase from Bacillus selenitireducens strain MLS10  

USGS Publications Warehouse

The respiratory arsenate reductase from the Gram-positive, haloalkaliphile, Bacillus selenitireducens strain MLS10 was purified and characterized. It is a membrane bound heterodimer (150 kDa) composed of two subunits ArrA (110 kDa) and ArrB (34 kDa), with an apparent Km for arsenate of 34 ??M and Vmax of 2.5 ??mol min-1 mg-1. Optimal activity occurred at pH 9.5 and 150 g l-1 of NaCl. Metal analysis (inductively coupled plasma mass spectrometry) of the holoenzyme and sequence analysis of the catalytic subunit (ArrA; the gene for which was cloned and sequenced) indicate it is a member of the DMSO reductase family of molybdoproteins. ?? 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

Afkar, E.; Lisak, J.; Saltikov, C.; Basu, P.; Oremland, R.S.; Stolz, J.F.

2003-01-01

390

Bacillus subtilis Biosensor Engineered To Assess Meat Spoilage.  

PubMed

Here, we developed a cell-based biosensor that can assess meat freshness using the Gram-positive model bacterium Bacillus subtilis as a chassis. Using transcriptome analysis, we identified promoters that are specifically activated by volatiles released from spoiled meat. The most strongly activated promoter was PsboA, which drives expression of the genes required for the bacteriocin subtilosin. Next, we created a novel BioBrick compatible integration plasmid for B. subtilis and cloned PsboA as a BioBrick in front of the gene encoding the chromoprotein amilGFP inside this vector. We show that the newly identified promoter could efficiently drive fluorescent protein production in B. subtilis in response to spoiled meat and thus can be used as a biosensor to detect meat spoilage. PMID:25524109

Daszczuk, Alicja; Dessalegne, Yonathan; Drenth, Ismaêl; Hendriks, Elbrich; Jo, Emeraldo; van Lente, Tom; Oldebesten, Arjan; Parrish, Jonathon; Poljakova, Wlada; Purwanto, Annisa A; van Raaphorst, Renske; Boonstra, Mirjam; van Heel, Auke; Herber, Martijn; van der Meulen, Sjoerd; Siebring, Jeroen; Sorg, Robin A; Heinemann, Matthias; Kuipers, Oscar P; Veening, Jan-Willem

2014-12-19

391

Nanoscale imaging of Bacillus thuringiensis flagella using atomic force microscopy  

NASA Astrophysics Data System (ADS)

Because bacterial flagella play essential roles in various processes (motility, adhesion, host interactions, secretion), studying their expression in relation to function is an important challenge. Here, we use atomic force microscopy (AFM) to gain insight into the nanoscale surface properties of two wild-type and four mutant strains of Bacillus thuringiensis exhibiting various levels of flagellation. We show that, unlike AFM in liquid, AFM in air is a simple and reliable approach to observe the morphological details of the bacteria, and to quantify the density and dimensions of their flagella. We found that the amount of flagella expressed by the six strains, as observed at the nanoscale, correlates with their microscopic swarming motility. These observations provide novel information on flagella expression in Gram-positive bacteria and demonstrate the power of AFM in genetic studies for the fast assessment of the phenotypic characteristics of bacterial strains altered in cell surface appendages.Because bacterial flagella play essential roles in various processes (motility, adhesion, host interactions, secretion), studying their expression in relation to function is an important challenge. Here, we use atomic force microscopy (AFM) to gain insight into the nanoscale surface properties of two wild-type and four mutant strains of Bacillus thuringiensis exhibiting various levels of flagellation. We show that, unlike AFM in liquid, AFM in air is a simple and reliable approach to observe the morphological details of the bacteria, and to quantify the density and dimensions of their flagella. We found that the amount of flagella expressed by the six strains, as observed at the nanoscale, correlates with their microscopic swarming motility. These observations provide novel information on flagella expression in Gram-positive bacteria and demonstrate the power of AFM in genetic studies for the fast assessment of the phenotypic characteristics of bacterial strains altered in cell surface appendages. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr11161b

Gillis, Annika; Dupres, Vincent; Delestrait, Guillaume; Mahillon, Jacques; Dufrêne, Yves F.

2012-02-01

392

[Treatment of multiresistant Gram positive endocarditis].  

PubMed

Epidemiology of infectious endocarditis has changed in last decades, endocarditis associated to hospital practices, sustained by multiresistant pathogens being highly increased. In particular, methicillin-resistant staphylococci (MRSA), almost resistant to a number of other antimicrobial classes, often exhibit a reduced susceptibility to vancomycin (h-VISA) with MICs' values more e than 1 mg/l, leading to suppose a reduced therapeutic efficacy of this drug. Thirty-one percent of MRSA strains in the ICE study, which prospectively collected more than 5000 endocarditis, were h-VISA. Daptomycin shows a rapid bactericidal activity against both methicillin-susceptible staphylococcci (MSSA) and MRSA, included those strains with reduced susceptibility to vancomycin. Daptomycin shows a good therapeutic efficacy in staphylococcal endocarditis: MRSA 71%, MSSA 75%. These data suggest the use of daptomycin as initial therapy for treatment of staphylococcal endocarditis, independently from methcillin susceptibility. Some experimental data showed that daptomycin efficacy can diminish, if it is used as a rescue therapy after vancomycin failure. The thickness of bacterial cell-wall recognized in h-VISA strains can represent a physical and electrical barrier to reach both the vancomycin and daptomycin target site. However, the reduced efficacy of daptomycin following vancomycin exposure is an extremely rare event in the clinical practice. It is preferrable to use daptomycin as first line therapy, at a proper dosage. As far as endocarditis is concerned, recent data proved the excellent daptomycin tolerability, with dosages up to 8-10 mg/kg/die. During the treatment, CPK values must be always monitored. For endocarditis sustained by vancomycin-resistant enterococci, therapeutic choices are based on linezolid or ampicillin-ceftriaxone combination therapy. Daptomycin alone, or in association with gentamycin and rifampin, can represent a promising therapeutic alternative. PMID:19838095

Utili, R

2009-07-01

393