Ralstonia solanacearum and R. pseudosolanacearum on Eucalyptus: Opportunists or Primary Pathogens?

PubMed Central

Coutinho, Teresa A.; Wingfield, Michael J.

2017-01-01

Ralstonia solanacearum and R. pseudosolanacearum are well known primary pathogens of herbaceous crops. Reports of wilt caused by these pathogens in tree species are limited other than on Eucalyptus species. Despite the widespread occurrence of so-called bacterial wilt on eucalypts in tropical and sub-tropical parts of Africa, Asia, and the Americas, there remain many contradictions relating to the disease. Our field observations over many years in most regions where the disease occurs on Eucalyptus show that it is always associated with trees that have been subjected to severe stress. The disease is typically diagnosed by immersing cut stems in water and observing bacterial streaming, but the identity of the bacteria within this suspension is seldom considered. To add to the confusion, pathogenicity tests on susceptible species or clones are rarely successful. When they do work, they are on small plants in greenhouse trials. It has become all to easy to attribute Eucalyptus death exclusively to Ralstonia infection. Our data strongly suggest that Ralstonia species and probably other bacteria are latent colonists commonly occurring in healthy and particularly clonally propagated eucalypts. The onset of stress factors provide the bacteria with an opportunity to develop. We believe that the resulting stress weakens the defense systems of the trees allowing Ralstonia and bacterial endophytes to proliferate. Overall our research suggests that R. solanacearum and R. pseudosolanacearum are not primary pathogens of Eucalyptus. Short of clear evidence that they are primary pathogens of Eucalyptus it is inappropriate to attribute this disease solely to infection by Ralstonia species. PMID:28553301

Prophage Rs551 and Its Repressor Gene orf14 Reduce Virulence and Increase Competitive Fitness of Its Ralstonia solanacearum Carrier Strain UW551.

PubMed

Ahmad, Abdelmonim Ali; Stulberg, Michael J; Huang, Qi

2017-01-01

We previously characterized a filamentous lysogenic bacteriophage, ϕRs551, isolated directly from the race 3 biovar 2 phylotype IIB sequevar 1 strain UW551 of Ralstonia solanacearum grown under normal culture conditions. The genome of ϕRs551 was identified with 100% identity in the deposited genomes of 11 race 3 biovar 2 phylotype IIB sequevar 1 strains of R. solanacearum , indicating evolutionary and biological importance, and ORF14 of ϕRs551 was annotated as a putative type-2 repressor. In this study, we determined the effect of the prophage and its ORF14 on the virulence and competitive fitness of its carrier strain UW551 by deleting the orf14 gene only (the UW551 orf14 mutant), and nine of the prophage's 14 genes including orf14 and six out of seven structural genes (the UW551 prophage mutant), respectively, from the genome of UW551. The two mutants were increased in extracellular polysaccharide production, twitching motility, expression of targeted virulence and virulence regulatory genes ( pilT, egl, pehC, hrPB, and phcA ), and virulence, suggesting that the virulence of UW551 was negatively regulated by ϕRs551, at least partially through ORF14. Interestingly, we found that the wt ϕRs551-carrying strain UW551 of R. solanacearum significantly outcompeted the wt strain RUN302 which lacks the prophage in tomato plants co-inoculated with the two strains. When each of the two mutant strains was co-inoculated with RUN302, however, the mutants were significantly out-competed by RUN302 for the same colonization site. Our results suggest that ecologically, ϕRs551 may play an important role by regulating the virulence of and offering a competitive fitness advantage to its carrier bacterial strain for persistence of the bacterium in the environment, which in turn prolongs the symbiotic relationship between the phage ϕRs551 and the R. solanacearum strain UW551. Our study is the first toward a better understanding of the co-existence between a lysogenic phage and

Genome Sequencing of Ralstonia solanacearum CQPS-1, a Phylotype I Strain Collected from a Highland Area with Continuous Cropping of Tobacco

PubMed Central

Liu, Ying; Tang, Yuanman; Qin, Xiyun; Yang, Liang; Jiang, Gaofei; Li, Shili; Ding, Wei

2017-01-01

Ralstonia solanacearum, an agent of bacterial wilt, is a highly variable species with a broad host range and wide geographic distribution. As a species complex, it has extensive genetic diversity and its living environment is polymorphic like the lowland and the highland area, so more genomes are needed for studying population evolution and environment adaptation. In this paper, we reported the genome sequencing of R. solanacearum strain CQPS-1 isolated from wilted tobacco in Pengshui, Chongqing, China, a highland area with severely acidified soil and continuous cropping of tobacco more than 20 years. The comparative genomic analysis among different R. solanacearum strains was also performed. The completed genome size of CQPS-1 was 5.89 Mb and contained the chromosome (3.83 Mb) and the megaplasmid (2.06 Mb). A total of 5229 coding sequences were predicted (the chromosome and megaplasmid encoded 3573 and 1656 genes, respectively). A comparative analysis with eight strains from four phylotypes showed that there was some variation among the species, e.g., a large set of specific genes in CQPS-1. Type III secretion system gene cluster (hrp gene cluster) was conserved in CQPS-1 compared with the reference strain GMI1000. In addition, most genes coding core type III effectors were also conserved with GMI1000, but significant gene variation was found in the gene ripAA: the identity compared with strain GMI1000 was 75% and the hrpII box promoter in the upstream had significantly mutated. This study provided a potential resource for further understanding of the relationship between variation of pathogenicity factors and adaptation to the host environment. PMID:28620361

Genetic diversity reflects geographical origin of Ralstonia solanacearum strains isolated from plant and water sources in Spain.

PubMed

Caruso, Paola; Biosca, Elena G; Bertolini, Edson; Marco-Noales, Ester; Gorris, María Teresa; Licciardello, Concetta; López, María M

2017-12-01

The characterization and intraspecific diversity of a collection of 45 Ralstonia solanacearum strains isolated in Spain from different sources and geographical origins is reported. To test the influence of the site and the host on strain diversity, phenotypic and genotypic analysis were performed by a polyphasic approach. Biochemical and metabolic profiles were compared. Serological relationship was evaluated by Indirect-ELISA using polyclonal and monoclonal antibodies. For genotypic analysis, hrpB and egl DNA sequence analysis, repetitive sequences (rep-PCR), amplified fragment length polymorphism (AFLP) profiles and macrorestriction with XbaI followed by pulsed field gel electrophoresis (PFGE) were performed. The biochemical and metabolic characterization, serological tests, rep-PCR typing and phylogenetic analysis showed that all analysed strains belonged to phylotype II sequevar 1 and shared homogeneous profiles. However, interesting differences among strains were found by AFLP and macrorestriction with XbaI followed by PFGE techniques, some profiles being related to the geographical origin of the strains. Diversity results obtained offer new insights into the biogeography of this quarantine organism and its possible sources and reservoirs in Spain and Mediterranean countries. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

Prophage Rs551 and Its Repressor Gene orf14 Reduce Virulence and Increase Competitive Fitness of Its Ralstonia solanacearum Carrier Strain UW551

PubMed Central

Ahmad, Abdelmonim Ali; Stulberg, Michael J.; Huang, Qi

2017-01-01

We previously characterized a filamentous lysogenic bacteriophage, ϕRs551, isolated directly from the race 3 biovar 2 phylotype IIB sequevar 1 strain UW551 of Ralstonia solanacearum grown under normal culture conditions. The genome of ϕRs551 was identified with 100% identity in the deposited genomes of 11 race 3 biovar 2 phylotype IIB sequevar 1 strains of R. solanacearum, indicating evolutionary and biological importance, and ORF14 of ϕRs551 was annotated as a putative type-2 repressor. In this study, we determined the effect of the prophage and its ORF14 on the virulence and competitive fitness of its carrier strain UW551 by deleting the orf14 gene only (the UW551 orf14 mutant), and nine of the prophage’s 14 genes including orf14 and six out of seven structural genes (the UW551 prophage mutant), respectively, from the genome of UW551. The two mutants were increased in extracellular polysaccharide production, twitching motility, expression of targeted virulence and virulence regulatory genes (pilT, egl, pehC, hrPB, and phcA), and virulence, suggesting that the virulence of UW551 was negatively regulated by ϕRs551, at least partially through ORF14. Interestingly, we found that the wt ϕRs551-carrying strain UW551 of R. solanacearum significantly outcompeted the wt strain RUN302 which lacks the prophage in tomato plants co-inoculated with the two strains. When each of the two mutant strains was co-inoculated with RUN302, however, the mutants were significantly out-competed by RUN302 for the same colonization site. Our results suggest that ecologically, ϕRs551 may play an important role by regulating the virulence of and offering a competitive fitness advantage to its carrier bacterial strain for persistence of the bacterium in the environment, which in turn prolongs the symbiotic relationship between the phage ϕRs551 and the R. solanacearum strain UW551. Our study is the first toward a better understanding of the co-existence between a lysogenic phage and

Necessity of OxyR for the hydrogen peroxide stress response and full virulence in Ralstonia solanacearum.

PubMed

Flores-Cruz, Zomary; Allen, Caitilyn

2011-09-01

The plant pathogen Ralstonia solanacearum, which causes bacterial wilt disease, is exposed to reactive oxygen species (ROS) during tomato infection and expresses diverse oxidative stress response (OSR) genes during midstage disease on tomato. The R. solanacearum genome predicts that the bacterium produces multiple and redundant ROS-scavenging enzymes but only one known oxidative stress response regulator, OxyR. An R. solanacearum oxyR mutant had no detectable catalase activity, did not grow in the presence of 250 μM hydrogen peroxide, and grew poorly in the oxidative environment of solid rich media. This phenotype was rescued by the addition of exogenous catalase, suggesting that oxyR is essential for the hydrogen peroxide stress response. Unexpectedly, the oxyR mutant strain grew better than the wild type in the presence of the superoxide generator paraquat. Gene expression studies indicated that katE, kaG, ahpC1, grxC, and oxyR itself were each differentially expressed in the oxyR mutant background and in response to hydrogen peroxide, suggesting that oxyR is necessary for hydrogen peroxide-inducible gene expression. Additional OSR genes were differentially regulated in response to hydrogen peroxide alone. The virulence of the oxyR mutant strain was significantly reduced in both tomato and tobacco host plants, demonstrating that R. solanacearum is exposed to inhibitory concentrations of ROS in planta and that OxyR-mediated responses to ROS during plant pathogenesis are important for R. solanacearum host adaptation and virulence.

Only One of the Five Ralstonia solanacearum Long-Chain 3-Ketoacyl-Acyl Carrier Protein Synthase Homologues Functions in Fatty Acid Synthesis

PubMed Central

Cheng, Juanli; Ma, Jincheng; Lin, Jinshui; Fan, Zhen-Chuan; Cronan, John E.

2012-01-01

Ralstonia solanacearum, a major phytopathogenic bacterium, causes a bacterial wilt disease in diverse plants. Although fatty acid analyses of total membranes of R. solanacearum showed that they contain primarily palmitic (C16:0), palmitoleic (C16:1) and cis-vaccenic (C18:1) acids, little is known regarding R. solanacearum fatty acid synthesis. The R. solanacearum GMI1000 genome is unusual in that it contains four genes (fabF1, fabF2, fabF3, and fabF4) annotated as encoding 3-ketoacyl-acyl carrier protein synthase II homologues and one gene (fabB) annotated as encoding 3-ketoacyl-acyl carrier protein synthase I. We have analyzed this puzzling apparent redundancy and found that only one of these genes, fabF1, encoded a long-chain 3-ketoacyl-acyl carrier protein synthase, whereas the other homologues did not play roles in R. solanacearum fatty acid synthesis. Mutant strains lacking fabF1 are nonviable, and thus, FabF1 is essential for R. solanacearum fatty acid biosynthesis. Moreover, R. solanacearum FabF1 has the activities of both 3-ketoacyl-acyl carrier protein synthase II and 3-ketoacyl-acyl carrier protein synthase I. PMID:22194290

Transcriptome Analysis of Quantitative Resistance-Specific Response upon Ralstonia solanacearum Infection in Tomato

PubMed Central

Ishihara, Takeaki; Mitsuhara, Ichiro; Takahashi, Hideki; Nakaho, Kazuhiro

2012-01-01

Bacterial wilt, caused by the soil-borne bacterium Ralstonia solanacearum, is a lethal disease of tomato, but the molecular mechanisms of the host resistance responses to R. solanacearum remain unclear. In this study, we report the first work describing the transcriptome of cultivar resistance and susceptible tomato cultivar after inoculation with R. solanacearum. To elucidate the characteristics of resistance early in the interaction, we analyzed microarrays for resistant cultivar LS-89 and susceptible cultivar Ponderosa 1 day after stem inoculation. No change in gene expression was detected for Ponderosa, but expression levels of over 140 genes, including pathogenesis-related, hormone signaling and lignin biosynthesis genes, increased in LS-89. Expression of β-1,3-glucanase genes increased substantially. In an immunohistochemical study, glucanase in LS-89 accumulated in the xylem and pith tissues surrounding xylem vessels filled with R. solanacearum. The expression of these genes also increased in four other resistant cultivars, but changed little in four susceptible cultivars in response to R. solanacearum, suggesting that similar reactions occur in other cultivars. These gene expression profiles will serve as fundamental information to elucidate the molecular mechanisms in the resistance response to R. solanacearum in tomato. PMID:23071630

Characterization of an antibiotic produced by Bacillus subtilis JW-1 that suppresses Ralstonia solanacearum.

PubMed

Kwon, Jae Won; Kim, Shin Duk

2014-01-01

Bacillus subtilis JW-1 was isolated from rhizosphere soil as a potential biocontrol agent of bacterial wilt caused by Ralstonia solanacearum. Seed treatment followed by a soil drench application with this strain resulted in >80% reduction in bacterial wilt disease compared with that in the untreated control under greenhouse conditions. The antibacterial compound produced by strain JW-1 was purified by bioactivity-guided fractionation. Based on mass spectroscopy and nuclear magnetic resonance spectral data ((1)H, (13)C, (1)H-(1)H correlation spectroscopies, rotating frame nuclear Overhauser effect spectroscopy, and heteronuclear multiple-bond correlation spectroscopy), the structure of this compound was elucidated as a cyclic lipopeptide composed of a heptapeptide (Gln-Leu-Leu-Val-Asp-Leu-Leu) bonded to a β-hydroxy-iso-hexadecanoic acid arranged in a lactone ring system.

The in planta transcriptome of Ralstonia solanacearum: conserved physiological and virulence strategies during bacterial wilt of tomato.

PubMed

Jacobs, Jonathan M; Babujee, Lavanya; Meng, Fanhong; Milling, Annett; Allen, Caitilyn

2012-01-01

Plant xylem fluid is considered a nutrient-poor environment, but the bacterial wilt pathogen Ralstonia solanacearum is well adapted to it, growing to 10(8) to 10(9) CFU/g tomato stem. To better understand how R. solanacearum succeeds in this habitat, we analyzed the transcriptomes of two phylogenetically distinct R. solanacearum strains that both wilt tomato, strains UW551 (phylotype II) and GMI1000 (phylotype I). We profiled bacterial gene expression at ~6 × 10(8) CFU/ml in culture or in plant xylem during early tomato bacterial wilt pathogenesis. Despite phylogenetic differences, these two strains expressed their 3,477 common orthologous genes in generally similar patterns, with about 12% of their transcriptomes significantly altered in planta versus in rich medium. Several primary metabolic pathways were highly expressed during pathogenesis. These pathways included sucrose uptake and catabolism, and components of these pathways were encoded by genes in the scrABY cluster. A UW551 scrA mutant was significantly reduced in virulence on resistant and susceptible tomato as well as on potato and the epidemiologically important weed host Solanum dulcamara. Functional scrA contributed to pathogen competitive fitness during colonization of tomato xylem, which contained ~300 µM sucrose. scrA expression was induced by sucrose, but to a much greater degree by growth in planta. Unexpectedly, 45% of the genes directly regulated by HrpB, the transcriptional activator of the type 3 secretion system (T3SS), were upregulated in planta at high cell densities. This result modifies a regulatory model based on bacterial behavior in culture, where this key virulence factor is repressed at high cell densities. The active transcription of these genes in wilting plants suggests that T3SS has a biological role throughout the disease cycle. IMPORTANCE Ralstonia solanacearum is a widespread plant pathogen that causes bacterial wilt disease. It inflicts serious crop losses on tropical

Isolation of Ralstonia solanacearum-infecting bacteriophages from tomato fields in Chiang Mai, Thailand, and their experimental use as biocontrol agents.

PubMed

Bhunchoth, A; Phironrit, N; Leksomboon, C; Chatchawankanphanich, O; Kotera, S; Narulita, E; Kawasaki, T; Fujie, M; Yamada, T

2015-04-01

To isolate and characterize novel bacteriophages infecting the phytopathogen, Ralstonia solanacearum, and to evaluate them as resources with potential uses in the biocontrol of bacterial wilt. Fourteen phages infecting R. solanacearum were isolated from soil samples collected in Chiang Mai, Thailand. The phages showed different host ranges when tested against 59 R. solanacearum strains isolated from Thailand and Japan. These phages were characterized as nine podoviruses and five myoviruses based on their morphology. Podovirus J2 in combination with another podovirus (φRSB2) lysed host cells very efficiently in contaminated soil. J2 treatment prevented wilting of tomato plants infected with a highly virulent R. solanacearum strain. Treatment with J2 effectively reduced the amount of the bacterial wilt pathogen in contaminated soil and prevented bacterial wilt of tomato in pot experiments. Myovirus J6 possessed jumbo phage features, giving a unique opportunity to study its utilization as a biocontrol agent. As exemplified by J2, the phages isolated in this study represent valuable resources with potential uses in biocontrol of bacterial wilt. A rare jumbo phage J6 served as a valuable subject to understand and utilize this new group of phages. © 2015 The Society for Applied Microbiology.

Interspecific Potato Breeding Lines Display Differential Colonization Patterns and Induced Defense Responses after Ralstonia solanacearum Infection

PubMed Central

Ferreira, Virginia; Pianzzola, María J.; Vilaró, Francisco L.; Galván, Guillermo A.; Tondo, María L.; Rodriguez, María V.; Orellano, Elena G.; Valls, Marc; Siri, María I.

2017-01-01

Potato (Solanum tuberosum L.) is one of the main hosts of Ralstonia solanacearum, the causative agent of bacterial wilt. This plant pathogen bacteria produce asymptomatic latent infections that promote its global spread, hindering disease control. A potato breeding program is conducted in Uruguay based on the introgression of resistance from the wild native species S. commersonii Dun. Currently, several backcrosses were generated exploiting the high genetic variability of this wild species resulting in advanced interspecific breeding lines with different levels of bacterial wilt resistance. The overall aim of this work was to characterize the interaction of the improved potato germplasm with R. solanacearum. Potato clones with different responses to R. solanacearum were selected, and colonization, dissemination and multiplication patterns after infection were evaluated. A R. solanacearum strain belonging to the phylotype IIB-sequevar 1, with high aggressiveness on potato was genetically modified to constitutively generate fluorescence and luminescence from either the green fluorescence protein gene or lux operon. These reporter strains were used to allow a direct and precise visualization of fluorescent and luminescent cells in plant tissues by confocal microscopy and luminometry. Based on wilting scoring and detection of latent infections, the selected clones were classified as susceptible or tolerant, while no immune-like resistance response was identified. Typical wilting symptoms in susceptible plants were correlated with high concentrations of bacteria in roots and along the stems. Tolerant clones showed a colonization pattern restricted to roots and a limited number of xylem vessels only in the stem base. Results indicate that resistance in potato is achieved through restriction of bacterial invasion and multiplication inside plant tissues, particularly in stems. Tolerant plants were also characterized by induction of anatomical and biochemical changes after

Effect of plant essential oils on Ralstonia solanacearum race 4 causing bacterial wilt of edible ginger

USDA-ARS?s Scientific Manuscript database

Palmarosa (Cymbopogon martini), lemongrass (C. citratus) and eucalyptus (Eucalyptus globulus) oils were investigated for their effects on Ralstonia solanacearum race 4, and their potential use as bio-fumigants for treating pathogen- infested edible ginger (Zingiber officinale R.) fields. Three conce...

Elicitor-Induced Defense Responses in Solanum lycopersicum against Ralstonia solanacearum

PubMed Central

Kar, Itishree; Mukherjee, Arup K.; Acharya, Priyambada

2013-01-01

We investigated on important parameters of induced resistance in hydroponic tomato (Solanum lycopersicum) against Ralstonia solanacearum using the elicitors chitosan (CHT), salicylic acid (SA), and jasmonic acid (JA). The increase in total phenolic content of roots by the elicitors was significantly higher than control. Most pronounced increase in lignin synthesis was triggered by SA followed by CHT. At 24 h post-elicitation (hpe), the activity of phenylalanine ammonia lyase was 4.5 times higher than control elicited by CHT. The peroxidase activity was about 86 nkat/mg protein at 24 hpe in case of SA and 78 nkat/mg protein in case of CHT. The activity of polyphenol oxidase increased several folds by the elicitors. Cinnamyl alcohol dehydrogenase activity increased to the maximum at 48 hpe under the influence of CHT. The results indicate that the elicitors SA and CHT induced effective defense responses in tomato plants against R. solanacearum. This was evident from reduced vascular browning and wilting symptoms of tomato plants treated with SA and CHT and challenged subsequently with R. solanacearum. This reduced disease incidence in tomato by SA and CHT may be a result of cell wall strengthening through deposition of lignin and the coincident induction of defense enzymes. PMID:24187521

Loop-Mediated Isothermal Amplification of Specific Endoglucanase Gene Sequence for Detection of the Bacterial Wilt Pathogen Ralstonia solanacearum

PubMed Central

Pirc, Manca; Llop, Pablo; Ravnikar, Maja; Dreo, Tanja

2014-01-01

The increased globalization of crops production and processing industries also promotes the side-effects of more rapid and efficient spread of plant pathogens. To prevent the associated economic losses, and particularly those related to bacterial diseases where their management relies on removal of the infected material from production, simple, easy-to-perform, rapid and cost-effective tests are needed. Loop-mediated isothermal amplification (LAMP) assays that target 16S rRNA, fliC and egl genes were compared and evaluated as on-site applications. The assay with the best performance was that targeted to the egl gene, which shows high analytical specificity for diverse strains of the betaproteobacterium Ralstonia solanacearum, including its non-European and non-race 3 biovar 2 strains. The additional melting curve analysis provides confirmation of the test results. According to our extensive assessment, the egl LAMP assay requires minimum sample preparation (a few minutes of boiling) for the identification of pure cultures and ooze from symptomatic material, and it can also be used in a high-throughput format in the laboratory. This provides sensitive and reliable detection of R. solanacearum strains of different phylotypes. PMID:24763488

A Single Regulator Mediates Strategic Switching between Attachment/Spread and Growth/Virulence in the Plant Pathogen Ralstonia solanacearum

PubMed Central

Khokhani, Devanshi; Lowe-Power, Tiffany M.; Tran, Tuan Minh

2017-01-01

ABSTRACT The PhcA virulence regulator in the vascular wilt pathogen Ralstonia solanacearum responds to cell density via quorum sensing. To understand the timing of traits that enable R. solanacearum to establish itself inside host plants, we created a ΔphcA mutant that is genetically locked in a low-cell-density condition. Comparing levels of gene expression of wild-type R. solanacearum and the ΔphcA mutant during tomato colonization revealed that the PhcA transcriptome includes an impressive 620 genes (>2-fold differentially expressed; false-discovery rate [FDR], ≤0.005). Many core metabolic pathways and nutrient transporters were upregulated in the ΔphcA mutant, which grew faster than the wild-type strain in tomato xylem sap and on dozens of specific metabolites, including 36 found in xylem. This suggests that PhcA helps R. solanacearum to survive in nutrient-poor environmental habitats and to grow rapidly during early pathogenesis. However, after R. solanacearum reaches high cell densities in planta, PhcA mediates a trade-off from maximizing growth to producing costly virulence factors. R. solanacearum infects through roots, and low-cell-density-mode-mimicking ΔphcA cells attached to tomato roots better than the wild-type cells, consistent with their increased expression of several adhesins. Inside xylem vessels, ΔphcA cells formed aberrantly dense mats. Possibly as a result, the mutant could not spread up or down tomato stems as well as the wild type. This suggests that aggregating improves R. solanacearum survival in soil and facilitates infection and that it reduces pathogenic fitness later in disease. Thus, PhcA mediates a second strategic switch between initial pathogen attachment and subsequent dispersal inside the host. PhcA helps R. solanacearum optimally invest resources and correctly sequence multiple steps in the bacterial wilt disease cycle. PMID:28951474

Assessing the Pathogenic Ability of Ralstonia pseudosolanacearum (Ralstonia solanacearum Phylotype I) from Ornamental Rosa spp. Plants.

PubMed

Tjou-Tam-Sin, Napoleon N A; van de Bilt, Jeroen L J; Westenberg, Marcel; Gorkink-Smits, Peggy P M A; Landman, N Marco; Bergsma-Vlami, Maria

2017-01-01

Ralstonia pseudosolanacearum ( Ralstonia solanacearum phylotype I) isolates found in stunted, yellowing, and wilted ornamental rose ( Rosa spp.) were assessed for their pathogenic ability in two rose cultivars (cv. "Armando" and cv. "Red Naomi") and in four solanaceous crops: tomato ( Solanum lycopersicum cv. "Money Maker"), tobacco ( Nicotiana tabacum cv. "White Burley"), eggplant ( Solanum melongena cv. "Black Beauty") and sweet pepper ( Capsicum annum cv. "Yolo Wonder"). Significant differences were observed in susceptibility between the two rose cultivars as well as between the two modes of inoculation performed. The cultivar "Armando" was significantly more susceptible than cultivar "Red Naomi," exhibiting higher disease severity and incidence. Similarly, stem inoculation after wounding was found to be significantly more effective than soil drenching, resulting in higher disease severity. Additionally, a temperature dependency in susceptibility was observed for both cultivars irrespective of the mode of inoculation, however, this was significantly more pronounced upon soil drenching. The solanaceous crops all showed to be susceptible to the R . pseudosolanacearum isolates originated from the Rosa spp. plants. Furthermore, both rose cultivars were able to harbor symptomless infections with other R . pseudosolanacearum and R. solanacearum isolates than those isolated from rose. Our results clearly demonstrated that latent infections in a rose cultivar such as cv. "Red Naomi" do occur even at temperatures as low as 20°C. This latency poses high risks for the entire floricultural industry as latently infected Rosa spp. plants are propagated and distributed over various continents, including areas where climatic conditions are optimal for the pathogen.

Ralstonia solanacearum uses inorganic nitrogen metabolism for virulence, ATP production, and detoxification in the oxygen-limited host xylem environment.

PubMed

Dalsing, Beth L; Truchon, Alicia N; Gonzalez-Orta, Enid T; Milling, Annett S; Allen, Caitilyn

2015-03-17

Genomic data predict that, in addition to oxygen, the bacterial plant pathogen Ralstonia solanacearum can use nitrate (NO3(-)), nitrite (NO2(-)), nitric oxide (NO), and nitrous oxide (N2O) as terminal electron acceptors (TEAs). Genes encoding inorganic nitrogen reduction were highly expressed during tomato bacterial wilt disease, when the pathogen grows in xylem vessels. Direct measurements found that tomato xylem fluid was low in oxygen, especially in plants infected by R. solanacearum. Xylem fluid contained ~25 mM NO3(-), corresponding to R. solanacearum's optimal NO3(-) concentration for anaerobic growth in vitro. We tested the hypothesis that R. solanacearum uses inorganic nitrogen species to respire and grow during pathogenesis by making deletion mutants that each lacked a step in nitrate respiration (ΔnarG), denitrification (ΔaniA, ΔnorB, and ΔnosZ), or NO detoxification (ΔhmpX). The ΔnarG, ΔaniA, and ΔnorB mutants grew poorly on NO3(-) compared to the wild type, and they had reduced adenylate energy charge levels under anaerobiosis. While NarG-dependent NO3(-) respiration directly enhanced growth, AniA-dependent NO2(-) reduction did not. NO2(-) and NO inhibited growth in culture, and their removal depended on denitrification and NO detoxification. Thus, NO3(-) acts as a TEA, but the resulting NO2(-) and NO likely do not. None of the mutants grew as well as the wild type in planta, and strains lacking AniA (NO2(-) reductase) or HmpX (NO detoxification) had reduced virulence on tomato. Thus, R. solanacearum exploits host NO3(-) to respire, grow, and cause disease. Degradation of NO2(-) and NO is also important for successful infection and depends on denitrification and NO detoxification systems. The plant-pathogenic bacterium Ralstonia solanacearum causes bacterial wilt, one of the world's most destructive crop diseases. This pathogen's explosive growth in plant vascular xylem is poorly understood. We used biochemical and genetic approaches to show

TALE-Like Effectors Are an Ancestral Feature of the Ralstonia solanacearum Species Complex and Converge in DNA Targeting Specificity.

PubMed

Schandry, Niklas; de Lange, Orlando; Prior, Philippe; Lahaye, Thomas

2016-01-01

Ralstonia solanacearum, a species complex of bacterial plant pathogens divided into four monophyletic phylotypes, causes plant diseases in tropical climates around the world. Some strains exhibit a broad host range on solanaceous hosts, while others are highly host-specific as for example some banana-pathogenic strains. Previous studies showed that transcription activator-like (TAL) effectors from Ralstonia, termed RipTALs, are capable of activating reporter genes in planta, if these are preceded by a matching effector binding element (EBE). RipTALs target DNA via their central repeat domain (CRD), where one repeat pairs with one DNA-base of the given EBE. The repeat variable diresidue dictates base repeat specificity in a predictable fashion, known as the TALE code. In this work, we analyze RipTALs across all phylotypes of the Ralstonia solanacearum species complex. We find that RipTALs are prevalent in phylotypes I and IV but absent from most phylotype III and II strains (10/12, 8/14, 1/24, and 1/5 strains contained a RipTAL, respectively). RipTALs originating from strains of the same phylotype show high levels of sequence similarity (>98%) in the N-terminal and C-terminal regions, while RipTALs isolated from different phylotypes show 47-91% sequence similarity in those regions, giving rise to four RipTAL classes. We show that, despite sequence divergence, the base preference for guanine, mediated by the N-terminal region, is conserved across RipTALs of all classes. Using the number and order of repeats found in the CRD, we functionally sub-classify RipTALs, introduce a new simple nomenclature, and predict matching EBEs for all seven distinct RipTALs identified. We experimentally study RipTAL EBEs and uncover that some RipTALs are able to target the EBEs of other RipTALs, referred to as cross-reactivity. In particular, RipTALs from strains with a broad host range on solanaceous hosts cross-react on each other's EBEs. Investigation of sequence divergence between

Breaking the DNA-binding code of Ralstonia solanacearum TAL effectors provides new possibilities to generate plant resistance genes against bacterial wilt disease.

PubMed

de Lange, Orlando; Schreiber, Tom; Schandry, Niklas; Radeck, Jara; Braun, Karl Heinz; Koszinowski, Julia; Heuer, Holger; Strauß, Annett; Lahaye, Thomas

2013-08-01

Ralstonia solanacearum is a devastating bacterial phytopathogen with a broad host range. Ralstonia solanacearum injected effector proteins (Rips) are key to the successful invasion of host plants. We have characterized Brg11(hrpB-regulated 11), the first identified member of a class of Rips with high sequence similarity to the transcription activator-like (TAL) effectors of Xanthomonas spp., collectively termed RipTALs. Fluorescence microscopy of in planta expressed RipTALs showed nuclear localization. Domain swaps between Brg11 and Xanthomonas TAL effector (TALE) AvrBs3 (avirulence protein triggering Bs3 resistance) showed the functional interchangeability of DNA-binding and transcriptional activation domains. PCR was used to determine the sequence of brg11 homologs from strains infecting phylogenetically diverse host plants. Brg11 localizes to the nucleus and activates promoters containing a matching effector-binding element (EBE). Brg11 and homologs preferentially activate promoters containing EBEs with a 5' terminal guanine, contrasting with the TALE preference for a 5' thymine. Brg11 and other RipTALs probably promote disease through the transcriptional activation of host genes. Brg11 and the majority of homologs identified in this study were shown to activate similar or identical target sequences, in contrast to TALEs, which generally show highly diverse target preferences. This information provides new options for the engineering of plants resistant to R. solanacearum. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Comparative Transcriptome Analysis Reveals Cool Virulence Factors of Ralstonia solanacearum Race 3 Biovar 2.

PubMed

Meng, Fanhong; Babujee, Lavanya; Jacobs, Jonathan M; Allen, Caitilyn

2015-01-01

While most strains of the plant pathogenic bacterium Ralstonia solanacearum are tropical, the race 3 biovar 2 (R3bv2) subgroup attacks plants in cooler climates. To identify mechanisms underlying this trait, we compared the transcriptional profiles of R. solanacearum R3bv2 strain UW551 and tropical strain GMI1000 at 20°C and 28°C, both in culture and during tomato pathogenesis. 4.2% of the ORFs in the UW551 genome and 7.9% of the GMI1000 ORFs were differentially expressed by temperature in planta. The two strains had distinct transcriptional responses to temperature change. GMI1000 up-regulated several stress response genes at 20°C, apparently struggling to cope with plant defenses. At the cooler temperature, R3bv2 strain UW551 up-regulated a cluster encoding a mannose-fucose binding lectin, LecM; a quorum sensing-dependent protein, AidA; and a related hypothetical protein, AidC. The last two genes are absent from the GMI1000 genome. In UW551, all three genes were positively regulated by the adjacent SolI/R quorum sensing system. These temperature-responsive genes were required for full virulence in R3bv2. Mutants lacking lecM, aidA, or aidC were each significantly more reduced in virulence on tomato at 20°C than at 28°C in both a naturalistic soil soak inoculation assay and when they were inoculated directly into tomato stems. The lecM and aidC mutants also survived poorly in potato tubers at the seed tuber storage temperature of 4°C, and the lecM mutant was defective in biofilm formation in vitro. Together, these results suggest novel mechanisms, including a lectin, are involved in the unique temperate epidemiology of R3bv2.

Hydroxycinnamic acid degradation, a broadly conserved trait, protects Ralstonia solanacearum from chemical plant defenses and contributes to root colonization and virulence

PubMed Central

Lowe, Tiffany M.; Ailloud, Florent; Allen, Caitilyn

2014-01-01

Plants produce hydroxycinnamic acid defense compounds (HCAs) to combat pathogens, such as the bacterium Ralstonia solanacearum. We showed that an HCA degradation pathway is genetically and functionally conserved across diverse R. solanacearum strains. Further, a Δfcs (feruloyl-CoA synthetase) mutant that cannot degrade HCAs was less virulent on tomato plants. To understand the role of HCA degradation in bacterial wilt disease, we tested the following hypotheses: HCA degradation helps the pathogen (1) grow, as a carbon source; (2) spread, by reducing physical barriers HCA-derived; and (3) survive plant antimicrobial compounds. Although HCA degradation enabled R. solanacearum growth on HCAs in vitro, HCA degradation was dispensable for growth in xylem sap and root exudate, suggesting that HCAs are not significant carbon sources in planta. Acetyl-bromide quantification of lignin demonstrated that R. solanacearum infections did not affect the gross quantity or distribution of stem lignin. However, the Δfcs mutant was significantly more susceptible to inhibition by two HCAs: caffeate and p-coumarate. Finally, plant colonization assays suggested that HCA degradation facilitates early stages of infection and root colonization. Together, these results indicated that ability to degrade HCAs contributes to bacterial wilt virulence by facilitating root entry and by protecting the pathogen from HCA toxicity. PMID:25423265

[Identification, colonization and disease prevention capacity of an antagonistic bacterium against Ralstonia Solanacearum].

PubMed

Li, Zhikun; Zhu, Honghui

2010-03-01

To isolate a bacterial strain YPP-9, dominantly colonizing the rhizosphere of tomato using root exudate medium. In this study, we investigated the antagnism and disease-controling effect against Ralstonia solanacearum, evaluated the ability to colonize the rhizosphere of tomato, and further analyzed the phylogeny of YPP-9. To evaluate the antagnism against R. solanacearum and the biocontrol on tomato bacterial wilt by YPP-9 respectively employing plate culture method and pot experiment in green house. We analyzed the rhizosphere colonization of YPP-9 by PCR-denaturing gradient gel electrophoresis, and also identified the taxonomic position of YPP-9 using morphological and chemotaxonomic characteristics together with 16S rRNA gene phylogenetic analysis. YPP-9 suppressed the growth of R. solanacearum (strains SSF-4) in vitro with the inhibition zone of 5 mm. The disease-control efficiency against tomato bacterial wilt in pot was 63.4%. YPP-9 also colonized the rhizosphere of tomato well. The colonies were cream in colour after 24 h culture. Cells were gram-positive, rods (1.8 -4.1 microm x 0.9 - 1.1 microm) and formed endospores. Endospores were mainly ellipsoidal to cylindrical and lied in subterminal, and occasionally paracentral, positions in no swollen sporangia. No crystal protein. The pH range for YPP-9 growth was 5.5 - 8.5 with the optimum at pH 6.0, and the temperature for YPP-9 growth was 20 to 45 degrees with the optimum at 30 degrees. The results of BIOLOG GP2 showed that YPP-9 was Bacillus. Phylogenetic analysis of the 16S rRNA gene sequence revealed that YPP-9 was the most closely related to Bacillus fumarioli, with the sequence similarity of 97.7%. The sequence number was FJ231500. The DNA G + C content was 41.9%. The major menaquinone was MK-7. The dominant fatty acids in cell wall were C14 : 0 iso, C15 : 0 iso, C16 : 0 iso and C16 : 1omega 7c alcohol, with the contents of 28.27%, 19.59%, 12.93% and 10.88%, respectively. Bacterium YPP-9 strongly

Two host-induced Ralstonia solanacearum genes, acrA and dinF, encode multidrug efflux pumps and contribute to bacterial wilt virulence.

PubMed

Brown, Darby G; Swanson, Jill K; Allen, Caitilyn

2007-05-01

Multidrug efflux pumps (MDRs) are hypothesized to protect pathogenic bacteria from toxic host defense compounds. We created mutations in the Ralstonia solanacearum acrA and dinF genes, which encode putative MDRs in the broad-host-range plant pathogen. Both mutations reduced the ability of R. solanacearum to grow in the presence of various toxic compounds, including antibiotics, phytoalexins, and detergents. Both acrAB and dinF mutants were significantly less virulent on the tomato plant than the wild-type strain. Complementation restored near-wild-type levels of virulence to both mutants. Addition of either dinF or acrAB to Escherichia coli MDR mutants KAM3 and KAM32 restored the resistance of these strains to several toxins, demonstrating that the R. solanacearum genes can function heterologously to complement known MDR mutations. Toxic and DNA-damaging compounds induced expression of acrA and dinF, as did growth in both susceptible and resistant tomato plants. Carbon limitation also increased expression of acrA and dinF, while the stress-related sigma factor RpoS was required at a high cell density (>10(7) CFU/ml) to obtain wild-type levels of acrA expression both in minimal medium and in planta. The type III secretion system regulator HrpB negatively regulated dinF expression in culture at high cell densities. Together, these results show that acrAB and dinF encode MDRs in R. solanacearum and that they contribute to the overall aggressiveness of this phytopathogen, probably by protecting the bacterium from the toxic effects of host antimicrobial compounds.

Recent trends in control methods for bacterial wilt diseases caused by Ralstonia solanacearum.

PubMed

Yuliar; Nion, Yanetri Asi; Toyota, Koki

2015-01-01

Previous studies have described the development of control methods against bacterial wilt diseases caused by Ralstonia solanacearum. This review focused on recent advances in control measures, such as biological, physical, chemical, cultural, and integral measures, as well as biocontrol efficacy and suppression mechanisms. Biological control agents (BCAs) have been dominated by bacteria (90%) and fungi (10%). Avirulent strains of R. solanacearum, Pseudomonas spp., Bacillus spp., and Streptomyces spp. are well-known BCAs. New or uncommon BCAs have also been identified such as Acinetobacter sp., Burkholderia sp., and Paenibacillus sp. Inoculation methods for BCAs affect biocontrol efficacy, such as pouring or drenching soil, dipping of roots, and seed coatings. The amendment of different organic matter, such as plant residue, animal waste, and simple organic compounds, have frequently been reported to suppress bacterial wilt diseases. The combined application of BCAs and their substrates was shown to more effectively suppress bacterial wilt in the tomato. Suppression mechanisms are typically attributed to the antibacterial metabolites produced by BCAs or those present in natural products; however, the number of studies related to host resistance to the pathogen is increasing. Enhanced/modified soil microbial communities are also indirectly involved in disease suppression. New promising types of control measures include biological soil disinfection using substrates that release volatile compounds. This review described recent advances in different control measures. We focused on the importance of integrated pest management (IPM) for bacterial wilt diseases.

Recent Trends in Control Methods for Bacterial Wilt Diseases Caused by Ralstonia solanacearum

PubMed Central

Yuliar; Nion, Yanetri Asi; Toyota, Koki

2015-01-01

Previous studies have described the development of control methods against bacterial wilt diseases caused by Ralstonia solanacearum. This review focused on recent advances in control measures, such as biological, physical, chemical, cultural, and integral measures, as well as biocontrol efficacy and suppression mechanisms. Biological control agents (BCAs) have been dominated by bacteria (90%) and fungi (10%). Avirulent strains of R. solanacearum, Pseudomonas spp., Bacillus spp., and Streptomyces spp. are well-known BCAs. New or uncommon BCAs have also been identified such as Acinetobacter sp., Burkholderia sp., and Paenibacillus sp. Inoculation methods for BCAs affect biocontrol efficacy, such as pouring or drenching soil, dipping of roots, and seed coatings. The amendment of different organic matter, such as plant residue, animal waste, and simple organic compounds, have frequently been reported to suppress bacterial wilt diseases. The combined application of BCAs and their substrates was shown to more effectively suppress bacterial wilt in the tomato. Suppression mechanisms are typically attributed to the antibacterial metabolites produced by BCAs or those present in natural products; however, the number of studies related to host resistance to the pathogen is increasing. Enhanced/modified soil microbial communities are also indirectly involved in disease suppression. New promising types of control measures include biological soil disinfection using substrates that release volatile compounds. This review described recent advances in different control measures. We focused on the importance of integrated pest management (IPM) for bacterial wilt diseases. PMID:25762345

Detection of plant quarantine pathogen Ralstonia solanacearum r3b2 with portable POCKIT™ and BLItz® systems

USDA-ARS?s Scientific Manuscript database

Ralstonia solanacearum (Rs) race 3 biovar 2 (r3b2) is designated as a quarantine pathogen in many countries and additionally as a Select Agent in the United States. Rapid, sensitive and accurate detection methods are urgently needed. We report here the development of two portable platforms for r3b...

Two Host-Induced Ralstonia solanacearum Genes, acrA and dinF, Encode Multidrug Efflux Pumps and Contribute to Bacterial Wilt Virulence▿ †

PubMed Central

Brown, Darby G.; Swanson, Jill K.; Allen, Caitilyn

2007-01-01

Multidrug efflux pumps (MDRs) are hypothesized to protect pathogenic bacteria from toxic host defense compounds. We created mutations in the Ralstonia solanacearum acrA and dinF genes, which encode putative MDRs in the broad-host-range plant pathogen. Both mutations reduced the ability of R. solanacearum to grow in the presence of various toxic compounds, including antibiotics, phytoalexins, and detergents. Both acrAB and dinF mutants were significantly less virulent on the tomato plant than the wild-type strain. Complementation restored near-wild-type levels of virulence to both mutants. Addition of either dinF or acrAB to Escherichia coli MDR mutants KAM3 and KAM32 restored the resistance of these strains to several toxins, demonstrating that the R. solanacearum genes can function heterologously to complement known MDR mutations. Toxic and DNA-damaging compounds induced expression of acrA and dinF, as did growth in both susceptible and resistant tomato plants. Carbon limitation also increased expression of acrA and dinF, while the stress-related sigma factor RpoS was required at a high cell density (>107 CFU/ml) to obtain wild-type levels of acrA expression both in minimal medium and in planta. The type III secretion system regulator HrpB negatively regulated dinF expression in culture at high cell densities. Together, these results show that acrAB and dinF encode MDRs in R. solanacearum and that they contribute to the overall aggressiveness of this phytopathogen, probably by protecting the bacterium from the toxic effects of host antimicrobial compounds. PMID:17337552

Filamentous phages of Ralstonia solanacearum: double-edged swords for pathogenic bacteria.

PubMed

Yamada, Takashi

2013-01-01

Some phages from genus Inovirus use host or bacteriophage-encoded site-specific integrases or recombinases establish a prophage state. During integration or excision, a superinfective form can be produced. The three states (free, prophage, and superinfective) of such phages exert different effects on host bacterial phenotypes. In Ralstonia solanacearum, the causative agent of bacterial wilt disease of crops, the bacterial virulence can be positively or negatively affected by filamentous phages, depending on their state. The presence or absence of a repressor gene in the phage genome may be responsible for the host phenotypic differences (virulent or avirulent) caused by phage infection. This strategy of virulence control may be widespread among filamentous phages that infect pathogenic bacteria of plants.

Draft Genome Sequence of Highly Virulent Race 4/Biovar 3 of Ralstonia solanacearum CaRs_Mep Causing Bacterial Wilt in Zingiberaceae Plants in India.

PubMed

Kumar, Aundy; Munjal, Vibhuti; Sheoran, Neelam; Prameela, Thekkan Puthiyaveedu; Suseelabhai, Rajamma; Aggarwal, Rashmi; Jain, Rakesh Kumar; Eapen, Santhosh J

2017-01-05

The genome of Ralstonia solanacearum CaRs_Mep, a race 4/biovar 3/phylotype I bacterium causing wilt in small cardamom and other Zingiberaceae plants, was sequenced. Analysis of the 5.7-Mb genome sequence will aid in better understanding of the genetic determinants of host range, host jump, survival, pathogenicity, and virulence of race 4 of R. solanacearum. Copyright © 2017 Kumar et al.

Metabolomics of tomato xylem sap during bacterial wilt reveals Ralstonia solanacearum produces abundant putrescine, a metabolite that accelerates wilt disease.

PubMed

Lowe-Power, Tiffany M; Hendrich, Connor G; von Roepenack-Lahaye, Edda; Li, Bin; Wu, Dousheng; Mitra, Raka; Dalsing, Beth L; Ricca, Patrizia; Naidoo, Jacinth; Cook, David; Jancewicz, Amy; Masson, Patrick; Thomma, Bart; Lahaye, Thomas; Michael, Anthony J; Allen, Caitilyn

2018-04-01

Ralstonia solanacearum thrives in plant xylem vessels and causes bacterial wilt disease despite the low nutrient content of xylem sap. We found that R. solanacearum manipulates its host to increase nutrients in tomato xylem sap, enabling it to grow better in sap from infected plants than in sap from healthy plants. Untargeted GC/MS metabolomics identified 22 metabolites enriched in R. solanacearum-infected sap. Eight of these could serve as sole carbon or nitrogen sources for R. solanacearum. Putrescine, a polyamine that is not a sole carbon or nitrogen source for R. solanacearum, was enriched 76-fold to 37 µM in R. solanacearum-infected sap. R. solanacearum synthesized putrescine via a SpeC ornithine decarboxylase. A ΔspeC mutant required ≥ 15 µM exogenous putrescine to grow and could not grow alone in xylem even when plants were treated with putrescine. However, co-inoculation with wildtype rescued ΔspeC growth, indicating R. solanacearum produced and exported putrescine to xylem sap. Intriguingly, treating plants with putrescine before inoculation accelerated wilt symptom development and R. solanacearum growth and systemic spread. Xylem putrescine concentration was unchanged in putrescine-treated plants, so the exogenous putrescine likely accelerated disease indirectly by affecting host physiology. These results indicate that putrescine is a pathogen-produced virulence metabolite. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Genomic characterization of Ralstonia solanacearum phage phiRSB1, a T7-like wide-host-range phage.

PubMed

Kawasaki, Takeru; Shimizu, Mio; Satsuma, Hideki; Fujiwara, Akiko; Fujie, Makoto; Usami, Shoji; Yamada, Takashi

2009-01-01

PhiRSB1 is a wide-host-range, T7-like bacteriophage that infects and efficiently lyses the phytopathogenic bacterium Ralstonia solanacearum. The phiRSB1 genome comprises 43,079 bp of double-stranded DNA (61.7% G+C) with 325-bp terminal repeats and contains 47 open reading frames. Strong activity of tandem early promoters and wide specificity of phage promoters of phiRSB1 were demonstrated.

Rhizophagus irregularis MUCL 41833 transitorily reduces tomato bacterial wilt incidence caused by Ralstonia solanacearum under in vitro conditions.

PubMed

Chave, Marie; Crozilhac, Patrice; Deberdt, Péninna; Plouznikoff, Katia; Declerck, Stéphane

2017-10-01

Bacterial wilt caused by Ralstonia solanacearum is one of the world's most important soil-borne plant diseases. In Martinique, French West Indies, a highly virulent new pathogenic variant of this bacterium (phylotype IIB/4NPB) severely impacts tomato production. Here we report on the effect of R. solanacearum CFBP 6783, classified in phytotype IIB/4NPB, on tomato plantlets grown under strict in vitro culture conditions in the presence or absence of the arbuscular mycorrhizal fungus Rhizophagus irregularis MUCL 41833. A mycelium donor plant (i.e. Crotalaria spectabilis) was used for rapid, uniform mycorrhization of tomato plantlets that were subsequently infected by the bacterium. Bacterial wilt was significantly delayed and the incidence of the disease consequently reduced in the mycorrhizal tomato plantlets. Conversely, R. solanacearum did not affect root colonization by the AMF within the 16 days of the experiment. These results suggested that the mycorrhizal fungus was able to reduce bacterial wilt symptoms, probably by eliciting defence mechanisms in the plant.

Differential Expression of Virulence Genes and Motility in Ralstonia (Pseudomonas) solanacearum during Exponential Growth.

PubMed

Clough, S J; Flavier, A B; Schell, M A; Denny, T P

1997-03-01

A complex network regulates virulence in Ralstonia solanacearum (formerly Pseudomonas solanacearum); central to this system is PhcA, a LysR-type transcriptional regulator. We report here that two PhcA-regulated virulence factors, endoglucanase (Egl) and acidic exopolysaccharide I (EPS I), and motility are expressed differentially during exponential growth in batch cultures. Tests with strains carrying lacZ fusions in a wild-type genetic background revealed that expression (on a per-cell basis) of phcA was constant but expression of egl and epsB increased 20- to 50-fold during multiplication from 1 x 10(sup7) to 5 x 10(sup8) CFU/ml. Expression of xpsR, an intermediate regulator downstream of PhcA in the regulatory cascade for eps expression, was similar to that of epsB and egl. Motility track photography revealed that all strains were essentially nonmotile at 10(sup6) CFU/ml. As cell density increased, 30 to 50% of wild-type cells were motile between 10(sup7) and 10(sup8) CFU/ml, but this population was again nonmotile at 10(sup9) CFU/ml. In contrast, about 60% of the cells of phcB and phcA mutants remained motile at 10(sup9) CFU/ml. Expression of phcB, which is not positively regulated by PhcA, was the inverse of epsB, egl, and xpsR (i.e., it decreased 20-fold at high cell density). PhcB is essential for production of an extracellular factor, tentatively identified as 3-hydroxypalmitic acid methyl ester (3-OH PAME), that might act as an exponential-phase signal to activate motility or expression of virulence genes. However, growth of the lacZ fusion strains in medium containing excess 3-OH PAME did not result in motility or expression of virulence genes at dramatically lower cell densities, suggesting that 3-OH PAME is not the only factor controlling these traits.

Sequencing, genome analysis and host range of a novel Ralstonia phage RsoP1EGY isolated from Egypt

USDA-ARS?s Scientific Manuscript database

A novel Ralstonia phage was isolated from soil in Egypt and designated RsPod1SoilEGY using our new four-part phage identifier naming system. When tested, this phage selectively infected only race 3 biovar 2 phylotype IIB sequevar 1, and not non-race 3 biovar 2 strains of Ralstonia solanacearum. The ...

Ecology, Epidemiology and Disease Management of Ralstonia syzygii in Indonesia

PubMed Central

Safni, Irda; Subandiyah, Siti; Fegan, Mark

2018-01-01

Ralstonia solanacearum species complex phylotype IV strains, which have been primarily isolated from Indonesia, Australia, Japan, Korea, and Malaysia, have undergone recent taxonomic and nomenclatural changes to be placed in the species Ralstonia syzygii. This species contains three subspecies; Ralstonia syzygii subsp. syzygii, a pathogen causing Sumatra disease of clove trees in Indonesia, Ralstonia syzygii subsp. indonesiensis, the causal pathogen of bacterial wilt disease on a wide range of host plants, and Ralstonia syzygii subsp. celebesensis, the causal pathogen of blood disease on Musa spp. In Indonesia, these three subspecies have devastated the cultivation of susceptible host plants which have high economic value. Limited knowledge on the ecology and epidemiology of the diseases has hindered the development of effective control strategies. In this review, we provide insights into the ecology, epidemiology and disease control of these three subspecies of Ralstonia syzygii. PMID:29662468

Ecology, Epidemiology and Disease Management of Ralstonia syzygii in Indonesia.

PubMed

Safni, Irda; Subandiyah, Siti; Fegan, Mark

2018-01-01

Ralstonia solanacearum species complex phylotype IV strains, which have been primarily isolated from Indonesia, Australia, Japan, Korea, and Malaysia, have undergone recent taxonomic and nomenclatural changes to be placed in the species Ralstonia syzygii . This species contains three subspecies; Ralstonia syzygii subsp. syzygii , a pathogen causing Sumatra disease of clove trees in Indonesia, Ralstonia syzygii subsp. indonesiensis , the causal pathogen of bacterial wilt disease on a wide range of host plants, and Ralstonia syzygii subsp. celebesensis , the causal pathogen of blood disease on Musa spp. In Indonesia, these three subspecies have devastated the cultivation of susceptible host plants which have high economic value. Limited knowledge on the ecology and epidemiology of the diseases has hindered the development of effective control strategies. In this review, we provide insights into the ecology, epidemiology and disease control of these three subspecies of Ralstonia syzygii .

Ethylene emission and PR protein synthesis in ACC deaminase producing Methylobacterium spp. inoculated tomato plants (Lycopersicon esculentum Mill.) challenged with Ralstonia solanacearum under greenhouse conditions.

PubMed

Yim, Woojong; Seshadri, Sundaram; Kim, Kiyoon; Lee, Gillseung; Sa, Tongmin

2013-06-01

Bacteria of genus Methylobacterium have been found to promote plant growth and regulate the level of ethylene in crop plants. This work is aimed to test the induction of defense responses in tomato against bacterial wilt by stress ethylene level reduction mediated by the ACC deaminase activity of Methylobacterium strains. Under greenhouse conditions, the disease index value in Methylobacterium sp. inoculated tomato plants was lower than control plants. Plants treated with Methylobacterium sp. challenge inoculated with Ralstonia solanacearum (RS) showed significantly reduced disease symptoms and lowered ethylene emission under greenhouse condition. The ACC and ACO (1-aminocyclopropane-1-carboxylate oxidase) accumulation in tomato leaves were significantly reduced with Methylobacterium strains inoculation. While ACC oxidase gene expression was found higher in plants treated with R. solanacearum than Methylobacterium sp. treatment, PR proteins related to induced systemic resistance like β-1,3-glucanase, PAL, PO and PPO were increased in Methylobacterium sp. inoculated plants. A significant increase in β-1,3-glucanase and PAL gene expression was found in all the Methylobacterium spp. treatments compared to the R. solanacearum treatment. This study confirms the activity of Methylobacterium sp. in increasing the defense enzymes by modulating the ethylene biosynthesis pathway and suggests the use of methylotrophic bacteria as potential biocontrol agents in tomato cultivation. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Effect of Seed Treatment by Cold Plasma on the Resistance of Tomato to Ralstonia solanacearum (Bacterial Wilt)

PubMed Central

Jiang, Jiafeng; Lu, Yufang; Li, Jiangang; Li, Ling; He, Xin; Shao, Hanliang; Dong, Yuanhua

2014-01-01

This study investigated the effect of cold plasma seed treatment on tomato bacterial wilt, caused by Ralstonia solanacearum (R. solanacearum), and the regulation of resistance mechanisms. The effect of cold plasma of 80W on seed germination, plant growth, nutrient uptake, disease severity, hydrogen peroxide (H2O2) concentration and activities of peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.2) and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) were examined in tomato plants. Plasma treatment increased tomato resistance to R. solanacearum with an efficacy of 25.0%. Plasma treatment significantly increased both germination and plant growth in comparison with the control treatment, and plasma-treated plants absorbed more calcium and boron than the controls. In addition, H2O2 levels in treated plants rose faster and reached a higher peak, at 2.579 µM gFW−1, 140% greater than that of the control. Activities of POD (421.3 U gFW−1), PPO (508.8 U gFW−1) and PAL (707.3 U gFW−1) were also greater in the treated plants than in the controls (103.0 U gFW−1, 166.0 U gFW−1 and 309.4 U gFW−1, respectively). These results suggest that plasma treatment affects the regulation of plant growth, H2O2 concentration, and POD, PPO and PAL activity in tomato, resulting in an improved resistance to R. solanacearum. Consequently, cold plasma seed treatment has the potential to control tomato bacterial wilt caused by R. solanacearum. PMID:24840508

Escaping Underground Nets: Extracellular DNases Degrade Plant Extracellular Traps and Contribute to Virulence of the Plant Pathogenic Bacterium Ralstonia solanacearum

PubMed Central

Tran, Tuan Minh; MacIntyre, April; Hawes, Martha; Allen, Caitilyn

2016-01-01

Plant root border cells have been recently recognized as an important physical defense against soil-borne pathogens. Root border cells produce an extracellular matrix of protein, polysaccharide and DNA that functions like animal neutrophil extracellular traps to immobilize pathogens. Exposing pea root border cells to the root-infecting bacterial wilt pathogen Ralstonia solanacearum triggered release of DNA-containing extracellular traps in a flagellin-dependent manner. These traps rapidly immobilized the pathogen and killed some cells, but most of the entangled bacteria eventually escaped. The R. solanacearum genome encodes two putative extracellular DNases (exDNases) that are expressed during pathogenesis, suggesting that these exDNases contribute to bacterial virulence by enabling the bacterium to degrade and escape root border cell traps. We tested this hypothesis with R. solanacearum deletion mutants lacking one or both of these nucleases, named NucA and NucB. Functional studies with purified proteins revealed that NucA and NucB are non-specific endonucleases and that NucA is membrane-associated and cation-dependent. Single ΔnucA and ΔnucB mutants and the ΔnucA/B double mutant all had reduced virulence on wilt-susceptible tomato plants in a naturalistic soil-soak inoculation assay. The ΔnucA/B mutant was out-competed by the wild-type strain in planta and was less able to stunt root growth or colonize plant stems. Further, the double nuclease mutant could not escape from root border cells in vitro and was defective in attachment to pea roots. Taken together, these results demonstrate that extracellular DNases are novel virulence factors that help R. solanacearum successfully overcome plant defenses to infect plant roots and cause bacterial wilt disease. PMID:27336156

Effects of Caatinga Plant Extracts in Planktonic Growth and Biofilm Formation in Ralstonia solanacearum.

PubMed

Malafaia, Carolina Barbosa; Jardelino, Ana Cláudia Silva; Silva, Alexandre Gomes; de Souza, Elineide Barbosa; Macedo, Alexandre José; Correia, Maria Tereza Dos Santos; Silva, Márcia Vanusa

2018-04-01

This study describes the first antibiofilm and antibacterial screening for plants from Caatinga against Ralstonia solanacearum, a causal agent of bacterial wilt that presents serious difficulties in control. There were prepared 22 aqueous extracts of plants collected in the Vale do Catimbau-PE, Brazil. The potential antibacterial activity was evaluated by absorbance in OD 600 and the antibiofilm activity through the crystal violet method, both of them performed in microplate against isolates of R. solanacearum biofilm formers. The results of the screening showed that Jacaranda rugosa presented antimicrobial activity higher than 90%, while Harpochilus neesianus and Myroxylon peruiferum presented antibiofilm activity higher than 50% for all tested isolates. However, Croton heliotropiifolius showed both the activities, being thus very promising for application in the control of this phytopathogen. The search for viable alternatives to the development of new bioactive compounds safe for the environment, humans, and animals from an adverse and scarce environment such as the Caatinga and encouraged us to find plants that produce effective metabolites against phytopathogenic microorganisms. This in vitro screening is important to guide the development of new products in addition to guide research studies of bioactive compounds.

Biocontrol of Ralstonia solanacearum by Treatment with Lytic Bacteriophages ▿ †

PubMed Central

Fujiwara, Akiko; Fujisawa, Mariko; Hamasaki, Ryosuke; Kawasaki, Takeru; Fujie, Makoto; Yamada, Takashi

2011-01-01

Ralstonia solanacearum is a Gram-negative bacterium and the causative agent of bacterial wilt in many important crops. We treated R. solanacearum with three lytic phages: φRSA1, φRSB1, and φRSL1. Infection with φRSA1 and φRSB1, either alone or in combination with the other phages, resulted in a rapid decrease in the host bacterial cell density. Cells that were resistant to infection by these phages became evident approximately 30 h after phage addition to the culture. On the other hand, cells infected solely with φRSL1 in a batch culture were maintained at a lower cell density (1/3 of control) over a long period. Pretreatment of tomato seedlings with φRSL1 drastically limited penetration, growth, and movement of root-inoculated bacterial cells. All φRSL1-treated tomato plants showed no symptoms of wilting during the experimental period, whereas all untreated plants had wilted by 18 days postinfection. φRSL1 was shown to be relatively stable in soil, especially at higher temperatures (37 to 50°C). Active φRSL1 particles were recovered from the roots of treated plants and from soil 4 months postinfection. Based on these observations, we propose an alternative biocontrol method using a unique phage, such as φRSL1, instead of a phage cocktail with highly virulent phages. Using this method, φRSL1 killed some but not all bacterial cells. The coexistence of bacterial cells and the phage resulted in effective prevention of wilting. PMID:21498752

Monitoring growth and movement of Ralstonia solanacearum cells harboring plasmid pRSS12 derived from bacteriophage phiRSS1.

PubMed

Fujie, Makoto; Takamoto, Hirofumi; Kawasaki, Takeru; Fujiwara, Akiko; Yamada, Takashi

2010-02-01

We monitored growth and movement of Ralstonia solanacearum harboring the plasmid pRSS12 in tomato seedlings. The plasmid contains a gene for green fluorescent protein (GFP) and is stably maintained in R. solanacearum cells without selection pressure. Bacteria harboring the plasmid can be tracked in planta by visualizing GFP fluorescence. Stems of seedlings were infected with R. solanacearum cells transformed with pRSS12, and bacterial growth and movement, particularly around the vascular bundles, were monitored for more than 7 days. Our results showed that vascular bundles are independent of each other within the stem, and that it takes a long time for R. solanacearum cells to migrate from one vascular bundle to another. For real-time monitoring of bacteria in planta, tomato seedlings were grown on agar medium and bacterial suspension was applied to the root apex. The bacterial invasion process was monitored by fluorescent microscopy. Bacteria invaded taproots within 6 h, and movement of the bacteria was observed until 144 h after inoculation. In susceptible tomato cultivars, strong GFP fluorescence was observed in hypocotyls and lateral roots as well as the taproot. In resistant cultivars, however, GFP fluorescence was rarely observed on lateral roots. Our results show that this monitoring system can be used to assess bacterial pathogenicity efficiently. Copyright (c) 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

CaWRKY58, encoding a group I WRKY transcription factor of Capsicum annuum, negatively regulates resistance to Ralstonia solanacearum infection.

PubMed

Wang, Yuna; Dang, Fengfeng; Liu, Zhiqin; Wang, Xu; Eulgem, Thomas; Lai, Yan; Yu, Lu; She, Jianju; Shi, Youliang; Lin, Jinhui; Chen, Chengcong; Guan, Deyi; Qiu, Ailian; He, Shuilin

2013-02-01

WRKY transcription factors are encoded by large gene families across the plant kingdom. So far, their biological and molecular functions in nonmodel plants, including pepper (Capsicum annuum) and other Solanaceae, remain poorly understood. Here, we report on the functional characterization of a new group I WRKY protein from pepper, termed CaWRKY58. Our data indicate that CaWRKY58 can be localized to the nucleus and can activate the transcription of the reporter β-glucuronidase (GUS) gene driven by the 35S core promoter with two copies of the W-box in its proximal upstream region. In pepper plants infected with the bacterial pathogen Ralstonia solanacearum, CaWRKY58 transcript levels showed a biphasic response, manifested in an early/transient down-regulation and late up-regulation. CaWRKY58 transcripts were suppressed by treatment with methyl jasmonate and abscisic acid. Tobacco plants overexpressing CaWRKY58 did not show any obvious morphological phenotypes, but exhibited disease symptoms of greater severity than did wild-type plants. The enhanced susceptibility of CaWRKY58-overexpressing tobacco plants correlated with the decreased expression of hypersensitive response marker genes, as well as various defence-associated genes. Consistently, CaWRKY58 pepper plants silenced by virus-induced gene silencing (VIGS) displayed enhanced resistance to the highly virulent R. solanacearum strain FJC100301, and this was correlated with enhanced transcripts of defence-related pepper genes. Our results suggest that CaWRKY58 acts as a transcriptional activator of negative regulators in the resistance of pepper to R. solanacearum infection. © 2012 THE AUTHORS. MOLECULAR PLANT PATHOLOGY © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

The Viable But Nonculturable State of Ralstonia solanacearum May Be Involved in Long-Term Survival and Plant Infection

PubMed Central

Grey, Brian E.; Steck, Todd R.

2001-01-01

The role of the dormant-like viable but nonculturable (VBNC) condition in the etiology of bacterial infection was examined using a plant system. The plant-pathogenic bacterium Ralstonia solanacearum was first shown to enter into the VBNC state both in response to cupric sulfate when in a saline solution and when placed in autoclaved soil. To determine if the VBNC condition is related to pathogenesis, the physiological status of bacteria recovered from different regions of inoculated tomato plants was determined at different stages of infection. The fraction of in planta bacteria that were VBNC increased during infection and became greater than 99% by the late stage of disease. The possibility that soil-dwelling VBNC bacteria may resuscitate and infect plants was also examined. When tomato seeds were germinated in sterile soil that contained VBNC but no detectable culturable forms of R. solanacearum cells, resuscitation was observed to occur in soil adjacent to plant roots; these resuscitated bacteria were able to infect plants. This is the first report of R. solanacearum entering the VBNC state and of resuscitation of any VBNC plant-pathogenic bacteria and provides evidence that the VBNC state may be involved in explaining the persistent nature of some infections. PMID:11525979

Characterization of the Agrobacterium vitis pehA gene and comparison of the encoded polygalacturonase with the homologous enzymes from Erwinia carotovora and Ralstonia solanacearum.

PubMed Central

Herlache, T C; Hotchkiss, A T; Burr, T J; Collmer, A

1997-01-01

DNA sequencing of the Agrobacterium vitis pehA gene revealed a predicted protein with an M(r) of 58,000 and significant similarity to the polygalacturonases of two other plant pathogens, Erwinia carotovora and Ralstonia (= Pseudomonas or Burkholderia) solanacearum. Sequencing of the N terminus of the PehA protein demonstrated cleavage of a 34-amino-acid signal peptide from pre-PehA. Mature PehA accumulated primarily in the periplasm of A. vitis and pehA+ Escherichia coli cells during exponential growth. A. vitis PehA released dimers, trimers, and monomers from polygalacturonic acid and caused less electrolyte leakage from potato tuber tissue than did the E. carotovora and R. solanacearum polygalacturonases. PMID:8979363

Overexpression of NtPR-Q Up-Regulates Multiple Defense-Related Genes in Nicotiana tabacum and Enhances Plant Resistance to Ralstonia solanacearum.

PubMed

Tang, Yuanman; Liu, Qiuping; Liu, Ying; Zhang, Linli; Ding, Wei

2017-01-01

Various classes of plant pathogenesis-related proteins have been identified in the past several decades. PR-Q, a member of the PR3 family encoding chitinases, has played an important role in regulating plant resistance and preventing pathogen infection. In this paper, we functionally characterized NtPR-Q in tobacco plants and found that the overexpression of NtPR-Q in tobacco Yunyan87 resulted in higher resistance to Ralstonia solanacearum inoculation. Surprisingly, overexpression of NtPR-Q led to the activation of many defense-related genes, such as salicylic acid (SA)-responsive genes NtPR1a/c , NtPR2 and NtCHN50 , JA-responsive gene NtPR1b and ET production-associated genes NtACC Oxidase and NtEFE26 . Consistent with the role of NtPR-Q in multiple stress responses, NtPR-Q transcripts were induced by the exogenous hormones SA, ethylene and methyl jasmonate, which could enhance the resistance of tobacco to R. solanacearum . Collectively, our results suggested that NtPR-Q overexpression led to the up-regulation of defense-related genes and enhanced plant resistance to R. solanacearum infection.

Host plant-dependent phenotypic reversion of Ralstonia solanacearum from non-pathogenic to pathogenic forms via alterations in the phcA gene.

PubMed

Poussier, Stéphane; Thoquet, Philippe; Trigalet-Demery, Danièle; Barthet, Séverine; Meyer, Damien; Arlat, Matthieu; Trigalet, André

2003-08-01

Ralstonia solanacearum is a plant pathogenic bacterium that undergoes a spontaneous phenotypic conversion (PC) from a wild-type pathogenic to a non-pathogenic form. PC is often associated with mutations in phcA, which is a key virulence regulatory gene. Until now, reversion to the wild-type pathogenic form has not been observed for PC variants and the biological significance of PC has been questioned. In this study, we characterized various alterations in phcA (eight IS element insertions, three tandem duplications, seven deletions and a base substitution) in 19 PC mutants from the model strain GMI1000. In five of these variants, reversion to the pathogenic form was observed in planta, while no reversion was ever noticed in vitro whatever culture media used. However, reversion was observed for a 64 bp tandem duplication in vitro in the presence of tomato root exudate. This is the first report showing a complete cycle of phenotypic conversion/reversion in a plant pathogenic bacterium.

An evaluation of the wilt-causing bacterium Ralstonia solanacearum as a potential biological control agent for the alien Kahili ginger (Hedychium gardnerianum) in Hawaiian forests

USGS Publications Warehouse

1999-01-01

Kahili ginger (Hedychium gardnerianum) is an invasive weed in tropical forests in Hawaii and elsewhere. Bacterial wilt caused by the ginger strain of Ralstonia(=Pseudomonas) solanacearum systemically infects edible ginger (Zingiber officinale) and ornamental gingers (Hedychium spp.), causing wilt in infected plants. The suitability of R. solanacearum as a biological control agent for kahili ginger was investigated by inoculating seedlings and rooted cuttings of native forest plants, ornamental ginger, and solanaceous species to confirm host specificity. Inoculation via stem injection or root wounding with a bacterial–water suspension was followed by observation for 8 weeks. Inoculations on H. gardnerianum were then carried out in ohia-lehua (Metrosideros polymorpha) wet forests of Hawaii Volcanoes National Park to determine the bacterium's efficacy in the field. No native forest or solanaceous species developed wilt or other symptoms during the study. The bacterium caused limited infection near the inoculation site on H. coronarium, Z. zerumbet, Heliconia latispatha, and Musa sapientum. However, infection did not become systemic in any of these species, and normal growth resumed following appearance of initial symptoms. All inoculated H. gardnerianum plants developed irreversible chlorosis and severe wilting 3–4 weeks following inoculation. Systemic infection also caused death and decay of rhizomes. Most plants were completely dead 16–20 weeks following inoculation. The destructiveness of the ginger strain of R. solanacearum to edible ginger has raised questions regarding its use for biological control. However, because locations of kahili ginger infestations are often remote, the risk of contaminating edible ginger plantings is unlikely. The ability of this bacterium to cause severe disease in H. gardnerianum in the field, together with its lack of virulence in other ginger species, contributes to its potential as a biological control agent.

The vascular plant-pathogenic bacterium Ralstonia solanacearum produces biofilms required for its virulence on the surfaces of tomato cells adjacent to intercellular spaces.

PubMed

Mori, Yuka; Inoue, Kanako; Ikeda, Kenichi; Nakayashiki, Hitoshi; Higashimoto, Chikaki; Ohnishi, Kouhei; Kiba, Akinori; Hikichi, Yasufumi

2016-08-01

The mechanism of colonization of intercellular spaces by the soil-borne and vascular plant-pathogenic bacterium Ralstonia solanacearum strain OE1-1 after invasion into host plants remains unclear. To analyse the behaviour of OE1-1 cells in intercellular spaces, tomato leaves with the lower epidermis layers excised after infiltration with OE1-1 were observed under a scanning electron microscope. OE1-1 cells formed microcolonies on the surfaces of tomato cells adjacent to intercellular spaces, and then aggregated surrounded by an extracellular matrix, forming mature biofilm structures. Furthermore, OE1-1 cells produced mushroom-type biofilms when incubated in fluids of apoplasts including intercellular spaces, but not xylem fluids from tomato plants. This is the first report of biofilm formation by R. solanacearum on host plant cells after invasion into intercellular spaces and mushroom-type biofilms produced by R. solanacearum in vitro. Sugar application led to enhanced biofilm formation by OE1-1. Mutation of lecM encoding a lectin, RS-IIL, which reportedly exhibits affinity for these sugars, led to a significant decrease in biofilm formation. Colonization in intercellular spaces was significantly decreased in the lecM mutant, leading to a loss of virulence on tomato plants. Complementation of the lecM mutant with native lecM resulted in the recovery of mushroom-type biofilms and virulence on tomato plants. Together, our findings indicate that OE1-1 produces mature biofilms on the surfaces of tomato cells after invasion into intercellular spaces. RS-IIL may contribute to biofilm formation by OE1-1, which is required for OE1-1 virulence. © 2015 BSPP AND JOHN WILEY & SONS LTD.

Complete factorial design to adjust pH and sugar concentrations in the inoculum phase of Ralstonia solanacearum to optimize P(3HB) production

PubMed Central

Alves, Mariane Igansi; Rodrigues, Amanda Ávila; Furlan, Lígia; da Silva Rodrigues, Rosane; Diaz de Oliveira, Patrícia; Vendruscolo, Claire Tondo; da Silveira Moreira, Angelita

2017-01-01

Poly(3-hydroxybutyrate) (P(3HB)) is a biodegradable plastic biopolymer that accumulates as lipophilic inclusions in the cytoplasm of some microorganisms. The biotechnological process by which P(3HB) is synthesized occurs in two phases. The first phase involves cell growth in a complex culture medium, while the second phase involves polymer accumulation in the presence of excess carbon sources. As such, the efficiency of the second phase depends on the first phase. The aim of this study was to evaluate culture media with different concentrations of sucrose and glucose and different pH values in the inoculum phase of Ralstonia solanacearum RS with the intention of identifying methods by which the biomass yield could be increased, subsequently enhancing the yield of P(3HB). The culture medium was formulated according to the experimental planning type of central composite rotational design 22. The independent variables were pH and sugar concentration (sucrose and glucose), and the dependent variables were OD600nm, dry cell weight (DCW), and P(3HB) yield. The highest cell growth, estimated by the OD600nm (20.6) and DCW (5.35) values, was obtained when sucrose was used in the culture medium at a concentration above 35 g.L-1 in combination with an acidic pH. High polymer (45%) accumulation was also achieved under these conditions. Using glucose, the best results for OD600nm (12.5) and DCW (2.74) were also obtained at acidic pH but with a sugar concentration at the minimum values evaluated. Due to the significant accumulation of polymer in the cells that were still in the growth phase, the accumulating microorganism P(3HB) Ralstonia solanacearum RS can be classified as having type II metabolism in relation to the polymer accumulation phase, which is different from other Ralstonia spp. studied until this time. PMID:28704411

PopF1 and PopF2, Two Proteins Secreted by the Type III Protein Secretion System of Ralstonia solanacearum, Are Translocators Belonging to the HrpF/NopX Family†

PubMed Central

Meyer, Damien; Cunnac, Sébastien; Guéneron, Mareva; Declercq, Céline; Van Gijsegem, Frédérique; Lauber, Emmanuelle; Boucher, Christian; Arlat, Matthieu

2006-01-01

Ralstonia solanacearum GMI1000 is a gram-negative plant pathogen which contains an hrp gene cluster which codes for a type III protein secretion system (TTSS). We identified two novel Hrp-secreted proteins, called PopF1 and PopF2, which display similarity to one another and to putative TTSS translocators, HrpF and NopX, from Xanthomonas spp. and rhizobia, respectively. They also show similarities with TTSS translocators of the YopB family from animal-pathogenic bacteria. Both popF1 and popF2 belong to the HrpB regulon and are required for the interaction with plants, but PopF1 seems to play a more important role in virulence and hypersensitive response (HR) elicitation than PopF2 under our experimental conditions. PopF1 and PopF2 are not necessary for the secretion of effector proteins, but they are required for the translocation of AvrA avirulence protein into tobacco cells. We conclude that PopF1 and PopF2 are type III translocators belonging to the HrpF/NopX family. The hrpF gene of Xanthomonas campestris pv. campestris partially restored HR-inducing ability to popF1 popF2 mutants of R. solanacearum, suggesting that translocators of R. solanacearum and Xanthomonas are functionally conserved. Finally, R. solanacearum strain UW551, which does not belong to the same phylotype as GMI1000, also possesses two putative translocator proteins. However, although one of these proteins is clearly related to PopF1 and PopF2, the other seems to be different and related to NopX proteins, thus showing that translocators might be variable in R. solanacearum. PMID:16788199

CaWRKY6 transcriptionally activates CaWRKY40, regulates Ralstonia solanacearum resistance, and confers high-temperature and high-humidity tolerance in pepper.

PubMed

Cai, Hanyang; Yang, Sheng; Yan, Yan; Xiao, Zhuoli; Cheng, Junbin; Wu, Ji; Qiu, Ailian; Lai, Yan; Mou, Shaoliang; Guan, Deyi; Huang, Ronghua; He, Shuilin

2015-06-01

High temperature (HT), high humidity (HH), and pathogen infection often co-occur and negatively affect plant growth. However, these stress factors and plant responses are generally studied in isolation. The mechanisms of synergistic responses to combined stresses are poorly understood. We isolated the subgroup IIb WRKY family member CaWRKY6 from Capsicum annuum and performed quantitative real-time PCR analysis. CaWRKY6 expression was upregulated by individual or simultaneous treatment with HT, HH, combined HT and HH (HTHH), and Ralstonia solanacearum inoculation, and responded to exogenous application of jasmonic acid (JA), ethephon, and abscisic acid (ABA). Virus-induced gene silencing of CaWRKY6 enhanced pepper plant susceptibility to R. solanacearum and HTHH, and downregulated the hypersensitive response (HR), JA-, ethylene (ET)-, and ABA-induced marker gene expression, and thermotolerance-associated expression of CaHSP24, ER-small CaSHP, and Chl-small CaHSP. CaWRKY6 overexpression in pepper attenuated the HTHH-induced suppression of resistance to R. solanacearum infection. CaWRKY6 bound to and activated the CaWRKY40 promoter in planta, which is a pepper WRKY that regulates heat-stress tolerance and R. solanacearum resistance. CaWRKY40 silencing significantly blocked HR-induced cell death and reduced transcriptional expression of CaWRKY40. These data suggest that CaWRKY6 is a positive regulator of R. solanacearum resistance and heat-stress tolerance, which occurs in part by activating CaWRKY40. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Ralstonia solanacearum novel E3 ubiquitin ligase (NEL) effectors RipAW and RipAR suppress pattern-triggered immunity in plants.

PubMed

Nakano, Masahito; Oda, Kenji; Mukaihara, Takafumi

2017-07-01

Ralstonia solanacearum is the causal agent of bacterial wilt in solanaceous crops. This pathogen injects more than 70 effector proteins into host plant cells via the Hrp type III secretion system to cause a successful infection. However, the function of these effectors in plant cells, especially in the suppression of plant immunity, remains largely unknown. In this study, we characterized two Ralstonia solanacearum effectors, RipAW and RipAR, which share homology with the IpaH family of effectors from animal and plant pathogenic bacteria, that have a novel E3 ubiquitin ligase (NEL) domain. Recombinant RipAW and RipAR show E3 ubiquitin ligase activity in vitro. RipAW and RipAR localized to the cytoplasm of plant cells and significantly suppressed pattern-triggered immunity (PTI) responses such as the production of reactive oxygen species and the expression of defence-related genes when expressed in leaves of Nicotiana benthamiana. Mutation in the conserved cysteine residue in the NEL domain of RipAW completely abolished the E3 ubiquitin ligase activity in vitro and the ability to suppress PTI responses in plant leaves. These results indicate that RipAW suppresses plant PTI responses through the E3 ubiquitin ligase activity. Unlike other members of the IpaH family of effectors, RipAW and RipAR had no leucine-rich repeat motifs in their amino acid sequences. A conserved C-terminal region of RipAW is indispensable for PTI suppression. Transgenic Arabidopsis plants expressing RipAW and RipAR showed increased disease susceptibility, suggesting that RipAW and RipAR contribute to bacterial virulence in plants.

Prophage Rs551 and its repressor gene orf14 reduce virulence and increase competitive fitness of its Ralstonia solanacearum carrier strain UW551

USDA-ARS?s Scientific Manuscript database

We previously characterized a filamentous lysogenic bacteriophage, 'Rs551, isolated directly from the race 3 biovar 2 phylotype IIB sequevar 1 strain UW551 of R. solanacearum grown under normal culture conditions. The genome of 'Rs551 was identified with 100% identity in the deposited genomes of 11 ...

[Genetic variability of the bacterium Ralstonia solanacearum (Burkholderiales: Burholderiaceae) in the banana-growing region of Uraba (Colombia)].

PubMed

Cardozo, Carolina; Rodríguez, Paola; Cotes, José Miguel; Marín, Mauricio

2010-03-01

The banana moko disease, caused by the bacterium Ralstonia solanacearum, is one of the most important phytopathological problems of the banana agribusiness in tropical countries. In Uraba and Magdalena (Colombia), the main exporting regions of banana in Colombia, this disease causes a destruction estimated in 16.5 ha/year. The bacterium presents an extremely high level of genetic variation that affects control measures. This is the first study of its variation in Colombia and was done with AFLP molecular markers on a population of 100 isolates from banana plants, soils and "weeds". The high level of genetic diversity, with Nei and Shannon indexes of h=0.32 and I=0.48, respectively, and the AMOVA, showed that this population is subestructured (Fst=0.66): the host is the main factor of differentiation. Even so, previous tests show that all varieties have pathogenicity on Musa.

Plant Genome Complexity May Be a Factor Limiting In Situ the Transfer of Transgenic Plant Genes to the Phytopathogen Ralstonia solanacearum

PubMed Central

Bertolla, Franck; Pepin, Regis; Passelegue-Robe, Eugenie; Paget, Eric; Simkin, Andrew; Nesme, Xavier; Simonet, Pascal

2000-01-01

The development of natural competence by bacteria in situ is considered one of the main factors limiting transformation-mediated gene exchanges in the environment. Ralstonia solanacearum is a plant pathogen that is also a naturally transformable bacterium that can develop the competence state during infection of its host. We have attempted to determine whether this bacterium could become the recipient of plant genes. We initially demonstrated that plant DNA was released close to the infecting bacteria. We constructed and tested various combinations of transgenic plants and recipient bacteria to show that the effectiveness of such transfers was directly related to the ratio of the complexity of the plant genome to the number of copies of the transgene. PMID:10966449

Overexpression of CaWRKY27, a subgroup IIe WRKY transcription factor of Capsicum annuum, positively regulates tobacco resistance to Ralstonia solanacearum infection.

PubMed

Dang, Fengfeng; Wang, Yuna; She, Jianju; Lei, Yufen; Liu, Zhiqin; Eulgem, Thomas; Lai, Yan; Lin, Jing; Yu, Lu; Lei, Dan; Guan, Deyi; Li, Xia; Yuan, Qian; He, Shuilin

2014-03-01

WRKY proteins are encoded by a large gene family and are linked to many biological processes across a range of plant species. The functions and underlying mechanisms of WRKY proteins have been investigated primarily in model plants such as Arabidopsis and rice. The roles of these transcription factors in non-model plants, including pepper and other Solanaceae, are poorly understood. Here, we characterize the expression and function of a subgroup IIe WRKY protein from pepper (Capsicum annuum), denoted as CaWRKY27. The protein localized to nuclei and activated the transcription of a reporter GUS gene construct driven by the 35S promoter that contained two copies of the W-box in its proximal upstream region. Inoculation of pepper cultivars with Ralstonia solanacearum induced the expression of CaWRKY27 transcript in 76a, a bacterial wilt-resistant pepper cultivar, whereas it downregulated the expression of CaWRKY27 transcript in Gui-1-3, a bacterial wilt-susceptible pepper cultivar. CaWRKY27 transcript levels were also increased by treatments with salicylic acid (SA), methyl jasmonate (MeJA) and ethephon (ETH). Transgenic tobacco plants overexpressing CaWRKY27 exhibited resistance to R. solanacearum infection compared to that of wild-type plants. This resistance was coupled with increased transcript levels in a number of marker genes, including hypersensitive response genes, and SA-, JA- and ET-associated genes. By contrast, virus-induced gene silencing (VIGS) of CaWRKY27 increased the susceptibility of pepper plants to R. solanacearum infection. These results suggest that CaWRKY27 acts as a positive regulator in tobacco resistance responses to R. solanacearum infection through modulation of SA-, JA- and ET-mediated signaling pathways. © 2013 Scandinavian Plant Physiology Society.

Defining the Metabolic Functions and Roles in Virulence of the rpoN1 and rpoN2 Genes in Ralstonia solanacearum GMI1000.

PubMed

Lundgren, Benjamin R; Connolly, Morgan P; Choudhary, Pratibha; Brookins-Little, Tiffany S; Chatterjee, Snigdha; Raina, Ramesh; Nomura, Christopher T

2015-01-01

The alternative sigma factor RpoN is a unique regulator found among bacteria. It controls numerous processes that range from basic metabolism to more complex functions such as motility and nitrogen fixation. Our current understanding of RpoN function is largely derived from studies on prototypical bacteria such as Escherichia coli. Bacillus subtilis and Pseudomonas putida. Although the extent and necessity of RpoN-dependent functions differ radically between these model organisms, each bacterium depends on a single chromosomal rpoN gene to meet the cellular demands of RpoN regulation. The bacterium Ralstonia solanacearum is often recognized for being the causative agent of wilt disease in crops, including banana, peanut and potato. However, this plant pathogen is also one of the few bacterial species whose genome possesses dual rpoN genes. To determine if the rpoN genes in this bacterium are genetically redundant and interchangeable, we constructed and characterized ΔrpoN1, ΔrpoN2 and ΔrpoN1 ΔrpoN2 mutants of R. solanacearum GMI1000. It was found that growth on a small range of metabolites, including dicarboxylates, ethanol, nitrate, ornithine, proline and xanthine, were dependent on only the rpoN1 gene. Furthermore, the rpoN1 gene was required for wilt disease on tomato whereas rpoN2 had no observable role in virulence or metabolism in R. solanacearum GMI1000. Interestingly, plasmid-based expression of rpoN2 did not fully rescue the metabolic deficiencies of the ΔrpoN1 mutants; full recovery was specific to rpoN1. In comparison, only rpoN2 was able to genetically complement a ΔrpoN E. coli mutant. These results demonstrate that the RpoN1 and RpoN2 proteins are not functionally equivalent or interchangeable in R. solanacearum GMI1000.

Overexpression of NtWRKY50 Increases Resistance to Ralstonia solanacearum and Alters Salicylic Acid and Jasmonic Acid Production in Tobacco

PubMed Central

Liu, Qiuping; Liu, Ying; Tang, Yuanman; Chen, Juanni; Ding, Wei

2017-01-01

WRKY transcription factors (TFs) modulate plant responses to biotic and abiotic stresses. Here, we characterized a WRKY IIc TF, NtWRKY50, isolated from tobacco (Nicotiana tabacum) plants. The results showed that NtWRKY50 is a nuclear-localized protein and that its gene transcript is induced in tobacco when inoculated with the pathogenic bacterium Ralstonia solanacearum. Overexpression of NtWRKY50 enhanced bacterial resistance, which correlated with enhanced SA and JA/ET signaling genes. However, silencing of the NtWRKY50 gene had no obvious effects on plant disease resistance, implying functional redundancy of NtWRKY50 with other TFs. In addition, it was found that NtWRKY50 can be induced by various biotic or abiotic stresses, such as Potato virus Y, Rhizoctonia solani, Phytophthora parasitica, hydrogen peroxide, heat, cold, and wounding as well as the hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). Importantly, additional analysis suggests that NtWRKY50 overexpression markedly promotes SA levels but prevents pathogen-induced JA production. These data indicate that NtWRKY50 overexpression leads to altered SA and JA content, increased expression of defense-related genes and enhanced plant resistance to R. solanacearum. These probably due to increased activity of endogenous NtWRKY50 gene or could be gain-of-function phenotypes by altering the profile of genes affected by NtWRKY50. PMID:29075272

Overexpression of NtWRKY50 Increases Resistance to Ralstonia solanacearum and Alters Salicylic Acid and Jasmonic Acid Production in Tobacco.

PubMed

Liu, Qiuping; Liu, Ying; Tang, Yuanman; Chen, Juanni; Ding, Wei

2017-01-01

WRKY transcription factors (TFs) modulate plant responses to biotic and abiotic stresses. Here, we characterized a WRKY IIc TF, NtWRKY50, isolated from tobacco ( Nicotiana tabacum ) plants. The results showed that NtWRKY50 is a nuclear-localized protein and that its gene transcript is induced in tobacco when inoculated with the pathogenic bacterium Ralstonia solanacearum . Overexpression of NtWRKY50 enhanced bacterial resistance, which correlated with enhanced SA and JA/ET signaling genes. However, silencing of the NtWRKY50 gene had no obvious effects on plant disease resistance, implying functional redundancy of NtWRKY50 with other TFs. In addition, it was found that NtWRKY50 can be induced by various biotic or abiotic stresses, such as Potato virus Y, Rhizoctonia solani, Phytophthora parasitica , hydrogen peroxide, heat, cold, and wounding as well as the hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). Importantly, additional analysis suggests that NtWRKY50 overexpression markedly promotes SA levels but prevents pathogen-induced JA production. These data indicate that NtWRKY50 overexpression leads to altered SA and JA content, increased expression of defense-related genes and enhanced plant resistance to R. solanacearum. These probably due to increased activity of endogenous NtWRKY50 gene or could be gain-of-function phenotypes by altering the profile of genes affected by NtWRKY50 .

A probable aculeacin A acylase from the Ralstonia solanacearum GMI1000 is N-acyl-homoserine lactone acylase with quorum-quenching activity

PubMed Central

2009-01-01

Background The infection and virulence functions of diverse plant and animal pathogens that possess quorum sensing systems are regulated by N-acylhomoserine lactones (AHLs) acting as signal molecules. AHL-acylase is a quorum quenching enzyme and degrades AHLs by removing the fatty acid side chain from the homoserine lactone ring of AHLs. This blocks AHL accumulation and pathogenic phenotypes in quorum sensing bacteria. Results An aac gene of undemonstrated function from Ralstonia solanacearum GMI1000 was cloned, expressed in Escherichia coli; it inactivated four AHLs that were tested. The sequence of the 795 amino acid polypeptide was considerably similar to the AHL-acylase from Ralstonia sp. XJ12B with 83% identity match and shared 39% identity with an aculeacin A acylase precursor from the gram-positive actinomycete Actinoplanes utahensis. Aculeacin A is a neutral lipopeptide antibiotic and an antifungal drug. An electrospray ionisation mass spectrometry (ESI-MS) analysis verified that Aac hydrolysed the amide bond of AHL, releasing homoserine lactone and the corresponding fatty acids. However, ESI-MS analysis demonstrated that the Aac could not catalyze the hydrolysis of the palmitoyl moiety of the aculeacin A. Moreover, the results of MIC test of aculeacin A suggest that Aac could not deacylate aculeacin A. The specificity of Aac for AHLs showed a greater preference for long acyl chains than for short acyl chains. Heterologous expression of the aac gene in Chromobacterium violaceum CV026 effectively inhibited violacein and chitinase activity, both of which were regulated by the quorum-sensing mechanism. These results indicated that Aac could control AHL-dependent pathogenicity. Conclusion This is the first study to find an AHL-acylase in a phytopathogen. Our data provide direct evidence that the functioning of the aac gene (NP520668) of R. solanacearum GMI1000 is via AHL-acylase and not via aculeacin A acylase. Since Aac is a therapeutic potential quorum

Protease Activities Triggered by Ralstonia solanacearum Infection in Susceptible and Tolerant Tomato Lines.

PubMed

Planas-Marquès, Marc; Bernardo-Faura, Martí; Paulus, Judith; Kaschani, Farnusch; Kaiser, Markus; Valls, Marc; van der Hoorn, Renier A L; Coll, Núria S

2018-06-01

Activity-based protein profiling (ABPP) is a powerful proteomic technique to display protein activities in a proteome. It is based on the use of small molecular probes that react with the active site of proteins in an activity-dependent manner. We used ABPP to dissect the protein activity changes that occur in the intercellular spaces of tolerant (Hawaii 7996) and susceptible (Marmande) tomato plants in response to R. solanacearum , the causing agent of bacterial wilt, one of the most destructive bacterial diseases in plants. The intercellular space -or apoplast- is the first battlefield where the plant faces R. solanacearum Here, we explore the possibility that the limited R. solanacearum colonization reported in the apoplast of tolerant tomato is partly determined by its active proteome. Our work reveals specific activation of papain-like cysteine proteases (PLCPs) and serine hydrolases (SHs) in the leaf apoplast of the tolerant tomato Hawaii 7996 on R. solanacearum infection. The P69 family members P69C and P69F, and an unannotated lipase (Solyc02g077110.2.1), were found to be post-translationally activated. In addition, protein network analysis showed that deeper changes in network topology take place in the susceptible tomato variety, suggesting that the tolerant cultivar might be more prepared to face R. solanacearum in its basal state. Altogether this work identifies significant changes in the activity of 4 PLCPs and 27 SHs in the tomato leaf apoplast in response to R. solanacearum , most of which are yet to be characterized. Our findings denote the importance of novel proteomic approaches such as ABPP to provide new insights on old and elusive questions regarding the molecular basis of resistance to R. solanacearum . © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Ferulic Acid, But Not All Hydroxycinnamic Acids, Is a Novel T3SS Inducer of Ralstonia solanacearum and Promotes Its Infection Process in Host Plants under Hydroponic Condition.

PubMed

Zhang, Yong; Li, Jing; Zhang, Weiqi; Wang, Rongsheng; Qiu, Qiaoqing; Luo, Feng; Hikichi, Yasufumi; Ohnishi, Kouhei; Ding, Wei

2017-01-01

Hydroxycinnamic acids (HCAs) are typical monocyclic phenylpropanoids, including cinnamic acid (Cin), coumaric acid (Cou), caffeic acid (Caf), ferulic acid (FA) and their isomers, and involved in the interactions between pathogens and host plants. Here, we focused on the impact of HCAs on expression of type III secretion system (T3SS) in Ralstonia solanacearum . FA significantly induced the expression of the T3SS and some type III effectors (T3Es) genes in hrp -inducing medium, while did not the other HCAs. However, exogenously supplemented FA did not affect the T3SS expression in planta and the elicitation of the hypersensitive response (HR) in tobacco leaves. Consistent with its central roles in pathogenicity, the FA-induced expression of the T3SS led to significant promotion on infection process of R. solanacearum in tomato plants under hydroponics cultivation. Moreover, the FA-induced expression of the T3SS was specifically mediated by the well-characterized signaling cascade PrhA-prhI/R-PrhJ-HrpG-HrpB, independent of the other known regulatory pathways. In summary, our results demonstrated that FA, a novel inducer of the T3SS in R. solanacearum , was able to promote its infection process in host plants under hydroponics condition.

Ralstonia solanacearum Type III Effector RipAY Is a Glutathione-Degrading Enzyme That Is Activated by Plant Cytosolic Thioredoxins and Suppresses Plant Immunity.

PubMed

Mukaihara, Takafumi; Hatanaka, Tadashi; Nakano, Masahito; Oda, Kenji

2016-04-12

The plant pathogen Ralstonia solanacearum uses a large repertoire of type III effector proteins to succeed in infection. To clarify the function of effector proteins in host eukaryote cells, we expressed effectors in yeast cells and identified seven effector proteins that interfere with yeast growth. One of the effector proteins, RipAY, was found to share homology with the ChaC family proteins that function as γ-glutamyl cyclotransferases, which degrade glutathione (GSH), a tripeptide that plays important roles in the plant immune system. RipAY significantly inhibited yeast growth and simultaneously induced rapid GSH depletion when expressed in yeast cells. The in vitro GSH degradation activity of RipAY is specifically activated by eukaryotic factors in the yeast and plant extracts. Biochemical purification of the yeast protein identified that RipAY is activated by thioredoxin TRX2. On the other hand, RipAY was not activated by bacterial thioredoxins. Interestingly, RipAY was activated by plant h-type thioredoxins that exist in large amounts in the plant cytosol, but not by chloroplastic m-, f-, x-, y- and z-type thioredoxins, in a thiol-independent manner. The transient expression of RipAY decreased the GSH level in plant cells and affected the flg22-triggered production of reactive oxygen species (ROS) and expression of pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) marker genes in Nicotiana benthamiana leaves. These results indicate that RipAY is activated by host cytosolic thioredoxins and degrades GSH specifically in plant cells to suppress plant immunity. Ralstonia solanacearum is the causal agent of bacterial wilt disease of plants. This pathogen injects virulence effector proteins into host cells to suppress disease resistance responses of plants. In this article, we report a biochemical activity of R. solanacearum effector protein RipAY. RipAY can degrade GSH, a tripeptide that plays important roles in the plant immune system, with

Non-Instrumented Nucleic Acid Amplification (NINA) for Rapid Detection of Ralstonia solanacearum Race 3 Biovar 2

PubMed Central

Kubota, Ryo; LaBarre, Paul; Singleton, Jered; Beddoe, Andy; Weigl, Bernhard H.; Alvarez, Anne M.; Jenkins, Daniel M.

2014-01-01

We report on the use of a non-instrumented device for the implementation of a loop-mediated amplification (LAMP) based assay for the select-agent bacterial-wilt pathogen Ralstonia solanacearum race 3 biovar 2. Heat energy is generated within the device by the exothermic hydration of calcium oxide, and the reaction temperature is regulated by storing latent energy at the melting temperature of a renewable lipid-based engineered phase-change material. Endpoint detection of the LAMP reaction is achieved without opening the reaction tube by observing the fluorescence of an innovative FRET-based hybridization probe with a simple custom fluorometer. Non-instrumented devices could maintain reactions near the design temperature of 63°C for at least an hour. Using this approach DNA extracted from the pathogen could be detected at fewer than ten copies within a 25 μL reaction mix, illustrating the potential of these technologies for simple, powerful agricultural diagnostics in the field. Furthermore, the assay was just as reliable when implemented in a tropical environment at 31°C as it was when implemented in an air-conditioned lab maintained at 22°C, illustrating the potential value of the technology for field conditions in the tropics and subtropics. PMID:25485176

Effect of volatile compounds produced by Ralstonia solanacearum on plant growth promoting and systemic resistance inducing potential of Bacillus volatiles.

PubMed

Tahir, Hafiz Abdul Samad; Gu, Qin; Wu, Huijun; Raza, Waseem; Safdar, Asma; Huang, Ziyang; Rajer, Faheem Uddin; Gao, Xuewen

2017-08-02

Microbial volatiles play an expedient role in the agricultural ecological system by enhancing plant growth and inducing systemic resistance against plant pathogens, without causing hazardous effects on the environment. To explore the effects of VOCs of Ralstonia solanacearum TBBS1 (Rs) on tobacco plant growth and on plant growth promoting efficiency of VOCs produced by Bacillus subtilis SYST2, experiments were conducted both in vitro and in planta. The VOCs produced by SYST2 significantly enhanced the plant growth and induced the systemic resistance (ISR) against wilt pathogen Rs in all experiments. The SYST2-VOCs significantly increased PPO and PAL activity and over-expressed the genes relating to expansin, wilt resistance, and plant defense while repressed the genes relating to ethylene production. More interestingly, VOCs produced by pathogen, Rs had no significant effect on plant growth; however, Rs-VOCs decreased the growth promoting potential of SYST2-VOCs when plants were exposed to VOCs produced by both SYST2 and Rs. The co-culture of SYST2 and Rs revealed that they inhibited the growth of each other; however, the inhibition of Rs by SYST2-VOCs appeared to be greater than that of SYST2 by Rs-VOCs. Our findings provide new insights regarding the interaction among SYST2-VOCs, Rs-VOCs and plant, resulting in growth promotion and induced systemic resistance against the bacterial wilt pathogen Rs. This is the first report of the effect of VOCs produced by pathogenic microorganism on plant growth and on plant growth-promoting and systemic resistance-inducing potential of PGPR strain SYST2.

Production and properties of the native Chromobacterium violaceum fucose-binding lectin (CV-IIL) compared to homologous lectins of Pseudomonas aeruginosa (PA-IIL) and Ralstonia solanacearum (RS-IIL).

PubMed

Zinger-Yosovich, Keren; Sudakevitz, Dvora; Imberty, Anne; Garber, Nachman C; Gilboa-Garber, Nechama

2006-02-01

Chromobacterium violaceum is a versatile, violet pigment (violacein)-producing beta-proteobacterium, confined to tropical and subtropical regions, dwelling in soil and water, like Pseudomonas aeruginosa and Ralstonia solanacearum. These three bacteria are saprophytes that occasionally become aggressive opportunistic pathogens virulently attacking animals (the first two) and plants (the third). The recent availability of their genome sequences enabled identification in the C. violaceum genome of an ORF (locus no. 1744) that is similar to those of P. aeruginosa and R. solanacearum lectins, PA-IIL and RS-IIL, respectively. A recombinant protein, CV-IIL, encoded by that ORF exhibited fucose>mannose-specific lectin activity resembling PA-IIL. This paper describes production and properties of the native CV-IIL, which, like PA-IIL and RS-IIL, is probably also a quorum-sensing-driven secondary metabolite, appearing concomitantly with violacein. Its formation is repressed in the CV026 mutant of C. violaceum, which lacks endogenous N-acylhomoserine lactone. The upstream extragenic sequence of its ORF contains a 20 bp sequence (5'-101-120) with partial similarities to the luxI-box and the related P. aeruginosa and R. solanacearum promoter boxes of quorum-sensing-controlled genes. The lectin level is augmented by addition of trehalose to the medium. The subunit size of CV-IIL (around 11.86 kDa) is similar to those of PA-IIL (11.73 kDa) and RS-IIL (11.60 kDa). Like PA-IIL, in the tetrameric form CV-IIL preferentially agglutinates alpha1-2 fucosylated H-positive human erythrocytes (regardless of their A, B or O type), as opposed to the O(h) Bombay type, but differs from it in having no interaction with rabbit erythrocytes and in displaying stronger affinity to l-galactose than to l-fucose. The greater similarity of CV-IIL to PA-IIL than to RS-IIL might be related to the selective adaptation of both C. violaceum and P. aeruginosa to animal tissues versus the preferential homing

Enhanced in planta Fitness through Adaptive Mutations in EfpR, a Dual Regulator of Virulence and Metabolic Functions in the Plant Pathogen Ralstonia solanacearum.

PubMed

Perrier, Anthony; Peyraud, Rémi; Rengel, David; Barlet, Xavier; Lucasson, Emmanuel; Gouzy, Jérôme; Peeters, Nemo; Genin, Stéphane; Guidot, Alice

2016-12-01

Experimental evolution of the plant pathogen Ralstonia solanacearum, where bacteria were maintained on plant lineages for more than 300 generations, revealed that several independent single mutations in the efpR gene from populations propagated on beans were associated with fitness gain on bean. In the present work, novel allelic efpR variants were isolated from populations propagated on other plant species, thus suggesting that mutations in efpR were not solely associated to a fitness gain on bean, but also on additional hosts. A transcriptomic profiling and phenotypic characterization of the efpR deleted mutant showed that EfpR acts as a global catabolic repressor, directly or indirectly down-regulating the expression of multiple metabolic pathways. EfpR also controls virulence traits such as exopolysaccharide production, swimming and twitching motilities and deletion of efpR leads to reduced virulence on tomato plants after soil drenching inoculation. We studied the impact of the single mutations that occurred in efpR during experimental evolution and found that these allelic mutants displayed phenotypic characteristics similar to the deletion mutant, although not behaving as complete loss-of-function mutants. These adaptive mutations therefore strongly affected the function of efpR, leading to an expanded metabolic versatility that should benefit to the evolved clones. Altogether, these results indicated that EfpR is a novel central player of the R. solanacearum virulence regulatory network. Independent mutations therefore appeared during experimental evolution in the evolved clones, on a crucial node of this network, to favor adaptation to host vascular tissues through regulatory and metabolic rewiring.

A Resource Allocation Trade-Off between Virulence and Proliferation Drives Metabolic Versatility in the Plant Pathogen Ralstonia solanacearum

PubMed Central

Marmiesse, Lucas; Gouzy, Jérôme

2016-01-01

Bacterial pathogenicity relies on a proficient metabolism and there is increasing evidence that metabolic adaptation to exploit host resources is a key property of infectious organisms. In many cases, colonization by the pathogen also implies an intensive multiplication and the necessity to produce a large array of virulence factors, which may represent a significant cost for the pathogen. We describe here the existence of a resource allocation trade-off mechanism in the plant pathogen R. solanacearum. We generated a genome-scale reconstruction of the metabolic network of R. solanacearum, together with a macromolecule network module accounting for the production and secretion of hundreds of virulence determinants. By using a combination of constraint-based modeling and metabolic flux analyses, we quantified the metabolic cost for production of exopolysaccharides, which are critical for disease symptom production, and other virulence factors. We demonstrated that this trade-off between virulence factor production and bacterial proliferation is controlled by the quorum-sensing-dependent regulatory protein PhcA. A phcA mutant is avirulent but has a better growth rate than the wild-type strain. Moreover, a phcA mutant has an expanded metabolic versatility, being able to metabolize 17 substrates more than the wild-type. Model predictions indicate that metabolic pathways are optimally oriented towards proliferation in a phcA mutant and we show that this enhanced metabolic versatility in phcA mutants is to a large extent a consequence of not paying the cost for virulence. This analysis allowed identifying candidate metabolic substrates having a substantial impact on bacterial growth during infection. Interestingly, the substrates supporting well both production of virulence factors and growth are those found in higher amount within the plant host. These findings also provide an explanatory basis to the well-known emergence of avirulent variants in R. solanacearum

Effect of calcium cyanamide, ammonium bicarbonate and lime mixture, and ammonia water on survival of Ralstonia solanacearum and microbial community

PubMed Central

Liu, Lijuan; Sun, Chengliang; Liu, Xingxing; He, Xiaolin; Liu, Miao; Wu, Hao; Tang, Caixian; Jin, Chongwei; Zhang, Yongsong

2016-01-01

The inorganic nitrogenous amendments calcium cyanamide (CC), ammonia water (AW), and a mixture of ammonium bicarbonate with lime (A+L) are popularly used as fumigants to control soil-borne disease in China. However, it is unclear which of these fumigants is more effective in controlling R. solanacearum. This present study compared the efficiencies of the three nitrogenous amendments listed above at four nitrogen levels in suppressing the survival of R. solanacearum in soil. The CC showed the best ability to suppress R. solanacearum due to its highest capacity to increase soil and NO2− contents and pH. However, AW was more suitable to controlling bacterial wilt caused by R. solanacearum because it had a lower cost and its application rate of 0.25 g N kg−1 soil could effectively suppress the survival of R. solanacearum. Additionally, soil microbial activity and community populations were restored to their initial state four weeks after the application of each fumigant, indicating that the three fumigants had few detrimental impacts on soil microbial activity and community structure with an exception of the suppression of R. solanacearum. The present study provides guidance for the selection of a suitable alkaline nitrogenous amendment and its application rate in controlling bacterial wilt. PMID:26738601

Effect of calcium cyanamide, ammonium bicarbonate and lime mixture, and ammonia water on survival of Ralstonia solanacearum and microbial community

NASA Astrophysics Data System (ADS)

Liu, Lijuan; Sun, Chengliang; Liu, Xingxing; He, Xiaolin; Liu, Miao; Wu, Hao; Tang, Caixian; Jin, Chongwei; Zhang, Yongsong

2016-01-01

The inorganic nitrogenous amendments calcium cyanamide (CC), ammonia water (AW), and a mixture of ammonium bicarbonate with lime (A+L) are popularly used as fumigants to control soil-borne disease in China. However, it is unclear which of these fumigants is more effective in controlling R. solanacearum. This present study compared the efficiencies of the three nitrogenous amendments listed above at four nitrogen levels in suppressing the survival of R. solanacearum in soil. The CC showed the best ability to suppress R. solanacearum due to its highest capacity to increase soil and NO2- contents and pH. However, AW was more suitable to controlling bacterial wilt caused by R. solanacearum because it had a lower cost and its application rate of 0.25 g N kg-1 soil could effectively suppress the survival of R. solanacearum. Additionally, soil microbial activity and community populations were restored to their initial state four weeks after the application of each fumigant, indicating that the three fumigants had few detrimental impacts on soil microbial activity and community structure with an exception of the suppression of R. solanacearum. The present study provides guidance for the selection of a suitable alkaline nitrogenous amendment and its application rate in controlling bacterial wilt.

Effect of calcium cyanamide, ammonium bicarbonate and lime mixture, and ammonia water on survival of Ralstonia solanacearum and microbial community.

PubMed

Liu, Lijuan; Sun, Chengliang; Liu, Xingxing; He, Xiaolin; Liu, Miao; Wu, Hao; Tang, Caixian; Jin, Chongwei; Zhang, Yongsong

2016-01-07

The inorganic nitrogenous amendments calcium cyanamide (CC), ammonia water (AW), and a mixture of ammonium bicarbonate with lime (A+L) are popularly used as fumigants to control soil-borne disease in China. However, it is unclear which of these fumigants is more effective in controlling R. solanacearum. This present study compared the efficiencies of the three nitrogenous amendments listed above at four nitrogen levels in suppressing the survival of R. solanacearum in soil. The CC showed the best ability to suppress R. solanacearum due to its highest capacity to increase soil and NO2(-) contents and pH. However, AW was more suitable to controlling bacterial wilt caused by R. solanacearum because it had a lower cost and its application rate of 0.25 g N kg(-1) soil could effectively suppress the survival of R. solanacearum. Additionally, soil microbial activity and community populations were restored to their initial state four weeks after the application of each fumigant, indicating that the three fumigants had few detrimental impacts on soil microbial activity and community structure with an exception of the suppression of R. solanacearum. The present study provides guidance for the selection of a suitable alkaline nitrogenous amendment and its application rate in controlling bacterial wilt.

Autoacetylation of the Ralstonia solanacearum effector PopP2 targets a lysine residue essential for RRS1-R-mediated immunity in Arabidopsis.

PubMed

Tasset, Céline; Bernoux, Maud; Jauneau, Alain; Pouzet, Cécile; Brière, Christian; Kieffer-Jacquinod, Sylvie; Rivas, Susana; Marco, Yves; Deslandes, Laurent

2010-11-18

Type III effector proteins from bacterial pathogens manipulate components of host immunity to suppress defence responses and promote pathogen development. In plants, host proteins targeted by some effectors called avirulence proteins are surveyed by plant disease resistance proteins referred to as "guards". The Ralstonia solanacearum effector protein PopP2 triggers immunity in Arabidopsis following its perception by the RRS1-R resistance protein. Here, we show that PopP2 interacts with RRS1-R in the nucleus of living plant cells. PopP2 belongs to the YopJ-like family of cysteine proteases, which share a conserved catalytic triad that includes a highly conserved cysteine residue. The catalytic cysteine mutant PopP2-C321A is impaired in its avirulence activity although it is still able to interact with RRS1-R. In addition, PopP2 prevents proteasomal degradation of RRS1-R, independent of the presence of an integral PopP2 catalytic core. A liquid chromatography/tandem mass spectrometry analysis showed that PopP2 displays acetyl-transferase activity leading to its autoacetylation on a particular lysine residue, which is well conserved among all members of the YopJ family. These data suggest that this lysine residue may correspond to a key binding site for acetyl-coenzyme A required for protein activity. Indeed, mutation of this lysine in PopP2 abolishes RRS1-R-mediated immunity. In agreement with the guard hypothesis, our results favour the idea that activation of the plant immune response by RRS1-R depends not only on the physical interaction between the two proteins but also on its perception of PopP2 enzymatic activity.

Identification and Chacterization of new strains of Enterobacter spp. causing Mulberry (Morus alba) wilt disease in China

USDA-ARS?s Scientific Manuscript database

A new mulberry wilt disease (MWD) was recently identified in Hangzhou, Zhejiang province, China. Typical symptoms of the disease are dark brown discolorations in vascular tissues, leaf wilt, defoliation, and tree decline. Unlike the bacterial wilt disease caused by Ralstonia solanacearum, the leaf w...

New Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Scheme for Fine-Scale Monitoring and Microevolution-Related Study of Ralstonia pseudosolanacearum Phylotype I Populations

PubMed Central

Guinard, Jérémy; Latreille, Anne; Guérin, Fabien; Poussier, Stéphane

2016-01-01

ABSTRACT Bacterial wilt caused by the Ralstonia solanacearum species complex (RSSC) is considered one of the most harmful plant diseases in the world. Special attention should be paid to R. pseudosolanacearum phylotype I due to its large host range, its worldwide distribution, and its high evolutionary potential. So far, the molecular epidemiology and population genetics of this bacterium are poorly understood. Until now, the genetic structure of the RSSC has been analyzed on the worldwide and regional scales. Emerging questions regarding evolutionary forces in RSSC adaptation to hosts now require genetic markers that are able to monitor RSSC field populations. In this study, we aimed to evaluate the multilocus variable-number tandem-repeat analysis (MLVA) approach for its ability to discriminate genetically close phylotype I strains and for population genetics studies. We developed a new MLVA scheme (MLVA-7) allowing us to genotype 580 R. pseudosolanacearum phylotype I strains extracted from susceptible and resistant hosts and from different habitats (stem, soil, and rhizosphere). Based on specificity, polymorphism, and the amplification success rate, we selected seven fast-evolving variable-number tandem-repeat (VNTR) markers. The newly developed MLVA-7 scheme showed higher discriminatory power than the previously published MLVA-13 scheme when applied to collections sampled from the same location on different dates and to collections from different locations on very small scales. Our study provides a valuable tool for fine-scale monitoring and microevolution-related study of R. pseudosolanacearum phylotype I populations. IMPORTANCE Understanding the evolutionary dynamics of adaptation of plant pathogens to new hosts or ecological niches has become a key point for the development of innovative disease management strategies, including durable resistance. Whereas the molecular mechanisms underlying virulence or pathogenicity changes have been studied thoroughly, the

Inventorying the molecular potential of Cupriavidus and Ralstonia strains surviving harsh space-related environments

NASA Astrophysics Data System (ADS)

Mijnendonckx, Kristel; van Houdt, Rob; Provoost, Ann; Bossus, Albert; Ott, C. Mark; Venkateswaran, Kasthuri; Leys, Natalie

The craving of modern man to explore life beyond earth presents a lot of challenges. The control of microbial contamination of the confined manned spacecraft is an important aspect that has to be taken into account in this journey. Because the human body contains a huge amount of microorganisms, the crew itself is the most important contamination source. But contamination can also originate from residing environmental microorganisms or from materials that are supplied from the Earth. These microbial contaminations can cause problems for the astronauts -well documented to have a decreased immunity -and the infrastructure of the space station. In this study, 14 different Cupriavidus metallidurans and Ralstonia pickettii strains, isolated from such space-related environments, where characterised in detail. These unique strains were isolated from drinking water that returned from ISS (3), from the cooling water system of the American ISS segment (4), from a swab sample of the Mars Odyssey Orbitor surface prior to flight (4), and from an air sample taken in the space assembly facility PHSF during Mars exploration Rover assembly (3). Their resistance to heavy metals and antibiotics was screened. The C. metallidurans isolates were more resistant to Zn2+ and Hg+ but more sensitive to Ni2+ than the R. pickettii strains. The MIC values for Cu2+ ranged from 1,5mM to 12mM, for Co2+ from 1,58mM to 12,63mM and for Cd2+ from 0,25mM to 1mM. For Ni2+ , the MIC values were between 2 and 8mM, except for the strain C. metallidurans IV (0502478) that was able to grow on Ni+2 concentrations up to 48mM. A metal of special interest was Ag+ because it is used to sanitize ISS drinking water. The strains isolated from air and surface samples showed a MIC value ranging from 0,35µM to 4µM. The isolates from the water samples had MIC values from 0,3µM to 2µM, which is lower than (or comparable with) the lowest limit of the silver concentration used in the ISS (1,9µM -4,6µM). However, all

Conserved Responses in a War of Small Molecules between a Plant-Pathogenic Bacterium and Fungi.

PubMed

Spraker, Joseph E; Wiemann, Philipp; Baccile, Joshua A; Venkatesh, Nandhitha; Schumacher, Julia; Schroeder, Frank C; Sanchez, Laura M; Keller, Nancy P

2018-05-22

Small-molecule signaling is one major mode of communication within the polymicrobial consortium of soil and rhizosphere. While microbial secondary metabolite (SM) production and responses of individual species have been studied extensively, little is known about potentially conserved roles of SM signals in multilayered symbiotic or antagonistic relationships. Here, we characterize the SM-mediated interaction between the plant-pathogenic bacterium Ralstonia solanacearum and the two plant-pathogenic fungi Fusarium fujikuroi and Botrytis cinerea We show that cellular differentiation and SM biosynthesis in F. fujikuroi are induced by the bacterially produced lipopeptide ralsolamycin (synonym ralstonin A). In particular, fungal bikaverin production is induced and preferentially accumulates in fungal survival spores (chlamydospores) only when exposed to supernatants of ralsolamycin-producing strains of R. solanacearum Although inactivation of bikaverin biosynthesis moderately increases chlamydospore invasion by R. solanacearum , we show that other metabolites such as beauvericin are also induced by ralsolamycin and contribute to suppression of R. solanacearum growth in vitro Based on our findings that bikaverin antagonizes R. solanacearum and that ralsolamycin induces bikaverin biosynthesis in F. fujikuroi , we asked whether other bikaverin-producing fungi show similar responses to ralsolamycin. Examining a strain of B. cinerea that horizontally acquired the bikaverin gene cluster from Fusarium , we found that ralsolamycin induced bikaverin biosynthesis in this fungus. Our results suggest that conservation of microbial SM responses across distantly related fungi may arise from horizontal transfer of protective gene clusters that are activated by conserved regulatory cues, e.g., a bacterial lipopeptide, providing consistent fitness advantages in dynamic polymicrobial networks. IMPORTANCE Bacteria and fungi are ubiquitous neighbors in many environments, including

Effect of organic fertilizers prepared from organic waste materials on the production of antibacterial volatile organic compounds by two biocontrol Bacillus amyloliquefaciens strains.

PubMed

Raza, Waseem; Wei, Zhong; Ling, Ning; Huang, Qiwei; Shen, Qirong

2016-06-10

Three organic fertilizers made of different animal and plant waste materials (BOFs) were evaluated for their effects on the production of antibacterial volatile organic compounds (VOCs) by two Bacillus amyloliquefaciens strains SQR-9 and T-5 against the tomato wilt pathogen Ralstonia solanacearum (RS). Both strains could produce VOCs that inhibited the growth and virulence traits of RS; however, in the presence of BOFs, the production of antibacterial VOCs was significantly increased. The maximum inhibition of growth and virulence traits of RS by VOCs of T-5 and SQR-9 was determined at 1.5% BOF2 and 2% BOF3, respectively. In case of strain T-5, 2-nonanone, nonanal, xylene, benzothiazole, and butylated hydroxy toluene and in case of strain SQR-9, 2-nonanone, nonanal, xylene and 2-undecanone were the main antibacterial VOCs whose production was increased in the presence of BOFs. The results of this study reveal another significance of using organic fertilizers to improve the antagonistic activity of biocontrol agents against phytopathogens. Copyright © 2016 Elsevier B.V. All rights reserved.

Physiological-biochemical properties and the ability to synthesize polyhydroxyalkanoates of the glucose-utilizing strain of the hydrogen bacterium Ralstonia eutropha B8562.

PubMed

Volova, T G; Trusova, M Y; Kalacheva, G S; Kozhevnicov, I V

2006-11-01

Physiological-biochemical, genetic, and cultural properties of the glucose-utilizing mutant strain Ralstonia eutropha B8562 have been compared with those of its parent strain R. eutropha B5786. It has been shown that growth characteristics of the strain cultured on glucose as the sole carbon and energy source are comparable with those of the parent strain. Strain B8562 is characterized by high polyhydroxyalkanoate (PHA) yields on different carbon sources (CO(2), fructose, and glucose). PHA accumulation in the strain batch cultured on glucose under nitrogen deficiency reaches 90 %. The major monomer in the PHA is beta-hydroxybutyric acid (more than 99 mol %); the identified minor components are beta-hydroxyvaleric acid (0.25-0.72 mol %) and beta-hydroxyhexanoic acid (0.08-1.5 mol %). The strain is a promising PHA producer on available sugar-containing media with glucose.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stulberg, Michael J.; Huang, Qi

Ralstonia solanacearum race 3 biovar 2 strains belonging to phylotype IIB, sequevars 1 and 2 (IIB-1&2) cause brown rot of potato in temperate climates, and are quarantined pathogens in Canada and Europe. Since these strains are not established in the U.S. and because of their potential risk to the potato industry, the U.S. government has listed them as select agents. Cultivated geraniums are also a host and have the potential to spread the pathogen through trade, and its extracts strongly inhibits DNA-based detection methods. We designed four primer and probe sets for an improved qPCR method that targets stable regionsmore » of DNA. RsSA1 and RsSA2 recognize IIB-1&2 strains, RsII recognizes the current phylotype II (the newly proposed R. solanacearum species) strains (and a non-plant associated R. mannitolilytica), and Cox1 recognizes eight plant species including major hosts of R. solanacearum such as potato, tomato and cultivated geranium as an internal plant control. We multiplexed the RsSA2 with the RsII and Cox1 sets to provide two layers of detection of a positive IIB-1&2 sample, and to validate plant extracts and qPCR reactions. The TaqMan-based uniplex and multiplex qPCR assays correctly identified 34 IIB-1&2 and 52 phylotype II strains out of 90 R. solanacearum species complex strains. Additionally, the multiplex qPCR assay was validated successfully using 169 artificially inoculated symptomatic and asymptomatic plant samples from multiple plant hosts including geranium. Moreover, we developed an extraction buffer that allowed for a quick and easy DNA extraction from infected plants including geranium for detection of R. solanacearum by qPCR. Our multiplex qPCR assay, especially when coupled with the quick extraction buffer method, allows for quick, easy and reliable detection and differentiation of the IIB-1&2 strains of R. solanacearum.« less

[Physiological and biochemical characteristics and capacity for polyhydroxyalkanoates synthesis in a glucose-utilizing strain of hydrogen-oxidizing bacteria, Ralstonia eutropha B8562].

PubMed

Volova, T G; Kozhevnikov, I V; Dolgopolova, Iu B; Trusova, M Iu; Kalacheva, G S; Aref'eva, Iu V

2005-01-01

The physiological, biochemical, genetic, and cultural characteristics of the glucose-utilizing mutant strain Ralstonia eutropha B8562 were investigated in comparison with the parent strain R. eutropha B5786. The morphological, cultural, and biochemical characteristics of strain R. eutropha B8562 were similar to those of strain R. eutropha B5786. Genetic analysis revealed differences between the 16S rRNA gene sequences of these strains. The growth characteristics of the mutant using glucose as the sole carbon and energy source were comparable with those of the parent strain grown on fructose. Strain B8562 was characterized by high yields of polyhydroxyalkanoate (PHA) from different carbon sources (CO2, fructose, and glucose). In batch culture with glucose under nitrogen limitation, PHA accumulation reached 90% of dry weight. In PHA, beta-hydroxybutyrate was predominant (over 99 mol %); beta-hydroxyvalerate (0.25-0.72 mol %) and beta-hydroxyhexanoate (0.008-1.5 mol %) were present as minor components. The strain has prospects as a PHA producer on glucose-containing media.

Identification and biochemical characterization of an acid sphingomyelinase-like protein from the bacterial plant pathogen Ralstonia solanacearum that hydrolyzes ATP to AMP but not sphingomyelin to ceramide.

PubMed

Airola, Michael V; Tumolo, Jessica M; Snider, Justin; Hannun, Yusuf A

2014-01-01

Acid sphingomyelinase (aSMase) is a human enzyme that catalyzes the hydrolysis of sphingomyelin to generate the bioactive lipid ceramide and phosphocholine. ASMase deficiency is the underlying cause of the genetic diseases Niemann-Pick Type A and B and has been implicated in the onset and progression of a number of other human diseases including cancer, depression, liver, and cardiovascular disease. ASMase is the founding member of the aSMase protein superfamily, which is a subset of the metallophosphatase (MPP) superfamily. To date, MPPs that share sequence homology with aSMase, termed aSMase-like proteins, have been annotated and presumed to function as aSMases. However, none of these aSMase-like proteins have been biochemically characterized to verify this. Here we identify RsASML, previously annotated as RSp1609: acid sphingomyelinase-like phosphodiesterase, as the first bacterial aSMase-like protein from the deadly plant pathogen Ralstonia solanacearum based on sequence homology with the catalytic and C-terminal domains of human aSMase. A biochemical characterization of RsASML does not support a role in sphingomyelin hydrolysis but rather finds RsASML capable of acting as an ATP diphosphohydrolase, catalyzing the hydrolysis of ATP and ADP to AMP. In addition, RsASML displays a neutral, not acidic, pH optimum and prefers Ni2+ or Mn2+, not Zn2+, for catalysis. This alters the expectation that all aSMase-like proteins function as acid SMases and expands the substrate possibilities of this protein superfamily to include nucleotides. Overall, we conclude that sequence homology with human aSMase is not sufficient to predict substrate specificity, pH optimum for catalysis, or metal dependence. This may have implications to the biochemically uncharacterized human aSMase paralogs, aSMase-like 3a (aSML3a) and aSML3b, which have been implicated in cancer and kidney disease, respectively, and assumed to function as aSMases.

Isolation and antifungal activity of 4-phenyl-3-butenoic acid from Streptomyces koyangensis strain VK-A60.

PubMed

Lee, Jee Yeon; Lee, Jung Yeop; Moon, Surk Sik; Hwang, Byung Kook

2005-10-05

An antifungal compound was isolated from the culture broth of Streptomyces koyangensis strain VK-A60 using various chromatographic procedures. On the basis of the high-resolution EI-mass and 1H and 13C NMR data, the compound was identified as 4-phenyl-3-butenoic acid. Colletotrichum orbiculare, Magnaporthe grisea, and Pythium ultimum were most sensitive to 4-phenyl-3-butenoic acid. Strong inhibitory effects of 4-phenyl-3-butenoic acid also were found against Pectobacterium carotovorum subsp. carotovorum and Ralstonia solanacearum. 4-Phenyl-3-butenoic acid effectively suppressed the development of M. grisea on rice leaves at the concentration of more than 10 microg/mL, and the protective activity was in general similar to that of the commercial fungicide tricyclazole. Treatment with 100 microg/mL of 4-phenyl-3-butenoic acid also effectively inhibited the anthracnose development on cucumber plants, although its in vivo efficacy was somewhat less effective than that of the commercial fungicide chlorothalonil.

New report of additional enterobacterial species causing wilt in West Bengal, India.

PubMed

Sarkar, Shamayeeta; Chaudhuri, Sujata

2015-07-01

Ralstonia solanacearum is known to be the most prominent causal agent of bacterial wilt worldwide. It has a wide host range comprising solanaceous and nonsolanaceous plants. Typical symptoms of the disease are leaf wilt, browning of vascular tissues, and collapsing of the plant. With the objective of studying the diversity of pathogens causing bacterial wilt in West Bengal, we collected samples of diseased symptomatic crops and adjacent symptomatic and asymptomatic weeds from widespread locations in West Bengal. By means of a routine molecular identification test specific to "R. solanacearum species complex", the majority of these strains (68 out of 71) were found to not be R. solanacearum. Presumptive identification of these isolates with conventional biochemicals, extensive testing of pathogenicity of a subset involving greenhouse trials fulfilling Koch's postulate test, and scanning electron microscopic analysis for the presence of pathogen in diseased plants were done. 16S rDNA sequencing of a subset of these strains (GenBank accession Nos. JX880249-JX880251) and analysis of sequences with the nBLAST programme showed a high similarity (97%-99%) to sequences of the Enterobacteriaceae group available in GenBank. Molecular phylogeny further established the taxonomic position of the strains. The 3 bacterial strain cultures have been submitted to MTCC, Institute of Microbial Technology, Chandigarh, India, and were identified as Klebsiella oxytoca, Enterobacter cowanii, and Klebsiella oxytoca, respectively. Although Enterobacter sp. has previously been reported to cause wilt in many plants, susceptibility of most of the dedicated hosts of R. solanacearum to wilt caused by Enterobacter and other bacteria from Enterobacteriaceae is being reported for the first time in this work.

A dual resistance gene system prevents infection by three distinct pathogens.

PubMed

Narusaka, Mari; Kubo, Yasuyuki; Shiraishi, Tomonori; Iwabuchi, Masaki; Narusaka, Yoshihiro

2009-10-01

Colletotrichum higginsianum causes typical anthracnose lesions on the leaves, petioles, and stems of cruciferous plants. Inoculation of Arabidopsis thaliana ecotype Columbia leaves with C. higginsianum results in fungal growth and disease symptoms reminiscent of those induced in other cruciferous plants. We performed map-based cloning and natural variation analysis of 19 A. thaliana ecotypes to identify a dominant resistance locus against C. higginsianum. We found that the A. thaliana RCH2 (for recognition of C. higginsianum) locus encodes two NB-LRR proteins, both of which are required for resistance to C. higginsianum in the A. thaliana ecotype Ws-0. Both proteins are well-characterized R proteins involved in resistance against bacterial pathogens; RRS1 (resistance to Ralstonia solanacearum 1) confers resistance to strain Rs1000 of R. solanacearum and RPS4 to Pseudomonas syringae pv. tomato strain DC3000 expressing avrRps4 (Pst-avrRps4). Furthermore, we found that both RRS1-Ws and RPS4-Ws genes are required for resistance to Pst-avrRps4 and to Rs1002 R. solanacearum. We therefore demonstrate that a pair of neighboring genes, RRS1-Ws and RPS4-Ws, function cooperatively as a dual R-gene system against at least three distinct pathogens.

Regulation of the cnr Cobalt and Nickel Resistance Determinant from Ralstonia sp. Strain CH34†

PubMed Central

Grass, Gregor; Große, Cornelia; Nies, Dietrich H.

2000-01-01

Ralstonia sp. strain CH34 is resistant to nickel and cobalt cations. Resistance is mediated by the cnr determinant located on plasmid pMOL28. The cnr genes are organized in two clusters, cnrYXH and cnrCBA. As revealed by reverse transcriptase PCR and primer extension, transcription from these operons is initiated from promoters located upstream of the cnrY and cnrC genes. These two promoters exhibit conserved sequences at the −10 (CCGTATA) and −35 (CRAGGGGRAG) regions. The CnrH gene product, which is required for expression of both operons, is a sigma factor belonging to the sigma L family, whose activity seems to be governed by the membrane-bound CnrY and CnrX gene products in response to Ni2+. Half-maximal activation from the cnrCBA operon was determined by using appropriate lacZ gene fusions and was shown to occur at an Ni2+ concentration of about 50 μM. PMID:10671463

Pepper CabZIP63 acts as a positive regulator during Ralstonia solanacearum or high temperature-high humidity challenge in a positive feedback loop with CaWRKY40.

PubMed

Shen, Lei; Liu, Zhiqin; Yang, Sheng; Yang, Tong; Liang, Jiaqi; Wen, Jiayu; Liu, Yanyan; Li, Jiazhi; Shi, Lanping; Tang, Qian; Shi, Wei; Hu, Jiong; Liu, Cailing; Zhang, Yangwen; Lin, Wei; Wang, Rongzhang; Yu, Huanxin; Mou, Shaoliang; Hussain, Ansar; Cheng, Wei; Cai, Hanyang; He, Li; Guan, Deyi; Wu, Yang; He, Shuilin

2016-04-01

CaWRKY40 is known to act as a positive regulator in the response of pepper (Capsicum annuum) to Ralstonia solanacearum inoculation (RSI) or high temperature-high humidity (HTHH), but the underlying mechanism remains elusive. Herein, we report that CabZIP63, a pepper bZIP family member, participates in this process by regulating the expression of CaWRKY40. CabZIP63 was found to localize in the nuclei, be up-regulated by RSI or HTHH, bind to promoters of both CabZIP63(pCabZIP63) and CaWRKY40(pCaWRKY40), and activate pCabZIP63- and pCaWRKY40-driven β-glucuronidase expression in a C- or G-box-dependent manner. Silencing of CabZIP63 by virus-induced gene silencing (VIGS) in pepper plants significantly attenuated their resistance to RSI and tolerance to HTHH, accompanied by down-regulation of immunity- or thermotolerance-associated CaPR1, CaNPR1, CaDEF1, and CaHSP24. Hypersensitive response-mediated cell death and expression of the tested immunity- and thermotolerance-associated marker genes were induced by transient overexpression (TOE) of CabZIP63, but decreased by that of CabZIP63-SRDX. Additionally, binding of CabZIP63 to pCaWRKY40 was up-regulated by RSI or HTHH, and the transcript level of CaWRKY40 and binding of CaWRKY40 to the promoters of CaPR1, CaNPR1, CaDEF1 and CaHSP24 were up-regulated by TOE of CabZIP63. On the other hand, CabZIP63 was also up-regulated transcriptionally by TOE of CaWRKY40. The data suggest collectively that CabZIP63 directly or indirectly regulates the expression of CaWRKY40 at both the transcriptional and post-transcriptional level, forming a positive feedback loop with CaWRKY40 during pepper's response to RSI or HTHH. Altogether, our data will help to elucidate the underlying mechanism of crosstalk between pepper's response to RSI and HTHH. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Cleaning-resistant Cupriavidus and Ralstonia bacteria contaminating spacecrafts and the ultra clean rooms they are assembled in.

NASA Astrophysics Data System (ADS)

Leys, N.; Dams, A.; Bossus, A.; Provoost, A.; Venkateswaran, K.; Mergeay, M.

Background Planetary Protection is preventing microbial contamination of both the target planet and the Earth when sending spacecrafts on interplanetary space mission It is important to preserve the natural conditions of other planets and to not bring with robots earthly microbes forward contamination when looking for spores of extra terrestrial life Spacecrafts and the ultra clean rooms they are assembled in are routinely monitored for microbial contamination It was shown that the floor air and surfaces of such spacecraft assembly rooms often contain Cupriavidu s and Ralstonia bacteria These bacteria not only contaminated the clean rooms but have also been found prior-to-flight on surfaces of space robots such as the Mars Odyssey Orbiter La Duc et al 2003 and even in-flight in ISS cooling water and Shuttle drinking water unpublished Aim In this study several Cupriavidus and Ralstonia strains isolated from space craft assembling rooms and spacecrafts were characterized and analysed in detail Results The analysis showed that all the Cupriavidus and Ralstonia clean-room isolates are able to use a wide variety of substrates as carbon sources including ethanol and acetone In addition they all have accumulated moderate resistances to an extraordinary collection of physical and chemical antimicrobial agents Some of the test strains were able to form biofilms on plastic and metal materials used for space robots a nutritional and

Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

PubMed Central

Álvarez, Belén; Biosca, Elena G.

2017-01-01

Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis, not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta. Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field. PMID:28769942

Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture.

PubMed

Álvarez, Belén; Biosca, Elena G

2017-01-01

Bacterial wilt diseases caused by Ralstonia solanacearum , R. pseudosolanacearum , and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis , not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta . Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field.

Classification of Plant Associated Bacteria Using RIF, a Computationally Derived DNA Marker

PubMed Central

Schneider, Kevin L.; Marrero, Glorimar; Alvarez, Anne M.; Presting, Gernot G.

2011-01-01

A DNA marker that distinguishes plant associated bacteria at the species level and below was derived by comparing six sequenced genomes of Xanthomonas, a genus that contains many important phytopathogens. This DNA marker comprises a portion of the dnaA replication initiation factor (RIF). Unlike the rRNA genes, dnaA is a single copy gene in the vast majority of sequenced bacterial genomes, and amplification of RIF requires genus-specific primers. In silico analysis revealed that RIF has equal or greater ability to differentiate closely related species of Xanthomonas than the widely used ribosomal intergenic spacer region (ITS). Furthermore, in a set of 263 Xanthomonas, Ralstonia and Clavibacter strains, the RIF marker was directly sequenced in both directions with a success rate approximately 16% higher than that for ITS. RIF frameworks for Xanthomonas, Ralstonia and Clavibacter were constructed using 682 reference strains representing different species, subspecies, pathovars, races, hosts and geographic regions, and contain a total of 109 different RIF sequences. RIF sequences showed subspecific groupings but did not place strains of X. campestris or X. axonopodis into currently named pathovars nor R. solanacearum strains into their respective races, confirming previous conclusions that pathovar and race designations do not necessarily reflect genetic relationships. The RIF marker also was sequenced for 24 reference strains from three genera in the Enterobacteriaceae: Pectobacterium, Pantoea and Dickeya. RIF sequences of 70 previously uncharacterized strains of Ralstonia, Clavibacter, Pectobacterium and Dickeya matched, or were similar to, those of known reference strains, illustrating the utility of the frameworks to classify bacteria below the species level and rapidly match unknown isolates to reference strains. The RIF sequence frameworks are available at the online RIF database, RIFdb, and can be queried for diagnostic purposes with RIF sequences obtained

Ralstonia insidiosa serves as bridges in biofilm formation by foodborne pathogens Listeria monocytogenes, Salmonella enterica, and enterohemorrhagic Escherichia coli

USDA-ARS?s Scientific Manuscript database

Biofilm formation on abiotic surfaces in fresh produce processing facilities might play a role in foodborne outbreaks by providing protective microniches for pathogenic bacteria. Our previous study showed that a strain of Ralstonia insidiosa isolated from a fresh produce processing plant could enhan...

Evaluation of edible ginger and turmeric cultivars for root-knot nematode resistance

USDA-ARS?s Scientific Manuscript database

Edible ginger and turmeric roots are important agricultural commodities for the State of Hawaii. Bacterial wilt, Ralstonia solanacearum, and root-knot nematodes, Meloidogyne spp. are major factors hindering optimum production. An evaluation of tolerance and resistance to M. incognita was undertake...

Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

USDA-ARS?s Scientific Manuscript database

A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

Impact of Bacillus amyloliquefaciens S13-3 on control of bacterial wilt and powdery mildew in tomato.

PubMed

Yamamoto, Shoko; Shiraishi, Soma; Kawagoe, Yumi; Mochizuki, Mai; Suzuki, Shunji

2015-05-01

Biological control is a non-hazardous technique to control plant diseases. Researchers have explored microorganisms that show high plant-disease control efficiency for use as biological control agents. A single soil application of Bacillus amyloliquefaciens strain S13-3 suppressed tomato bacterial wilt caused by Ralstonia solanacearum, a soilborne bacterial pathogen, through production of antibiotics augmented possibly by induction of systemic acquired resistance. Soil application also controlled tomato powdery mildew disease through induction of systemic acquired resistance. S13-3 showing bifunctional activity with a single application to soil may be an innovative biological control agent against bacterial wilt and powdery mildew in tomato. © 2014 Society of Chemical Industry.

Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions.

PubMed

Wei, Zhong; Huang, Jianfeng; Yang, Tianjie; Jousset, Alexandre; Xu, Yangchun; Shen, Qirong; Friman, Ville-Petri

2017-10-01

Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions.Here, we assessed how environmental temperature variation correlates with ability of Ralstonia pickettii , an endophytic bacterial biocontrol agent, to suppress the Ralstonia solanacearum pathogen during different tomato crop seasons in China.We found that suppression of the pathogen was highest when the seasonal mean temperatures were around 20 °C and rapidly decreased with increasing mean crop season temperatures. Interestingly, low levels of disease incidence did not correlate with low pathogen or high biocontrol agent absolute densities. Instead, the biocontrol to pathogen density ratio was a more important predictor of disease incidence levels between different crop seasons. To understand this mechanistically, we measured the growth and strength of competition between the biocontrol agent and the pathogen over a naturally occurring temperature gradient in vitro . We found that the biocontrol strain grew relatively faster at low temperature ranges, and the pathogen at high temperature ranges, and that similar to field experiments, pathogen suppression peaked at 20 °C.Together, our results suggest that temperature-mediated changes in the strength of bacterial competition could potentially explain the variable R. solanacearum biocontrol outcomes between different crop seasons in China. Synthesis and applications . Our results suggest that abiotic environmental conditions, such as temperature, can affect the efficacy of biocontrol applications. Thus, in order to develop more consistent biocontrol applications in the future, we might need to find and isolate bacterial strains that can retain their functionality regardless of the changing environmental conditions.

Optimization of cyanophycin production in recombinant strains of Pseudomonas putida and Ralstonia eutropha employing elementary mode analysis and statistical experimental design.

PubMed

Diniz, Simone Cardoso; Voss, Ingo; Steinbüchel, Alexander

2006-03-05

Elementary mode analysis was applied to simulate conditions for cyanophycin (CGP) biosynthesis and to optimize its production in bacteria. The conclusions from these simulations were confirmed by experiments with recombinant strains of the wild types and polyhydroxyalkanoate (PHA)-negative mutants of Ralstonia eutropha and Pseudomonas putida expressing CGP synthetase genes (cphA) of Synechocystis sp. strain PCC6308 or Anabaena sp. strain PCC7120. In particular, the effects of suitable precursor substrates and of oxygen supply as well as of the capability to accumulate PHA in addition to CGP biosynthesis were investigated. Since CGP consists of the amino acids aspartate and arginine, the tricarboxylic acid cycle (TCC), which provides intermediates for biosynthesis of these amino acids, seems to be important. Excretion of intermediates of the TCC upon cultivation at restricted oxygen supply and conversion of fumarate mainly to malate and to only little succinate in the absence of oxygen indicated that TCC intermediates for arginine and aspartate biosynthesis were provided by the oxidative or reductive parts of the TCC, respectively. The following important conclusions were made from the experiments and the simulations: (i) external arginine additionally supplied to the medium, (ii) oxygen limitation, and (iii) absence of PHA accumulation exerted positive effects on CGP accumulation. These conclusions were utilized to obtain CGP contents in the cells of as high as 17.9% (w x w(-1)) during cultivation of the investigated bacteria at the 30-L scale using mineral salts medium. Such high CGP contents were previously not obtained with these bacteria at a 30-L scale, even if complex media were used.

Native Valve Endocarditis due to Ralstonia pickettii: A Case Report and Literature Review.

PubMed

Orme, Joseph; Rivera-Bonilla, Tomas; Loli, Akil; Blattman, Negin N

2015-01-01

Ralstonia pickettii is a rare pathogen and even more rare in healthy individuals. Here we report a case of R. pickettii bacteremia leading to aortic valve abscess and complete heart block. To our knowledge this is the first case report of Ralstonia species causing infective endocarditis with perivalvular abscess.

Native Valve Endocarditis due to Ralstonia pickettii: A Case Report and Literature Review

PubMed Central

Orme, Joseph; Rivera-Bonilla, Tomas; Loli, Akil; Blattman, Negin N.

2015-01-01

Ralstonia pickettii is a rare pathogen and even more rare in healthy individuals. Here we report a case of R. pickettii bacteremia leading to aortic valve abscess and complete heart block. To our knowledge this is the first case report of Ralstonia species causing infective endocarditis with perivalvular abscess. PMID:25648998

Biological Potential of Bioorganic Fertilizer Fortified with Bacterial Antagonist for the Control of Tomato Bacterial Wilt and the Promotion of Crop Yields.

PubMed

Wu, Kai; Fang, Zhiying; Wang, Lili; Yuan, Saifei; Guo, Rong; Shen, Biao; Shen, Qirong

2016-10-28

The application of Bacillus sp. in the biological control of plant soilborne diseases has been shown to be an environmentally friendly alternative to the use of chemical fungicides. In this study, the effects of bioorganic fertilizer (BOF) fortified with Bacillus amyloliquefaciens SQY 162 on the suppression of tomato bacterial wilt were investigated in pot experiments. The disease incidence of tomato wilt after the application of BOF was 65.18% and 41.62% lower at 10 and 20 days after transplantation, respectively, than in the control condition. BOF also promoted the plant growth. The SQY 162 populations efficiently colonized the tomato rhizosphere, which directly suppressed the number of Ralstonia solanacearum in the tomato rhizosphere soil. In the presence of BOF, the activities of defense-related enzymes in tomato were lower than in the presence of the control treatment, but the expression levels of the defense-related genes of the plants in the salicylic acid and jasmonic acid pathways were enhanced. It was also found that strain SQY 162 could secrete antibiotic surfactin, but not volatile organic compounds, to suppress Ralstonia . The strain could also produce plant growth promotion compounds such as siderophores and indole-3-acetic acid. Thus, owing to its innate multiple-functional traits and its broad biocontrol activities, we found that this antagonistic strain isolated from the tobacco rhizosphere could establish itself successfully in the tomato rhizosphere to control soilborne diseases.

Ralstonia pickettii-Induced Ataxia in Immunodeficient Mice

PubMed Central

Berard, Marion; Medaille, Christine; Simon, Meredith; Serre, Stéphanie; Pritchett-Corning, Kathleen; Dangles-Marie, Virginie

2009-01-01

We report here the characterization of an asymmetric ataxia syndrome (head tilt and circling, with death in the most severe cases) demonstrated by profoundly immunodeficient mice housed at the Institut Curie SPF facility. The immune system of the affected mice had been genetically modified so that they were deficient in both B and T cells. Extensive bacteriologic, parasitic, serologic, and histopathologic analysis of the affected animals and their healthy controls led us to identify Ralstonia pickettii as the causative agent of the ataxic syndrome. The outbreak was managed through a test-and-cull process. Even though they also carried Ralstonia pickettii, immunocompetent mice that were kept in the same facility, did not show any of the signs that were expressed by their immunodeficient counterparts. This case highlights the difficulty of maintaining immunocompetent and immunodeficient mice in the same microbiologic unit and the importance of enlarging the spectrum of health monitoring to opportunistic agents when investigating clinical cases in populations of immunocompromised rodents. PMID:19389312

Cloning and Expression of a Ralstonia eutropha HF39 Gene Mediating Indigo Formation in Escherichia coli

PubMed Central

Drewlo, Sascha; Brämer, Christian O.; Madkour, Mohamed; Mayer, Frank; Steinbüchel, Alexander

2001-01-01

On complex medium Escherichia coli strains carrying hybrid plasmid pBEC/EE:11.0, pSKBEC/BE:9.0, pSKBEC/PP:3.3, or pSKBEC/PP:2.4 harboring genomic DNA of Ralstonia eutropha HF39 produced a blue pigment characterized as indigo by several chemical and spectroscopic methods. A 1,251-bp open reading frame (bec) was cloned and sequenced. The deduced amino acid sequence of bec showed only weak similarities to short-chain acyl-coenzyme A dehydrogenases, and the gene product catalyzed formation of indoxyl, a reactive preliminary stage for production of indigo. PMID:11282658

Biocontrol of tomato wilt disease by Bacillus subtilis isolates from natural environments depends on conserved genes mediating biofilm formation

PubMed Central

Liu, Hongxia; Kolter, Roberto; Losick, Richard; Guo, Jian-hua

2014-01-01

Summary Bacillus subtilis and other Bacilli have long been used as biological control agents against plant bacterial diseases but the mechanisms by which the bacteria confer protection are not well understood. Our goal in this study was to isolate strains of B. subtilis that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. We screened a total of sixty isolates collected from various locations across China and obtained six strains that exhibited above 50% biocontrol efficacy on tomato plants against the plant pathogen Ralstonia solanacearum under greenhouse conditions. These wild strains were able to form robust biofilms both in defined medium and on tomato plant roots and exhibited strong antagonistic activities against various plant pathogens in plate assays. We show that plant protection by those strains depended on widely conserved genes required for biofilm formation, including regulatory genes and genes for matrix production. We provide evidence suggesting that matrix production is critical for bacterial colonization on plant root surfaces. Finally, we have established a model system for studies of B. subtilis-tomato plant interactions in protection against a plant pathogen. PMID:22934631

Synergistic interaction in dual-species biofilms formation by Escherichia coli O157:H7 and Ralstonia spp

USDA-ARS?s Scientific Manuscript database

Introduction: Ralstonia spp., a heterotrophic bacterium that are isolated from produce processing environments as part of the native microflora, have strong potentials for formaing biofilms on various surfaces. When co-cultured, Escherichia coli O157:H7 (EcO157) and Ralstonia spp. displayed a synerg...

Polyhydroxyalkanoates production with Ralstonia eutropha from low quality waste animal fats.

PubMed

Riedel, Sebastian L; Jahns, Stefan; Koenig, Steven; Bock, Martina C E; Brigham, Christopher J; Bader, Johannes; Stahl, Ulf

2015-11-20

Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible polyesters considered as alternatives to petroleum-based plastics. Ralstonia eutropha is a model organism for PHA production. Utilizing industrially rendered waste animal fats as inexpensive carbon feedstocks for PHA production is demonstrated here. An emulsification strategy, without any mechanical or chemical pre-treatment, was developed to increase the bioavailability of solid, poorly-consumable fats. Wild type R. eutropha strain H16 produced 79-82% (w/w) polyhydroxybutyrate (PHB) per cell dry weight (CDW) when cultivated on various fats. A productivity of 0.3g PHB/(L × h) with a total PHB production of 24 g/L was achieved using tallow as carbon source. Using a recombinant strain of R. eutropha that produces poly(hydroxybutyrate-co-hydroxyhexanoate) [P(HB-co-HHx)], 49-72% (w/w) of PHA per CDW with a HHx content of 16-27 mol% were produced in shaking flask experiments. The recombinant strain was grown on waste animal fat of the lowest quality available at lab fermenter scale, resulting in 45 g/L CDW with 60% (w/w) PHA per CDW and a productivity of 0.4 g PHA/(L × h). The final HHx content of the polymer was 19 mol%. The use of low quality waste animal fats as an inexpensive carbon feedstock exhibits a high potential to accelerate the commercialization of PHAs. Copyright © 2015 Elsevier B.V. All rights reserved.

A prophage tail-like protein is deployed by Burkholderia bacteria to feed on fungi.

PubMed

Swain, Durga Madhab; Yadav, Sunil Kumar; Tyagi, Isha; Kumar, Rahul; Kumar, Rajeev; Ghosh, Srayan; Das, Joyati; Jha, Gopaljee

2017-09-01

Some bacteria can feed on fungi, a phenomenon known as mycophagy. Here we show that a prophage tail-like protein (Bg_9562) is essential for mycophagy in Burkholderia gladioli strain NGJ1. The purified protein causes hyphal disintegration and inhibits growth of several fungal species. Disruption of the Bg_9562 gene abolishes mycophagy. Bg_9562 is a potential effector secreted by a type III secretion system (T3SS) and is translocated into fungal mycelia during confrontation. Heterologous expression of Bg_9562 in another bacterial species, Ralstonia solanacearum, confers mycophagous ability in a T3SS-dependent manner. We propose that the ability to feed on fungi conferred by Bg_9562 may help the bacteria to survive in certain ecological niches. Furthermore, considering its broad-spectrum antifungal activity, the protein may be potentially useful in biotechnological applications to control fungal diseases.Some bacteria can feed on live fungi through unclear mechanisms. Here, the authors show that a T3SS-secreted protein, which is homologous to phage tail proteins, allows a Burkholderia gladioli strain to kill and feed on various fungal species.

New Polyphenols from a Deep Sea Spiromastix sp. Fungus, and Their Antibacterial Activities

PubMed Central

Niu, Siwen; Liu, Dong; Proksch, Peter; Shao, Zongze; Lin, Wenhan

2015-01-01

Eleven new polyphenols namely spiromastols A–K (1–11) were isolated from the fermentation broth of a deep sea-derived fungus Spiromastix sp. MCCC 3A00308. Their structures were determined by extensive NMR data and mass spectroscopic analysis in association with chemical conversion. The structures are classified as diphenyl ethers, diphenyl esters and isocoumarin derivatives, while the n-propyl group in the analogues is rarely found in natural products. Compounds 1–3 exhibited potent inhibitory effects against a panel of bacterial strains, including Xanthomanes vesicatoria, Pseudomonas lachrymans, Agrobacterium tumefaciens, Ralstonia solanacearum, Bacillus thuringensis, Staphylococcus aureus and Bacillus subtilis, with minimal inhibitory concentration (MIC) values ranging from 0.25 to 4 µg/mL. The structure-activity relationships are discussed, while the polychlorinated analogues 1–3 are assumed to be a promising structural model for further development as antibacterial agents. PMID:25913707

Priming by Rhizobacterium Protects Tomato Plants from Biotrophic and Necrotrophic Pathogen Infections through Multiple Defense Mechanisms

PubMed Central

Ahn, Il-Pyung; Lee, Sang-Woo; Kim, Min Gab; Park, Sang-Ryeol; Hwang, Duk-Ju; Bae, Shin-Chul

2011-01-01

A selected strain of rhizobacterium, Pseudomonas putida strain LSW17S (LSW17S), protects tomato plants (Lycopersicon esculentum L. cv. Seokwang) from bacterial speck by biotrophic Pseudomonas syringae pv. tomato strain DC3000 (DC3000) and bacterial wilt by necrotrophic Ralstonia solanacearum KACC 10703 (Rs10703). To investigate defense mechanisms induced by LSW17S in tomato plants, transcription patterns of pathogenesis-related (PR) genes and H2O2 production were analyzed in plants treated with LSW17S and subsequent pathogen inoculation. LSW17S alone did not induce transcriptions of employed PR genes in leaves and roots. DC3000 challenge following LSW17S triggered rapid transcriptions of PR genes and H2O2 production in leaves and roots. Catalase infiltration with DC3000 attenuated defense-related responses and resistance against DC3000 infection. Despite depriving H2O2 production and PR1b transcription by the same treatment, resistance against Rs10703 infection was not deterred significantly. H2O2 is indispensable for defense signaling and/or mechanisms primed by LSW17S and inhibition of bacterial speck, however, it is not involved in resistance against bacterial wilt. PMID:21710203

Sequence analysis of Candidatus Liberibacter solanacearum (Lso-C) isolated from carrot psyllids collected in Scandinavia

USDA-ARS?s Scientific Manuscript database

The fastidious prokaryote Candidatus Liberibacter solanacearum (Lso), transmitted by the tomato potato psyllid (Bactericera cockerelli), is associated with the Zebra Chip disease of potato. Plants infected with Liberibacter may experience significant yield losses and these plants also serve as pote...

Combined use of Bacillus subtilis strain B-001 and bactericide for the control of tomato bacterial wilt.

PubMed

Peng, Di; Luo, Kun; Jiang, Huidan; Deng, Yanan; Bai, Lianyang; Zhou, Xiaomao

2017-06-01

Tomato bacterial wilt caused by Ralstonia solanacearum poses a serious threat to tomato production. However, no effective control measures are available. In this study, the bactericide Saisentong was combined with an effective biological control agent, Bacillus subtilis B-001, to control tomato bacterial wilt under greenhouse and field conditions. Growth of B-001 in vitro was unaffected by Saisentong. In greenhouse experiments, the combined application of B-001 and Saisentong via root irrigation or spray resulted in better disease control compared with either agent alone. In two field trials, at a Saisentong concentration of 400 or 500 mg kg -1 , the combined treatment was more effective than expected and showed a synergistic effect. A lower concentration of Saisentong (200 or 300 mg kg -1 ) in combination with B-001 resulted in an antagonistic effect. However, disease control was significantly greater compared with either treatment alone. The combination of Saisentong and B-001 effectively controls tomato bacterial wilt. The integrated strategy represents a promising new tool to control this disease. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Solvent production by engineered Ralstonia eutropha: channeling carbon to biofuel.

PubMed

Chakravarty, Jayashree; Brigham, Christopher J

2018-06-01

Microbial production of solvents like acetone and butanol was a couple of the first industrial fermentation processes to gain global importance. These solvents are important feedstocks for the chemical and biofuel industry. Ralstonia eutropha is a facultatively chemolithoautotrophic bacterium able to grow with organic substrates or H 2 and CO 2 under aerobic conditions. This bacterium is a natural producer of polyhydroxyalkanoate biopolymers. Recently, with the advances in the development of genetic engineering tools, the range of metabolites R. eutropha can produce has enlarged. Its ability to utilize various carbon sources renders it an interesting candidate host for synthesis of renewable biofuel and solvent production. This review focuses on progress in metabolic engineering of R. eutropha for the production of alcohols, terpenes, methyl ketones, and alka(e)nes using various resources. Biological synthesis of solvents still presents the challenge of high production costs and competition from chemical synthesis. Better understanding of R. eutropha biology will support efforts to engineer and develop superior microbial strains for solvent production. Continued research on multiple fronts is required to engineer R. eutropha for truly sustainable and economical solvent production.

Transformation of Chlorinated Benzenes and Toluenes by Ralstonia sp. Strain PS12 tecA (Tetrachlorobenzene Dioxygenase) and tecB (Chlorobenzene Dihydrodiol Dehydrogenase) Gene Products

PubMed Central

Pollmann, Katrin; Beil, Stefan; Pieper, Dietmar H.

2001-01-01

The tecB gene, located downstream of tecA and encoding tetrachlorobenzene dioxygenase, in Ralstonia sp. strain PS12 was cloned into Escherichia coli DH5α together with the tecA gene. The identity of the tecB gene product as a chlorobenzene dihydrodiol dehydrogenase was verified by transformation into the respective catechols of chlorobenzene, the three isomeric dichlorobenzenes, as well as 1,2,3- and 1,2,4-trichlorobenzenes, all of which are transformed by TecA into the respective dihydrodihydroxy derivatives. Di- and trichlorotoluenes were either subject to TecA-mediated dioxygenation (the major or sole reaction observed for the 1,2,4-substituted 2,4-, 2,5-, and 3,4-dichlorotoluenes), resulting in the formation of the dihydrodihydroxy derivatives, or to monooxygenation of the methyl substituent (the major or sole reaction observed for 2,3-, 2,6-, and 3,5-dichloro- and 2,4,5-trichlorotoluenes), resulting in formation of the respective benzyl alcohols. All of the chlorotoluenes subject to dioxygenation by TecA were transformed, without intermediate accumulation of dihydrodihydroxy derivatives, into the respective catechols by TecAB, indicating that dehydrogenation is no bottleneck for chlorobenzene or chlorotoluene degradation. However, only those chlorotoluenes subject to a predominant dioxygenation were growth substrates for PS12, confirming that monooxygenation is an unproductive pathway in PS12. PMID:11526005

Water Extract from Spent Mushroom Substrate of Hericium erinaceus Suppresses Bacterial Wilt Disease of Tomato

PubMed Central

Kwak, A Min; Min, Kyeong Jin; Lee, Sang Yeop

2015-01-01

Culture filtrates of six different edible mushroom species were screened for antimicrobial activity against tomato wilt bacteria Ralstonia solanacearum B3. Hericium erinaceus, Lentinula edodes (Sanjo 701), Grifola frondosa, and Hypsizygus marmoreus showed antibacterial activity against the bacteria. Water, n-butanol, and ethyl acetate extracts of spent mushroom substrate (SMS) of H. erinaceus exhibited high antibacterial activity against different phytopathogenic bacteria: Pectobacterium carotovorum subsp. carotovorum, Agrobacterium tumefaciens, R. solanacearum, Xanthomonas oryzae pv. oryzae, X. campestris pv. campestris, X. axonopodis pv. vesicatoria, X. axonopodis pv. citiri, and X. axonopodis pv. glycine. Quantitative real-time PCR revealed that water extracts of SMS (WESMS) of H. erinaceus induced expressions of plant defense genes encoding β-1,3-glucanase (GluA) and pathogenesis-related protein-1a (PR-1a), associated with systemic acquired resistance. Furthermore, WESMS also suppressed tomato wilt disease caused by R. solanacearum by 85% in seedlings and promoted growth (height, leaf number, and fresh weight of the root and shoot) of tomato plants. These findings suggest the WESMS of H. erinaceus has the potential to suppress bacterial wilt disease of tomato through multiple effects including antibacterial activity, plant growth promotion, and defense gene induction. PMID:26539048

Production of branched-chain alcohols by recombinant Ralstonia eutropha in fed-batch cultivation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fei, Q; Brigham, CJ; Lu, JN

Branched-chain alcohols are considered promising green energy sources due to their compatibility with existing infrastructure and their high energy density. We utilized a strain of Ralstonia eutropha capable of producing branched-chain alcohols and examined its production in flask cultures. In order to increase isobutanol and 3-methyl-1-butanol (isoamyl alcohol) productivity in the engineered strain, batch, fed-batch, and two-stage fed-batch cultures were carried out in this work. The effects of nitrogen source concentration on branched-chain alcohol production were investigated under four different initial concentrations in fermenters. A maximum 380 g m(-3) of branched-chain alcohol production was observed with 2 kg m(-3) initialmore » NH4Cl concentration in batch cultures. A pH-stat control strategy was utilized to investigate the optimum carbon source amount fed during fed-batch cultures for higher cell density. In cultures of R. eutropha strains that did not produce polyhydroxyalkanoate or branched-chain alcohols, a maximum cell dry weight of 36 kg m(-3) was observed using a fed-batch strategy, when 10 kg m(-3) carbon source was fed into culture medium. Finally, a total branched-chain alcohol titer of 790 g m(-3), the highest branched-chain alcohol yield of 0.03 g g(-1), and the maximum branched-chain alcohol productivity of 8.23 g m(-3) h(-1) were obtained from the engineered strain Re2410/pJL26 in a two-stage fed-batch culture system with pH-stat control. Isobutanol made up over 95% (mass fraction) of the total branched-chain alcohols titer produced in this study. (C) 2013 Published by Elsevier Ltd.« less

Phasin Proteins Activate Aeromonas caviae Polyhydroxyalkanoate (PHA) Synthase but Not Ralstonia eutropha PHA Synthase

PubMed Central

Ushimaru, Kazunori; Motoda, Yoko; Numata, Keiji

2014-01-01

In this study, we performed in vitro and in vivo activity assays of polyhydroxyalkanoate (PHA) synthases (PhaCs) in the presence of phasin proteins (PhaPs), which revealed that PhaPs are activators of PhaC derived from Aeromonas caviae (PhaCAc). In in vitro assays, among the three PhaCs tested, PhaCAc was significantly activated when PhaPs were added at the beginning of polymerization (prepolymerization PhaCAc), whereas the prepolymerization PhaCRe (derived from Ralstonia eutropha) and PhaCDa (Delftia acidovorans) showed reduced activity with PhaPs. The PhaP-activated PhaCAc showed a slight shift of substrate preference toward 3-hydroxyhexanoyl-CoA (C6). PhaPAc also activated PhaCAc when it was added during polymerization (polymer-elongating PhaCAc), while this effect was not observed for PhaCRe. In an in vivo assay using Escherichia coli TOP10 as the host strain, the effect of PhaPAc expression on PHA synthesis by PhaCAc or PhaCRe was examined. As PhaPAc expression increased, PHA production was increased by up to 2.3-fold in the PhaCAc-expressing strain, whereas it was slightly increased in the PhaCRe-expressing strain. Taken together, this study provides evidence that PhaPs function as activators for PhaCAc both in vitro and in vivo but do not activate PhaCRe. This activating effect may be attributed to the new role of PhaPs in the polymerization reaction by PhaCAc. PMID:24584238

Bacterial Diseases of Bananas and Enset: Current State of Knowledge and Integrated Approaches Toward Sustainable Management

PubMed Central

Blomme, Guy; Dita, Miguel; Jacobsen, Kim Sarah; Pérez Vicente, Luis; Molina, Agustin; Ocimati, Walter; Poussier, Stephane; Prior, Philippe

2017-01-01

Bacterial diseases of bananas and enset have not received, until recently, an equal amount of attention compared to other major threats to banana production such as the fungal diseases black leaf streak (Mycosphaerella fijiensis) and Fusarium wilt (Fusarium oxysporum f. sp. cubense). However, bacteria cause significant impacts on bananas globally and management practices are not always well known or adopted by farmers. Bacterial diseases in bananas and enset can be divided into three groups: (1) Ralstonia-associated diseases (Moko/Bugtok disease caused by Ralstonia solanacearum and banana blood disease caused by R. syzygii subsp. celebesensis); (2) Xanthomonas wilt of banana and enset, caused by Xanthomonas campestris pv. musacearum and (3) Erwinia-associated diseases (bacterial head rot or tip-over disease Erwinia carotovora ssp. carotovora and E. chrysanthemi), bacterial rhizome and pseudostem wet rot (Dickeya paradisiaca formerly E. chrysanthemi pv. paradisiaca). Other bacterial diseases of less widespread importance include: bacterial wilt of abaca, Javanese vascular wilt and bacterial fingertip rot (probably caused by Ralstonia spp., unconfirmed). This review describes global distribution, symptoms, pathogenic diversity, epidemiology and the state of the art for sustainable disease management of the major bacterial wilts currently affecting banana and enset. PMID:28785275

Suppression of Bacterial Wilt and Fusarium Wilt by a Burkholderia nodosa Strain Isolated from Kalimantan Soils, Indonesia.

PubMed

Nion, Yanetri Asi; Toyota, Koki

2008-01-01

A trial was conducted to suppress bacterial wilt of tomato (BWT) caused by Ralstonia solanacearum using biocontrol agents (BCAs) isolated from soils in Kalimantan, Indonesia. Five isolates were selected from 270 isolates as better performing BCAs through screening four times using a pumice medium. The isolates selected were identified as Burkholderia nodosa, Burkholderia sacchari, Burkholderia pyrrocinia and Burkholderia terricola according to 16S rDNA sequences, fatty acid composition and carbon source utilization patterns. Among them, B. nodosa G5.2.rif1 had significant suppressive effects on Fusarium wilt of tomato (FWT) and spinach (FWS) as well as BWT. When B. nodosa G5.2rif1 was inoculated into a pumice medium in combination with sucrose, it showed even more stable disease suppression for BWT, but not for FWS. This suppression was considered to mainly occur through competition for nutrients. In two times greenhouse experiments for BWT using pots comparable in size to those used commercially, B. nodosa G5.2rif1 significantly suppressed the disease index by 33-79%, with no inhibitory effects on the growth, yield and quality of tomatoes.

Evaluation of antimicrobial activity of silver nanoparticles synthesized from Piper betle leaves against human and plant pathogens

NASA Astrophysics Data System (ADS)

Jha, Babita; Rao, Mugdha; Prasad, K.; Jha, Anal K.

2018-05-01

The present work encompasses the fabrication of biocompatible silver nanoparticles from the leaves of the medicinal plant Piper betle using green chemistry approach. The synthesized nanoparticles were characterized by different standard techniques like: UV-visible spectroscopy, X-ray diffraction, scanning electron microscopy and Fourier transformed infrared spectroscopy. The antimicrobial efficacy of the silver nanoparticles was assessed against human and plant pathogens namely Ralstonia solanacearum, Burkholderia gladioli, Escherichia coli and Sacchromyces cerevisiae by agar well diffusion method. The obtained results clearly indicate its possible use as an alternative to antibiotics and pesticides in near future.

Comparison of Candiatus Liberibacter solanacearum genomic sequences isolated from carrot psyllids in Scandinavia and potato psyllids from Texas

USDA-ARS?s Scientific Manuscript database

The fastidious prokaryote Candidatus Liberibacter solanacearum (Lso), transmitted by the tomato potato psyllid (Bactericera cockerelli), is associated with the Zebra Chip disease of potato. Plants infected with Liberibacter may experience significant yield losses and these plants also serve as poten...

Enhanced biofilm formation in dual-species culture of Listeria monocytogenes and Ralstonia insidiosa

USDA-ARS?s Scientific Manuscript database

In the environment, many microorganisms coexist in communities as biofilms. The objective of this study was to investigate the interactions between Listeria monocytogenes and Ralstonia insidiosa in dual species biofilms. Biofilm development was measured using crystal violet in 96-well microtiter pla...

Cell death-inducing stresses are required for defense activation in DS1-phosphatidic acid phosphatase-silenced Nicotiana benthamiana.

PubMed

Nakano, Masahito; Yoshioka, Hirofumi; Ohnishi, Kouhei; Hikichi, Yasufumi; Kiba, Akinori

2015-07-20

We previously identified DS1 plants that showed resistance to compatible Ralstonia solanacearum with accelerated defense responses. Here, we describe activation mechanisms of defense responses in DS1 plants. After inoculation with incompatible R. solanacearum 8107, DS1 plants showed hyperinduction of hypersensitive response (HR) and reactive oxygen species (ROS) generation. Transient expression of PopP1 and AvrA induced hyperinduction of HR and ROS generation. Furthermore, Pseudomonas cichorii (Pc) and a type III secretion system (TTSS)-deficient mutant of P. cichorii showed accelerated induction of HR and ROS generation. Chitin and flg22 did not induce either HR or ROS hyperaccumulation; however, INF1 accelerated HR and ROS in DS1 plants. Activation of these defense responses was closely associated with increased phosphatidic acid (PA) content. Our results show that DS1 plants exhibit PA-mediated sensitization of plant defenses and that cell death-inducing stress is required to achieve full activation of defense responses. Copyright © 2015 Elsevier GmbH. All rights reserved.

Chemical composition and antibacterial activity of methanolic extract and essential oil of Iranian Teucrium polium against some of phytobacteria.

PubMed

Purnavab, S; Ketabchi, S; Rowshan, V

2015-01-01

The antibacterial activity of essential oil and methanolic extract of Teucrium polium was determined against Pseudomonas aeruginosa, Pantoea agglomerans, Brenneria nigrifluens, Rhizobium radiobacter, Rhizobium vitis, Streptomyces scabies, Ralstonia solanacearum, Xanthomonas campestris and Pectobacterium cartovorum by disc diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration were determined by using the serial dilution method. Chemical composition of essential oil and methanolic extract was determined by GC-MS and HPLC. α-Pinene (25.769%) and myrcene (12.507) were of the highest percentage in T. polium essential oil, and sinapic acid (15.553 mg/g) and eugenol (6.805 mg/g) were the major compounds in the methanolic extract. Our results indicate that both methanolic extract and essential oil did not show antibacterial activity against P. aeruginosa. Also the essential oil did not show antibacterial activity against P. cartovorum. In general, both methanolic extract and essential oil showed the same antibacterial activity against R. solanacearum, P. agglomerans, B. nigrifluens and S. scabies.

Comparison of the Transcriptomes of Ginger (Zingiber officinale Rosc.) and Mango Ginger (Curcuma amada Roxb.) in Response to the Bacterial Wilt Infection

PubMed Central

Prasath, Duraisamy; Karthika, Raveendran; Habeeba, Naduva Thadath; Suraby, Erinjery Jose; Rosana, Ottakandathil Babu; Shaji, Avaroth; Eapen, Santhosh Joseph; Deshpande, Uday; Anandaraj, Muthuswamy

2014-01-01

Bacterial wilt in ginger (Zingiber officinale Rosc.) caused by Ralstonia solanacearum is one of the most important production constraints in tropical, sub-tropical and warm temperature regions of the world. Lack of resistant genotype adds constraints to the crop management. However, mango ginger (Curcuma amada Roxb.), which is resistant to R. solanacearum, is a potential donor, if the exact mechanism of resistance is understood. To identify genes involved in resistance to R. solanacearum, we have sequenced the transcriptome from wilt-sensitive ginger and wilt-resistant mango ginger using Illumina sequencing technology. A total of 26387032 and 22268804 paired-end reads were obtained after quality filtering for C. amada and Z. officinale, respectively. A total of 36359 and 32312 assembled transcript sequences were obtained from both the species. The functions of the unigenes cover a diverse set of molecular functions and biological processes, among which we identified a large number of genes associated with resistance to stresses and response to biotic stimuli. Large scale expression profiling showed that many of the disease resistance related genes were expressed more in C. amada. Comparative analysis also identified genes belonging to different pathways of plant defense against biotic stresses that are differentially expressed in either ginger or mango ginger. The identification of many defense related genes differentially expressed provides many insights to the resistance mechanism to R. solanacearum and for studying potential pathways involved in responses to pathogen. Also, several candidate genes that may underline the difference in resistance to R. solanacearum between ginger and mango ginger were identified. Finally, we have developed a web resource, ginger transcriptome database, which provides public access to the data. Our study is among the first to demonstrate the use of Illumina short read sequencing for de novo transcriptome assembly and comparison in

Comparison of the transcriptomes of ginger (Zingiber officinale Rosc.) and mango ginger (Curcuma amada Roxb.) in response to the bacterial wilt infection.

PubMed

Prasath, Duraisamy; Karthika, Raveendran; Habeeba, Naduva Thadath; Suraby, Erinjery Jose; Rosana, Ottakandathil Babu; Shaji, Avaroth; Eapen, Santhosh Joseph; Deshpande, Uday; Anandaraj, Muthuswamy

2014-01-01

Bacterial wilt in ginger (Zingiber officinale Rosc.) caused by Ralstonia solanacearum is one of the most important production constraints in tropical, sub-tropical and warm temperature regions of the world. Lack of resistant genotype adds constraints to the crop management. However, mango ginger (Curcuma amada Roxb.), which is resistant to R. solanacearum, is a potential donor, if the exact mechanism of resistance is understood. To identify genes involved in resistance to R. solanacearum, we have sequenced the transcriptome from wilt-sensitive ginger and wilt-resistant mango ginger using Illumina sequencing technology. A total of 26387032 and 22268804 paired-end reads were obtained after quality filtering for C. amada and Z. officinale, respectively. A total of 36359 and 32312 assembled transcript sequences were obtained from both the species. The functions of the unigenes cover a diverse set of molecular functions and biological processes, among which we identified a large number of genes associated with resistance to stresses and response to biotic stimuli. Large scale expression profiling showed that many of the disease resistance related genes were expressed more in C. amada. Comparative analysis also identified genes belonging to different pathways of plant defense against biotic stresses that are differentially expressed in either ginger or mango ginger. The identification of many defense related genes differentially expressed provides many insights to the resistance mechanism to R. solanacearum and for studying potential pathways involved in responses to pathogen. Also, several candidate genes that may underline the difference in resistance to R. solanacearum between ginger and mango ginger were identified. Finally, we have developed a web resource, ginger transcriptome database, which provides public access to the data. Our study is among the first to demonstrate the use of Illumina short read sequencing for de novo transcriptome assembly and comparison in

Synthesis and antimicrobial activity of 1-benzhydryl-sulfonyl-4-(3-(piperidin-4-yl) propyl)piperidine derivatives against pathogens of Lycopersicon esculentum: a structure-activity evaluation study.

PubMed

Vinaya, K; Kavitha, R; Ananda Kumar, C S; Benaka Prasad, S B; Chandrappa, S; Deepak, S A; Nanjunda Swamy, S; Umesha, S; Rangappa, K S

2009-01-01

Several 1-benzhydryl-sulfonyl-4-(3-(piperidin-4-yl)propyl)piperidine derivatives 8(a-j) were prepared by the treatment of substituted benzhydryl chlorides with 4-(3-(piperidin-4-yl)propyl)piperidine followed by N-sulfonation with sulfonyl chlorides in the presence of dry methylene dichloride and triethyl amine. The synthesized compounds were characterized by (1)H-NMR, IR, and elemental analysis. All the synthesized compounds were evaluated in vitro for their efficacy as antimicrobial agents by artificial inoculation technique against standard strains of two important bacterial viz., Xanthomonas axonopodis pv. vesicatoria and Ralstonia solanacearum as well as and two fungal pathogens namely Alternaria solani and Fusarium solani of tomato plants. We have briefly investigated the structure-activity relation studies and reveal that the nature of substitutions on benzhydryl ring and sulfonamide ring influences the antibacterial activity. Among the synthesized new compounds 8b, 8d, 8g, 8h, 8i, and 8j were showed significant potent antimicrobial activities compared to the standard drugs chloramphenicol, mancozeb.

Abundance of Dioxygenase Genes Similar to Ralstonia sp. Strain U2 nagAc Is Correlated with Naphthalene Concentrations in Coal Tar-Contaminated Freshwater Sediments

PubMed Central

Dionisi, Hebe M.; Chewning, Christopher S.; Morgan, Katherine H.; Menn, Fu-Min; Easter, James P.; Sayler, Gary S.

2004-01-01

We designed a real-time PCR assay able to recognize dioxygenase large-subunit gene sequences with more than 90% similarity to the Ralstonia sp. strain U2 nagAc gene (nagAc-like gene sequences) in order to study the importance of organisms carrying these genes in the biodegradation of naphthalene. Sequencing of PCR products indicated that this real-time PCR assay was specific and able to detect a variety of nagAc-like gene sequences. One to 100 ng of contaminated-sediment total DNA in 25-μl reaction mixtures produced an amplification efficiency of 0.97 without evident PCR inhibition. The assay was applied to surficial freshwater sediment samples obtained in or in close proximity to a coal tar-contaminated Superfund site. Naphthalene concentrations in the analyzed samples varied between 0.18 and 106 mg/kg of dry weight sediment. The assay for nagAc-like sequences indicated the presence of (4.1 ± 0.7) × 103 to (2.9 ± 0.3) × 105 copies of nagAc-like dioxygenase genes per μg of DNA extracted from sediment samples. These values corresponded to (1.2 ± 0.6) × 105 to (5.4 ± 0.4) × 107 copies of this target per g of dry weight sediment when losses of DNA during extraction were taken into account. There was a positive correlation between naphthalene concentrations and nagAc-like gene copies per microgram of DNA (r = 0.89) and per gram of dry weight sediment (r = 0.77). These results provide evidence of the ecological significance of organisms carrying nagAc-like genes in the biodegradation of naphthalene. PMID:15240274

Genome-Based Analysis and Gene Dosage Studies Provide New Insight into 3-Hydroxy-4-Methylvalerate Biosynthesis in Ralstonia eutropha

PubMed Central

Ushimaru, Kazunori; Mizuno, Shoji

2015-01-01

Recombinant Ralstonia eutropha strain PHB−4 expressing the broad-substrate-specificity polyhydroxyalkanoate (PHA) synthase 1 from Pseudomonas sp. strain 61-3 (PhaC1Ps) synthesizes a PHA copolymer containing the branched side-chain unit 3-hydroxy-4-methylvalerate (3H4MV), which has a carbon backbone identical to that of leucine. Mutant strain 1F2 was derived from R. eutropha strain PHB−4 by chemical mutagenesis and shows higher levels of 3H4MV production than does the parent strain. In this study, to understand the mechanisms underlying the enhanced production of 3H4MV, whole-genome sequencing of strain 1F2 was performed, and the draft genome sequence was compared to that of parent strain PHB−4. This analysis uncovered four point mutations in the 1F2 genome. One point mutation was found in the ilvH gene at amino acid position 36 (A36T) of IlvH. ilvH encodes a subunit protein that regulates acetohydroxy acid synthase III (AHAS III). AHAS catalyzes the conversion of pyruvate to 2-acetolactate, which is the first reaction in the biosynthesis of branched amino acids such as leucine and valine. Thus, the A36T IlvH mutation may show AHAS tolerance to feedback inhibition by branched amino acids, thereby increasing carbon flux toward branched amino acid and 3H4MV biosynthesis. Furthermore, a gene dosage study and an isotope tracer study were conducted to investigate the 3H4MV biosynthesis pathway. Based on the observations in these studies, we propose a 3H4MV biosynthesis pathway in R. eutropha that involves a condensation reaction between isobutyryl coenzyme A (isobutyryl-CoA) and acetyl-CoA to form the 3H4MV carbon backbone. PMID:25645560

RubisCO selection using the vigorously aerobic and metabolically versatile bacterium Ralstonia eutropha.

PubMed

Satagopan, Sriram; Tabita, F Robert

2016-08-01

Recapturing atmospheric CO2 is key to reducing global warming and increasing biological carbon availability. Ralstonia eutropha is a biotechnologically useful aerobic bacterium that uses the Calvin-Benson-Bassham (CBB) cycle and the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) for CO2 utilization, suggesting that it may be a useful host to bioselect RubisCO molecules with improved CO2 -capture capabilities. A host strain of R. eutropha was constructed for this purpose after deleting endogenous genes encoding two related RubisCOs. This strain could be complemented for CO2 -dependent growth by introducing native or heterologous RubisCO genes. Mutagenesis and suppressor selection identified amino acid substitutions in a hydrophobic region that specifically influences RubisCO's interaction with its substrates, particularly O2 , which competes with CO2 at the active site. Unlike most RubisCOs, the R. eutropha enzyme has evolved to retain optimal CO2 -fixation rates in a fast-growing host, despite the presence of high levels of competing O2 . Yet its structure-function properties resemble those of several commonly found RubisCOs, including the higher plant enzymes, allowing strategies to engineer analogous enzymes. Because R. eutropha can be cultured rapidly under harsh environmental conditions (e.g., with toxic industrial flue gas), in the presence of near saturation levels of oxygen, artificial selection and directed evolution studies in this organism could potentially impact efforts toward improving RubisCO-dependent biological CO2 utilization in aerobic environments. d-ribulose 1,5-bisphosphate carboxylase/oxygenase, EC 4.1.1.39; phosphoribulokinase, EC 2.7.1.19. © 2016 Federation of European Biochemical Societies.

Production of rhamnolipids and diesel oil degradation by bacteria isolated from soil contaminated by petroleum.

PubMed

Leite, Giuseppe G F; Figueirôa, Juciane V; Almeida, Thiago C M; Valões, Jaqueline L; Marques, Walber F; Duarte, Maria D D C; Gorlach-Lira, Krystyna

2016-03-01

Biosurfactants are microbial secondary metabolites. The most studied are rhamnolipids, which decrease the surface tension and have emulsifying capacity. In this study, the production of biosurfactants, with emphasis on rhamnolipids, and diesel oil degradation by 18 strains of bacteria isolated from waste landfill soil contaminated by petroleum was analyzed. Among the studied bacteria, gram-positive endospore forming rods (39%), gram positive rods without endospores (17%), and gram-negative rods (44%) were found. The following methods were used to test for biosurfactant production: oil spreading, emulsification, and hemolytic activity. All strains showed the ability to disperse the diesel oil, while 77% and 44% of the strains showed hemolysis and emulsification of diesel oil, respectively. Rhamnolipids production was observed in four strains that were classified on the basis of the 16S rRNA sequences as Pseudomonas aeruginosa. Only those strains showed the rhlAB gene involved in rhamnolipids synthesis, and antibacterial activity against Escherichia coli, P. aeruginosa, Staphylococcus aureus, Bacillus cereus, Erwinia carotovora, and Ralstonia solanacearum. The highest production of rhamnolipids was 565.7 mg/L observed in mineral medium containing olive oil (pH 8). With regard to the capacity to degrade diesel oil, it was observed that 7 strains were positive in reduction of the dye 2,6-dichlorophenolindophenol (2,6-DCPIP) while 16 had the gene alkane mono-oxygenase (alkB), and the producers of rhamnolipids were positive in both tests. Several bacterial strains have shown high potential to be explored further for bioremediation purposes due to their simultaneous ability to emulsify, disperse, and degrade diesel oil. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:262-270, 2016. © 2015 American Institute of Chemical Engineers.

Absence of ppGpp Leads to Increased Mobilization of Intermediately Accumulated Poly(3-Hydroxybutyrate) in Ralstonia eutropha H16

PubMed Central

Juengert, Janina R.; Borisova, Marina; Wolz, Christiane; Brigham, Christopher J.; Sinskey, Anthony J.

2017-01-01

ABSTRACT In this study, we constructed a set of Ralstonia eutropha H16 strains with single, double, or triple deletions of the (p)ppGpp synthase/hydrolase (spoT1), (p)ppGpp synthase (spoT2), and/or polyhydroxybutyrate (PHB) depolymerase (phaZa1 or phaZa3) gene, and we determined the impact on the levels of (p)ppGpp and on accumulated PHB. Mutants with deletions of both the spoT1 and spoT2 genes were unable to synthesize detectable amounts of (p)ppGpp and accumulated only minor amounts of PHB, due to PhaZa1-mediated depolymerization of PHB. In contrast, unusually high levels of PHB were found in strains in which the (p)ppGpp concentration was increased by the overexpression of (p)ppGpp synthase (SpoT2) and the absence of (p)ppGpp hydrolase. Determination of (p)ppGpp levels in wild-type R. eutropha under different growth conditions and induction of the stringent response by amino acid analogs showed that the concentrations of (p)ppGpp during the growth phase determine the amount of PHB remaining in later growth phases by influencing the efficiency of the PHB mobilization system in stationary growth. The data reported for a previously constructed ΔspoT2 strain (C. J. Brigham, D. R. Speth, C. Rha, and A. J. Sinskey, Appl Environ Microbiol 78:8033–8044, 2012, https://doi.org/10.1128/AEM.01693-12) were identified as due to an experimental error in strain construction, and our results are in contrast to the previous indication that the spoT2 gene product is essential for PHB accumulation in R. eutropha. IMPORTANCE Polyhydroxybutyrate (PHB) is an important intracellular carbon and energy storage compound in many prokaryotes and helps cells survive periods of starvation and other stress conditions. Research activities in several laboratories over the past 3 decades have shown that both PHB synthase and PHB depolymerase are constitutively expressed in most PHB-accumulating bacteria, such as Ralstonia eutropha. This implies that PHB synthase and depolymerase activities

Ralstonia eutropha H16 in progress: Applications beside PHAs and establishment as production platform by advanced genetic tools.

PubMed

Raberg, Matthias; Volodina, Elena; Lin, Kaichien; Steinbüchel, Alexander

2018-06-01

Ralstonia eutropha strain H16 is a Gram-negative non-pathogenic betaproteobacterium ubiquitously found in soils and has been the subject of intensive research for more than 50 years. Due to its remarkable metabolically versatility, it utilizes a broad range of renewable heterotrophic resources. The substrate utilization range can be further extended by metabolic engineering as genetic tools are available. It has become the best studied "Knallgas" bacterium capable of chemolithoautotrophic growth with hydrogen as the electron donor and carbon dioxide as the carbon source. It also serves as a model organism to study the metabolism of poly(β-hydroxybutyrate), a polyester which is accumulated within the cells for storage of both carbon and energy. Thermoplastic and biodegradable properties of this polyhydroxyalkanoate (PHA) have attracted much biotechnical interest as a replacement for fossil resource-based plastics. The first applications of R. eutropha aimed at chemolithoautotrophic production of single cell protein (SCP) for food and feed and the synthesis of various PHAs. The complete annotated genome is available allowing systematic biology approaches together with data provided by available omics studies. Besides PHAs, novel biopolymers of 2-hydroxyalkanoates and polythioesters or cyanophycin as well as chemicals such as alcohols, alkanes, alkenes, and further interesting value added chemicals significantly recently extended the range of products synthesized by R. eutropha. High cell density cultivations can be performed without too much effort and the available repertoire of genetic tools is rapidly growing. Altogether, this qualifies R. eutropha strain H16 to become a production platform strain for a large spectrum of products.

Differential Control Efficacies of Vitamin Treatments against Bacterial Wilt and Grey Mould Diseases in Tomato Plants.

PubMed

Hong, Jeum Kyu; Kim, Hyeon Ji; Jung, Heesoo; Yang, Hye Ji; Kim, Do Hoon; Sung, Chang Hyun; Park, Chang-Jin; Chang, Seog Won

2016-10-01

Bacterial wilt and grey mould in tomato plants are economically destructive bacterial and fungal diseases caused by Ralstonia solanacearum and Botrytis cinerea , respectively. Various approaches including chemical and biological controls have been attempted to arrest the tomato diseases so far. In this study, in vitro growths of bacterial R. solanacearum and fungal B. cinerea were evaluated using four different vitamins including thiamine (vitamin B1), niacin (vitamin B3), pyridoxine (vitamin B6), and menadione (vitamin K3). In planta efficacies of the four vitamin treatments on tomato protection against both diseases were also demonstrated. All four vitamins showed different in vitro antibacterial activities against R. solanacearum in dose-dependent manners. However, treatment with 2 mM thiamine was only effective in reducing bacterial wilt of detached tomato leaves without phytotoxicity under lower disease pressure (10 6 colony-forming unit [cfu]/ml). Treatment with the vitamins also differentially reduced in vitro conidial germination and mycelial growth of B. cinerea . The four vitamins slightly reduced the conidial germination, and thiamine, pyridoxine and menadione inhibited the mycelial growth of B. cinerea . Menadione began to drastically suppress the conidial germination and mycelial growth by 5 and 0.5 mM, respectively. Grey mould symptoms on the inoculated tomato leaves were significantly reduced by pyridoxine and menadione pretreatments one day prior to the fungal challenge inoculation. These findings suggest that disease-specific vitamin treatment will be integrated for eco-friendly management of tomato bacterial wilt and grey mould.

Differential Control Efficacies of Vitamin Treatments against Bacterial Wilt and Grey Mould Diseases in Tomato Plants

PubMed Central

Hong, Jeum Kyu; Kim, Hyeon Ji; Jung, Heesoo; Yang, Hye Ji; Kim, Do Hoon; Sung, Chang Hyun; Park, Chang-Jin; Chang, Seog Won

2016-01-01

Bacterial wilt and grey mould in tomato plants are economically destructive bacterial and fungal diseases caused by Ralstonia solanacearum and Botrytis cinerea, respectively. Various approaches including chemical and biological controls have been attempted to arrest the tomato diseases so far. In this study, in vitro growths of bacterial R. solanacearum and fungal B. cinerea were evaluated using four different vitamins including thiamine (vitamin B1), niacin (vitamin B3), pyridoxine (vitamin B6), and menadione (vitamin K3). In planta efficacies of the four vitamin treatments on tomato protection against both diseases were also demonstrated. All four vitamins showed different in vitro antibacterial activities against R. solanacearum in dose-dependent manners. However, treatment with 2 mM thiamine was only effective in reducing bacterial wilt of detached tomato leaves without phytotoxicity under lower disease pressure (106 colony-forming unit [cfu]/ml). Treatment with the vitamins also differentially reduced in vitro conidial germination and mycelial growth of B. cinerea. The four vitamins slightly reduced the conidial germination, and thiamine, pyridoxine and menadione inhibited the mycelial growth of B. cinerea. Menadione began to drastically suppress the conidial germination and mycelial growth by 5 and 0.5 mM, respectively. Grey mould symptoms on the inoculated tomato leaves were significantly reduced by pyridoxine and menadione pretreatments one day prior to the fungal challenge inoculation. These findings suggest that disease-specific vitamin treatment will be integrated for eco-friendly management of tomato bacterial wilt and grey mould. PMID:27721697

Identification of an antibacterial compound, benzylideneacetone, from Xenorhabdus nematophila against major plant-pathogenic bacteria.

PubMed

Ji, Dongjin; Yi, Youngkeun; Kang, Ga-Hwa; Choi, Yong-Hwa; Kim, Pankyung; Baek, Nam-In; Kim, Yonggyun

2004-10-15

An entomopathogenic bacterium, Xenorhabdus nematophila, is known to have potent antibiotic activities to maintain monoxenic condition in its insect host for effective pathogenesis and ultimately for optimal development of its nematode symbiont, Steinernema carpocapsae. In this study we assess its antibacterial activity against plant-pathogenic bacteria and identify its unknown antibiotics. The bacterial culture broth had significant antibacterial activity that increased with development of the bacteria and reached its maximum at the stationary growth phase. The antibiotic activities were significant against five plant-pathogenic bacterial strains: Agrobacterium vitis, Pectobacterium carotovorum subsp. atrosepticum, P. carotovorum subsp. carotovorum, Pseudomonas syringae pv. tabaci, and Ralstonia solanacearum. The antibacterial factors were extracted with butanol and fractionated using column chromatography with the eluents of different hydrophobic intensities. Two active antibacterial subfractions were purified, and the higher active fraction was further fractionated and identified as a single compound of benzylideneacetone (trans-4-phenyl-3-buten-2-one). With heat stability, the synthetic compound showed equivalent antibiotic activity and spectrum to the purified compound. This study reports a new antibiotic compound synthesized by X. nematophila, which is a monoterpenoid compound and active against some Gram-negative bacteria.

An oligonucleotide array for the identification and differentiation of bacteria pathogenic on potato.

PubMed

Fessehaie, Anania; De Boer, Solke H; Lévesque, C André

2003-03-01

ABSTRACT Oligonucleotides, 16 to 24 bases long, were selected from the 3' end of the 16S gene and the 16S-23S intergenic spacer regions of bacteria pathogenic on potato, including Clavibacter michiganensis subsp. sepedonicus, Ralstonia solanacearum, and the pectolytic erwinias, including Erwinia carotovora subsp. atroseptica and carotovora and E. chrysanthemi. Oligonucleotides were designed and formatted into an array by pin spotting on nylon membranes. Genomic DNA from bacterial cultures was amplified by polymerase chain reaction using conserved ribosomal primers and labeled simultaneously with digoxigenin-dUTP. Hybridization of amplicons to the array and subsequent serological detection of digoxigenin label revealed different hybridization patterns that were distinct for each species and subspecies tested. Hybridization of amplicons generally was restricted to appropriate homologous oligonucleotides and cross-hybridization with heterologous oligonucleotides was rare. Hybridization patterns were recorded as separate gray values for each hybridized spot and revealed a consistent pattern for multiple strains of each species or subspecies isolated from diverse geographical regions. In preliminary tests, bacteria could be correctly identified and detected by hybridizing to the array amplicons from mixed cultures and inoculated potato tissue.

Rutin-Mediated Priming of Plant Resistance to Three Bacterial Pathogens Initiating the Early SA Signal Pathway

PubMed Central

Li, Yang; Wang, Yingzi; Li, Ming; Wang, Yong; Ding, Xinhua; Chu, Zhaohui

2016-01-01

Flavonoids are ubiquitous in the plant kingdom and have many diverse functions, including UV protection, auxin transport inhibition, allelopathy, flower coloring and insect resistance. Here we show that rutin, a proud member of the flavonoid family, could be functional as an activator to improve plant disease resistances. Three plant species pretreated with 2 mM rutin were found to enhance resistance to Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Pseudomonas syringae pv. tomato strain DC3000 in rice, tobacco and Arabidopsis thaliana respectively. While they were normally propagated on the cultural medium supplemented with 2 mM rutin for those pathogenic bacteria. The enhanced resistance was associated with primed expression of several pathogenesis-related genes. We also demonstrated that the rutin-mediated priming resistance was attenuated in npr1, eds1, eds5, pad4-1, ndr1 mutants, and NahG transgenic Arabidopsis plant, while not in either snc1-11, ein2-5 or jar1 mutants. We concluded that the rutin-priming defense signal was modulated by the salicylic acid (SA)-dependent pathway from an early stage upstream of NDR1 and EDS1. PMID:26751786

Soil-based systemic delivery and phyllosphere in vivo propagation of bacteriophages: Two possible strategies for improving bacteriophage persistence for plant disease control.

PubMed

Iriarte, Fanny B; Obradović, Aleksa; Wernsing, Mine H; Jackson, Lee E; Balogh, Botond; Hong, Jason A; Momol, M Timur; Jones, Jeffrey B; Vallad, Gary E

2012-10-01

Soil-based root applications and attenuated bacterial strains were evaluated as means to enhance bacteriophage persistence on plants for bacterial disease control. In addition, the systemic nature of phage applied to tomato roots was also evaluated. Several experiments were conducted applying either single phages or phage mixtures specific for Ralstonia solanacearum , Xanthomonas perforans or X. euvesicatoria to soil surrounding tomato plants and measuring the persistence and translocation of the phages over time. In general, all phages persisted in the roots of treated plants and were detected in stems and leaves; although phage level varied and persistence in stems and leaves was at a much lower level compared with persistence in roots. Bacterial wilt control was typically best if the phage or phage mixtures were applied to the soil surrounding tomatoes at the time of inoculation, less effective if applied 3 days before inoculation, and ineffective if applied 3 days after inoculation. The use of an attenuated X. perforans strain was also evaluated to improve the persistence of phage populations on tomato leaf surfaces. In greenhouse and field experiments, foliar applications of an attenuated mutant X. perforans 91-118:∆ OPGH strain prior to phage applications significantly improved phage persistence on tomato foliage compared with untreated tomato foliage. Both the soil-based bacteriophage delivery and the use of attenuated bacterial strains improved bacteriophage persistence on respective root and foliar tissues, with evidence of translocation with soil-based bacteriophage applications. Both strategies could lead to improved control of bacterial pathogens on plants.

PHB granules are attached to the nucleoid via PhaM in Ralstonia eutropha.

PubMed

Wahl, Andreas; Schuth, Nora; Pfeiffer, Daniel; Nussberger, Stephan; Jendrossek, Dieter

2012-11-16

Poly(3-hydroxybutyrate) (PHB) granules are important storage compounds of carbon and energy in many prokaryotes which allow survival of the cells in the absence of suitable carbon sources. Formation and subcellular localization of PHB granules was previously assumed to occur randomly in the cytoplasm of PHB accumulating bacteria. However, contradictionary results on subcellular localization of PHB granules in Ralstonia eutropha were published, recently. Here, we provide evidence by transmission electron microscopy that PHB granules are localized in close contact to the nucleoid region in R. eutropha during growth on nutrient broth. Binding of PHB granules to the nucleoid is mediated by PhaM, a PHB granule associated protein with phasin-like properties that is also able to bind to DNA and to phasin PhaP5. Over-expression of PhaM resulted in formation of many small PHB granules that were always attached to the nucleoid region. In contrast, PHB granules of ∆phaM strains became very large and distribution of granules to daughter cells was impaired. Association of PHB granules to the nucleoid region was prevented by over-expression of PhaP5 and clusters of several PHB granules were mainly localized near the cell poles. Subcellular localization of PHB granules is controlled in R. eutropha and depends on the presence and concentrations of at least two PHB granule associated proteins, PhaM and PhaP5.

Impact of Ralstonia eutropha's poly(3-Hydroxybutyrate) (PHB) Depolymerases and Phasins on PHB storage in recombinant Escherichia coli.

PubMed

Eggers, Jessica; Steinbüchel, Alexander

2014-12-01

The model organism for polyhydroxybutyrate (PHB) biosynthesis, Ralstonia eutropha H16, possesses multiple isoenzymes of granules coating phasins as well as of PHB depolymerases, which degrade accumulated PHB under conditions of carbon limitation. In this study, recombinant Escherichia coli BL21(DE3) strains were used to study the impact of selected PHB depolymerases of R. eutropha H16 on the growth behavior and on the amount of accumulated PHB in the absence or presence of phasins. For this purpose, 20 recombinant E. coli BL21(DE3) strains were constructed, which harbored a plasmid carrying the phaCAB operon from R. eutropha H16 to ensure PHB synthesis and a second plasmid carrying different combinations of the genes encoding a phasin and a PHB depolymerase from R. eutropha H16. It is shown in this study that the growth behavior of the respective recombinant E. coli strains was barely affected by the overexpression of the phasin and PHB depolymerase genes. However, the impact on the PHB contents was significantly greater. The strains expressing the genes of the PHB depolymerases PhaZ1, PhaZ2, PhaZ3, and PhaZ7 showed 35% to 94% lower PHB contents after 30 h of cultivation than the control strain. The strain harboring phaZ7 reached by far the lowest content of accumulated PHB (only 2.0% [wt/wt] PHB of cell dry weight). Furthermore, coexpression of phasins in addition to the PHB depolymerases influenced the amount of PHB stored in cells of the respective strains. It was shown that the phasins PhaP1, PhaP2, and PhaP4 are not substitutable without an impact on the amount of stored PHB. In particular, the phasins PhaP2 and PhaP4 seemed to limit the degradation of PHB by the PHB depolymerases PhaZ2, PhaZ3, and PhaZ7, whereas almost no influence of the different phasins was observed if phaZ1 was coexpressed. This study represents an extensive analysis of the impact of PHB depolymerases and phasins on PHB accumulation and provides a deeper insight into the complex interplay

Impact of Ralstonia eutropha's Poly(3-Hydroxybutyrate) (PHB) Depolymerases and Phasins on PHB Storage in Recombinant Escherichia coli

PubMed Central

Eggers, Jessica

2014-01-01

The model organism for polyhydroxybutyrate (PHB) biosynthesis, Ralstonia eutropha H16, possesses multiple isoenzymes of granules coating phasins as well as of PHB depolymerases, which degrade accumulated PHB under conditions of carbon limitation. In this study, recombinant Escherichia coli BL21(DE3) strains were used to study the impact of selected PHB depolymerases of R. eutropha H16 on the growth behavior and on the amount of accumulated PHB in the absence or presence of phasins. For this purpose, 20 recombinant E. coli BL21(DE3) strains were constructed, which harbored a plasmid carrying the phaCAB operon from R. eutropha H16 to ensure PHB synthesis and a second plasmid carrying different combinations of the genes encoding a phasin and a PHB depolymerase from R. eutropha H16. It is shown in this study that the growth behavior of the respective recombinant E. coli strains was barely affected by the overexpression of the phasin and PHB depolymerase genes. However, the impact on the PHB contents was significantly greater. The strains expressing the genes of the PHB depolymerases PhaZ1, PhaZ2, PhaZ3, and PhaZ7 showed 35% to 94% lower PHB contents after 30 h of cultivation than the control strain. The strain harboring phaZ7 reached by far the lowest content of accumulated PHB (only 2.0% [wt/wt] PHB of cell dry weight). Furthermore, coexpression of phasins in addition to the PHB depolymerases influenced the amount of PHB stored in cells of the respective strains. It was shown that the phasins PhaP1, PhaP2, and PhaP4 are not substitutable without an impact on the amount of stored PHB. In particular, the phasins PhaP2 and PhaP4 seemed to limit the degradation of PHB by the PHB depolymerases PhaZ2, PhaZ3, and PhaZ7, whereas almost no influence of the different phasins was observed if phaZ1 was coexpressed. This study represents an extensive analysis of the impact of PHB depolymerases and phasins on PHB accumulation and provides a deeper insight into the complex interplay

RpA, an extracellular protease similar to the metalloprotease of serralysin family, is required for pathogenicity of Ralstonia pickettii.

PubMed

Chen, C-M; Liu, J-J; Chou, C-W; Lai, C-H; Wu, L-T

2015-10-01

To investigate the biochemical and functional properties of an extracellular protease, RpA, in Ralstonia pickettii WP1 isolated from water supply systems. An extracellular protease was identified and characterized from R. pickettii WP1. A mutant strain WP1M2 was created from strain WP1 by mini-Tn5 transposition. The culture filtrates from WP1M2 had a lower cytotoxic effect than the parental WP1 on several mammalian cell lines. Cloning and sequence analysis revealed the Tn5 transposon inserted at a protease gene (rpA) which is 81% homologous to prtA and aprX genes of Pseudomonas fluorescens. The rpA gene encodes a 482-residue protein showing sequence similarity to metalloproteases of the serralysin family. The RpA protein was expressed in Escherichia coli using a pET expression vector and purified as a 55 kDa molecular weight protein. Furthermore, the protease activity of RpA was inhibited by protease inhibitor and heat treatment. The in vitro cytotoxic activity of R. pickettii culture filtrates was attributed to RpA protease. An extracellular protease, RpA, was identified from R. pickettii WP1 isolated from water supply system. The RpA metalloproteases is required for the pathogenicity of R. pickettii to mammalian cell lines. © 2015 The Society for Applied Microbiology.

Characterization of Acrylamidase isolated from a newly isolated acrylamide-utilizing bacterium, Ralstonia eutropha AUM-01.

PubMed

Cha, Minseok; Chambliss, Glenn H

2011-02-01

A mesophilic bacterium capable of utilizing acrylamide was isolated, AUM-01, from soil collected from leaf litter at Picnic Point on the UW-Madison campus. In minimal medium with acrylamide as the sole carbon and nitrogen source, a batch culture of AUM-01 completely converted 28.0 mM acrylamide to acrylic acid in 8 h and reached a cell density of 0.3 (A₆₀₀)). Afterward all the acrylic acid was degraded by 20 h with the cell density increasing to 1.9 (A₆₀₀). The acrylamide-utilizing bacterium was identified as Ralstonia eutropha based on morphological observations, the BiOLOG GN2 MicroPlate™ identification system for Gram-negative bacteria, and additional physiological tests. An acrylamidase that hydrolyzes acrylamide to acrylic acid was purified from the strain AUM-01. The molecular weight of the enzyme from AUM-01 was determined to be 38 kDa by SDS-PAGE. The enzyme had pH and temperature optima of 6.3 and 55°C, and the influence of different metals and amino acids on the ability of the purified protein to transform acrylamide to acrylic acid was evaluated. The enzyme from AUM-01 was totally inhibited by ZnSO₄ and AgNO₃.

PHB granules are attached to the nucleoid via PhaM in Ralstonia eutropha

PubMed Central

2012-01-01

Background Poly(3-hydroxybutyrate) (PHB) granules are important storage compounds of carbon and energy in many prokaryotes which allow survival of the cells in the absence of suitable carbon sources. Formation and subcellular localization of PHB granules was previously assumed to occur randomly in the cytoplasm of PHB accumulating bacteria. However, contradictionary results on subcellular localization of PHB granules in Ralstonia eutropha were published, recently. Results Here, we provide evidence by transmission electron microscopy that PHB granules are localized in close contact to the nucleoid region in R. eutropha during growth on nutrient broth. Binding of PHB granules to the nucleoid is mediated by PhaM, a PHB granule associated protein with phasin-like properties that is also able to bind to DNA and to phasin PhaP5. Over-expression of PhaM resulted in formation of many small PHB granules that were always attached to the nucleoid region. In contrast, PHB granules of ∆phaM strains became very large and distribution of granules to daughter cells was impaired. Association of PHB granules to the nucleoid region was prevented by over-expression of PhaP5 and clusters of several PHB granules were mainly localized near the cell poles. Conclusion Subcellular localization of PHB granules is controlled in R. eutropha and depends on the presence and concentrations of at least two PHB granule associated proteins, PhaM and PhaP5. PMID:23157596

Bioorganic Fertilizer Enhances Soil Suppressive Capacity against Bacterial Wilt of Tomato

PubMed Central

Liu, Shuangri; Chai, Rushan; Huang, Weiqing; Liu, Xingxing; Tang, Caixian; Zhang, Yongsong

2015-01-01

Tomato bacterial wilt caused by Ralstonia solanacearum is one of the most destructive soil-borne diseases. Many strategies have been taken to improve soil suppressiveness against this destructive disease, but limited success has been achieved. In this study, a novel bioorganic fertilizer revealed a higher suppressive ability against bacterial wilt compared with several soil management methods in the field over four growing seasons from March 2011 to July 2013. The application of the bioorganic fertilizer significantly (P<0.05) reduced disease incidence of tomato and increased fruit yields in four independent trials. The association among the level of disease incidence, soil physicochemical and biological properties was investigated. The soil treated with the bioorganic fertilizer increased soil pH value, electric conductivity, organic carbon, NH4 +-N, NO3 --N and available K content, microbial activities and microbial biomass carbon content, which were positively related with soil suppressiveness. Bacterial and actinomycete populations assessed using classical plate counts were highest, whereas R. solanacearum and fungal populations were lowest in soil applied with the bioorganic fertilizer. Microbial community diversity and richness were assessed using denaturing gel gradient electrophoresis profile analysis. The soil treated with the bioorganic fertilizer exhibited higher bacterial community diversity but lower fungal community diversity. Redundancy analysis showed that bacterial community diversity and richness negatively related with bacterial wilt suppressiveness, while fungal community richness positively correlated with R. solanacearum population. We concluded that the alteration of soil physicochemical and biological properties in soil treated with the bioorganic fertilizer induced the soil suppressiveness against tomato bacterial wilt. PMID:25830639

Genetic variation of 'Candidatus Liberibacter solanacearum' haplotype C and identification of a novel haplotype from Trioza urticae and stinging nettle.

PubMed

Haapalainen, Minna L; Wang, Jinhui; Latvala, Satu; Lehtonen, Mikko T; Pirhonen, Minna; Nissinen, Anne I

2018-03-30

'Candidatus Liberibacter solanacearum' (CLso) haplotype C is associated with disease in carrots and transmitted by the carrot psyllid Trioza apicalis. To identify possible other sources and vectors of this pathogen in Finland, samples were taken of wild plants within and near the carrot fields, the psyllids feeding on these plants, parsnips growing next to carrots, and carrot seeds. For analyzing the genotype of the CLso positive samples, a multi-locus sequence typing (MLST) scheme was developed. CLso haplotype C was detected in 11% of the Trioza anthrisci samples, in 35% of the Anthriscus sylvestris plants with discoloration, and in parsnips showing leaf discoloration. MLST revealed that the CLso in T. anthrisci and most A. sylvestris plants represent different strains than the bacteria found in T. apicalis and the cultivated plants. CLso haplotype D was detected in two of the 34 carrot seed lots tested, but was not detected in the plants grown from these seeds. Phylogenetic analysis by UPGMA clustering suggested that the haplotype D is more closely related to the haplotype A than to C. A novel, sixth haplotype of CLso, most closely related to A and D, was found in the psyllid Trioza urticae and stinging nettle (Urtica dioica, Urticaceae), and named as haplotype U.

Enzymatic modification of chitosan by cinnamic acids: Antibacterial activity against Ralstonia solanacearum.

PubMed

Yang, Caifeng; Zhou, Yu; Zheng, Yu; Li, Changlong; Sheng, Sheng; Wang, Jun; Wu, Fuan

2016-06-01

This study aimed to identify chitosan polymers that have antibacterial activity against the bacterial wilt pathogen. The chitosan polymers were enzymatically synthesized using chitosan and five cinnamic acids (CADs): caffeic acid (CA), ferulic acid (FA), cinnamic acid (CIA), p-coumaric acid (COA) and chlorogenic acid (CHA), using laccase from Pleurotus ostreatus as a catalyst. The reaction was performed in a phosphate buffered solution under heterogenous reaction conditions. The chitosan derivatives (CTS-g-CADs) were characterized by FT-IR, XRD, TGA and SEM. FT-IR demonstrated that the reaction products bound covalently to the free amino groups or hydroxyl groups of chitosan via band of amide I or ester band. XRD showed a reduced packing density for grafted chitosan comparing to original chitosan. TGA demonstrated that CTS-g-CADs have a higher thermostability than chitosan. Additionally, chitosan and its derivatives showed similar antibacterial activity. However, the IC50 value of the chitosan-caffeic acid derivative (CTS-g-CA) against the mulberry bacterial wilt pathogen RS-5 was 0.23mg/mL, which was two-fifths of the IC50 value of chitosan. Therefore, the enzymatically synthesized chitosan polymers can be used to control plant diseases in biotechnological domains. Copyright © 2016 Elsevier B.V. All rights reserved.

Mobilization of Selenite by Ralstonia metallidurans CH34

PubMed Central

Roux, Murielle; Sarret, Géraldine; Pignot-Paintrand, Isabelle; Fontecave, Marc; Coves, Jacques

2001-01-01

Ralstonia metallidurans CH34 (formerly Alcaligenes eutrophus CH34) is a soil bacterium characteristic of metal-contaminated biotopes, as it is able to grow in the presence of a variety of heavy metals. R. metallidurans CH34 is reported now to resist up to 6 mM selenite and to reduce selenite to elemental red selenium as shown by extended X-ray absorption fine-structure analysis. Growth kinetics analysis suggests an adaptation of the cells to the selenite stress during the lag-phase period. Depending on the culture conditions, the medium can be completely depleted of selenite. Selenium accumulates essentially in the cytoplasm as judged from electron microscopy and energy-dispersive X-ray analysis. Elemental selenium, highly insoluble, represents a nontoxic storage form for the bacterium. The ability of R. metallidurans CH34 to reduce large amounts of selenite may be of interest for bioremediation processes targeting selenite-polluted sites. PMID:11157242

Concurrent Drought Stress and Vascular Pathogen Infection Induce Common and Distinct Transcriptomic Responses in Chickpea

PubMed Central

Sinha, Ranjita; Gupta, Aarti; Senthil-Kumar, Muthappa

2017-01-01

Chickpea (Cicer arietinum); the second largest legume grown worldwide is prone to drought and various pathogen infections. These drought and pathogen stresses often occur concurrently in the field conditions. However, the molecular events in response to that are largely unknown. The present study examines the transcriptome dynamics in chickpea plants exposed to a combination of water-deficit stress and Ralstonia solanacearum infection. R. solanacearum is a potential wilt disease causing pathogen in chickpea. Drought stressed chickpea plants were infected with this pathogen and the plants were allowed to experience progressive drought with 2 and 4 days of R. solanacearum infection called short duration stress (SD stresses) and long duration stress (LD stresses), respectively. Our study showed that R. solanacearum multiplication decreased under SD-combined stress compared to SD-pathogen but there was no significant change in LD-combined stress compared to LD-pathogen. The microarray analysis during these conditions showed that 821 and 1039 differentially expressed genes (DEGs) were unique to SD- and LD-combined stresses, respectively, when compared with individual stress conditions. Three and fifteen genes were common among all the SD-stress treatments and LD-stress treatments, respectively. Genes involved in secondary cell wall biosynthesis, alkaloid biosynthesis, defense related proteins, and osmo-protectants were up-regulated during combined stress. The expression of genes involved in lignin and cellulose biosynthesis were specifically up-regulated in SD-combined, LD-combined, and LD-pathogen stress. A close transcriptomic association of LD-pathogen stress with SD-combined stress was observed in this study which indicates that R. solanacearum infection also exerts drought stress along with pathogen stress thus mimics combined stress effect. Furthermore the expression profiling of candidate genes using real-time quantitative PCR validated the microarray data. The

Characterization and Functional Analyses of R-Specific Enoyl Coenzyme A Hydratases in Polyhydroxyalkanoate-Producing Ralstonia eutropha

PubMed Central

Kawashima, Yui; Cheng, Wen; Mifune, Jun; Orita, Izumi; Nakamura, Satoshi

2012-01-01

A genome survey of polyhydroxyalkanoate (PHA)-producing Ralstonia eutropha H16 detected the presence of 16 orthologs of R-specific enoyl coenzyme A (enoyl-CoA) hydratase, among which three proteins shared high homologies with the enzyme specific to enoyl-CoAs of medium chain length encoded by phaJ4 from Pseudomonas aeruginosa (phaJ4Pa). The recombinant forms of the three proteins, termed PhaJ4aRe to PhaJ4cRe, actually showed enoyl-CoA hydratase activity with R specificity, and the catalytic efficiencies were elevated as the substrate chain length increased from C4 to C8. PhaJ4aRe and PhaJ4bRe showed >10-fold-higher catalytic efficiency than PhaJ4cRe. The functions of the new PhaJ4 proteins were investigated using previously engineered R. eutropha strains as host strains; these strains are capable of synthesizing poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) [P(3HB-co-3HHx)] from soybean oil. Deletion of phaJ4aRe from the chromosome resulted in significant decrease of 3HHx composition in the accumulated copolyester, whereas no change was observed with deletion of phaJ4bRe or phaJ4cRe, indicating that only PhaJ4aRe was one of the major enzymes supplying the (R)-3HHx-CoA monomer through β-oxidation. Introduction of phaJ4aRe or phaJ4bRe into the R. eutropha strains using a broad-host-range vector enhanced the 3HHx composition of the copolyesters, but the introduction of phaJ4cRe did not. The two genes were then inserted into the pha operon on chromosome 1 of the engineered R. eutropha by homologous recombination. These modifications enabled the biosynthesis of P(3HB-co-3HHx) composed of a larger 3HHx fraction without a negative impact on cell growth and PHA production on soybean oil, especially when phaJ4aRe or phaJ4bRe was tandemly introduced with phaJAc from Aeromonas caviae. PMID:22081565

Genome editing of Ralstonia eutropha using an electroporation-based CRISPR-Cas9 technique.

PubMed

Xiong, Bin; Li, Zhongkang; Liu, Li; Zhao, Dongdong; Zhang, Xueli; Bi, Changhao

2018-01-01

Ralstonia eutropha is an important bacterium for the study of polyhydroxyalkanoates (PHAs) synthesis and CO 2 fixation, which makes it a potential strain for industrial PHA production and attractive host for CO 2 conversion. Although the bacterium is not recalcitrant to genetic manipulation, current methods for genome editing based on group II introns or single crossover integration of a suicide plasmid are inefficient and time-consuming, which limits the genetic engineering of this organism. Thus, developing an efficient and convenient method for R. eutropha genome editing is imperative. An efficient genome editing method for R. eutropha was developed using an electroporation-based CRISPR-Cas9 technique. In our study, the electroporation efficiency of R. eutropha was found to be limited by its restriction-modification (RM) systems. By searching the putative RM systems in R. eutropha H16 using REBASE database and comparing with that in E. coli MG1655, five putative restriction endonuclease genes which are related to the RM systems in R. eutropha were predicated and disrupted. It was found that deletion of H16_A0006 and H16_A0008 - 9 increased the electroporation efficiency 1658 and 4 times, respectively. Fructose was found to reduce the leaky expression of the arabinose-inducible pBAD promoter, which was used to optimize the expression of cas9 , enabling genome editing via homologous recombination based on CRISPR-Cas9 in R. eutropha . A total of five genes were edited with efficiencies ranging from 78.3 to 100%. The CRISPR-Cpf1 system and the non-homologous end joining mechanism were also investigated, but failed to yield edited strains. We present the first genome editing method for R. eutropha using an electroporation-based CRISPR-Cas9 approach, which significantly increased the efficiency and decreased time to manipulate this facultative chemolithoautotrophic microbe. The novel technique will facilitate more advanced researches and applications of R. eutropha

Piper betle-mediated synthesis, characterization, antibacterial and rat splenocyte cytotoxic effects of copper oxide nanoparticles.

PubMed

Praburaman, Loganathan; Jang, Jum-Suk; Muthusamy, Govarthanan; Arumugam, Sengottaiyan; Manoharan, Koildhasan; Cho, Kwang-Min; Min, Cho; Kamala-Kannan, Seralathan; Byung-Taek, Oh

2016-09-01

The study reports a simple, inexpensive, and eco-friendly synthesis of copper oxide nanoparticles (CuONPs) using Piper betle leaf extract. Formation of CuONPs was confirmed by UV-visible spectroscopy at 280 nm. Transmission electron microscopy (TEM) images showed that the CuONPs were spherical, with an average size of 50-100 nm. The scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS) peak was observed approximately at 1 and 8 keV. The X-ray diffraction (XRD) studies indicated that the particles were crystalline in nature. CuONPs effectively inhibited the growth of phytopathogens Ralstonia solanacearum and Xanthomonas axonopodis. The cytotoxic effect of the synthesized CuONPs was analyzed using rat splenocytes. The cell viability was decreased to 94% at 300 μg/mL.

[Construction of transgenic tobacco expressing popW and analysis of its biological phenotype].

PubMed

Wang, Cui; Liu, Hongxia; Cao, Jing; Wang, Chao; Guo, Jianhua

2014-04-01

In a previous study, we cloned popW from Ralstonia solanacearum strain ZJ3721, coding PopW, a new harpin protein. The procaryotically expressed PopW can induce resistance to Tobacco mosaic virus (TMV), enhance growth and improve quality of tobacco, when sprayed onto tobacco leaves. Here, we constructed an expression vector pB- popW by cloning popW into the bionary vector pBI121 and transformed it into Agrobacterium tumefaciens strain EHA105 via freeze-thaw method. Tobacco (Nicotiana tobacum cv. Xanthi nc.) transformation was conducted by infection of tobacco leaf discs with recombinant A. tumefaciens. After screening on MS medium containing kanamycin, PCR and RT-PCR analysis, 21 T3 lines were identified as positive transgenic. Genomic intergration and expression of the transferred gene were determined by PCR and RT-PCR. And GUS staining analysis indicated that the protein expressed in transgenic tobacco was bioactive and exhibited different expression levels among lines. Disease bioassays showed that the transgenic tobacco had enhanced resistance to TMV with biocontrol efficiency up to 54.25%. Transgenic tobacco also exhibited enhanced plant growth, the root length of 15 d old seedlings was 1.7 times longer than that of wild type tobacco. 60 d after transplanting to pots, the height, fresh weight and dry weight of transgenic tobacco were 1.4, 1.7, 1.8 times larger than that of wild type tobacco, respectively.

Oxalic Acid from Lentinula edodes Culture Filtrate: Antimicrobial Activity on Phytopathogenic Bacteria and Qualitative and Quantitative Analyses

PubMed Central

Kwak, A-Min; Lee, In-Kyoung; Lee, Sang-Yeop

2016-01-01

The culture filtrate of Lentinula edodes shows potent antimicrobial activity against the plant pathogenic bacteria Ralstonia solanacearum. Bioassay-guided fractionation was conducted using Diaion HP-20 column chromatography, and the insoluble active compound was not adsorbed on the resin. Further fractionation by high-performance liquid chromatography (HPLC) suggested that the active compounds were organic acids. Nine organic acids were detected in the culture filtrate of L. edodes; oxalic acid was the major component and exhibited antibacterial activity against nine different phytopathogenic bacteria. Quantitative analysis by HPLC revealed that the content of oxalic acid was higher in the water extract from spent mushroom substrate than in liquid culture. This suggests that the water extract of spent L. edodes substrate is an eco-friendly control agent for plant diseases. PMID:28154495

The auxiliary protein HypX provides oxygen tolerance to the soluble [NiFe]-hydrogenase of ralstonia eutropha H16 by way of a cyanide ligand to nickel.

PubMed

Bleijlevens, Boris; Buhrke, Thorsten; van der Linden, Eddy; Friedrich, Bärbel; Albracht, Simon P J

2004-11-05

The hypX gene of the facultative lithoautotrophic bacterium Ralstonia eutropha is part of a cassette of accessory genes (the hyp cluster) required for the proper assembly of the active site of the [NiFe]-hydrogenases in the bacterium. A deletion of the hypX gene led to a severe growth retardation under lithoautotrophic conditions with 5 or 15% oxygen, when the growth was dependent on the activity of the soluble NAD+ -reducing hydrogenase. The enzymatic and infrared spectral properties of the soluble hydrogenase purified from a HypX-negative strain were compared with those from an enzyme purified from a HypX-positive strain. In activity assays under anaerobic conditions both enzyme preparations behaved the same. Under aerobic conditions, however, the mutant enzyme became irreversibly inactivated during H2 oxidation with NAD+ or benzyl viologen as the electron acceptor. Infrared spectra and chemical determination of cyanide showed that one of the four cyanide groups in the wild-type enzyme was missing in the mutant enzyme. The data are consistent with the proposal that the HypX protein is specifically involved in the biosynthetic pathway that delivers the nickel-bound cyanide. The data support the proposal that this cyanide is crucial for the enzyme to function under aerobic conditions.

Colonization and Intrusive Invasion of Potato Psyllid by 'Candidatus Liberibacter solanacearum'.

PubMed

Cicero, Joseph M; Fisher, Tonja W; Qureshi, Jawwad A; Stansly, Philip A; Brown, Judith K

2017-01-01

Previous studies have shown that the fastidious bacterial plant pathogen 'Candidatus Liberibacter solanacearum' (CLso) is transmitted circulatively and propagatively by the potato psyllid (PoP) Bactericera cockerelli. In this study, the temporal and spatial interrelationships between CLso PoP were investigated by scanning electron microscopy of the digestive system of PoP immature and adult instars and salivary glands of adults post CLso ingestion. CLso biofilms were not detectable on the outer midgut surface of the first and second instars; however, for third to fifth instars and teneral and mature adults, biofilms were observed in increasing numbers in each successive developmental stage. In adult PoP midguts, CLso cells were observed between the basal lamina and basal epithelial cell membranes; in basal laminar perforations, on the outer basal laminar surface, and in the ventricular lumen, epithelial cytosol, and filter chamber periventricular space. CLso were also abundantly visible in the salivary gland pericellular spaces and in the epidermal cell cytosol of the head. Collectively, these results point to an intrusive, systemic invasion of PoP by CLso that employs an endo/exocytosis-like mechanism, in the context of a propagative, circulative mode of transmission.

Antibacterial activity of tannins isolated from Sapium baccatum extract and use for control of tomato bacterial wilt.

PubMed

Vu, Thuy Thu; Kim, Hun; Tran, Vu Khac; Vu, Hoang Dinh; Hoang, Tien Xuan; Han, Jae Woo; Choi, Yong Ho; Jang, Kyoung Soo; Choi, Gyung Ja; Kim, Jin-Cheol

2017-01-01

In the search for new antibacterial agents from natural sources, we revealed that a crude methanol extract of Sapium baccatum was highly active against Ralstonia solanacearum, a causal agent of a serious disease called bacterial wilt of tomato. The bioassay-guided fractionation of this extract resulted in the isolation of seven known active compounds, including gallic acid, methyl gallate, corilagin, tercatain, chebulagic acid, chebulinic acid, and quercetin 3-O-α-L-arabinopyranoside. Their chemical structures were determined by electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. An in vitro antibacterial bioassay using a broth microdilution method revealed that, except for quercetin 3-O-α-L-arabinopyranoside (MIC = 250 μg/mL), the isolated compounds exhibited strong antibacterial activity against R. solanacearum (MIC = 26-52 μg/mL). Among the seven compounds, methyl gallate exhibited the strongest broad-spectrum activity against most of the plant pathogenic bacteria tested (MIC = 26-250 μg/mL). In the in vivo experiments, the crude extract of S. baccatum at 2000 and 1000 μg/mL reduced the development of tomato bacterial wilt by 83 and 63%, respectively, under greenhouse conditions after 14 days of infection. The results suggested that the extracts of S. baccatum or isolated tannins could be used as natural bactericides for the control of bacterial wilt of tomato.

Cationic Oligo(thiophene ethynylene) with Broad-Spectrum and High Antibacterial Efficiency under White Light and Specific Biocidal Activity against S. aureus in Dark.

PubMed

Zhao, Qi; Li, Junting; Zhang, Xiaoqian; Li, Zhengping; Tang, Yanli

2016-01-13

We designed and synthesized a novel oligo(thiophene ethynylene) (OTE) to investigate the antibacterial activities against Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative (Ralstonia solanacearum and Escherichia coli) bacteria in vitro by photodynamic therapy (PDT). Notably, OTE presents broad-spectrum and greatly high antibacterial activities after white light irradiation at nanogram per milliliter concentrations. The half inhibitory concentrations (IC50) values obtained for S. aureus, S. epidermidis, E. coli, and R. solanacearum are 8, 13, 24, and 52 ng/mL after illumination for 30 min, respectively, which are lower than that of other PDT agents. Interestingly, OTE shows the specific and very strong dark killing capability against S. aureus at the concentration of 180 ng/mL for 30 min, which is the highest efficiency biocide against S. aureus without the need of irradiation to date. The antibacterial mechanism investigated demonstrated that reactive oxygen species or singlet-oxygen generated by OTE kills bacteria irreversibly upon white light irradiation, and OTE as a v-type oligomer exerts its toxicity directly on destroying bacterial cytoplasmic membrane in the dark. Importantly, the OTE shows no cell cytotoxicity and excellent biocompatibility. The results indicate that it is potential to provide versatile applications in the efficient control of pathogenic organisms and specific application for killing S. aureus.

Antibacterial activity of tannins isolated from Sapium baccatum extract and use for control of tomato bacterial wilt

PubMed Central

Vu, Thuy Thu; Kim, Hun; Tran, Vu Khac; Vu, Hoang Dinh; Hoang, Tien Xuan; Han, Jae Woo; Choi, Yong Ho; Jang, Kyoung Soo; Choi, Gyung Ja

2017-01-01

In the search for new antibacterial agents from natural sources, we revealed that a crude methanol extract of Sapium baccatum was highly active against Ralstonia solanacearum, a causal agent of a serious disease called bacterial wilt of tomato. The bioassay-guided fractionation of this extract resulted in the isolation of seven known active compounds, including gallic acid, methyl gallate, corilagin, tercatain, chebulagic acid, chebulinic acid, and quercetin 3-O-α-L-arabinopyranoside. Their chemical structures were determined by electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. An in vitro antibacterial bioassay using a broth microdilution method revealed that, except for quercetin 3-O-α-L-arabinopyranoside (MIC = 250 μg/mL), the isolated compounds exhibited strong antibacterial activity against R. solanacearum (MIC = 26–52 μg/mL). Among the seven compounds, methyl gallate exhibited the strongest broad-spectrum activity against most of the plant pathogenic bacteria tested (MIC = 26–250 μg/mL). In the in vivo experiments, the crude extract of S. baccatum at 2000 and 1000 μg/mL reduced the development of tomato bacterial wilt by 83 and 63%, respectively, under greenhouse conditions after 14 days of infection. The results suggested that the extracts of S. baccatum or isolated tannins could be used as natural bactericides for the control of bacterial wilt of tomato. PMID:28742863

The expansion of brown rot disease throughout Bolivia: possible role of climate change.

PubMed

Castillo, José Antonio; Plata, Giovanna

2016-05-01

Bacterial wilt is a devastating plant disease caused by the bacterial pathogen Ralstonia solanacearum species complex and affects different crops. Bacterial wilt infecting potato is also known as brown rot (BR) and is responsible for significant economic losses in potato production, especially in developing countries. In Bolivia, BR affects up to 75% of the potato crop in areas with high incidence and 100% of stored potatoes. The disease has disseminated since its introduction to the country in the mid-1980s mostly through contaminated seed tubers. To avoid this, local farmers multiply seed tubers in highlands because the strain infecting potatoes cannot survive near-freezing temperatures that are typical in the high mountains. Past disease surveys have shown an increase in seed tubers with latent infection in areas at altitudes lower than 3000 m a.s.l. Since global warming is increasing in the Andes Mountains, in this work, we explored the incidence of BR in areas at altitudes above 3000 m a.s.l. Results showed BR presence in the majority of these areas, suggesting a correlation between the increase in disease incidence and the increase in temperature and the number of irregular weather events resulting from climate change. However, it cannot be excluded that the increasing availability of latently infected seed tubers has boosted the spread of BR.

Comparative Large-Scale Analysis of Interactions between Several Crop Species and the Effector Repertoires from Multiple Pathovars of Pseudomonas and Ralstonia1[W][OA

PubMed Central

Wroblewski, Tadeusz; Caldwell, Katherine S.; Piskurewicz, Urszula; Cavanaugh, Keri A.; Xu, Huaqin; Kozik, Alexander; Ochoa, Oswaldo; McHale, Leah K.; Lahre, Kirsten; Jelenska, Joanna; Castillo, Jose A.; Blumenthal, Daniel; Vinatzer, Boris A.; Greenberg, Jean T.; Michelmore, Richard W.

2009-01-01

Bacterial plant pathogens manipulate their hosts by injection of numerous effector proteins into host cells via type III secretion systems. Recognition of these effectors by the host plant leads to the induction of a defense reaction that often culminates in a hypersensitive response manifested as cell death. Genes encoding effector proteins can be exchanged between different strains of bacteria via horizontal transfer, and often individual strains are capable of infecting multiple hosts. Host plant species express diverse repertoires of resistance proteins that mediate direct or indirect recognition of bacterial effectors. As a result, plants and their bacterial pathogens should be considered as two extensive coevolving groups rather than as individual host species coevolving with single pathovars. To dissect the complexity of this coevolution, we cloned 171 effector-encoding genes from several pathovars of Pseudomonas and Ralstonia. We used Agrobacterium tumefaciens-mediated transient assays to test the ability of each effector to induce a necrotic phenotype on 59 plant genotypes belonging to four plant families, including numerous diverse accessions of lettuce (Lactuca sativa) and tomato (Solanum lycopersicum). Known defense-inducing effectors (avirulence factors) and their homologs commonly induced extensive necrosis in many different plant species. Nonhost species reacted to multiple effector proteins from an individual pathovar more frequently and more intensely than host species. Both homologous and sequence-unrelated effectors could elicit necrosis in a similar spectrum of plants, suggesting common effector targets or targeting of the same pathways in the plant cell. PMID:19571308

First report of bacterial wilt caused by Ralstonia solanacearum on Mesona chinensis in China

USDA-ARS?s Scientific Manuscript database

Jellywort (Mesona chinensis Benth) is a herbaceous plant in the Lamiaceae Family. The plant is referred to as ‘Xiancao’ (Weed from Angels) in Chinese and is primarily used to make grass jelly, a popular refreshing drink. Currently, Xiancao cultivation is a fast growing industry with a high profit ma...

Nanofilms of hyaluronan/chitosan assembled layer-by-layer: An antibacterial surface for Xylella fastidiosa.

PubMed

Hernández-Montelongo, Jacobo; Nascimento, Vicente F; Murillo, Duber; Taketa, Thiago B; Sahoo, Prasana; de Souza, Alessandra A; Beppu, Marisa M; Cotta, Monica A

2016-01-20

In this work, nanofilms of hyaluronan/chitosan (HA/CHI) assembled layer by layer were synthesized; their application as a potential antimicrobial material was demonstrated for the phytopathogen Xylella fastidiosa, a gram-negative bacterium, here used as a model. For the synthesis, the influence of pH and ionic strength of these natural polymer stem-solutions on final characteristics of the HA/CHI nanofilms was studied in detail. The antibacterial effect was evaluated using widefield fluorescence microscopy. These results were correlated with the chemical properties of the nanofilms, studied by FTIR and Raman spectroscopy, as well as with their morphology and surface properties characterized using SEM and AFM. The present findings can be extended to design and optimize HA/CHI nanofilms with enhanced antimicrobial behavior for other type of phytopathogenic gram-negative bacteria species, such as Xanthomonas citri, Xanthomas campestri and Ralstonia solanacearum. Copyright © 2015 Elsevier Ltd. All rights reserved.

Genome-wide identification and expression profile analysis of the NAC transcription factor family during abiotic and biotic stress in woodland strawberry

PubMed Central

Qi, Yanxiang; Liu, Xiaomei; Pu, Jinji

2018-01-01

The NAC transcription factors involved plant development and response to various stress stimuli. However, little information is available concerning the NAC family in the woodland strawberry. Herein, 37 NAC genes were identified from the woodland strawberry genome and were classified into 13 groups based on phylogenetic analysis. And further analyses of gene structure and conserved motifs showed closer relationship of them in every subgroup. Quantitative real-time PCR evaluation different tissues revealed distinct spatial expression profiles of the FvNAC genes. The comprehensive expression of FvNAC genes revealed under abiotic stress (cold, heat, drought, salt), signal molecule treatments (H2O2, ABA, melatonin, rapamycin), biotic stress (Colletotrichum gloeosporioides and Ralstonia solanacearum). Expression profiles derived from quantitative real-time PCR suggested that 5 FvNAC genes responded dramatically to the various abiotic and biotic stresses, indicating their contribution to abiotic and biotic stresses resistance in woodland strawberry. Interestingly, FvNAC genes showed greater extent responded to the cold treatment than other abiotic stress, and H2O2 exhibited a greater response than ABA, melatonin, and rapamycin. For biotic stresses, 3 FvNAC genes were up-regulated during infection with C. gloeosporioides, while 6 FvNAC genes were down-regulated during infection with R. solanacearum. In conclusion, this study identified candidate FvNAC genes to be used for the genetic improvement of abiotic and biotic stress tolerance in woodland strawberry. PMID:29897926

Effects of an inducible aiiA gene on disease resistance in Eucalyptus urophylla × Eucalyptus grandis.

PubMed

Ouyang, L J; Li, L M

2016-08-01

N-acyl-homoserine lactones (AHLs) are metabolites of mostly gram-negative bacteria and are critical signaling molecules in bacterial quorum-sensing systems. At threshold concentrations, AHLs can activate the expression of pathogenic genes and induce diseases. Therefore, reducing AHL concentrations is a key point of disease control in plants. AHL-lactonase, which is expressed by aiiA, is widespread in Bacillus sp and can hydrolyze AHLs. In the present study, we cloned aiiA from Bacillus subtilis by PCR. A plant expression vector of aiiA was constructed and name Pcam-PPP3-aiiA, in which expression of aiiA was controlled by the pathogen-inducible plant promoter PPP3. The recombinant plasmid was transferred into Eucalyptus × urophylla × E. grandis by an Agrobacterium-mediated transformation. PCR and Southern blotting showed that aiiA was successfully integrated into the E. urophylla × E. grandis genome and its expression was induced by Ralstonia solanacearum 12 h after inoculation, as shown by reverse transcription-PCR. The transcription efficacy of aiiA increased 43.88-, 30.65-, and 18.95-fold after inoculation with R. solanacearum, Erwinia carotovora ssp. zeae (Sabet) and Cylindrocladium quinqueseptatum, respectively as shown by RT-real-time PCR. Transgenic E.urophylla × E.grandis expressing the AIIA protein exhibited significantly enhanced disease resistance compared to non-transgenic plants by delaying the onset of wilting and reducing the disease index.

Physiological changes induced in four bacterial strains following oxidative stress.

PubMed

Baatout, S; De Boever, P; Mergeay, M

2006-01-01

In order to study the behaviour and resistance of bacteria under extreme conditions, physiological changes associated with oxidative stress were monitored using flow cytometry. The study was conducted to assess the maintenance of membrane integrity and potential as well as the esterase activity, the intracellular pH and the production of superoxide anions in four bacterial strains (Ralstonia metallidurans, Escherichia coli, Shewanella oneidensis and Deinococcus radiodurans). The strains were chosen for their potential usefulness in bioremediation. Suspensions of R. metallidurans, E. coli, S. oneidensis and D. radiodurans were submitted to 1 h oxidative stress (H2O2 at various concentrations from 0 to 880 mM). Cell membrane permeability (propidium iodide) and potential (rhodamine-123, 3,3'-dihexyloxacarbocyanine iodide), intracellular esterase activity (fluorescein diacetate), intracellular reactive oxygen species concentration (hydroethidine) and intracellular pH (carboxyflurorescein diacetate succinimidyl ester (5(6)) were monitored to evaluate the physiological state and the overall fitness of individual bacterial cells under oxidative stress. The four bacterial strains exhibited varying sensitivities towards H2O2. However, for all bacterial strains, some physiological damage could already be observed from 13.25 mM H2O2 onwards, in particular with regard to their membrane permeability. Depending on the bacterial strains, moderate to high physiological damage could be observed between 13.25 mM and 220 mM H2O2. Membrane potential, esterase activity, intracellular pH and production of superoxide anion production were considerably modified at high H2O2 concentrations in all four strains. In conclusion, we show that a range of significant physiological alterations occurs when bacteria are challenged with H2O2 and fluorescent staining methods coupled with flow cytometry are useful for monitoring the changes induced not only by oxidative stress but also by other

Ralstonia eutropha as a biocatalyst for desulfurization of dibenzothiophene.

PubMed

Dejaloud, Azita; Vahabzadeh, Farzaneh; Habibi, Alireza

2017-07-01

The potential of Ralstonia eutropha as a biocatalyst for desulfurization of dibenzothiophene (DBT) was studied in growing and resting cell conditions. The results of both conditions showed that sulfur was removed from DBT which accompanied by the formation of 2-hydroxybiphenyl (2-HBP). In growing cell experiments, glucose was used as an energy supplying substrate in initial concentrations of 55 mM (energy-limited) and 111 mM (energy-sufficient). The growing cell behaviors were quantitatively described using the logistic equation and maintenance concept. The results indicated that 2-HBP production was higher for the energy-sufficient cultures, while the values of the specific growth rate and the maintenance coefficient for these media were lower than those of the energy-limited cultures. Additionally, the kinetic studies showed that the half-saturation constant for the energy-limited cultures was 2 times higher than the energy-sufficient ones where the inhibition constant (0.08 mM) and the maximum specific DBT desulfurization rate (0.002 mmol g cell -1  h -1 ) were almost constant. By defining desulfurizing capacity (D DBT ) including both the biomass concentration and time to reach a particular percentage of DBT conversion, the best condition for desulfurizing cell was determined at 23% g cell L -1  h -1 which corresponded with the resting cells that were harvested at the mid-exponential growth phase.

Engineering of Ralstonia eutropha for production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from fructose and solid-state properties of the copolymer.

PubMed

Fukui, Toshiaki; Abe, Hideki; Doi, Yoshiharu

2002-01-01

Recombinant Ralstonia eutropha capable of producing poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer [P(3HB-co-3HHx)] from fructose was engineered by introduction of genes for crotonyl-CoA reductase (CCR) from Streptomyces cinnamonensis (ccrSc) and for PHA synthase and (R)-specific enoyl-CoA hydratase from Aeromonas caviae (phaC-JAc). In this recombinant strain, C6-acyl-CoA intermediates were provided via beta-ketothiolase-mediated elongation of butyryl-CoA, which was generated from crotonyl-CoA by the function of CCR. The recombinant strain could accumulate the copolyester up to 48 wt % of dry cell weight with 1.5 mol % of 3HHx fraction from fructose, when the expression of ccrSc under the control of the PBAD promoter was induced with 0.01% L-arabinose. The absence of L-arabinose or the deletion of ccrSc from the plasmid resulted in accumulation of poly(3-hydroxybutyrate) homopolymer, indicating the critical role of CCR in the formation of the 3-hydroxyhexanoate unit. Higher CCR activity obtained by the addition of a larger amount of L-arabinose did not affect the composition but reduced the intracellular content of the copolyester. The P(3HB-co-1.5 mol % 3HHx) copolyester produced from fructose by the recombinant R. eutropha showed relatively lower melting temperatures (150 degrees C and 161 degrees C) and lower crystallinity (48 +/- 5%) compared to those (175 degrees C and 60 +/- 5%) of P(3HB) homopolymer. It has been found that the incorporation of a small amount (1.5 mol %) of 3HHx units into P(3HB) sequences leads to a remarkable change in the solid-state properties of P(3HB) crystals. The present study demonstrates the potential of the engineered pathway for the production of copolyesters having favorable characteristics from inexpensive carbon resources.

Effects of environmental parameters on the dual-species biofilms formed by Escherichia coli O157:H7 and Ralstonia insidiosa, a strong biofilm producer isolated from a fresh-cut processing plant

USDA-ARS?s Scientific Manuscript database

Biofilm forming bacteria resident to food processing facilities are a food safety concern due to the potential of biofilms to harbor foodborne bacterial pathogens. When cultured together, Ralstonia insidiosa, a strong biofilm former frequently isolated from produce processing environments, has been ...

Population diversity of bacterial endophytes from jute (Corchorus olitorius) and evaluation of their potential role as bioinoculants.

PubMed

Haidar, Badrul; Ferdous, Mahbuba; Fatema, Babry; Ferdous, Ahlan Sabah; Islam, Mohammad Riazul; Khan, Haseena

2018-03-01

Endophytes are bacterial or fungal organisms associated with plants in an obligate or facultative manner. In order to maintain a stable symbiosis, many of the endophytes produce compounds that promote plant growth and help them adapt better to the environment. This study was conducted to explore the potential of jute bacterial endophytes for their growth promotion ability in direct and indirect ways. A total of 27 different bacterial species were identified from different varieties of a jute plant (Corchorus olitorius) and different parts of the plant (leaf, root, seed, and seedling) based on 16S rRNA gene sequence. Two of the isolates showed ACC deaminase activity with Staphylococcus pasteuri strain MBL_B3 and Ralstonia solanacearum strain MBL_B6 producing 18.1 and 8.08 μM mg -1  h -1 α-ketobutyrate respectively while eighteen had the ACC deaminase gene (acdS). Fourteen were positive for siderophore activity while Kocuria sp. strain MBL_B19 (133.36 μg/ml) and Bacillus sp. strain MBL_B17 (124.72 μg/ml) showed high IAA production ability. Seven bacterial strains were able to fix nitrogen with only one testing positive for nifH gene. Five isolates exhibited phosphorus utilization ability with Bacillus sp. strain MBL_B17 producing 218.47 μg P/ml. Three bacteria were able to inhibit the growth of a phytopathogen, Macrophomina phaseolina and among them Bacillus subtilis strain MBL_B4 was found to be the most effective, having 82% and 53% of relative inhibition ratio (RIR) and percent growth inhibition (PGI) values respectively. Nine bacteria were tested for their in vivo growth promotion ability and most of these isolates increased seed germination potential and vigour index significantly. Bacillus subtilis strain MBL_B13 showed 26.8% more vigour index than the control in which no bacterial inoculum was used. All inoculants were found to increase the dry weight of jute seedlings in comparison to the control plants and the most increase in fresh weight

Production of lipopeptides by Bacillus amyloliquefaciens XZ-173 in solid state fermentation using soybean flour and rice straw as the substrate.

PubMed

Zhu, Zhen; Zhang, Guoyi; Luo, Yi; Ran, Wei; Shen, Qirong

2012-05-01

This work was aimed to produce lipopeptides by Bacillus amyloliquefaciens XZ-173 in solid state fermentation using agro-industrial byproducts. A central composite design was used to get the highest lipopeptides production. Results revealed that the optimal conditions for maximum lipopeptides production were 1.79% starch and 1.91% yeast extract by employing 5.58 g soybean flour and 3.67 g rice straw as the solid substrate with initial pH 7.5, moisture content 55% and a 10% inoculum level at 30°C for 2 days. Under these conditions, the experimental yield of lipopeptides reached 50.01 mg/gds, which was very close to the predicted value (49.91 mg/gds). At high concentration, the lipopeptides extracted from fermented substrates showed strong antibiotic activity against Rhizoctonia solani and Ralstonia solanacearum and certain emulsification but good emulsion stability. This is the first report on lipopeptides production that uses rice straw as a major substrate. Copyright © 2012 Elsevier Ltd. All rights reserved.

Root Border Cells and Their Role in Plant Defense.

PubMed

Hawes, Martha; Allen, Caitilyn; Turgeon, B Gillian; Curlango-Rivera, Gilberto; Minh Tran, Tuan; Huskey, David A; Xiong, Zhongguo

2016-08-04

Root border cells separate from plant root tips and disperse into the soil environment. In most species, each root tip can produce thousands of metabolically active cells daily, with specialized patterns of gene expression. Their function has been an enduring mystery. Recent studies suggest that border cells operate in a manner similar to mammalian neutrophils: Both cell types export a complex of extracellular DNA (exDNA) and antimicrobial proteins that neutralize threats by trapping pathogens and thereby preventing invasion of host tissues. Extracellular DNases (exDNases) of pathogens promote virulence and systemic spread of the microbes. In plants, adding DNase I to root tips eliminates border cell extracellular traps and abolishes root tip resistance to infection. Mutation of genes encoding exDNase activity in plant-pathogenic bacteria (Ralstonia solanacearum) and fungi (Cochliobolus heterostrophus) results in reduced virulence. The study of exDNase activities in plant pathogens may yield new targets for disease control.

Gene expression analysis of six GC-rich Gram-negative phytopathogens.

PubMed

Fu, Qing-Shan; Li, Feng; Chen, Ling-Ling

2005-07-01

Predicted highly expressed (PHX) genes are comparatively analyzed for six GC-rich Gram-negative phytopathogens, i.e., Ralstonia solanacearum, Agrobacterium tumefaciens, Xanthomonas campestris pv. campestris (Xcc), Xanthomonas axonopodis pv. citri (Xac), Pseudomonas syringae pv. tomato, and Xylella fastidiosa. Enzymes involved in energy metabolism, such as ATP synthase, and genes involved in TCA cycle, are PHX in most bacteria except X. fastidiosa, which prefers an anaerobic environment. Most pathogenicity-related factors, including flagellar proteins and some outer membrane proteins, are PHX, except that flagellar proteins are missing in X. fastidiosa which is spread by insects and does not need to move during invasion. Although type III secretion system apparatus are homologous to flagellar proteins, none of them is PHX, which support the viewpoint that the two types of genes have evolved independently. Furthermore, it is revealed that some biosynthesis-related enzymes are highly expressed in certain bacteria. The PHX genes may provide potential drug targets for the design of new bactericide.

Large scale extraction of poly(3-hydroxybutyrate) from Ralstonia eutropha H16 using sodium hypochlorite

PubMed Central

2012-01-01

Isolation of polyhydroxyalkanoates (PHAs) from bacterial cell matter is a critical step in order to achieve a profitable production of the polymer. Therefore, an extraction method must lead to a high recovery of a pure product at low costs. This study presents a simplified method for large scale poly(3-hydroxybutyrate), poly(3HB), extraction using sodium hypochlorite. Poly(3HB) was extracted from cells of Ralstonia eutropha H16 at almost 96% purity. At different extraction volumes, a maximum recovery rate of 91.32% was obtained. At the largest extraction volume of 50 L, poly(3HB) with an average purity of 93.32% ± 4.62% was extracted with a maximum recovery of 87.03% of the initial poly(3HB) content. This process is easy to handle and requires less efforts than previously described processes. PMID:23164136

Transient Hypermutagenesis Accelerates the Evolution of Legume Endosymbionts following Horizontal Gene Transfer

PubMed Central

Remigi, Philippe; Capela, Delphine; Clerissi, Camille; Tasse, Léna; Torchet, Rachel; Bouchez, Olivier; Batut, Jacques; Cruveiller, Stéphane; Rocha, Eduardo P. C.; Masson-Boivin, Catherine

2014-01-01

Horizontal gene transfer (HGT) is an important mode of adaptation and diversification of prokaryotes and eukaryotes and a major event underlying the emergence of bacterial pathogens and mutualists. Yet it remains unclear how complex phenotypic traits such as the ability to fix nitrogen with legumes have successfully spread over large phylogenetic distances. Here we show, using experimental evolution coupled with whole genome sequencing, that co-transfer of imuABC error-prone DNA polymerase genes with key symbiotic genes accelerates the evolution of a soil bacterium into a legume symbiont. Following introduction of the symbiotic plasmid of Cupriavidus taiwanensis, the Mimosa symbiont, into pathogenic Ralstonia solanacearum we challenged transconjugants to become Mimosa symbionts through serial plant-bacteria co-cultures. We demonstrate that a mutagenesis imuABC cassette encoded on the C. taiwanensis symbiotic plasmid triggered a transient hypermutability stage in R. solanacearum transconjugants that occurred before the cells entered the plant. The generated burst in genetic diversity accelerated symbiotic adaptation of the recipient genome under plant selection pressure, presumably by improving the exploration of the fitness landscape. Finally, we show that plasmid imuABC cassettes are over-represented in rhizobial lineages harboring symbiotic plasmids. Our findings shed light on a mechanism that may have facilitated the dissemination of symbiotic competency among α- and β-proteobacteria in natura and provide evidence for the positive role of environment-induced mutagenesis in the acquisition of a complex lifestyle trait. We speculate that co-transfer of complex phenotypic traits with mutagenesis determinants might frequently enhance the ecological success of HGT. PMID:25181317

Antibacterial Activity of Pharbitin, Isolated from the Seeds of Pharbitis nil, against Various Plant Pathogenic Bacteria.

PubMed

Nguyen, Hoa Thi; Yu, Nan Hee; Park, Ae Ran; Park, Hae Woong; Kim, In Seon; Kim, Jin-Cheol

2017-10-28

This study aimed to isolate and characterize antibacterial metabolites from Pharbitis nil seeds and investigate their antibacterial activity against various plant pathogenic bacteria. The methanol extract of P. nil seeds showed the strongest activity against Xanthomonas arboricola pv. pruni (Xap) with a minimum inhibition concentration (MIC) value of 250 μg/ml. Among the three solvent layers obtained from the methanol extract of P. nil seeds, only the butanol layer displayed the activity with an MIC value of 125 μg/ml against Xap. An antibacterial fraction was obtained from P. nil seeds by repeated column chromatography and identified as pharbitin, a crude resin glycoside, by instrumental analysis. The antibacterial activity of pharbitin was tested in vitro against 14 phytopathogenic bacteria, and it was found to inhibit Ralstonia solanacearum and four Xanthomonas species. The minimum inhibitory concentration values against the five bacteria were 125-500 μg/ml for the n-butanol layer and 31.25-125 μg/ml for pharbitin. In a detached peach leaf assay, it effectively suppressed the development of bacterial leaf spot, with a control value of 87.5% at 500 μg/ml. In addition, pharbitin strongly reduced the development of bacterial wilt on tomato seedlings by 97.4% at 250 μg/ml, 7 days after inoculation. These findings suggest that the crude extract of P. nil seeds can be used as an alternative biopesticide for the control of plant diseases caused by R. solanacearum and Xanthomonas spp. This is the first report on the antibacterial activity of pharbitin against phytopathogenic bacteria.

Isolation of Phyllosilicate–Iron Redox Cycling Microorganisms from an Illite–Smectite Rich Hydromorphic Soil

PubMed Central

Shelobolina, Evgenya; Konishi, Hiromi; Xu, Huifang; Benzine, Jason; Xiong, Mai Yia; Wu, Tao; Blöthe, Marco; Roden, Eric

2012-01-01

The biogeochemistry of phyllosilicate–Fe redox cycling was studied in a Phalaris arundinacea (reed canary grass) dominated redoximorphic soil from Shovelers Sink, a small glacial depression near Madison, WI. The clay size fraction of Shovelers Sink soil accounts for 16% of the dry weight of the soil, yet contributes 74% of total Fe. The dominant mineral in the clay size fraction is mixed layer illite–smectite, and in contrast to many other soils and sediments, Fe(III) oxides are present in low abundance. We examined the Fe biogeochemistry of Shovelers Sink soils, estimated the abundance of Fe redox cycling microorganisms, and isolated in pure culture representative phyllosilicate–Fe oxidizing and reducing organisms. The abundance of phyllosilicate–Fe reducing and oxidizing organisms was low compared to culturable aerobic heterotrophs. Both direct isolation and dilution-to-extinction approaches using structural Fe(II) in Bancroft biotite as a Fe(II) source, and O2 as the electron acceptor, resulted in recovery of common rhizosphere organisms including Bradyrhizobium spp. and strains of Cupriavidus necator and Ralstonia solanacearum. In addition to oxidizing biotite and soluble Fe(II) with O2, each of these isolates was able to oxidize Fe(II) in reduced NAu-2 smectite with NO3- as the electron acceptor. Oxidized NAu-2 smectite or amorphous Fe(III) oxide served as electron acceptors for enrichment and isolation of Fe(III)-reducing microorganisms, resulting in recovery of a strain related to Geobacter toluenoxydans. The ability of the recovered microorganisms to cycle phyllosilicate–Fe was verified in an experiment with native Shovelers Sink clay. This study confirms that Fe in the native Shovelers Sink clay is readily available for microbial redox transformation and can be cycled by the Fe(III)-reducing and Fe(II)-oxidizing microorganisms recovered from the soil. PMID:22493596

Isolation of phyllosilicate-iron redox cycling microorganisms from an illite-smectite rich hydromorphic soil.

PubMed

Shelobolina, Evgenya; Konishi, Hiromi; Xu, Huifang; Benzine, Jason; Xiong, Mai Yia; Wu, Tao; Blöthe, Marco; Roden, Eric

2012-01-01

The biogeochemistry of phyllosilicate-Fe redox cycling was studied in a Phalaris arundinacea (reed canary grass) dominated redoximorphic soil from Shovelers Sink, a small glacial depression near Madison, WI. The clay size fraction of Shovelers Sink soil accounts for 16% of the dry weight of the soil, yet contributes 74% of total Fe. The dominant mineral in the clay size fraction is mixed layer illite-smectite, and in contrast to many other soils and sediments, Fe(III) oxides are present in low abundance. We examined the Fe biogeochemistry of Shovelers Sink soils, estimated the abundance of Fe redox cycling microorganisms, and isolated in pure culture representative phyllosilicate-Fe oxidizing and reducing organisms. The abundance of phyllosilicate-Fe reducing and oxidizing organisms was low compared to culturable aerobic heterotrophs. Both direct isolation and dilution-to-extinction approaches using structural Fe(II) in Bancroft biotite as a Fe(II) source, and O(2) as the electron acceptor, resulted in recovery of common rhizosphere organisms including Bradyrhizobium spp. and strains of Cupriavidus necator and Ralstonia solanacearum. In addition to oxidizing biotite and soluble Fe(II) with O(2), each of these isolates was able to oxidize Fe(II) in reduced NAu-2 smectite with [Formula: see text] as the electron acceptor. Oxidized NAu-2 smectite or amorphous Fe(III) oxide served as electron acceptors for enrichment and isolation of Fe(III)-reducing microorganisms, resulting in recovery of a strain related to Geobacter toluenoxydans. The ability of the recovered microorganisms to cycle phyllosilicate-Fe was verified in an experiment with native Shovelers Sink clay. This study confirms that Fe in the native Shovelers Sink clay is readily available for microbial redox transformation and can be cycled by the Fe(III)-reducing and Fe(II)-oxidizing microorganisms recovered from the soil.

Crystal structure and biochemical characterization of beta-keto thiolase B from polyhydroxyalkanoate-producing bacterium Ralstonia eutropha H16

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Eun-Jung; Son, Hyeoncheol Francis; Kim, Sangwoo

Highlights: • We determined a crystal structure of β-keto thiolase from Ralstonia eutropha H16 (ReBktB). • Distinct substrate binding mode ReBktB was elucidated. • Enzymatic kinetic parameters of ReBktB were revealed. - Abstract: ReBktB is a β-keto thiolase from Ralstonia eutropha H16 that catalyzes condensation reactions between acetyl-CoA with acyl-CoA molecules that contains different numbers of carbon atoms, such as acetyl-CoA, propionyl-CoA, and butyryl-CoA, to produce valuable bioproducts, such as polyhydroxybutyrate, polyhydroxybutyrate-hydroxyvalerate, and hexanoate. We solved a crystal structure of ReBktB at 2.3 Å, and the overall structure has a similar fold to that of type II biosynthetic thiolases, suchmore » as PhbA from Zoogloea ramigera (ZrPhbA). The superposition of this structure with that of ZrPhbA complexed with CoA revealed the residues that comprise the catalytic and substrate binding sites of ReBktB. The catalytic site of ReBktB contains three conserved residues, Cys90, His350, and Cys380, which may function as a covalent nucleophile, a general base, and second nucleophile, respectively. For substrate binding, ReBktB stabilized the ADP moiety of CoA in a distinct way compared to ZrPhbA with His219, Arg221, and Asp228 residues, whereas the stabilization of β-mercaptoethyamine and pantothenic acid moieties of CoA was quite similar between these two enzymes. Kinetic study of ReBktB revealed that K{sub m}, V{sub max}, and K{sub cat} values of 11.58 μM, 1.5 μmol/min, and 102.18 s{sup −1}, respectively, and the catalytic and substrate binding sites of ReBktB were further confirmed by site-directed mutagenesis experiments.« less

3-Hydroxylaminophenol Mutase from Ralstonia eutropha JMP134 Catalyzes a Bamberger Rearrangement

PubMed Central

Schenzle, Andreas; Lenke, Hiltrud; Spain, Jim C.; Knackmuss, Hans-Joachim

1999-01-01

3-Hydroxylaminophenol mutase from Ralstonia eutropha JMP134 is involved in the degradative pathway of 3-nitrophenol, in which it catalyzes the conversion of 3-hydroxylaminophenol to aminohydroquinone. To show that the reaction was really catalyzed by a single enzyme without the release of intermediates, the corresponding protein was purified to apparent homogeneity from an extract of cells grown on 3-nitrophenol as the nitrogen source and succinate as the carbon and energy source. 3-Hydroxylaminophenol mutase appears to be a relatively hydrophobic but soluble and colorless protein consisting of a single 62-kDa polypeptide. The pI was determined to be at pH 4.5. In a database search, the NH2-terminal amino acid sequence of the undigested protein and of two internal sequences of 3-hydroxylaminophenol mutase were found to be most similar to those of glutamine synthetases from different species. Hydroxylaminobenzene, 4-hydroxylaminotoluene, and 2-chloro-5-hydroxylaminophenol, but not 4-hydroxylaminobenzoate, can also serve as substrates for the enzyme. The enzyme requires no oxygen or added cofactors for its reaction, which suggests an enzymatic mechanism analogous to the acid-catalyzed Bamberger rearrangement. PMID:10049374

Heterologous expression and localization of gentisate transporter Ncg12922 from Corynebacterium glutamicum ATCC 13032

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu Ying; Graduate School of Chinese Academy of Sciences, Beijing 100049; Yan Dazhong

2006-07-28

Ralstonia sp. strain U2 metabolizes naphthalene via gentisate (2,5-dihydroxybenzoate) to central metabolites, but it was found unable to utilize gentisate as growth substrate. A putative gentisate transporter encoded by ncg12922 from Corynebacterium glutamicum ATCC 13032 was functionally expressed in Ralstonia sp. strain U2, converting strain U2 to a gentisate utilizer. After ncg12922 was inserted into plasmid pGFPe with green fluorescence protein gene gfp, the expressed fusion protein Ncg12922-GFP could be visualized in the periphery of Escherichia coli cells under confocal microscope, consistent with a cytoplasmic membrane location. In contrast, GFP was ubiquitous in the cytoplasm of E. coli cells carryingmore » pGFPe only. Gentisate 1,2-dioxygenase activity was present in the cell extract from strain U2 induced with gentisate but at a much lower level (one-fifth) than that obtained with salicylate. However, it exhibited a similar level in strain U2 containing Ncg12922 induced either by salicylate or gentisate.« less

Production and purification of a soluble hydrogenase from Ralstonia eutropha H16 for potential hydrogen fuel cell applications.

PubMed

Jugder, Bat-Erdene; Lebhar, Helene; Aguey-Zinsou, Kondo-Francois; Marquis, Christopher P

2016-01-01

The soluble hydrogenase (SH) from Ralstonia eutropha H16 is a promising candidate enzyme for H2-based biofuel application as it favours H2 oxidation and is relatively oxygen-tolerant. In this report, bioprocess development studies undertaken to produce and purify an active SH are described, based on the methods previously reported [1], [2], [3], [4]. Our modifications are: •Upstream method optimizations were undertaken on heterotrophic growth media and cell lysis involving ultrasonication.•Two anion exchangers (Q Sepharose and RESOURCE Q) and size exclusion chromatographic (Superdex 200) matrices were successfully employed for purification of a hexameric SH from R. eutropha.•The H2 oxidizing activity of the SH was demonstrated spectrophotometrically in solution and also immobilized on an EPG electrode using cyclic voltammetry.

Aerobic biodegradation of N-nitrosodimethylamine (NDMA) by axenic bacterial strains.

PubMed

Sharp, Jonathan O; Wood, Thomas K; Alvarez-Cohen, Lisa

2005-03-05

The water contaminant N-nitrosodimethylamine (NDMA) is a probable human carcinogen whose appearance in the environment is related to the release of rocket fuel and to chlorine-based disinfection of water and wastewater. Although this compound has been shown to be biodegradable, there is minimal information about the organisms capable of this degradation, and little is understood of the mechanisms or biochemistry involved. This study shows that bacteria expressing monooxygenase enzymes functionally similar to those demonstrated to degrade NDMA in eukaryotes have the capability to degrade NDMA. Specifically, induction of the soluble methane monooxygenase (sMMO) expressed by Methylosinus trichosporium OB3b, the propane monooxygenase (PMO) enzyme of Mycobacterium vaccae JOB-5, and the toluene 4-monooxygenases found in Ralstonia pickettii PKO1 and Pseudomonas mendocina KR1 resulted in NDMA degradation by these strains. In each of these cases, brief exposure to acetylene gas, a suicide substrate for certain monooxygenases, inhibited the degradation of NDMA. Further, Escherichia coli TG1/pBS(Kan) containing recombinant plasmids derived from the toluene monooxygenases found in strains PKO1 and KR1 mimicked the behavior of the parent strains. In contrast, M. trichosporium OB3b expressing the particulate form of MMO, Burkholderia cepacia G4 expressing the toluene 2-monooxygenase, and Pseudomonas putida mt-2 expressing the toluene sidechain monooxygenase were not capable of NDMA degradation. In addition, bacteria expressing aromatic dioxygenases were not capable of NDMA degradation. Finally, Rhodococcus sp. RR1 exhibited the ability to degrade NDMA by an unidentified, constitutively expressed enzyme that, unlike the confirmed monooxygenases, was not inhibited by acetylene exposure. 2005 Wiley Periodicals, Inc.

Characterization and modification of enzymes in the 2-ketoisovalerate biosynthesis pathway of Ralstonia eutropha H16.

PubMed

Lu, Jingnan; Brigham, Christopher J; Plassmeier, Jens K; Sinskey, Anthony J

2015-01-01

2-Ketoisovalerate is an important cellular intermediate for the synthesis of branched-chain amino acids as well as other important molecules, such as pantothenate, coenzyme A, and glucosinolate. This ketoacid can also serve as a precursor molecule for the production of biofuels, pharmaceutical agents, and flavor agents in engineered organisms, such as the betaproteobacterium Ralstonia eutropha. The biosynthesis of 2-ketoisovalerate from pyruvate is carried out by three enzymes: acetohydroxyacid synthase (AHAS, encoded by ilvBH), acetohydroxyacid isomeroreductase (AHAIR, encoded by ilvC), and dihydroxyacid dehydratase (DHAD, encoded by ilvD). In this study, enzymatic activities and kinetic parameters were determined for each of the three R. eutropha enzymes as heterologously purified proteins. AHAS, which serves as a gatekeeper for the biosynthesis of all three branched-chain amino acids, demonstrated the tightest regulation through feedback inhibition by L-valine (IC50=1.2 mM), L-isoleucine (IC50=2.3 mM), and L-leucine (IC50=5.4 mM). Intermediates in the valine biosynthesis pathway also exhibit feedback inhibitory control of the AHAS enzyme. In addition, AHAS has a very weak affinity for pyruvate (KM=10.5 μM) and is highly selective towards 2-ketobutyrate (R=140) as a second substrate. AHAIR and DHAD are also inhibited by the branched-chain amino acids, although to a lesser extent when compared to AHAS. Experimental evolution and rational site-directed mutagenesis revealed mutants of the regulatory subunit of AHAS (IlvH) (N11S, T34I, A36V, T104S, N11F, G14E, and N29H), which, when reconstituted with wild-type IlvB, lead to AHAS having reduced valine, leucine, and isoleucine sensitivity. The study of the kinetics and inhibition mechanisms of R. eutropha AHAS, AHAIR, and DHAD has shed light on interactions between these enzymes and the products they produce; it, therefore, can be used to engineer R. eutropha strains with optimal production of 2-ketoisovalerate for

Characterization and modification of enzymes in the 2-ketoisovalerate biosynthesis pathway of Ralstonia eutropha H16

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, JN; Brigham, CJ; Plassmeier, JK

2014-08-01

2-Ketoisovalerate is an important cellular intermediate for the synthesis of branched-chain amino acids as well as other important molecules, such as pantothenate, coenzyme A, and glucosinolate. This ketoacid can also serve as a precursor molecule for the production of biofuels, pharmaceutical agents, and flavor agents in engineered organisms, such as the betaproteobacterium Ralstonia eutropha. The biosynthesis of 2-ketoisovalerate from pyruvate is carried out by three enzymes: acetohydroxyacid synthase (AHAS, encoded by ilvBH), acetohydroxyacid isomeroreductase (AHAIR, encoded by ilvC), and dihydroxyacid dehydratase (DHAD, encoded by ilvD). In this study, enzymatic activities and kinetic parameters were determined for each of the threemore » R. eutropha enzymes as heterologously purified proteins. AHAS, which serves as a gatekeeper for the biosynthesis of all three branched-chain amino acids, demonstrated the tightest regulation through feedback inhibition by l-valine (IC50 = 1.2 mM), l-isoleucine (IC50 = 2.3 mM), and l-leucine (IC50 = 5.4 mM). Intermediates in the valine biosynthesis pathway also exhibit feedback inhibitory control of the AHAS enzyme. In addition, AHAS has a very weak affinity for pyruvate (K-M = 10.5 mu M) and is highly selective towards 2-ketobutyrate (R = 140) as a second substrate. AHAIR and DHAD are also inhibited by the branched-chain amino acids, although to a lesser extent when compared to AHAS. Experimental evolution and rational site-directed mutagenesis revealed mutants of the regulatory subunit of AHAS (IlvH) (N11S, T34I, A36V, T104S, N11F, G14E, and N29H), which, when reconstituted with wild-type IlvB, lead to AHAS having reduced valine, leucine, and isoleucine sensitivity. The study of the kinetics and inhibition mechanisms of R. eutropha AHAS, AHAIR, and DHAD has shed light on interactions between these enzymes and the products they produce; it, therefore, can be used to engineer R. eutropha strains with optimal production of 2

Multiple β-Ketothiolases Mediate Poly(β-Hydroxyalkanoate) Copolymer Synthesis in Ralstonia eutropha

PubMed Central

Slater, Steven; Houmiel, Kathryn L.; Tran, Minhtien; Mitsky, Timothy A.; Taylor, Nancy B.; Padgette, Stephen R.; Gruys, Kenneth J.

1998-01-01

Polyhydroxyalkanoates (PHAs) are a class of carbon and energy storage polymers produced by numerous bacteria in response to environmental limitation. The type of polymer produced depends on the carbon sources available, the flexibility of the organism’s intermediary metabolism, and the substrate specificity of the PHA biosynthetic enzymes. Ralstonia eutropha produces both the homopolymer poly-β-hydroxybutyrate (PHB) and, when provided with the appropriate substrate, the copolymer poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV). A required step in production of the hydroxyvalerate moiety of PHBV is the condensation of acetyl coenzyme A (acetyl-CoA) and propionyl-CoA to form β-ketovaleryl-CoA. This activity has generally been attributed to the β-ketothiolase encoded by R. eutropha phbA. However, we have determined that PhbA does not significantly contribute to catalyzing this condensation reaction. Here we report the cloning and genetic analysis of bktB, which encodes a β-ketothiolase from R. eutropha that is capable of forming β-ketovaleryl-CoA. Genetic analyses determined that BktB is the primary condensation enzyme leading to production of β-hydroxyvalerate derived from propionyl-CoA. We also report an additional β-ketothiolase, designated BktC, that probably serves as a secondary route toward β-hydroxyvalerate production. PMID:9555876

Comparative genomics and functional analysis of the NiaP family uncover nicotinate transporters from bacteria, plants, and mammals.

PubMed

Jeanguenin, Linda; Lara-Núñez, Aurora; Rodionov, Dmitry A; Osterman, Andrei L; Komarova, Nataliya Y; Rentsch, Doris; Gregory, Jesse F; Hanson, Andrew D

2012-03-01

The transporter(s) that mediate uptake of nicotinate and its N-methyl derivative trigonelline are not known in plants, and certain mammalian nicotinate transporters also remain unidentified. Potential candidates for these missing transporters include proteins from the ubiquitous NiaP family. In bacteria, niaP genes often belong to NAD-related regulons, and genetic evidence supports a role for Bacillus subtilis and Acinetobacter baumannii NiaP proteins in uptake of nicotinate or nicotinamide. Other bacterial niaP genes are, however, not in NAD-related regulons but cluster on the chromosome with choline-related (e.g., Ralstonia solanacearum and Burkholderia xenovorans) or thiamin-related (e.g., Thermus thermophilus) genes, implying that they might encode transporters for these compounds. Radiometric uptake assays using Lactococcus lactis cells expressing NiaP proteins showed that B. subtilis, R. solanacearum, and B. xenovorans NiaP transport nicotinate via an energy-dependent mechanism. Likewise, NiaP proteins from maize (GRMZM2G381453, GRMZM2G066801, and GRMZM2G081774), Arabidopsis (At3g13050), and mouse (SVOP) transported nicotinate; the Arabidopsis protein also transported trigonelline. In contrast, T. thermophilus NiaP transported only thiamin. None of the proteins tested transported choline or the thiazole and pyrimidine products of thiamin breakdown. The maize and Arabidopsis NiaP proteins are the first nicotinate transporters reported in plants, the Arabidopsis protein is the first trigonelline transporter, and mouse SVOP appears to represent a novel type of mammalian nicotinate transporter. More generally, these results indicate that specificity for nicotinate is conserved widely, but not absolutely, among pro- and eukaryotic NiaP family proteins.

Déjà vu: Ralstonia mannitolilytica infection associated with a humidifying respiratory therapy device, Israel, June to July 2011.

PubMed

Block, C; Ergaz-Shaltiel, Z; Valinsky, L; Temper, V; Hidalgo-Grass, C; Minster, N; Weissman, C; Benenson, S; Jaffe, J; Moses, A E; Bar-Oz, B

2013-05-02

Following a bloodstream infection in June 2011 with Ralstonia mannitolilytica in a premature infant treated with a humidifying respiratory therapy device, an investigation was initiated at the Hadassah Medical Centres in Jerusalem. The device delivers a warmed and humidified mixture of air and oxygen to patients by nasal cannula. The investigation revealed colonisation with R. mannitolilytica of two of 15 patients and contamination of components of five of six devices deployed in the premature units of the Hadassah hospitals. Ten isolates from the investigation were highly related and indistinguishable from isolates described in an outbreak in 2005 in the United States (US). Measures successful in containing the US outbreak were not included in user instructions provided to our hospitals by the distributor of the device.

Synthesis and Evaluation of Ester Derivatives of 10-Hydroxycanthin-6-one as Potential Antimicrobial Agents.

PubMed

Zhao, Fei; Dai, Jiang-Kun; Liu, Dan; Wang, Shi-Jun; Wang, Jun-Ru

2016-03-21

As part of our continuing research on canthin-6-one antimicrobial agents, a new series of ester derivatives of 10-hydroxycanthin-6-one were synthesized using a simple and effective synthetic route. The structure of each compound was characterized by NMR, ESI-MS, FT-IR, UV, and elemental analysis. The antimicrobial activity of these compounds against three phytopathogenic fungi (Alternaria solani, Fusarium graminearum, and Fusarium solani) and four bacteria (Bacillus cereus, Bacillus subtilis, Ralstonia solanacearum, and Pseudomonas syringae) were evaluated using the mycelium linear growth rate method and micro-broth dilution method, respectively. The structure-activity relationship is discussed. Of the tested compounds, 4 and 7s displayed significant antifungal activity against F. graminearum, with inhibition rates of 100% at a concentration of 50 μg/mL. Compounds 5, 7s, and 7t showed the best inhibitory activity against all the tested bacteria, with minimum inhibitory concentrations (MICs) between 3.91 and 31.25 μg/mL. Thus, 7s emerged as a promising lead compound for the development of novel canthine-6-one antimicrobial agents.

Greenhouse evaluation of Bacillus subtilis AP-01 and Trichoderma harzianum AP-001 in controlling tobacco diseases.

PubMed

Maketon, Monchan; Apisitsantikul, Jirasak; Siriraweekul, Chatchai

2008-04-01

Two biological control agents, Bacillus subtilis AP-01 (Larminar(™)) and Trichoderma harzianum AP-001 (Trisan(™)) alone or/in combination were investigated in controlling three tobacco diseases, including bacterial wilt (Ralstonia solanacearum), damping-off (Pythium aphanidermatum), and frogeye leaf spot (Cercospora nicotiana). Tests were performed in greenhouse by soil sterilization prior to inoculation of the pathogens. Bacterial-wilt and damping off pathogens were drenched first and followed with the biological control agents and for comparison purposes, two chemical fungicides. But for frogeye leaf spot, which is an airborne fungus, a spraying procedure for every treatment including a chemical fungicide was applied instead of drenching. Results showed that neither B. subtilis AP-01 nor T harzianum AP-001 alone could control the bacterial wilt, but when combined, their controlling capabilities were as effective as a chemical treatment. These results were also similar for damping-off disease when used in combination. In addition, the combined B. subtilis AP-01 and T. harzianum AP-001 resulted in a good frogeye leaf spot control, which was not significantly different from the chemical treatment.

Leucine zipper motif in RRS1 is crucial for the regulation of Arabidopsis dual resistance protein complex RPS4/RRS1

PubMed Central

Narusaka, Mari; Toyoda, Kazuhiro; Shiraishi, Tomonori; Iuchi, Satoshi; Takano, Yoshitaka; Shirasu, Ken; Narusaka, Yoshihiro

2016-01-01

Arabidopsis thaliana leucine-rich repeat-containing (NLR) proteins RPS4 and RRS1, known as dual resistance proteins, confer resistance to multiple pathogen isolates, such as the bacterial pathogens Pseudomonas syringae and Ralstonia solanacearum and the fungal pathogen Colletotrichum higginsianum. RPS4 is a typical Toll/interleukin 1 Receptor (TIR)-type NLR, whereas RRS1 is an atypical TIR-NLR that contains a leucine zipper (LZ) motif and a C-terminal WRKY domain. RPS4 and RRS1 are localised near each other in a head-to-head orientation. In this study, direct mutagenesis of the C-terminal LZ motif in RRS1 caused an autoimmune response and stunting in the mutant. Co-immunoprecipitation analysis indicated that full-length RPS4 and RRS1 are physically associated with one another. Furthermore, virus-induced gene silencing experiments showed that hypersensitive-like cell death triggered by RPS4/LZ motif-mutated RRS1 depends on EDS1. In conclusion, we suggest that the RRS1-LZ motif is crucial for the regulation of the RPS4/RRS1 complex. PMID:26750751

Efficient biological conversion of carbon monoxide (CO) to carbon dioxide (CO2) and for utilization in bioplastic production by Ralstonia eutropha through the display of an enzyme complex on the cell surface.

PubMed

Hyeon, Jeong Eun; Kim, Seung Wook; Park, Chulhwan; Han, Sung Ok

2015-06-25

An enzyme complex for biological conversion of CO to CO2 was anchored on the cell surface of the CO2-utilizing Ralstonia eutropha and successfully resulted in a 3.3-fold increase in conversion efficiency. These results suggest that this complexed system may be a promising strategy for CO2 utilization as a biological tool for the production of bioplastics.

Growth of bacterial phytopathogens in animal manures.

PubMed

Sledz, Wojciech; Zoledowska, Sabina; Motyka, Agata; Kadziński, Leszek; Banecki, Bogdan

2017-01-01

Animal manures are routinely applied to agricultural lands to improve crop yield, but the possibility to spread bacterial phytopathogens through field fertilization has not been considered yet. We monitored 49 cattle, horse, swine, sheep or chicken manure samples collected in 14 Polish voivodeships for the most important plant pathogenic bacteria - Ralstonia solanacearum (Rsol), Xanthomonas campestris pv. campestris (Xcc), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pectobacterium atrosepticum (Pba), Erwinia amylovora (Eam), Clavibacter michiganensis subsp. sepedonicus (Cms) and Dickeya sp. (Dsp). All of the tested animal fertilizers were free of these pathogens. Subsequently, the growth dynamics of Pba, Pcc, Rsol, and Xcc in cattle, horse, swine, sheep and chicken manures sterilized either by autoclaving or filtration was evaluated. The investigated phytopathogens did not exhibit any growth in the poultry manure. However, the manure filtrates originating from other animals were suitable for microbial growth, which resulted in the optical density change of 0.03-0.22 reached within 26 h (48 h Rsol, 120 h Xcc), depending on bacterial species and the manure source. Pcc and Pba multiplied most efficiently in the cattle manure filtrate. These bacteria grew faster than Rsol and Xcc in all the tested manure samples, both the filtrates and the autoclaved semi-solid ones. Though the growth dynamics of investigated strains in different animal fertilizers was unequal, all of the tested bacterial plant pathogens were proven to use cattle, horse, swine and sheep manures as the sources of nutrients. These findings may contribute to further research on the alternative routes of spread of bacterial phytopathogens, especially because of the fact that the control of pectionolytic bacteria is only based on preventive methods.

Novel 2,4-Dichlorophenoxyacetic Acid Degradation Genes from Oligotrophic Bradyrhizobium sp. Strain HW13 Isolated from a Pristine Environment

PubMed Central

Kitagawa, Wataru; Takami, Sachiko; Miyauchi, Keisuke; Masai, Eiji; Kamagata, Yoichi; Tiedje, James M.; Fukuda, Masao

2002-01-01

The tfd genes of Ralstonia eutropha JMP134 are the only well-characterized set of genes responsible for 2,4-dichlorophenoxyacetic acid (2,4-D) degradation among 2,4-D-degrading bacteria. A new family of 2,4-D degradation genes, cadRABKC, was cloned and characterized from Bradyrhizobium sp. strain HW13, a strain that was isolated from a buried Hawaiian soil that has never experienced anthropogenic chemicals. The cadR gene was inferred to encode an AraC/XylS type of transcriptional regulator from its deduced amino acid sequence. The cadABC genes were predicted to encode 2,4-D oxygenase subunits from their deduced amino acid sequences that showed 46, 44, and 37% identities with the TftA and TftB subunits of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) oxygenase of Burkholderia cepacia AC1100 and with a putative ferredoxin, ThcC, of Rhodococcus erythropolis NI86/21, respectively. They are thoroughly different from the 2,4-D dioxygenase gene, tfdA, of R. eutropha JMP134. The cadK gene was presumed to encode a 2,4-D transport protein from its deduced amino acid sequence that showed 60% identity with the 2,4-D transporter, TfdK, of strain JMP134. Sinorhizobium meliloti Rm1021 cells containing cadRABKC transformed several phenoxyacetic acids, including 2,4-D and 2,4,5-T, to corresponding phenol derivatives. Frameshift mutations indicated that each of the cadRABC genes was essential for 2,4-D conversion in strain Rm1021 but that cadK was not. Five 2,4-D degraders, including Bradyrhizobium and Sphingomonas strains, were found to have cadA gene homologs, suggesting that these 2,4-D degraders share 2,4-D degradation genes similar to those of strain HW13 cadABC. PMID:11751829

Ralstonia eutropha's Poly(3-hydroxybutyrate)(PHB) polymerase PhaC1 and PHB depolymerase PhaZa1 are phosphorylated in vivo.

PubMed

Jüngert, Janina R; Patterson, Cameron; Jendrossek, Dieter

2018-04-20

In this study, we screened PHB synthase PhaC1 and PHB depolymerase PhaZa1 of Ralstonia eutropha for the presence of phosphorylated residues during the PHB accumulation and PHB degradation phase. Thr373 of PHB synthase PhaC1 was phosphorylated in the stationary growth phase but was not modified in the exponential and PHB accumulation phases. Ser35 of PHB depolymerase PhaZa1 was identified in phosphorylated form both in the exponential and in the stationary growth phase. Additional phosphosites were identified for both proteins in sample-dependent forms. Site-directed mutagenesis of the codon for Thr373 and other phosphosites of PhaC1 revealed a strong negative impact on PHB synthase activity. Modification of Thr26 and Ser35 of PhaZa1 reduced the ability of R. eutropha to mobilize PHB in the stationary growth phase. Our results show that phosphorylation of PhaC1 and PhaZa1 can be important for modulation of the activities of PHB synthase and PHB depolymerase. Importance Polyhydroxybutyrate (PHB) and related polyhydroxyalkanoates (PHAs) are important intracellular carbon and energy storage compounds in many prokaryotes. The accumulation of PHB or PHAs increases the fitness of cells during periods of starvation and other stress conditions. The simultaneous presence of poly(3-hydroxybutyrate) (PHB) synthase (PhaC1) and PHB depolymerase (PhaZa1) on synthesized PHB granules in Ralstonia eutropha (alternative designation Cupriavidus necator ) has been previously shown in several laboratories. These findings imply that the activities of PHB synthase and PHB depolymerase should be regulated to avoid a futile cycle of simultaneous synthesis and degradation of PHB. Here, we addressed this question by identifying phosphorylation sites on PhaC1 and PhaZa1 and by site-directed mutagenesis of identified residues. Furthermore, we conducted in vitro and in vivo analysis of PHB synthase activity and PHB contents. Copyright © 2018 American Society for Microbiology.

Spectroscopic and Kinetic Properties of the Molybdenum-containing, NAD+-dependent Formate Dehydrogenase from Ralstonia eutropha*

PubMed Central

Niks, Dimitri; Duvvuru, Jayant; Escalona, Miguel; Hille, Russ

2016-01-01

We have examined the rapid reaction kinetics and spectroscopic properties of the molybdenum-containing, NAD+-dependent FdsABG formate dehydrogenase from Ralstonia eutropha. We confirm previous steady-state studies of the enzyme and extend its characterization to a rapid kinetic study of the reductive half-reaction (the reaction of formate with oxidized enzyme). We have also characterized the electron paramagnetic resonance signal of the molybdenum center in its MoV state and demonstrated the direct transfer of the substrate Cα hydrogen to the molybdenum center in the course of the reaction. Varying temperature, microwave power, and level of enzyme reduction, we are able to clearly identify the electron paramagnetic resonance signals for four of the iron/sulfur clusters of the enzyme and find suggestive evidence for two others; we observe a magnetic interaction between the molybdenum center and one of the iron/sulfur centers, permitting assignment of this signal to a specific iron/sulfur cluster in the enzyme. In light of recent advances in our understanding of the structure of the molybdenum center, we propose a reaction mechanism involving direct hydride transfer from formate to a molybdenum-sulfur group of the molybdenum center. PMID:26553877

Lactoferrin-derived resistance against plant pathogens in transgenic plants.

PubMed

Lakshman, Dilip K; Natarajan, Savithiry; Mandal, Sudhamoy; Mitra, Amitava

2013-12-04

Lactoferrin (LF) is a ubiquitous cationic iron-binding milk glycoprotein that contributes to nutrition and exerts a broad-spectrum primary defense against bacteria, fungi, protozoa, and viruses in mammals. These qualities make lactoferrin protein and its antimicrobial motifs highly desirable candidates to be incorporated in plants to impart broad-based resistance against plant pathogens or to economically produce them in bulk quantities for pharmaceutical and nutritional purposes. This study introduced bovine LF (BLF) gene into tobacco ( Nicotiana tabacum var. Xanthi), Arabidopsis ( A. thaliana ) and wheat ( Triticum aestivum ) via Agrobacterium -mediated plant transformation. Transgenic plants or detached leaves exhibited high levels of resistance against the damping-off causing fungal pathogen Rhizoctonia solani and the head blight causing fungal pathogen Fusarium graminearum . LF also imparted resistance to tomato plants against a bacterial pathogen, Ralstonia solanacearum . Similarly, other researchers demonstrated expression of LF and LF-mediated high-quality resistance to several other aggressive fungal and bacterial plant pathogens in transgenic plants and against viral pathogens by foliar applications of LF or its derivatives. Taken together, these studies demonstrated the effectiveness of LF for improving crop quality and its biopharming potentials for pharmaceautical and nutritional applications.

Synthesis and bio-inspired optimization of drimenal: Discovery of chiral drimane fused oxazinones as promising antifungal and antibacterial candidates.

PubMed

Li, Dangdang; Zhang, Shasha; Song, Zehua; Li, Wei; Zhu, Feng; Zhang, Jiwen; Li, Shengkun

2018-01-01

The synthesis of antifungal natural product drimenal was accomplished. Bio-inspired optimization protruded chiral 8-(R)-drimane fused oxazinone D as a lead, considering favorable physicochemical profiles for novel pesticides. The improved scalable synthesis of scaffold D was implemented by Hofmann rearrangment under mild conditions. Detailed structural optimization was discussed for both antifungal and antibacterial exploration. Substituted groups (SGs) with C 3 ∼C 5 hydrocarbon chain are recommended for exploration of antifungal agents, while substituents with C 4 ∼C 6 carbon length are preferred for antibacterial ingredients. The chiral drimane fused oxazinone D8 was selected as a promising antifungal candidate against Botrytis cirerea, with an EC 50 value of 1.18 mg/L, with the enhancement of up to >25 folds and >80 folds than the mother compound D, and acyclic counterpart AB5, respectively. The in vivo bioassay confirmed much better preservative effect of D8 than that of Carbendazim. The chiral oxazinone variant D10 possessed prominent antibacterial activity, with MIC values of 8 mg/L against both Bacillus subtilis and Ralstonia solanacearum, showing advantages over the positive control streptomycin sulfate. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Infection processes of xylem-colonizing pathogenic bacteria: possible explanations for the scarcity of qualitative disease resistance genes against them in crops.

PubMed

Bae, Chungyun; Han, Sang Wook; Song, Yu-Rim; Kim, Bo-Young; Lee, Hyung-Jin; Lee, Je-Min; Yeam, Inhwa; Heu, Sunggi; Oh, Chang-Sik

2015-07-01

Disease resistance against xylem-colonizing pathogenic bacteria in crops. Plant pathogenic bacteria cause destructive diseases in many commercially important crops. Among these bacteria, eight pathogens, Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, X. campestris pv. campestris, Erwinia amylovora, Pantoea stewartii subsp. stewartii, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. actinidiae, and Xylella fastidiosa, infect their host plants through different infection sites and paths and eventually colonize the xylem tissues of their host plants, resulting in wilting symptoms by blocking water flow or necrosis of xylem tissues. Noticeably, only a relatively small number of resistant cultivars in major crops against these vascular bacterial pathogens except X. oryzae pv. oryzae have been found or generated so far, although these pathogens threaten productivity of major crops. In this review, we summarize the lifestyles of major xylem-colonizing bacterial pathogens and then discuss the progress of current research on disease resistance controlled by qualitative disease resistance genes or quantitative trait loci against them. Finally, we propose infection processes of xylem-colonizing bacterial pathogens as one of possible reasons for why so few qualitative disease resistance genes against these pathogens have been developed or identified so far in crops.

Direct and Indirect Visualization of Bacterial Effector Delivery into Diverse Plant Cell Types during Infection[OPEN

PubMed Central

Henry, Elizabeth; Jauneau, Alain; Deslandes, Laurent

2017-01-01

To cause disease, diverse pathogens deliver effector proteins into host cells. Pathogen effectors can inhibit defense responses, alter host physiology, and represent important cellular probes to investigate plant biology. However, effector function and localization have primarily been investigated after overexpression in planta. Visualizing effector delivery during infection is challenging due to the plant cell wall, autofluorescence, and low effector abundance. Here, we used a GFP strand system to directly visualize bacterial effectors delivered into plant cells through the type III secretion system. GFP is a beta barrel that can be divided into 11 strands. We generated transgenic Arabidopsis thaliana plants expressing GFP1-10 (strands 1 to 10). Multiple bacterial effectors tagged with the complementary strand 11 epitope retained their biological function in Arabidopsis and tomato (Solanum lycopersicum). Infection of plants expressing GFP1-10 with bacteria delivering GFP11-tagged effectors enabled direct effector detection in planta. We investigated the temporal and spatial delivery of GFP11-tagged effectors during infection with the foliar pathogen Pseudomonas syringae and the vascular pathogen Ralstonia solanacearum. Thus, the GFP strand system can be broadly used to investigate effector biology in planta. PMID:28600390

Temporal and multiple quantitative trait loci analyses of resistance to bacterial wilt in tomato permit the resolution of linked loci.

PubMed

Mangin, B; Thoquet, P; Olivier, J; Grimsley, N H

1999-03-01

Ralstonia solanacearum is a soil-borne bacterium that causes the serious disease known as bacterial wilt in many plant species. In tomato, several QTL controlling resistance have been found, but in different studies, markers spanning a large region of chromosome 6 showed strong association with the resistance. By using two different approaches to analyze the data from a field test F3 population, we show that at least two separate loci approximately 30 cM apart on this chromosome are most likely involved in the resistance. First, a temporal analysis of the progression of symptoms reveals a distal locus early in the development of the disease. As the disease progresses, the maximum LOD peak observed shifts toward the proximal end of the chromosome, obscuring the distal locus. Second, although classical interval mapping could only detect the presence of one locus, a statistical "two-QTL model" test, specifically adapted for the resolution of linked QTL, strongly supported the hypothesis for the presence of two loci. These results are discussed in the context of current molecular knowledge about disease resistance genes on chromosome 6 and observations made by tomato breeders during the production of bacterial wilt-resistant varieties.

Temporal and multiple quantitative trait loci analyses of resistance to bacterial wilt in tomato permit the resolution of linked loci.

PubMed Central

Mangin, B; Thoquet, P; Olivier, J; Grimsley, N H

1999-01-01

Ralstonia solanacearum is a soil-borne bacterium that causes the serious disease known as bacterial wilt in many plant species. In tomato, several QTL controlling resistance have been found, but in different studies, markers spanning a large region of chromosome 6 showed strong association with the resistance. By using two different approaches to analyze the data from a field test F3 population, we show that at least two separate loci approximately 30 cM apart on this chromosome are most likely involved in the resistance. First, a temporal analysis of the progression of symptoms reveals a distal locus early in the development of the disease. As the disease progresses, the maximum LOD peak observed shifts toward the proximal end of the chromosome, obscuring the distal locus. Second, although classical interval mapping could only detect the presence of one locus, a statistical "two-QTL model" test, specifically adapted for the resolution of linked QTL, strongly supported the hypothesis for the presence of two loci. These results are discussed in the context of current molecular knowledge about disease resistance genes on chromosome 6 and observations made by tomato breeders during the production of bacterial wilt-resistant varieties. PMID:10049932

Characterization of poly-3-hydroxybutyrate (PHB) produced from Ralstonia eutropha using an alkali-pretreated biomass feedstock.

PubMed

Saratale, Ganesh D; Oh, Min-Kyu

2015-09-01

Alkaline pretreatment using NaOH, KOH, or NaOCl has been applied to various types of waste biomass to enhance enzymatic digestibility. Pretreatment (2% NaOH, 121 °C, 30 min) of rice paddy straw (PS) resulted in a maximum yield of 703 mg of reducing sugar per gram of PS with 84.19% hydrolysis yield after a two-step enzymatic hydrolysis process. Ralstonia eutropha ATCC 17699 was tested for its ability to synthesize poly-3-hydroxybutyrate (PHB) using PS hydrolysates as its sole carbon source. It is noteworthy that dry cell weight, polyhydroxyalkanoate (PHA) accumulation and PHB yield with the use of laboratory-grade sugars were similar to those achieved with PS-derived sugars. Under optimized conditions, we observed maximal PHA accumulation (75.45%) and PHB production (11.42 g/L) within 48 h of fermentation. After PHB recovery, the physicochemical properties of PHB were determined by various analytical techniques, showed the results were consistent with the characteristics of a standard polymer of PHB. Thus, the PS hydrolysate proved to be an excellent cheap carbon substrate for PHB production. Copyright © 2015 Elsevier B.V. All rights reserved.

Chemoselective Nitro Group Reduction and Reductive Dechlorination Initiate Degradation of 2-Chloro-5-Nitrophenol by Ralstonia eutropha JMP134

PubMed Central

Schenzle, Andreas; Lenke, Hiltrud; Spain, Jim C.; Knackmuss, Hans-Joachim

1999-01-01

Ralstonia eutropha JMP134 utilizes 2-chloro-5-nitrophenol as a sole source of nitrogen, carbon, and energy. The initial steps for degradation of 2-chloro-5-nitrophenol are analogous to those of 3-nitrophenol degradation in R. eutropha JMP134. 2-Chloro-5-nitrophenol is initially reduced to 2-chloro-5-hydroxylaminophenol, which is subject to an enzymatic Bamberger rearrangement yielding 2-amino-5-chlorohydroquinone. The chlorine of 2-amino-5-chlorohydroquinone is removed by a reductive mechanism, and aminohydroquinone is formed. 2-Chloro-5-nitrophenol and 3-nitrophenol induce the expression of 3-nitrophenol nitroreductase, of 3-hydroxylaminophenol mutase, and of the dechlorinating activity. 3-Nitrophenol nitroreductase catalyzes chemoselective reduction of aromatic nitro groups to hydroxylamino groups in the presence of NADPH. 3-Nitrophenol nitroreductase is active with a variety of mono-, di-, and trinitroaromatic compounds, demonstrating a relaxed substrate specificity of the enzyme. Nitrosobenzene serves as a substrate for the enzyme and is converted faster than nitrobenzene. PMID:10347008

Characterization of binding preference of polyhydroxyalkanoate biosynthesis-related multifunctional protein PhaM from Ralstonia eutropha.

PubMed

Ushimaru, Kazunori; Tsuge, Takeharu

2016-05-01

The binding preference of a polyhydroxyalkanoate (PHA) biosynthesis-related multifunctional protein from Ralstonia eutropha (PhaMRe) was characterized. In vitro activity assay showed that PHA synthase from R. eutropha (PhaCRe) was activated by the presence of PhaMRe but PHA synthase from Aeromonas caviae (PhaCAc) was not. Additionally, in vitro assays of protein-protein interactions demonstrated that PhaMRe interacted with PhaCRe directly, but did not interact with PhaCAc. These results suggest that the protein-protein interaction is important for the activation of PhaC by PhaMRe. Further analyses indicated that PhaMRe has little or no direct interaction with the PHA polymer chain. Subsequently, PHA biosynthesis genes (phaA Re, phaB Re, and phaC Re/phaC Ac) and the phaM Re gene were introduced into recombinant Escherichia coli and cultivated for PHA accumulation. Contrary to our expectations, the expression of PhaMRe decreased PHA accumulation and changed the morphology of PHA granules to be microscopically obscure shape in PhaCRe-expressing E. coli. No change in the amount of P(3HB) or the morphology of granules by PhaMRe expression was observed in PhaCAc-expressing E. coli. These observations suggest that PhaMRe affects cellular physiology through the PhaM-PhaC interaction.

Monoclonal outbreak of catheter-related bacteraemia by Ralstonia mannitolilytica on two haemato-oncology wards.

PubMed

Gröbner, Sabine; Heeg, Peter; Autenrieth, Ingo B; Schulte, Berit

2007-12-01

Ralstonia mannitolilytica is a non-fermentative, gram-negative bacterium isolated infrequently from clinical samples. However, within a period of 11 weeks five inpatients of the tertiary care hospital of the University of Tübingen developed clinical signs of infection and R. mannitolilytica was cultivated from blood samples of all patients suggesting an outbreak. Blood cultures and one catheter tip were analysed by standard microbiological procedures. Genetic relatedness of the isolates was investigated by pulsed-field gel electrophoresis. To ascertain the possible source of the outbreak, environmental sampling and challenge-recovery experiments to test filters used for multi-dose solution bottles were performed. In the present study a monoclonal outbreak with R. mannitolilytica causing catheter-related infection of five haematological patients is reported. Underlying severe diseases with consecutive immunosuppression, permanent indwelling intravenous devices, multiple intravenous applications, and chemotherapy were possible risk factors promoting the infection. Challenge-recovery experiments revealed that R. mannitolilytica to a high extent even passed through Mini-spike Plus filters of pore size 0.2 microm. Although the source of the outbreak could not be identified, it is possible that solutions given intravenously were contaminated. Since R. mannitolilytica had never been isolated in our laboratory before and environmental testings performed were negative, it cannot be excluded that commercial products like drugs, saline solutions or infusion systems (filters) were contaminated.

H2 conversion in the presence of O2 as performed by the membrane-bound [NiFe]-hydrogenase of Ralstonia eutropha.

PubMed

Lenz, Oliver; Ludwig, Marcus; Schubert, Torsten; Bürstel, Ingmar; Ganskow, Stefanie; Goris, Tobias; Schwarze, Alexander; Friedrich, Bärbel

2010-04-26

[NiFe]-hydrogenases catalyze the oxidation of H(2) to protons and electrons. This reversible reaction is based on a complex interplay of metal cofactors including the Ni-Fe active site and several [Fe-S] clusters. H(2) catalysis of most [NiFe]-hydrogenases is sensitive to dioxygen. However, some bacteria contain hydrogenases that activate H(2) even in the presence of O(2). There is now compelling evidence that O(2) affects hydrogenase on three levels: 1) H(2) catalysis, 2) hydrogenase maturation, and 3) H(2)-mediated signal transduction. Herein, we summarize the genetic, biochemical, electrochemical, and spectroscopic properties related to the O(2) tolerance of hydrogenases resident in the facultative chemolithoautotroph Ralstonia eutropha H16. A focus is given to the membrane-bound [NiFe]-hydogenase, which currently represents the best-characterized member of O(2)-tolerant hydrogenases.

Induction of innate immune responses by flagellin from the intracellular bacterium, 'Candidatus Liberibacter solanacearum'.

PubMed

Hao, Guixia; Pitino, Marco; Ding, Fang; Lin, Hong; Stover, Ed; Duan, Yongping

2014-08-05

'Candidatus Liberibacter solanacearum' (Lso) is a phloem-limited alphaproteobacterium associated with the devastating zebra chip disease of potato (Solanum tuberosum). Like other members of Liberibacter, Lso-ZC1 encodes a flagellin domain-containing protein (Fla Lso ) with a conserved 22 amino-acid peptide (flg22 Lso ). To understand the innate immune responses triggered by this unculturable intracellular bacterium, we studied the pathogen-associated molecular patterns (PAMPs) that triggered immunity in Nicotiana benthamiana, using the flg22 Lso peptide and the full length fla Lso gene. Our results showed that the expression of fla Lso via Agrobacterium-mediated transient expression induced a slow necrotic cell death in the inoculated leaves of N. benthamiana, which was coupled with a burst of reactive oxygen species (ROS) production. Moreover, the expression of several representative genes involved in innate immunity was transiently up-regulated by the flg22 Lso in N. benthamiana. The Fla Lso , however, induced stronger up-regulation of these representative genes compared to the flg22 Lso , especially that of flagellin receptor FLAGELLIN SENSING2 (FLS2) and respiratory burst oxidase (RbohB) in N. benthamiana. Although neither cell death nor ROS were induced by the synthetic flg22 Lso , a weak callose deposition was observed in infiltrated leaves of tobacco, tomato, and potato plants. The flagellin of Lso and its functional domain, flg22 Lso share characteristics of pathogen-associated molecular patterns, and trigger unique innate immune responses in N. benthamiana. Slow and weak activation of the innate immune response in host plants by the flagellin of Lso may reflect the nature of its intracellular life cycle. Our findings provide new insights into the role of the Lso flagellin in the development of potato zebra chip disease and potential application in breeding for resistance.

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper.

PubMed

Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

2012-07-01

Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks.

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper

PubMed Central

Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

2012-01-01

Background and Aims Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Methods Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Key Results Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. Conclusions The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent

The long-term effect of uranium and pH on the community composition of an artificial consortium.

PubMed

Brzoska, Ryann M; Bollmann, Annette

2016-01-01

In the environment, microorganisms are living in diverse communities, which are impacted by the prevailing environmental conditions. Here, we present a study investigating the effect of low pH and elevated uranium concentration on the dynamics of an artificial microbial consortium. The members (Caulobacter sp. OR37, Asinibacterium sp. OR53, Ralstonia sp. OR214 and Rhodanobacter sp. OR444) were isolated from a uranium contaminated and acidic subsurface sediment. In pure culture, Ralstonia sp. OR214 had the highest growth rate at neutral and low pH and only Caulobacter sp. OR37 and Asinibacterium sp. OR53 grew in the presence uranium. The four strains were mixed in equal ratios, incubated at neutral and low pH and in the presence uranium and transferred to fresh medium once per week for 30 weeks. After 30 weeks, Ralstonia sp. OR214 was dominant at low and neutral pH and Caulobacter sp. OR37 and Asinibacterium sp. OR53 were dominant in the presence of uranium. After 12 weeks, the cultures were also transferred to new conditions to access the response of the consortia to changing conditions. The transfers showed an irreversible effect of uranium, but not of low pH on the consortia. Overall, the strains initially tolerant to the respective conditions persisted over time in high abundances in the consortia. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Investigation of the NADH/NAD+ ratio in Ralstonia eutropha using the fluorescence reporter protein Peredox.

PubMed

Tejwani, Vijay; Schmitt, Franz-Josef; Wilkening, Svea; Zebger, Ingo; Horch, Marius; Lenz, Oliver; Friedrich, Thomas

2017-01-01

Ralstonia eutropha is a hydrogen-oxidizing ("Knallgas") bacterium that can easily switch between heterotrophic and autotrophic metabolism to thrive in aerobic and anaerobic environments. Its versatile metabolism makes R. eutropha an attractive host for biotechnological applications, including H 2 -driven production of biodegradable polymers and hydrocarbons. H 2 oxidation by R. eutropha takes place in the presence of O 2 and is mediated by four hydrogenases, which represent ideal model systems for both biohydrogen production and H 2 utilization. The so-called soluble hydrogenase (SH) couples reversibly H 2 oxidation with the reduction of NAD + to NADH and has already been applied successfully in vitro and in vivo for cofactor regeneration. Thus, the interaction of the SH with the cellular NADH/NAD + pool is of major interest. In this work, we applied the fluorescent biosensor Peredox to measure the [NADH]:[NAD + ] ratio in R. eutropha cells under different metabolic conditions. The results suggest that the sensor operates close to saturation level, indicating a rather high [NADH]:[NAD + ] ratio in aerobically grown R. eutropha cells. Furthermore, we demonstrate that multicomponent analysis of spectrally-resolved fluorescence lifetime data of the Peredox sensor response to different [NADH]:[NAD + ] ratios represents a novel and sensitive tool to determine the redox state of cells. Copyright © 2016 Elsevier B.V. All rights reserved.

A glimpse into the genetic basis of symbiosis between Hydrogenophaga and their helper strains in the biodegradation of 4-aminobenzenesulfonate

PubMed Central

Kim, Kangsan; Gan, Han Ming

2017-01-01

We report the whole genome sequences of Hydrogenophaga intermedia S1 and Agrobacterium radiobacter S2, the first reported bacterial co-culture capable of degrading 4-aminobenzenesulfonate (4-ABS), a recalcitrant industrial waste product. To gain insights into the genetic basis for the syntrophic interaction between this symbiotic pair and also another recently reported Hydrogenophaga associated co-culture, Hydrogenophaga sp. PBC and Ralstonia sp. PBA, we performed detailed genetic analysis of these four strains focusing on the metabolic pathways associated with biotin, para-aminobenzoic acid (pABA), and protocatechuate metabolism. Both assembled Hydrogenophaga draft genomes are missing a majority of the genetic components associated in the biosynthetic pathway of pABA and biotin. Interestingly, a fused pABA synthase was found in R. sp PBA but not in A. radiobacter S2. Furthermore, using whole genome data, the taxonomic classification of R. sp. PBA and A. radiobacter S2 (both previously inferred from 16S rRNA gene) was re-investigated, providing new evidence to propose for their re-classification at the genus and species level, respectively PMID:28775791

Horizontal Transmission of "Candidatus Liberibacter solanacearum" by Bactericera cockerelli (Hemiptera: Triozidae) on Convolvulus and Ipomoea (Solanales: Convolvulaceae).

PubMed

Torres, Glenda L; Cooper, W Rodney; Horton, David R; Swisher, Kylie D; Garczynski, Stephen F; Munyaneza, Joseph E; Barcenas, Nina M

2015-01-01

"Candidatus Liberibacter solanacearum" (Proteobacteria) is an important pathogen of solanaceous crops (Solanales: Solanaceae) in North America and New Zealand, and is the putative causal agent of zebra chip disease of potato. This phloem-limited pathogen is transmitted to potato and other solanaceous plants by the potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae). While some plants in the Convolvulaceae (Solanales) are also known hosts for B. cockerelli, previous efforts to detect Liberibacter in Convolvulaceae have been unsuccessful. Moreover, studies to determine whether Liberibacter can be acquired from these plants by B. cockerelli are lacking. The goal of this study was to determine whether horizontal transmission of Liberibacter occurs among potato psyllids on two species of Convolvulaceae, sweet potato (Ipomoea batatas) and field bindweed (Convolvulus arvensis), which grows abundantly in potato growing regions of the United States. Results indicated that uninfected psyllids acquired Liberibacter from both I. batatas and C. arvensis if infected psyllids were present on plants concurrently with the uninfected psyllids. Uninfected psyllids did not acquire Liberibacter from plants if the infected psyllids were removed from the plants before the uninfected psyllids were allowed access. In contrast with previous reports, PCR did detect the presence of Liberibacter DNA in some plants. However, visible amplicons were faint and did not correspond with acquisition of the pathogen by uninfected psyllids. None of the plants exhibited disease symptoms. Results indicate that horizontal transmission of Liberibacter among potato psyllids can occur on Convolvulaceae, and that the association between Liberibacter and Convolvulaceae merits additional attention.

Identification of boric acid as a novel chemoattractant and elucidation of its chemoreceptor in Ralstonia pseudosolanacearum Ps29.

PubMed

Hida, Akiko; Oku, Shota; Nakashimada, Yutaka; Tajima, Takahisa; Kato, Junichi

2017-08-17

Chemotaxis enables bacteria to move toward more favorable environmental conditions. We observed chemotaxis toward boric acid by Ralstonia pseudosolanacearum Ps29. At higher concentrations, the chemotactic response of R. pseudosolanacearum toward boric acid was comparable to or higher than that toward L-malate, indicating that boric acid is a strong attractant for R. pseudosolanacearum. Chemotaxis assays under different pH conditions suggested that R. pseudosolanacearum recognizes B(OH) 3 (or B(OH 3 ) + B(OH) 4 - ) but not B(OH) 4 - alone. Our previous study revealed that R. pseudosolanacearum Ps29 harbors homologs of all 22R. pseudosolanacearum GMI1000 mcp genes. Screening of 22 mcp single-deletion mutants identified the RS_RS17100 homolog as the boric acid chemoreceptor, which was designated McpB. The McpB ligand-binding domain (LBD) was purified in order to characterize its binding to boric acid. Using isothermal titration calorimetry, we demonstrated that boric acid binds directly to the McpB LBD with a K D (dissociation constant) of 5.4 µM. Analytical ultracentrifugation studies revealed that the McpB LBD is present as a dimer that recognizes one boric acid molecule.

Engineering Ralstonia eutropha for Production of Isobutanol (IBT) Motor Fuel from Carbon Dioxide, Hydrogen, and Oxygen Project Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinskey, Anthony J.; Worden, Robert Mark; Brigham, Christopher

This research project is a collaboration between the Sinskey laboratory at MIT and the Worden laboratory at Michigan State University. The goal of the project is to produce Isobutanol (IBT), a branched-chain alcohol that can serve as a drop-in transportation fuel, through the engineered microbial biosynthesis of Carbon Dioxide, Hydrogen, and Oxygen using a novel bioreactor. This final technical report presents the findings of both the biological engineering work at MIT that extended the native branched-chain amino acid pathway of the wild type Ralstonia eutropha H16 to perform this biosynthesis, as well as the unique design, modeling, and construction ofmore » a bioreactor for incompatible gasses at Michigan State that enabled the operational testing of the complete system. This 105 page technical report summarizing the three years of research includes 72 figures and 11 tables of findings. Ralstonia eutropha (also known as Cupriavidus necator) is a Gram-negative, facultatively chemolithoautotrophic bacteria. It has been the principle organism used for the study of polyhydroxybutyrate (PHB) polymer biosynthesis. The wild-type Ralstonia eutropha H16 produces PHB as an intracellular carbon storage material while under nutrient stress in the presence of excess carbon. Under this stress, it can accumulate approximately 80 % of its cell dry weight (CDW) as this intracellular polymer. With the restoration of the required nutrients, the cells are then able to catabolize this polymer. If extracted from the cell, this PHB polymer can be processed into biodegradable and biocompatible plastics, however for this research, it is the efficient metabolic pathway channeling the captured carbon that is of interest. R. eutropha is further unique in that it contains two carbon-fixation Calvin–Benson–Bassham cycle operons, two oxygen-tolerant hydrogenases, and several formate dehydrogenases. It has also been much studied for its ability in the presence of oxygen, to fix carbon

Spectroscopic insights into the oxygen-tolerant membrane-associated [NiFe] hydrogenase of Ralstonia eutropha H16.

PubMed

Saggu, Miguel; Zebger, Ingo; Ludwig, Marcus; Lenz, Oliver; Friedrich, Bärbel; Hildebrandt, Peter; Lendzian, Friedhelm

2009-06-12

This study provides the first spectroscopic characterization of the membrane-bound oxygen-tolerant [NiFe] hydrogenase (MBH) from Ralstonia eutropha H16 in its natural environment, the cytoplasmic membrane. The H2-converting MBH is composed of a large subunit, harboring the [NiFe] active site, and a small subunit, capable in coordinating one [3Fe4S] and two [4Fe4S] clusters. The hydrogenase dimer is electronically connected to a membrane-integral cytochrome b. EPR and Fourier transform infrared spectroscopy revealed a strong similarity of the MBH active site with known [NiFe] centers from strictly anaerobic hydrogenases. Most redox states characteristic for anaerobic [NiFe] hydrogenases were identified except for one remarkable difference. The formation of the oxygen-inhibited Niu-A state was never observed. Furthermore, EPR data showed the presence of an additional paramagnetic center at high redox potential (+290 mV), which couples magnetically to the [3Fe4S] center and indicates a structural and/or redox modification at or near the proximal [4Fe4S] cluster. Additionally, significant differences regarding the magnetic coupling between the Nia-C state and [4Fe4S] clusters were observed in the reduced form of the MBH. The spectroscopic properties are discussed with regard to the unusual oxygen tolerance of this hydrogenase and in comparison with those of the solubilized, dimeric form of the MBH.

Antibacterial activity of caffeine against plant pathogenic bacteria.

PubMed

Sledz, Wojciech; Los, Emilia; Paczek, Agnieszka; Rischka, Jacek; Motyka, Agata; Zoledowska, Sabina; Piosik, Jacek; Lojkowska, Ewa

2015-01-01

The objective of the present study was to evaluate the antibacterial properties of a plant secondary metabolite - caffeine. Caffeine is present in over 100 plant species. Antibacterial activity of caffeine was examined against the following plant-pathogenic bacteria: Ralstonia solanacearum (Rsol), Clavibacter michiganesis subsp. sepedonicus (Cms), Dickeya solani (Dsol), Pectobacterium atrosepticum (Pba), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pseudomonas syringae pv. tomato (Pst), and Xanthomonas campestris subsp. campestris (Xcc). MIC and MBC values ranged from 5 to 20 mM and from 43 to 100 mM, respectively. Caffeine increased the bacterial generation time of all tested species and caused changes in cell morphology. The influence of caffeine on the synthesis of DNA, RNA and proteins was investigated in cultures of plant pathogenic bacteria with labelled precursors: [(3)H]thymidine, [(3)H]uridine or (14)C leucine, respectively. RNA biosynthesis was more affected than DNA or protein biosynthesis in bacterial cells treated with caffeine. Treatment of Pba with caffeine for 336 h did not induce resistance to this compound. Caffeine application reduced disease symptoms caused by Dsol on chicory leaves, potato slices, and whole potato tubers. The data presented indicate caffeine as a potential tool for the control of diseases caused by plant-pathogenic bacteria, especially under storage conditions.

Differential staining of Western blots of human secreted glycoproteins from serum, milk, saliva, and seminal fluid using lectins displaying diverse sugar specificities.

PubMed

Gilboa-Garber, Nechama; Lerrer, Batya; Lesman-Movshovich, Efrat; Dgani, Orly

2005-12-01

Human milk, serum, saliva, and seminal fluid glycoproteins (gps) nourish and protect newborn and adult tissues. Their saccharides, which resemble cell membrane components, may block pathogen adhesion and infection. In the present study, they were examined by a battery of lectins from plants, animals, and bacteria, using hemagglutination inhibition and Western blot analyses. The lectins included galactophilic ones from Aplysia gonad, Erythrina corallodendron, Maclura pomifera (MPL), peanut, and Pseudomonas aeruginosa (PA-IL); fucose-binding lectins from Pseudomonas aeruginosa (PA-IIL), Ralstonia solanacearum (RSL), and Ulex europaeus (UEA-I), and mannose/glucose-binding Con A. The results demonstrated the chosen lectin efficiency for differential analysis of human secreted gps as compared to CBB staining. They unveiled the diversity of these body fluid gp glycans (those of the milk and seminal fluid being highest): the milk gps interacted most strongly with PA-IIL, followed by RSL; the saliva gps with RSL, followed by PA-IIL and MPL; the serum gps with Con A and MPL, followed by PA-IIL and RSL, and the seminal plasma gps with RSL and MPL, followed by UEA-I and PA-IIL. The potential usage of these lectins as probes for scientific, industrial, and medical purposes, and for quality control of the desired gps is clearly indicated.

Microbial diversity of traditional Vietnamese alcohol fermentation starters (banh men) as determined by PCR-mediated DGGE.

PubMed

Thanh, Vu Nguyen; Mai, Le Thuy; Tuan, Duong Anh

2008-12-10

The diversity of fungi and bacteria associated with traditional Vietnamese alcohol fermentation starters (banh men) was investigated by PCR-mediated DGGE. From 52 starter samples, 13 species of fungi (including yeasts) and 23 species of bacteria were identified. The fungal composition of the starters was consistent with little variation among samples. It consisted of amylase producers (Rhizopus oryzae, R. microsporus, Absidia corymbifera, Amylomyces sp., Saccharomycopsis fibuligera), ethanol producers (Saccharomyces cerevisiae, Issatchenkia sp., Pichia anomala, Candida tropicalis, P. ranongensis, Clavispora lusitaniae), and (opportunistic) contaminants (Xeromyces bisporus, Botryobasidium subcoronatum). The bacterial microflora of starters was highly variable in species composition and dominated by lactic acid bacteria (LAB). The most frequent LAB were Pediococcus pentosaceus, Lactobacillus plantarum, L. brevis, Weissella confusa, and W. paramesenteroides. Species of amylase-producing Bacillus (Bacillus subtilis, B. circulans, B. amyloliquefaciens, B. sporothermodurans), acetic acid bacteria (Acetobacter orientalis, A. pasteurianus), and plant pathogens/environment contaminants (Burkholderia ubonensis, Ralstonia solanacearum, Pelomonas puraquae) were also detected. Fungal DGGE was found to be useful for evaluating starter type and starter quality. Moreover, in view of the high biological diversity of these substrates, bacterial DGGE may be useful in determining the identity of a starter. The constant occurrence of opportunistic contaminants highlights the need for careful examination of the role of individual components in starters.

DNA-binding proteins from marine bacteria expand the known sequence diversity of TALE-like repeats

PubMed Central

de Lange, Orlando; Wolf, Christina; Thiel, Philipp; Krüger, Jens; Kleusch, Christian; Kohlbacher, Oliver; Lahaye, Thomas

2015-01-01

Transcription Activator-Like Effectors (TALEs) of Xanthomonas bacteria are programmable DNA binding proteins with unprecedented target specificity. Comparative studies into TALE repeat structure and function are hindered by the limited sequence variation among TALE repeats. More sequence-diverse TALE-like proteins are known from Ralstonia solanacearum (RipTALs) and Burkholderia rhizoxinica (Bats), but RipTAL and Bat repeats are conserved with those of TALEs around the DNA-binding residue. We study two novel marine-organism TALE-like proteins (MOrTL1 and MOrTL2), the first to date of non-terrestrial origin. We have assessed their DNA-binding properties and modelled repeat structures. We found that repeats from these proteins mediate sequence specific DNA binding conforming to the TALE code, despite low sequence similarity to TALE repeats, and with novel residues around the BSR. However, MOrTL1 repeats show greater sequence discriminating power than MOrTL2 repeats. Sequence alignments show that there are only three residues conserved between repeats of all TALE-like proteins including the two new additions. This conserved motif could prove useful as an identifier for future TALE-likes. Additionally, comparing MOrTL repeats with those of other TALE-likes suggests a common evolutionary origin for the TALEs, RipTALs and Bats. PMID:26481363

Analyses of natural variation indicates that the absence of RPS4/RRS1 and amino acid change in RPS4 cause loss of their functions and resistance to pathogens.

PubMed

Narusaka, Mari; Iuchi, Satoshi; Narusaka, Yoshihiro

2017-03-04

A pair of Arabidopsis thaliana resistance proteins, RPS4 and RRS1, recognizes the cognate Avr effector from the bacterial pathogens Pseudomonas syringae pv. tomato expressing avrRps4 (Pst-avrRps4), Ralstonia solanacearum, and the fungal pathogen Colletotrichum higginsianum and leads to defense signaling activation against the pathogens. In the present study, we analyzed 14 A. thaliana accessions for natural variation in Pst-avrRps4 and C. higginsianum susceptibility, and found new compatible and incompatible Arabidopsis-pathogen interactions. We first found that A. thaliana accession Cvi-0 is susceptible to Pst-avrRps4. Interestingly, the genome sequence assembly indicated that Cvi-0 lost both RPS4 and RRS1, but not RPS4B and RRS1B, compared to the reference genome sequence from A. thaliana accession Col-0. On the other hand, the natural variation analysis of RPS4 alleles from various Arabidopsis accessions revealed that one amino-acid change, Y950H, is responsible for the loss of resistance to Pst-avrRps4 and C. higginsianum in RLD-0. Our data indicate that the amino acid change, Y950H, in RPS4 resulted in the loss of both RPS4 and RRS1 functions and resistance to pathogens.

Versatile plasmid-based expression systems for Gram-negative bacteria--General essentials exemplified with the bacterium Ralstonia eutropha H16.

PubMed

Gruber, Steffen; Schwab, Helmut; Koefinger, Petra

2015-12-25

The Gram-negative bacterium Escherichia coli is currently the most efficient and widely used prokaryotic host for recombinant protein and metabolite production. However, due to some limitations and to various interesting features of other Gram-negative bacteria efficient vector systems applicable to a broad range are desired. Basic building blocks for plasmid-based vectors include besides the need for a suitable selection marker in the first line a proper replication and maintenance system. In addition to these basic requirements, further elements are needed for Gram-negative bacteria beyond E. coli, such as Pseudomonas pudita, Ralstonia eutropha, Burkholderia glumae or Acinetobacter sp.. Established building blocks have to be adapted and new building blocks providing the desired functions need to be identified and exploited. This minireview addresses so far described and used genetic elements for broad host range replication, efficient plasmid maintenance, and conjugative plasmid transfer as well as expression elements and protein secretion signals. The industrially important bacterium R. eutropha H16 was chosen as a model organism to provide specific data on the effectivity and utility of building blocks based on such genetic elements. Copyright © 2015 Elsevier B.V. All rights reserved.

Versatile and stable vectors for efficient gene expression in Ralstonia eutropha H16.

PubMed

Gruber, Steffen; Hagen, Jeremias; Schwab, Helmut; Koefinger, Petra

2014-09-30

The Gram-negative β-proteobacterium Ralstonia eutropha H16 is primarily known for polyhydroxybutyrate (PHB) production and its ability to grow chemolithoautotrophically by using CO2 and H2 as sole carbon and energy sources. The majority of metabolic engineering and heterologous expression studies conducted so far rely on a small number of suitable expression systems. Particularly the plasmid based expression systems already developed for the use in R. eutropha H16 suffer from high segregational instability and plasmid loss after a short time of fermentation. In order to develop efficient and highly stable plasmid expression vectors for the use in R. eutropha H16, a new plasmid design was created including the RP4 partitioning system, as well as various promoters and origins of replication. The application of minireplicons derived from broad-host-range plasmids RSF1010, pBBR1, RP4 and pSa for the construction of expression vectors and the use of numerous, versatile promoters extend the range of feasible expression levels considerably. In particular, the use of promoters derived from the bacteriophage T5 was described for the first time in this work, characterizing the j5 promoter as the strongest promoter yet to be applied in R. eutropha H16. Moreover, the implementation of the RP4 partition sequence in plasmid design increased plasmid stability significantly and enables fermentations with marginal plasmid loss of recombinant R. eutropha H16 for at least 96 h. The utility of the new vector family in R. eutropha H16 is demonstrated by providing expression data with different model proteins and consequently further raises the value of this organism as cell factory for biotechnological applications including protein and metabolite production. Copyright © 2014 Elsevier B.V. All rights reserved.

Phenology of the Potato Psyllid, Bactericera cockerelli (Hemiptera: Triozidae), and "Candidatus Liberibacter solanacearum" in Commercial Potato Fields in Idaho.

PubMed

Wenninger, Erik J; Carroll, Amy; Dahan, Jennifer; Karasev, Alexander V; Thornton, Michael; Miller, Jeff; Nolte, Philip; Olsen, Nora; Price, William

2017-12-08

Zebra chip disease (ZC) is an emerging disease of potato in which tubers are produced with striped necrotic patterns that make them unmarketable. ZC is associated with the bacterium "Candidatus Liberibacter solanacearum" (Lso), which is transmitted by the potato psyllid, Bactericera cockerelli (Šulc; Hemiptera: Triozidae). First found in Idaho during 2011, ZC now contributes to increased production costs each season via additional insecticide sprays. To clarify the extent and severity of the threat of ZC in Idaho, we sampled potato psyllids in commercial potato fields across the state over four growing seasons (2012-2015). All life stages of psyllids were sampled using a combination of methods (yellow sticky traps, vacuum samples, and leaf samples), and adult psyllids were tested for the presence of Lso by Polymerase Chain Reaction (PCR). Abundance of potato psyllids initially increased gradually over each growing season, then exhibited a sharp late-season rise and a sharp decline as most fields were being harvested. Abundance of psyllids was higher at warmer, lower elevation sites, but infestation onset did not differ between growing regions. Fewer psyllids were collected in vacuum samples than in sticky trap samples. Nymphs and eggs were found only late season and during years with high abundance of adults. Overall incidence of Lso was similar among all years but one. The results presented here clarify our understanding of the seasonal phenology of potato psyllids and Lso in Idaho potato fields and will aid in developing integrated management strategies against this important pest of potato. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A novel elicitor protein from Phytophthora parasitica induces plant basal immunity and systemic acquired resistance.

PubMed

Chang, Yi-Hsuan; Yan, Hao-Zhi; Liou, Ruey-Fen

2015-02-01

The interaction between Phytophthora pathogens and host plants involves the exchange of complex molecular signals from both sides. Recent studies of Phytophthora have led to the identification of various apoplastic elicitors known to trigger plant immunity. Here, we provide evidence that the protein encoded by OPEL of Phytophthora parasitica is a novel elicitor. Homologues of OPEL were identified only in oomycetes, but not in fungi and other organisms. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) revealed that OPEL is expressed throughout the development of P. parasitica and is especially highly induced after plant infection. Infiltration of OPEL recombinant protein from Escherichia coli into leaves of Nicotiana tabacum (cv. Samsun NN) resulted in cell death, callose deposition, the production of reactive oxygen species and induced expression of pathogen-associated molecular pattern (PAMP)-triggered immunity markers and salicylic acid-responsive defence genes. Moreover, the infiltration conferred systemic resistance against a broad spectrum of pathogens, including Tobacco mosaic virus, the bacteria wilt pathogen Ralstonia solanacearum and P. parasitica. In addition to the signal peptide, OPEL contains three conserved domains: a thaumatin-like domain, a glycine-rich protein domain and a glycosyl hydrolase (GH) domain. Intriguingly, mutation of a putative laminarinase active site motif in the predicted GH domain abolished its elicitor activity, which suggests enzymatic activity of OPEL in triggering the defence response. © 2014 BSPP AND JOHN WILEY & SONS LTD.

DNA-binding proteins from marine bacteria expand the known sequence diversity of TALE-like repeats.

PubMed

de Lange, Orlando; Wolf, Christina; Thiel, Philipp; Krüger, Jens; Kleusch, Christian; Kohlbacher, Oliver; Lahaye, Thomas

2015-11-16

Transcription Activator-Like Effectors (TALEs) of Xanthomonas bacteria are programmable DNA binding proteins with unprecedented target specificity. Comparative studies into TALE repeat structure and function are hindered by the limited sequence variation among TALE repeats. More sequence-diverse TALE-like proteins are known from Ralstonia solanacearum (RipTALs) and Burkholderia rhizoxinica (Bats), but RipTAL and Bat repeats are conserved with those of TALEs around the DNA-binding residue. We study two novel marine-organism TALE-like proteins (MOrTL1 and MOrTL2), the first to date of non-terrestrial origin. We have assessed their DNA-binding properties and modelled repeat structures. We found that repeats from these proteins mediate sequence specific DNA binding conforming to the TALE code, despite low sequence similarity to TALE repeats, and with novel residues around the BSR. However, MOrTL1 repeats show greater sequence discriminating power than MOrTL2 repeats. Sequence alignments show that there are only three residues conserved between repeats of all TALE-like proteins including the two new additions. This conserved motif could prove useful as an identifier for future TALE-likes. Additionally, comparing MOrTL repeats with those of other TALE-likes suggests a common evolutionary origin for the TALEs, RipTALs and Bats. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Synthesis of novel quinazolin-4(3H)-one derivatives containing the 7-oxo-1,2,4-triazolo[1,5-a]pyrimidine moiety as effective agricultural bactericides against the pathogen Xanthomonas oryzae pv. oryzae.

PubMed

Du, Huan; Fan, Zhijiang; Yang, Lan; Bao, Xiaoping

2018-02-01

A series of novel quinazolin-4-one derivatives (7a-7n) bearing the 7-oxo-1,2,4-triazolo[1,5-a]pyrimidine moiety were designed, synthesized and evaluated for their inhibition activities against phytopathogenic bacteria and fungi in vitro. All of the target compounds were fully characterized through [Formula: see text] NMR, [Formula: see text] NMR, HRMS and IR spectra. Among these compounds, the structure of compound 7e was unambiguously confirmed via single-crystal X-ray diffraction analysis. The turbidimetric assays indicated that compounds 7b, 7d, 7g, 7k and 7n exhibited much more potent inhibition activities against the pathogen Xanthomonas oryzae pv. oryzae (Xoo), relative to control Bismerthiazol. Moreover, antibacterial activities of compounds 7j, 7k and 7n against the pathogen Xanthomonas axonopodis pv. citri (Xac) were comparable to that of control Bismerthiazol. As for the pathogen Ralstonia solanacearum (Rs), only compounds 7g and 7i demonstrated inhibition activities similar to control Thiadiazole-copper. Moreover, this class of compounds did not display inhibition activity against three fungi tested. The above findings indicated that quinazolin-4-one derivatives containing the 7-oxo-1,2,4-triazolo[1,5-a]pyrimidine moiety have a potential as promising candidates for the development of new and more efficient agricultural bactericides.

Comparative Genome Analyses of Serratia marcescens FS14 Reveals Its High Antagonistic Potential

PubMed Central

Li, Pengpeng; Kwok, Amy H. Y.; Jiang, Jingwei; Ran, Tingting; Xu, Dongqing; Wang, Weiwu; Leung, Frederick C.

2015-01-01

S. marcescens FS14 was isolated from an Atractylodes macrocephala Koidz plant that was infected by Fusarium oxysporum and showed symptoms of root rot. With the completion of the genome sequence of FS14, the first comprehensive comparative-genomic analysis of the Serratia genus was performed. Pan-genome and COG analyses showed that the majority of the conserved core genes are involved in basic cellular functions, while genomic factors such as prophages contribute considerably to genome diversity. Additionally, a Type I restriction-modification system, a Type III secretion system and tellurium resistance genes are found in only some Serratia species. Comparative analysis further identified that S. marcescens FS14 possesses multiple mechanisms for antagonism against other microorganisms, including the production of prodigiosin, bacteriocins, and multi-antibiotic resistant determinants as well as chitinases. The presence of two evolutionarily distinct Type VI secretion systems (T6SSs) in FS14 may provide further competitive advantages for FS14 against other microbes. To our knowledge, this is the first report of comparative analysis on T6SSs in the genus, which identifies four types of T6SSs in Serratia spp.. Competition bioassays of FS14 against the vital plant pathogenic bacterium Ralstonia solanacearum and fungi Fusarium oxysporum and Sclerotinia sclerotiorum were performed to support our genomic analyses, in which FS14 demonstrated high antagonistic activities against both bacterial and fungal phytopathogens. PMID:25856195

Reprint of "versatile and stable vectors for efficient gene expression in Ralstonia eutropha H16".

PubMed

Gruber, Steffen; Hagen, Jeremias; Schwab, Helmut; Koefinger, Petra

2014-12-20

The Gram-negative β-proteobacterium Ralstonia eutropha H16 is primarily known for polyhydroxybutyrate (PHB) production and its ability to grow chemolithoautotrophically by using CO2 and H2 as sole carbon and energy sources. The majority of metabolic engineering and heterologous expression studies conducted so far rely on a small number of suitable expression systems. Particularly the plasmid based expression systems already developed for the use in R. eutropha H16 suffer from high segregational instability and plasmid loss after a short time of fermentation. In order to develop efficient and highly stable plasmid expression vectors for the use in R. eutropha H16, a new plasmid design was created including the RP4 partitioning system, as well as various promoters and origins of replication. The application of minireplicons derived from broad-host-range plasmids RSF1010, pBBR1, RP4 and pSa for the construction of expression vectors and the use of numerous, versatile promoters extend the range of feasible expression levels considerably. In particular, the use of promoters derived from the bacteriophage T5 was described for the first time in this work, characterizing the j5 promoter as the strongest promoter yet to be applied in R. eutropha H16. Moreover, the implementation of the RP4 partition sequence in plasmid design increased plasmid stability significantly and enables fermentations with marginal plasmid loss of recombinant R. eutropha H16 for at least 96h. The utility of the new vector family in R. eutropha H16 is demonstrated by providing expression data with different model proteins and consequently further raises the value of this organism as cell factory for biotechnological applications including protein and metabolite production. Copyright © 2014 Elsevier B.V. All rights reserved.

PhaM is the physiological activator of poly(3-hydroxybutyrate) (PHB) synthase (PhaC1) in Ralstonia eutropha.

PubMed

Pfeiffer, Daniel; Jendrossek, Dieter

2014-01-01

Poly(3-hydroxybutyrate) (PHB) synthase (PhaC1) is the key enzyme of PHB synthesis in Ralstonia eutropha and other PHB-accumulating bacteria and catalyzes the polymerization of 3-hydroxybutyryl-CoA to PHB. Activity assays of R. eutropha PHB synthase are characterized by the presence of lag phases and by low specific activity. It is assumed that the lag phase is caused by the time necessary to convert the inactive PhaC1 monomer into the active dimeric form by an unknown priming process. The lag phase can be reduced by addition of nonionic detergents such as hecameg [6-O-(N-heptyl-carbamoyl)-methyl-α-D-glucopyranoside], which apparently accelerates the formation of PhaC1 dimers. We identified the PHB granule-associated protein (PGAP) PhaM as the natural primer (activator) of PHB synthase activity. PhaM was recently discovered as a novel type of PGAP with multiple functions in PHB metabolism. Addition of PhaM to PHB synthase assays resulted in immediate polymerization of 3HB coenzyme A with high specific activity and without a significant lag phase. The effect of PhaM on (i) PhaC1 activity, (ii) oligomerization of PhaC1, (iii) complex formation with PhaC1, and (iv) PHB granule formation in vitro and in vivo was shown by cross-linking experiments of purified proteins (PhaM, PhaC1) with glutardialdehyde, by size exclusion chromatography, and by fluorescence microscopic detection of de novo-synthesized PHB granules.

Comparative Proteome Analysis Reveals Four Novel Polyhydroxybutyrate (PHB) Granule-Associated Proteins in Ralstonia eutropha H16

PubMed Central

Sznajder, Anna; Pfeiffer, Daniel

2014-01-01

Identification of proteins that were present in a polyhydroxybutyrate (PHB) granule fraction isolated from Ralstonia eutropha but absent in the soluble, membrane, and membrane-associated fractions revealed the presence of only 12 polypeptides with PHB-specific locations plus 4 previously known PHB-associated proteins with multiple locations. None of the previously postulated PHB depolymerase isoenzymes (PhaZa2 to PhaZa5, PhaZd1, and PhaZd2) and none of the two known 3-hydroxybutyrate oligomer hydrolases (PhaZb and PhaZc) were significantly present in isolated PHB granules. Four polypeptides were found that had not yet been identified in PHB granules. Three of the novel proteins are putative α/β-hydrolases, and two of those (A0671 and B1632) have a PHB synthase/depolymerase signature. The third novel protein (A0225) is a patatin-like phospholipase, a type of enzyme that has not been described for PHB granules of any PHB-accumulating species. No function has been ascribed to the fourth protein (A2001), but its encoding gene forms an operon with phaB2 (acetoacetyl-coenzyme A [CoA] reductase) and phaC2 (PHB synthase), and this is in line with a putative function in PHB metabolism. The localization of the four new proteins at the PHB granule surface was confirmed in vivo by fluorescence microscopy of constructed fusion proteins with enhanced yellow fluorescent protein (eYFP). Deletion of A0671 and B1632 had a minor but detectable effect on the PHB mobilization ability in the stationary growth phase of nutrient broth (NB)-gluconate cells, confirming the functional involvement of both proteins in PHB metabolism. PMID:25548058

The clinical and microbiological characteristics of infections in burn patients from the Formosa Fun Coast Dust Explosion.

PubMed

Lin, Tzu-Chao; Wu, Rui-Xin; Chiu, Chih-Chien; Yang, Ya-Sung; Lee, Yi; Lin, Jung-Chung; Chang, Feng-Yee

2018-04-01

Bloodstream infection is a leading cause of mortality among burn patients. This study aimed to evaluate the risk factors, causative pathogens, and the relationship between bloodstream infections and other infections among burn patients from the Formosa Fun Coast Dust Explosion. This retrospective study evaluated the demographic and clinical characteristics, infection types, causative pathogen(s), and isolates' antibiotic susceptibilities from patients who were hospitalized between June 27 and September 31, 2015. Fifty-eight patients were admitted during the study period (36 males, mean age: 22.6 years). The mean burned total body surface area (TBSA) was 40% for all patients. Eighteen (31%) patients with mean TBSA of 80% had 66 episodes of bloodstream infections caused by 92 isolates. Twelve (18.2%) episodes of bloodstream infections were polymicrobial. Acinetobacter baumannii (19, 20.7%), Ralstonia pickettii (17, 18.5%), and Chryseobacterium meningosepticum (13, 14.1%) were the most common pathogens causing bloodstream infections. A high concordance rate of wound cultures with blood cultures was seen in Staphylococcus aureus (3, 75%) and C. meningosepticum (8, 61.5%) infections. However, no Ralstonia isolate was found in burn wounds of patients with Ralstonia bacteremia. A high concordance rate of central venous catheter cultures with blood cultures was noted in Ralstonia mannitolilytica (5, 62.5%) and Chryseobacterium indologenes (3, 60%) infections. Approximately 21.1% of A. baumannii strains were resistant to carbapenem. All S. aureus isolates were susceptible to methicillin. Waterborne bacteria should be considered in patients of burns with possible water contact. Empirical broad-spectrum antibiotics should be considered for patients who were hospitalized for severe sepsis, or septic shock with a large burn. Antibiotic treatment should be administered based on the specific pathogens and their detection points. Copyright © 2017. Published by Elsevier B.V.

The nuclear immune receptor RPS4 is required for RRS1SLH1-dependent constitutive defense activation in Arabidopsis thaliana.

PubMed

Sohn, Kee Hoon; Segonzac, Cécile; Rallapalli, Ghanasyam; Sarris, Panagiotis F; Woo, Joo Yong; Williams, Simon J; Newman, Toby E; Paek, Kyung Hee; Kobe, Bostjan; Jones, Jonathan D G

2014-10-01

Plant nucleotide-binding leucine-rich repeat (NB-LRR) disease resistance (R) proteins recognize specific "avirulent" pathogen effectors and activate immune responses. NB-LRR proteins structurally and functionally resemble mammalian Nod-like receptors (NLRs). How NB-LRR and NLR proteins activate defense is poorly understood. The divergently transcribed Arabidopsis R genes, RPS4 (resistance to Pseudomonas syringae 4) and RRS1 (resistance to Ralstonia solanacearum 1), function together to confer recognition of Pseudomonas AvrRps4 and Ralstonia PopP2. RRS1 is the only known recessive NB-LRR R gene and encodes a WRKY DNA binding domain, prompting suggestions that it acts downstream of RPS4 for transcriptional activation of defense genes. We define here the early RRS1-dependent transcriptional changes upon delivery of PopP2 via Pseudomonas type III secretion. The Arabidopsis slh1 (sensitive to low humidity 1) mutant encodes an RRS1 allele (RRS1SLH1) with a single amino acid (leucine) insertion in the WRKY DNA-binding domain. Its poor growth due to constitutive defense activation is rescued at higher temperature. Transcription profiling data indicate that RRS1SLH1-mediated defense activation overlaps substantially with AvrRps4- and PopP2-regulated responses. To better understand the genetic basis of RPS4/RRS1-dependent immunity, we performed a genetic screen to identify suppressor of slh1 immunity (sushi) mutants. We show that many sushi mutants carry mutations in RPS4, suggesting that RPS4 acts downstream or in a complex with RRS1. Interestingly, several mutations were identified in a domain C-terminal to the RPS4 LRR domain. Using an Agrobacterium-mediated transient assay system, we demonstrate that the P-loop motif of RPS4 but not of RRS1SLH1 is required for RRS1SLH1 function. We also recapitulate the dominant suppression of RRS1SLH1 defense activation by wild type RRS1 and show this suppression requires an intact RRS1 P-loop. These analyses of RRS1SLH1 shed new light

The Nuclear Immune Receptor RPS4 Is Required for RRS1SLH1-Dependent Constitutive Defense Activation in Arabidopsis thaliana

PubMed Central

Sarris, Panagiotis F.; Woo, Joo Yong; Williams, Simon J.; Newman, Toby E.; Paek, Kyung Hee; Kobe, Bostjan; Jones, Jonathan D. G.

2014-01-01

Plant nucleotide-binding leucine-rich repeat (NB-LRR) disease resistance (R) proteins recognize specific “avirulent” pathogen effectors and activate immune responses. NB-LRR proteins structurally and functionally resemble mammalian Nod-like receptors (NLRs). How NB-LRR and NLR proteins activate defense is poorly understood. The divergently transcribed Arabidopsis R genes, RPS4 (resistance to Pseudomonas syringae 4) and RRS1 (resistance to Ralstonia solanacearum 1), function together to confer recognition of Pseudomonas AvrRps4 and Ralstonia PopP2. RRS1 is the only known recessive NB-LRR R gene and encodes a WRKY DNA binding domain, prompting suggestions that it acts downstream of RPS4 for transcriptional activation of defense genes. We define here the early RRS1-dependent transcriptional changes upon delivery of PopP2 via Pseudomonas type III secretion. The Arabidopsis slh1 (sensitive to low humidity 1) mutant encodes an RRS1 allele (RRS1SLH1) with a single amino acid (leucine) insertion in the WRKY DNA-binding domain. Its poor growth due to constitutive defense activation is rescued at higher temperature. Transcription profiling data indicate that RRS1SLH1-mediated defense activation overlaps substantially with AvrRps4- and PopP2-regulated responses. To better understand the genetic basis of RPS4/RRS1-dependent immunity, we performed a genetic screen to identify suppressor of slh1 immunity (sushi) mutants. We show that many sushi mutants carry mutations in RPS4, suggesting that RPS4 acts downstream or in a complex with RRS1. Interestingly, several mutations were identified in a domain C-terminal to the RPS4 LRR domain. Using an Agrobacterium-mediated transient assay system, we demonstrate that the P-loop motif of RPS4 but not of RRS1SLH1 is required for RRS1SLH1 function. We also recapitulate the dominant suppression of RRS1SLH1 defense activation by wild type RRS1 and show this suppression requires an intact RRS1 P-loop. These analyses of RRS1SLH1 shed new

Comparative proteome analysis reveals four novel polyhydroxybutyrate (PHB) granule-associated proteins in Ralstonia eutropha H16.

PubMed

Sznajder, Anna; Pfeiffer, Daniel; Jendrossek, Dieter

2015-03-01

Identification of proteins that were present in a polyhydroxybutyrate (PHB) granule fraction isolated from Ralstonia eutropha but absent in the soluble, membrane, and membrane-associated fractions revealed the presence of only 12 polypeptides with PHB-specific locations plus 4 previously known PHB-associated proteins with multiple locations. None of the previously postulated PHB depolymerase isoenzymes (PhaZa2 to PhaZa5, PhaZd1, and PhaZd2) and none of the two known 3-hydroxybutyrate oligomer hydrolases (PhaZb and PhaZc) were significantly present in isolated PHB granules. Four polypeptides were found that had not yet been identified in PHB granules. Three of the novel proteins are putative α/β-hydrolases, and two of those (A0671 and B1632) have a PHB synthase/depolymerase signature. The third novel protein (A0225) is a patatin-like phospholipase, a type of enzyme that has not been described for PHB granules of any PHB-accumulating species. No function has been ascribed to the fourth protein (A2001), but its encoding gene forms an operon with phaB2 (acetoacetyl-coenzyme A [CoA] reductase) and phaC2 (PHB synthase), and this is in line with a putative function in PHB metabolism. The localization of the four new proteins at the PHB granule surface was confirmed in vivo by fluorescence microscopy of constructed fusion proteins with enhanced yellow fluorescent protein (eYFP). Deletion of A0671 and B1632 had a minor but detectable effect on the PHB mobilization ability in the stationary growth phase of nutrient broth (NB)-gluconate cells, confirming the functional involvement of both proteins in PHB metabolism. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Catalytic properties of the isolated diaphorase fragment of the NAD-reducing [NiFe]-hydrogenase from Ralstonia eutropha.

PubMed

Lauterbach, Lars; Idris, Zulkifli; Vincent, Kylie A; Lenz, Oliver

2011-01-01

The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha H16 catalyzes the H₂-driven reduction of NAD+, as well as reverse electron transfer from NADH to H+, in the presence of O₂. It comprises six subunits, HoxHYFUI₂, and incorporates a [NiFe] H+/H₂ cycling catalytic centre, two non-covalently bound flavin mononucleotide (FMN) groups and an iron-sulfur cluster relay for electron transfer. This study provides the first characterization of the diaphorase sub-complex made up of HoxF and HoxU. Sequence comparisons with the closely related peripheral subunits of Complex I in combination with UV/Vis spectroscopy and the quantification of the metal and FMN content revealed that HoxFU accommodates a [2Fe2S] cluster, FMN and a series of [4Fe4S] clusters. Protein film electrochemistry (PFE) experiments show clear electrocatalytic activity for both NAD+ reduction and NADH oxidation with minimal overpotential relative to the potential of the NAD+/NADH couple. Michaelis-Menten constants of 56 µM and 197 µM were determined for NADH and NAD+, respectively. Catalysis in both directions is product inhibited with K(I) values of around 0.2 mM. In PFE experiments, the electrocatalytic current was unaffected by O₂, however in aerobic solution assays, a moderate superoxide production rate of 54 nmol per mg of protein was observed, meaning that the formation of reactive oxygen species (ROS) observed for the native SH can be attributed mainly to HoxFU. The results are discussed in terms of their implications for aerobic functioning of the SH and possible control mechanism for the direction of catalysis.

PhaM Is the Physiological Activator of Poly(3-Hydroxybutyrate) (PHB) Synthase (PhaC1) in Ralstonia eutropha

PubMed Central

Pfeiffer, Daniel

2014-01-01

Poly(3-hydroxybutyrate) (PHB) synthase (PhaC1) is the key enzyme of PHB synthesis in Ralstonia eutropha and other PHB-accumulating bacteria and catalyzes the polymerization of 3-hydroxybutyryl-CoA to PHB. Activity assays of R. eutropha PHB synthase are characterized by the presence of lag phases and by low specific activity. It is assumed that the lag phase is caused by the time necessary to convert the inactive PhaC1 monomer into the active dimeric form by an unknown priming process. The lag phase can be reduced by addition of nonionic detergents such as hecameg [6-O-(N-heptyl-carbamoyl)-methyl-α-d-glucopyranoside], which apparently accelerates the formation of PhaC1 dimers. We identified the PHB granule-associated protein (PGAP) PhaM as the natural primer (activator) of PHB synthase activity. PhaM was recently discovered as a novel type of PGAP with multiple functions in PHB metabolism. Addition of PhaM to PHB synthase assays resulted in immediate polymerization of 3HB coenzyme A with high specific activity and without a significant lag phase. The effect of PhaM on (i) PhaC1 activity, (ii) oligomerization of PhaC1, (iii) complex formation with PhaC1, and (iv) PHB granule formation in vitro and in vivo was shown by cross-linking experiments of purified proteins (PhaM, PhaC1) with glutardialdehyde, by size exclusion chromatography, and by fluorescence microscopic detection of de novo-synthesized PHB granules. PMID:24212577

Comparison of 2,4-Dichlorophenoxyacetic Acid Degradation and Plasmid Transfer in Soil Resulting from Bioaugmentation with Two Different pJP4 Donors

PubMed Central

Newby, D. T.; Gentry, T. J.; Pepper, I. L.

2000-01-01

A pilot field study was conducted to assess the impact of bioaugmentation with two plasmid pJP4-bearing microorganisms: the natural host, Ralstonia eutropha JMP134, and a laboratory-generated strain amenable to donor counterselection, Escherichia coli D11. The R. eutropha strain contained chromosomal genes necessary for mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D), while the E. coli strain did not. The soil system was contaminated with 2,4-D alone or was cocontaminated with 2,4-D and Cd. Plasmid transfer to indigenous populations, plasmid persistence in soil, and degradation of 2,4-D were monitored over a 63-day period in the bioreactors. To assess the impact of contaminant reexposure, aliquots of bioreactor soil were reamended with additional 2,4-D. Both introduced donors remained culturable and transferred plasmid pJP4 to indigenous recipients, although to different extents. Isolated transconjugants were members of the Burkholderia and Ralstonia genera, suggesting multiple, if not successive, plasmid transfers. Upon a second exposure to 2,4-D, enhanced degradation was observed for all treatments, suggesting microbial adaptation to 2,4-D. Upon reexposure, degradation was most rapid for the E. coli D11-inoculated treatments. Cd did not significantly impact 2,4-D degradation or transconjugant formation. This study demonstrated that the choice of donor microorganism might be a key factor to consider for bioaugmentation efforts. In addition, the establishment of an array of stable indigenous plasmid hosts at sites with potential for reexposure or long-term contamination may be particularly useful. PMID:10919798

DNA repair in Chromobacterium violaceum.

PubMed

Duarte, Fábio Teixeira; Carvalho, Fabíola Marques de; Bezerra e Silva, Uaska; Scortecci, Kátia Castanho; Blaha, Carlos Alfredo Galindo; Agnez-Lima, Lucymara Fassarella; Batistuzzo de Medeiros, Silvia Regina

2004-03-31

Chromobacterium violaceum is a Gram-negative beta-proteobacterium that inhabits a variety of ecosystems in tropical and subtropical regions, including the water and banks of the Negro River in the Brazilian Amazon. This bacterium has been the subject of extensive study over the last three decades, due to its biotechnological properties, including the characteristic violacein pigment, which has antimicrobial and anti-tumoral activities. C. violaceum promotes the solubilization of gold in a mercury-free process, and has been used in the synthesis of homopolyesters suitable for the production of biodegradable polymers. The complete genome sequence of this organism has been completed by the Brazilian National Genome Project Consortium. The aim of our group was to study the DNA repair genes in this organism, due to their importance in the maintenance of genomic integrity. We identified DNA repair genes involved in different pathways in C. violaceum through a similarity search against known sequences deposited in databases. The phylogenetic analyses were done using programs of the PHILYP package. This analysis revealed various metabolic pathways, including photoreactivation, base excision repair, nucleotide excision repair, mismatch repair, recombinational repair, and the SOS system. The similarity between the C. violaceum sequences and those of Neisserie miningitidis and Ralstonia solanacearum was greater than that between the C. violaceum and Escherichia coli sequences. The peculiarities found in the C. violaceum genome were the absence of LexA, some horizontal transfer events and a large number of repair genes involved with alkyl and oxidative DNA damage.

Matrix approach to the simultaneous detection of multiple potato pathogens by real-time PCR.

PubMed

Nikitin, M M; Statsyuk, N V; Frantsuzov, P A; Dzhavakhiya, V G; Golikov, A G

2018-03-01

Create a method for highly sensitive, selective, rapid and easy-to-use detection and identification of economically significant potato pathogens, including viruses, bacteria and oomycetes, be it single pathogen, or a range of various pathogens occurring simultaneously. Test-systems for real-time PCR, operating in the unified amplification regime, have been developed for Phytophthora infestans, Pectobacterium atrosepticum, Dickeya dianthicola, Dickeya solani, Ralstonia solanacearum, Pectobacterium carotovorum, Clavibacter michiganensis subsp. sepedonicus, potato viruses Y (ordinary and necrotic forms as well as indiscriminative test system, detecting all forms), A, X, S, M, potato leaf roll virus, potato mop top virus and potato spindle tuber viroid. The test-systems (including polymerase and revertase) were immobilized and lyophilized in miniature microreactors (1·2 μl) on silicon DNA/RNA microarrays (micromatrices) to be used with a mobile AriaDNA ® amplifier. Preloaded 30-reaction micromatrices having shelf life of 3 and 6 months (for RNA- and DNA-based pathogens, respectively) at room temperature with no special conditions were successfully tested on both reference and field samples in comparison with traditional ELISA and microbiological methods, showing perfect performance and sensitivity (1 pg). The accurate, rapid and user-friendly diagnostic system in a micromatrix format may significantly contribute to pathogen screening and phytopathological studies. © 2018 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of The Society for Applied Microbiology.

Ralstonia eutropha H16 Flagellation Changes According to Nutrient Supply and State of Poly(3-Hydroxybutyrate) Accumulation▿

PubMed Central

Raberg, Matthias; Reinecke, Frank; Reichelt, Rudolf; Malkus, Ursula; König, Simone; Pötter, Markus; Fricke, Wolfgang Florian; Pohlmann, Anne; Voigt, Birgit; Hecker, Michael; Friedrich, Bärbel; Bowien, Botho; Steinbüchel, Alexander

2008-01-01

Two-dimensional polyacrylamide gel electrophoresis (2D PAGE), in combination with matrix-assisted laser desorption ionization-time of flight analysis, and the recently revealed genome sequence of Ralstonia eutropha H16 were employed to detect and identify proteins that are differentially expressed during different phases of poly(3-hydroxybutyric acid) (PHB) metabolism. For this, a modified protein extraction protocol applicable to PHB-harboring cells was developed to enable 2D PAGE-based proteome analysis of such cells. Subsequently, samples from (i) the exponential growth phase, (ii) the stationary growth phase permissive for PHB biosynthesis, and (iii) a phase permissive for PHB mobilization were analyzed. Among several proteins exhibiting quantitative changes during the time course of a cultivation experiment, flagellin, which is the main protein of bacterial flagella, was identified. Initial investigations that report on changes of flagellation for R. eutropha were done, but 2D PAGE and electron microscopic examinations of cells revealed clear evidence that R. eutropha exhibited further significant changes in flagellation depending on the life cycle, nutritional supply, and, in particular, PHB metabolism. The results of our study suggest that R. eutropha is strongly flagellated in the exponential growth phase and loses a certain number of flagella in transition to the stationary phase. In the stationary phase under conditions permissive for PHB biosynthesis, flagellation of cells admittedly stagnated. However, under conditions permissive for intracellular PHB mobilization after a nitrogen source was added to cells that are carbon deprived but with full PHB accumulation, flagella are lost. This might be due to a degradation of flagella; at least, the cells stopped flagellin synthesis while normal degradation continued. In contrast, under nutrient limitation or the loss of phasins, cells retained their flagella. PMID:18502919

Cometabolic degradation of ethyl mercaptan by phenol-utilizing Ralstonia eutropha in suspended growth and gas-recycling trickle-bed reactor.

PubMed

Sedighi, Mahsa; Zamir, Seyed Morteza; Vahabzadeh, Farzaneh

2016-01-01

The degradability of ethyl mercaptan (EM), by phenol-utilizing cells of Ralstonia eutropha, in both suspended and immobilized culture systems, was investigated in the present study. Free-cells experiments conducted at EM concentrations ranging from 1.25 to 14.42 mg/l, showed almost complete removal of EM at concentrations below 10.08 mg/l, which is much higher than the maximum biodegradable EM concentration obtained in experiments that did not utilize phenol as the primary substrate, i.e. 2.5 mg/l. The first-order kinetic rate constant (kSKS) for EM biodegradation by the phenol-utilizing cells (1.7 l/g biomass/h) was about 10 times higher than by cells without phenol utilization. Immobilized-cells experiments performed in a gas recycling trickle-bed reactor packed with kissiris particles at EM concentrations ranging from 1.6 to 36.9 mg/l, showed complete removal at all tested concentrations in a much shorter time, compared with free cells. The first-order kinetic rate constant (rmaxKs) for EM utilization was 0.04 l/h for the immobilized system compared to 0.06 for the suspended-growth culture, due to external mass transfer diffusion. Diffusion limitation was decreased by increasing the recycling-liquid flow rate from 25 to 65 ml/min. The removed EM was almost completely mineralized according to TOC and sulfate measurements. Shut down and starvation experiments revealed that the reactor could effectively handle the starving conditions and was reliable for full-scale application. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chemical Forms of Selenium in the Metal-Resistant Bacterium Ralstonia metallidurans CH34 Exposed to Selenite and Selenate

PubMed Central

Sarret, Géraldine; Avoscan, Laure; Carrière, Marie; Collins, Richard; Geoffroy, Nicolas; Carrot, Francine; Covès, Jacques; Gouget, Barbara

2005-01-01

Ralstonia metallidurans CH34, a soil bacterium resistant to a variety of metals, is known to reduce selenite to intracellular granules of elemental selenium (Se0). We have studied the kinetics of selenite (SeIV) and selenate (SeVI) accumulation and used X-ray absorption spectroscopy to identify the accumulated form of selenate, as well as possible chemical intermediates during the transformation of these two oxyanions. When introduced during the lag phase, the presence of selenite increased the duration of this phase, as previously observed. Selenite introduction was followed by a period of slow uptake, during which the bacteria contained Se0 and alkyl selenide in equivalent proportions. This suggests that two reactions with similar kinetics take place: an assimilatory pathway leading to alkyl selenide and a slow detoxification pathway leading to Se0. Subsequently, selenite uptake strongly increased (up to 340 mg Se per g of proteins) and Se0 was the predominant transformation product, suggesting an activation of selenite transport and reduction systems after several hours of contact. Exposure to selenate did not induce an increase in the lag phase duration, and the bacteria accumulated approximately 25-fold less Se than when exposed to selenite. SeIV was detected as a transient species in the first 12 h after selenate introduction, Se0 also occurred as a minor species, and the major accumulated form was alkyl selenide. Thus, in the present experimental conditions, selenate mostly follows an assimilatory pathway and the reduction pathway is not activated upon selenate exposure. These results show that R. metallidurans CH34 may be suitable for the remediation of selenite-, but not selenate-, contaminated environments. PMID:15870319

Localization of Poly(3-Hydroxybutyrate) (PHB) Granule-Associated Proteins during PHB Granule Formation and Identification of Two New Phasins, PhaP6 and PhaP7, in Ralstonia eutropha H16

PubMed Central

Pfeiffer, Daniel

2012-01-01

Poly(3-hydroxybutyrate) (PHB) granules are covered by a surface layer consisting of mainly phasins and other PHB granule-associated proteins (PGAPs). Phasins are small amphiphilic proteins that determine the number and size of accumulated PHB granules. Five phasin proteins (PhaP1 to PhaP5) are known for Ralstonia eutropha. In this study, we identified three additional potential phasin genes (H16_B1988, H16_B2296, and H16_B2326) by inspection of the R. eutropha genome for sequences with “phasin 2 motifs.” To determine whether the corresponding proteins represent true PGAPs, fusions with eYFP (enhanced yellow fluorescent protein) were constructed. Similar fusions of eYFP with PhaP1 to PhaP5 as well as fusions with PHB synthase (PhaC1), an inactive PhaC1 variant (PhaC1-C319A), and PhaC2 were also made. All fusions were investigated in wild-type and PHB-negative backgrounds. Colocalization with PHB granules was found for all PhaC variants and for PhaP1 to PhaP5. Additionally, eYFP fusions with H16_B1988 and H16_B2326 colocalized with PHB. Fusions of H16_B2296 with eYFP, however, did not colocalize with PHB granules but did colocalize with the nucleoid region. Notably, all fusions (except H16_B2296) were soluble in a ΔphaC1 strain. These data confirm that H16_B1988 and H16_B2326 but not H16_B2296 encode true PGAPs, for which we propose the designation PhaP6 (H16_B1988) and PhaP7 (H16_B2326). When localization of phasins was investigated at different stages of PHB accumulation, fusions of PhaP6 and PhaP7 were soluble in the first 3 h under PHB-permissive conditions, although PHB granules appeared after 10 min. At later time points, the fusions colocalized with PHB. Remarkably, PHB granules of strains expressing eYFP fusions with PhaP5, PhaP6, or PhaP7 localized predominantly near the cell poles or in the area of future septum formation. This phenomenon was not observed for the other PGAPs (PhaP1 to PhaP4, PhaC1, PhaC1-C319A, and PhaC2) and indicated that some

Localization of poly(3-hydroxybutyrate) (PHB) granule-associated proteins during PHB granule formation and identification of two new phasins, PhaP6 and PhaP7, in Ralstonia eutropha H16.

PubMed

Pfeiffer, Daniel; Jendrossek, Dieter

2012-11-01

Poly(3-hydroxybutyrate) (PHB) granules are covered by a surface layer consisting of mainly phasins and other PHB granule-associated proteins (PGAPs). Phasins are small amphiphilic proteins that determine the number and size of accumulated PHB granules. Five phasin proteins (PhaP1 to PhaP5) are known for Ralstonia eutropha. In this study, we identified three additional potential phasin genes (H16_B1988, H16_B2296, and H16_B2326) by inspection of the R. eutropha genome for sequences with "phasin 2 motifs." To determine whether the corresponding proteins represent true PGAPs, fusions with eYFP (enhanced yellow fluorescent protein) were constructed. Similar fusions of eYFP with PhaP1 to PhaP5 as well as fusions with PHB synthase (PhaC1), an inactive PhaC1 variant (PhaC1-C319A), and PhaC2 were also made. All fusions were investigated in wild-type and PHB-negative backgrounds. Colocalization with PHB granules was found for all PhaC variants and for PhaP1 to PhaP5. Additionally, eYFP fusions with H16_B1988 and H16_B2326 colocalized with PHB. Fusions of H16_B2296 with eYFP, however, did not colocalize with PHB granules but did colocalize with the nucleoid region. Notably, all fusions (except H16_B2296) were soluble in a ΔphaC1 strain. These data confirm that H16_B1988 and H16_B2326 but not H16_B2296 encode true PGAPs, for which we propose the designation PhaP6 (H16_B1988) and PhaP7 (H16_B2326). When localization of phasins was investigated at different stages of PHB accumulation, fusions of PhaP6 and PhaP7 were soluble in the first 3 h under PHB-permissive conditions, although PHB granules appeared after 10 min. At later time points, the fusions colocalized with PHB. Remarkably, PHB granules of strains expressing eYFP fusions with PhaP5, PhaP6, or PhaP7 localized predominantly near the cell poles or in the area of future septum formation. This phenomenon was not observed for the other PGAPs (PhaP1 to PhaP4, PhaC1, PhaC1-C319A, and PhaC2) and indicated that some phasins

Natural Strain

NASA Technical Reports Server (NTRS)

Freed, Alan D.

1995-01-01

The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

Degradation of formaldehyde at high concentrations by phenol-adapted Ralstonia eutropha closely related to pink-pigmented facultative methylotrophs.

PubMed

Habibi, Alireza; Vahabzadeh, Farzaneh

2013-01-01

The ability of the phenol-adapted Ralstonia eutropha to utilize formaldehyde (FD) as the sole source of carbon and energy was studied. Adaptation to FD was accomplished by substituting FD for glucose in a stepwise manner. The bacterium in the liquid test culture could tolerate concentrations of FD up to 900 mg L(-1). Degradation of FD was complete in 528 h at 30°C with shaking at 150 rpm (r = 1.67 mg L(-1) h(-1)), q = 0.035 g(FD) g(cell) (-1) h(-1). Substrate inhibition kinetics (Haldane and Luong equations) are used to describe the experimental data. At non-inhibitory concentrations of FD, the Monod equation was used. According to the Luong model, the values of the maximum specific growth rate (μ(max)), half-saturation coefficient (k(S)), the maximum allowable formaldehyde concentration (S(m)), and the shape factor (n) were 0.117 h(-1), 47.6 mg L(-1), 900 mg L(-1), and 2.2, respectively. The growth response of the test bacterium to consecutive FD feedings was examined, and the FD-adapted R. eutropha cells were able to degrade 1000 mg L(-1) FD in 150 h through 4 cycles of FD feeds. During FD degradation, formic acid metabolite was formed. Assimilation of FD, methanol, formic acid, and oxalate by the test bacterium was accompanied by the formation of a pink pigment. The carotenoid nature of the cellular pigment has been confirmed and the test bacterium appeared to be closely related to pink-pigmented facultative methylotrophs (PPFM). The extent of harm to soil exposed to biotreated wastewaters containing FD may be moderated due to the association between methylotrophic/oxalotrophic bacteria and plants.

Natural Strain

NASA Technical Reports Server (NTRS)

Freed, Alan D.

1997-01-01

Logarithmic strain is the preferred measure of strain used by materials scientists, who typically refer to it as the "true strain." It was Nadai who gave it the name "natural strain," which seems more appropriate. This strain measure was proposed by Ludwik for the one-dimensional extension of a rod with length l. It was defined via the integral of dl/l to which Ludwik gave the name "effective specific strain." Today, it is after Hencky, who extended Ludwik's measure to three-dimensional analysis by defining logarithmic strains for the three principal directions.

Whole-Genome Microarray and Gene Deletion Studies Reveal Regulation of the Polyhydroxyalkanoate Production Cycle by the Stringent Response in Ralstonia eutropha H16

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brigham, CJ; Speth, DR; Rha, C

Poly(3-hydroxybutyrate) (PHB) production and mobilization in Ralstonia eutropha are well studied, but in only a few instances has PHB production been explored in relation to other cellular processes. We examined the global gene expression of wild-type R. eutropha throughout the PHB cycle: growth on fructose, PHB production using fructose following ammonium depletion, and PHB utilization in the absence of exogenous carbon after ammonium was resupplied. Our results confirm or lend support to previously reported results regarding the expression of PHB-related genes and enzymes. Additionally, genes for many different cellular processes, such as DNA replication, cell division, and translation, are selectivelymore » repressed during PHB production. In contrast, the expression levels of genes under the control of the alternative sigma factor sigma(54) increase sharply during PHB production and are repressed again during PHB utilization. Global gene regulation during PHB production is strongly reminiscent of the gene expression pattern observed during the stringent response in other species. Furthermore, a ppGpp synthase deletion mutant did not show an accumulation of PHB, and the chemical induction of the stringent response with DL-norvaline caused an increased accumulation of PHB in the presence of ammonium. These results indicate that the stringent response is required for PHB accumulation in R. eutropha, helping to elucidate a thus-far-unknown physiological basis for this process.« less

Screening and identification of aerobic denitrifiers

NASA Astrophysics Data System (ADS)

Shao, K.; Deng, H. M.; Chen, Y. T.; Zhou, H. J.; Yan, G. X.

2016-08-01

With the standards of the effluent quality more stringent, it becomes a quite serious problem for municipalities and industries to remove nitrogen from wastewater. Bioremediation is a potential method for the removal of nitrogen and other pollutants because of its high efficiency and low cost. Seven predominant aerobic denitrifiers were screened and characterized from the activated sludge in the CAST unit. Some of these strains removed 87% nitrate nitrogen at least. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Ralstonia, Achromobacter, Aeromonas and Enterobacter.

Crystallographic analysis and structure-guided engineering of NADPH-dependent Ralstonia sp. alcohol dehydrogenase toward NADH cosubstrate specificity.

PubMed

Lerchner, Alexandra; Jarasch, Alexander; Meining, Winfried; Schiefner, André; Skerra, Arne

2013-11-01

The NADP⁺-dependent alcohol dehydrogenase from Ralstonia sp. (RasADH) belongs to the protein superfamily of short-chain dehydrogenases/reductases (SDRs). As an enzyme that accepts different types of substrates--including bulky-bulky as well as small-bulky secondary alcohols or ketones--with high stereoselectivity, it offers potential as a biocatalyst for industrial biotechnology. To understand substrate and cosubstrate specificities of RasADH we determined the crystal structure of the apo-enzyme as well as its NADP⁺-bound state with resolutions down to 2.8 Å. RasADH displays a homotetrameric quaternary structure that can be described as a dimer of homodimers while in each subunit a seven-stranded parallel β-sheet, flanked by three α-helices on each side, forms a Rossmann fold-type dinucleotide binding domain. Docking of the well-known substrate (S)-1-phenylethanol clearly revealed the structural determinants of stereospecificity. To favor practical RasADH application in the context of established cofactor recycling systems, for example, those involving an NADH-dependent amino acid dehydrogenase, we attempted to rationally change its cosubstrate specificity from NADP⁺ to NAD⁺ utilizing the structural information that NADP⁺ specificity is largely governed by the residues Asn15, Gly37, Arg38, and Arg39. Furthermore, an extensive sequence alignment with homologous dehydrogenases that have different cosubstrate specificities revealed a modified general SDR motif ASNG (instead of NNAG) at positions 86-89 of RasADH. Consequently, we constructed mutant enzymes with one (G37D), four (N15G/G37D/R38V/R39S), and six (N15G/G37D/R38V/R39S/A86N/S88A) amino acid exchanges. RasADH (N15G/G37D/R38V/R39S) was better able to accept NAD⁺ while showing much reduced catalytic efficiency with NADP⁺, leading to a change in NADH/NADPH specificity by a factor of ∼3.6 million. © 2013 Wiley Periodicals, Inc.

Formation of a dinitrosyl iron complex by NorA, a nitric oxide-binding di-iron protein from Ralstonia eutropha H16.

PubMed

Strube, Katja; de Vries, Simon; Cramm, Rainer

2007-07-13

In Ralstonia eutropha H16, two genes, norA and norB, form a dicistronic operon that is controlled by the NO-responsive transcriptional regulator NorR. NorB has been identified as a membrane-bound NO reductase, but the physiological function of NorA is unknown. We found that, in a NorA deletion mutant, the promoter activity of the norAB operon was increased 3-fold, indicating that NorA attenuates activation of NorR. NorA shows limited sequence similarity to the oxygen carrier hemerythrin, which contains a di-iron center. Indeed, optical and EPR spectroscopy of purified NorA revealed the presence of a di-iron center, which binds oxygen in a similar way as hemerythrin. Diferrous NorA binds two molecules of NO maximally. Unexpectedly, binding of NO to the diferrous NorA required an external reductant. Two different NorA-NO species could be resolved. A minor species (up to 20%) showed an S = (1/2) EPR signal with g( perpendicular) = 2.041, and g( parallel) = 2.018, typical of a paramagnetic dinitrosyl iron complex. The major species was EPR-silent, showing characteristic signals at 420 nm and 750 nm in the optical spectrum. This species is proposed to represent a novel dinitrosyl iron complex of the form Fe(2+)-[NO](2)(2-), i.e. NO is bound as NO(-). The NO binding capacity of NorA in conjunction with its high cytoplasmic concentration (20 mum) suggests that NorA regulates transcription by lowering the free cytoplasmic concentration of NO.

Multiplex real-time PCR for detection, identification and quantification of 'Candidatus Liberibacter solanacearum' in potato plants with zebra chip.

PubMed

Li, Wenbin; Abad, Jorge A; French-Monar, Ronald D; Rascoe, John; Wen, Aimin; Gudmestad, Neil C; Secor, Gary A; Lee, Ing-Ming; Duan, Yongping; Levy, Laurene

2009-07-01

The new Liberibacter species, 'Candidatus Liberibacter solanacearum' (Lso) recently associated with potato/tomato psyllid-transmitted diseases in tomato and capsicum in New Zealand, was found to be consistently associated with a newly emerging potato zebra chip (ZC) disease in Texas and other southwestern states in the USA. A species-specific primer LsoF was developed for both quantitative real-time PCR (qPCR) and conventional PCR (cPCR) to detect and quantify Lso in infected samples. In multiplex qPCR, a plant cytochrome oxidase (COX)-based probe-primer set was used as a positive internal control for host plants, which could be used to reliably access the DNA extraction quality and to normalize qPCR data for accurate quantification of the bacterial populations in environment samples. Neither the qPCR nor the cPCR using the primer and/or probe sets with LsoF reacted with other Liberibacter species infecting citrus or other potato pathogens. The low detection limit of the multiplex qPCR was about 20 copies of the target 16S rDNA templates per reaction for field samples. Lso was readily detected and quantified in various tissues of ZC-affected potato plants collected from fields in Texas. A thorough but uneven colonization of Lso was revealed in various tissues of potato plants. The highest Lso populations were about 3x10(8) genomes/g tissue in the root, which were 3-order higher than those in the above-ground tissues of potato plants. The Lso bacterial populations were normally distributed across the ZC-affected potato plants collected from fields in Texas, with 60% of ZC-affected potato plants harboring an average Lso population from 10(5) to 10(6) genomes/g tissue, 4% of plants hosting above 10(7) Lso genomes/g tissue, and 8% of plants holding below 10(3) Lso genomes/g tissue. The rapid, sensitive, specific and reliable multiplex qPCR showed its potential to become a powerful tool for early detection and quantification of the new Liberibacter species associated

VpWRKY3, a biotic and abiotic stress-related transcription factor from the Chinese wild Vitis pseudoreticulata.

PubMed

Zhu, Ziguo; Shi, Jiangli; Cao, Jiangling; He, Mingyang; Wang, Yuejin

2012-11-01

Chinese wild grapevine Vitis pseudoreticulata accession 'Baihe-35-1' is identified as the precious resource with multiple resistances to pathogens. A directional cDNA library was constructed from the young leaves inoculated with Erysiphe necator. A total of 3,500 clones were sequenced, yielding 1,727 unigenes. Among them, 762 unigenes were annotated and classified into three classes, respectively, using Gene Ontology, including 22 ESTs related to transcription regulator activity. A novel WRKY transcription factor was isolated from the library, and designated as VpWRKY3 (GenBank Accession No. JF500755). The full-length cDNA is 1,280 bp, encoding a WRKY protein of 320 amino acids. VpWRKY3 is localized to nucleus and functions as a transcriptional activator. QRT-PCR analysis showed that the VpWRKY3 specifically accumulated in response to pathogen, salicylic acid, ethylene and drought stress. Overexpression of VpWRKY3 in tobacco increased the resistance to Ralstonia solanacearum, indicating that VpWRKY3 participates in defense response. Furthermore, VpWRKY3 is also involved in abscisic acid signal pathway and salt stress. This experiment provided an important basis for understanding the defense mechanisms mediated by WRKY genes in China wild grapevine. Generation of the EST collection from the cDNA library provided valuable information for the grapevine breeding. Key message We constructed a cDNA library from Chinese wild grapevine leaves inoculated with powdery mildew. VpWRKY3 was isolated and demonstrated that it was involved in biotic and abiotic stress responses.

A single amino acid insertion in the WRKY domain of the Arabidopsis TIR-NBS-LRR-WRKY-type disease resistance protein SLH1 (sensitive to low humidity 1) causes activation of defense responses and hypersensitive cell death.

PubMed

Noutoshi, Yoshiteru; Ito, Takuya; Seki, Motoaki; Nakashita, Hideo; Yoshida, Shigeo; Marco, Yves; Shirasu, Ken; Shinozaki, Kazuo

2005-09-01

In this study we characterized the sensitive to low humidity 1 (slh1) mutant of Arabidopsis ecotype No-0 which exhibits normal growth on agar plate medium but which on transfer to soil shows growth arrest and development of necrotic lesions. cDNA microarray hybridization and RNA gel blot analysis revealed that genes associated with activation of disease resistance were upregulated in the slh1 mutants in response to conditions of low humidity. Furthermore, the slh1 mutants accumulate callose, autofluorescent compounds and salicylic acid (SA). We demonstrate that SA is required for the slh1 phenotype but not PAD4 or NPR1. SLH1 was isolated by map-based cloning and it encodes a resistance (R)-like protein consisting of a domain with Toll and interleukin-1 receptor homology (TIR), a nucleotide-binding domain (NB), leucine-rich repeats (LRR) and a carboxy-terminal WRKY domain. SLH1 is identical to the R gene RRS1-R of the Arabidopsis ecotype Nd-1, a gene which confers resistance to the bacterial pathogen Ralstonia solanacearum GMI1000 and also functions as an R gene to this pathogen in No-0. We identified a 3 bp insertion mutation in slh1 that results in the addition of a single amino acid in the WRKY domain; thereby impairing its DNA-binding activity. Our data suggest that SLH1 disease resistance signaling may be negatively regulated by its WRKY domain in the R protein and that the constitutive defense activation conferred by the slh1 mutation is inhibited by conditions of high humidity.

Detection of and Response to Signals Involved in Host-Microbe Interactions by Plant-Associated Bacteria

PubMed Central

Brencic, Anja; Winans, Stephen C.

2005-01-01

Diverse interactions between hosts and microbes are initiated by the detection of host-released chemical signals. Detection of these signals leads to altered patterns of gene expression that culminate in specific and adaptive changes in bacterial physiology that are required for these associations. This concept was first demonstrated for the members of the family Rhizobiaceae and was later found to apply to many other plant-associated bacteria as well as to microbes that colonize human and animal hosts. The family Rhizobiaceae includes various genera of rhizobia as well as species of Agrobacterium. Rhizobia are symbionts of legumes, which fix nitrogen within root nodules, while Agrobacterium tumefaciens is a pathogen that causes crown gall tumors on a wide variety of plants. The plant-released signals that are recognized by these bacteria are low-molecular-weight, diffusible molecules and are detected by the bacteria through specific receptor proteins. Similar phenomena are observed with other plant pathogens, including Pseudomonas syringae, Ralstonia solanacearum, and Erwinia spp., although here the signals and signal receptors are not as well defined. In some cases, nutritional conditions such as iron limitation or the lack of nitrogen sources seem to provide a significant cue. While much has been learned about the process of host detection over the past 20 years, our knowledge is far from being complete. The complex nature of the plant-microbe interactions makes it extremely challenging to gain a comprehensive picture of host detection in natural environments, and thus many signals and signal recognition systems remain to be described. PMID:15755957

Role of the HoxZ subunit in the electron transfer pathway of the membrane-bound [NiFe]-hydrogenase from Ralstonia eutropha immobilized on electrodes.

PubMed

Sezer, Murat; Frielingsdorf, Stefan; Millo, Diego; Heidary, Nina; Utesch, Tillman; Mroginski, Maria-Andrea; Friedrich, Bärbel; Hildebrandt, Peter; Zebger, Ingo; Weidinger, Inez M

2011-09-01

The role of the diheme cytochrome b (HoxZ) subunit in the electron transfer pathway of the membrane-bound [NiFe]-hydrogenase (MBH) heterotrimer from Ralstonia eutropha H16 has been investigated. The MBH in its native heterotrimeric state was immobilized on electrodes and subjected to spectroscopic and electrochemical analysis. Surface enhanced resonance Raman spectroscopy was used to monitor the redox and coordination state of the HoxZ heme cofactors while concomitant protein film voltammetric measurements gave insights into the catalytic response of the enzyme on the electrode. The entire MBH heterotrimer as well as its isolated HoxZ subunit were immobilized on silver electrodes coated with self-assembled monolayers of ω-functionalized alkylthiols, displaying the preservation of the native heme pocket structure and an electrical communication between HoxZ and the electrode. For the immobilized MBH heterotrimer, catalytic reduction of the HoxZ heme cofactors was observed upon H(2) addition. The catalytic currents of MBH with and without the HoxZ subunit were measured and compared with the heterogeneous electron transfer rates of the isolated HoxZ. On the basis of the spectroscopic and electrochemical results, we conclude that the HoxZ subunit under these artificial conditions is not primarily involved in the electron transfer to the electrode but plays a crucial role in stabilizing the enzyme on the electrode. © 2011 American Chemical Society

Highly stretchable miniature strain sensor for large dynamic strain measurement

DOE PAGES

Song, Bo; Yao, Shurong; Nie, Xu; ...

2016-01-01

In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

High-level heterologous expression and properties of a novel lipase from Ralstonia sp. M1.

PubMed

Quyen, Dinh Thi; Giang Le, Thi Thu; Nguyen, Thi Thao; Oh, Tae-Kwang; Lee, Jung-Kee

2005-01-01

The mature lipase LipA and its 56aa-truncated chaperone DeltaLipBhis (with 6xhis-tag) from Ralstonia sp. M1 were over-expressed in Escherichia coli BL21 under the control of T7 promoter with a high level of 70 and 12mg protein per gram of wet cells, respectively. The simply purified lipase LipA was effectively refolded by Ni-NTA purified chaperone DeltaLipBhis in molar ratio 1:1 at 4 degrees C for 24 hours in H2O. The in vitro refolded lipase LipA had an optimal activity in the temperature range of 50-55 degrees C and was stable up to 45 degrees C with more than 84% activity retention. The maximal activity was observed at pH 10.75 for hydrolysis of olive oil and found to be stable over alkaline pH range 8.0-10.5 with more than 52% activity retention. The enzyme was found to be highly resistant to many organic solvents especially induced by ethanolamine (remaining activity 137-334%), but inhibited by 1-butanol and acetonitrile (40-86%). Metal ions Cu2+, Sn2+, Mn2+, Mg2+, and Ca2+ stimulated the lipase slightly with increase in activity by up to 22%, whereas Zn2+ significantly inhibited the enzyme with the residual activity of 30-65% and Fe3+ to a lesser degree (activity retention of 77-86%). Tween 80, Tween 60, and Tween 40 induced the activation of the lipase LipA (222-330%) and 0.2-1% (w/v) of Triton X-100, X-45, and SDS increased the lipase activity by up to 52%. However, 5% (w/v) of Triton X-100, X-45, and SDS inhibited strongly the activity by 31-89%. The inhibitors including DEPC, EDTA, PMSF, and 2-mercaptoethanol (0.1-10mM) inhibited moderately the lipase with remaining activity of 57-105%. The lipase LipA hydrolyzed a wide range of triglycerides, but preferentially short length acyl chains (C4 and C6). In contrast to the triglycerides, medium length acyl chains (C8 and C14) of p-nitrophenyl (p-NP) esters were preferential substrates of this lipase. The enzyme preferentially catalyzed the hydrolysis of cottonseed oil (317%), cornoil (227%), palm oil (222

An improved purification procedure for the soluble [NiFe]-hydrogenase of Ralstonia eutropha: new insights into its (in)stability and spectroscopic properties.

PubMed

van der Linden, Eddy; Burgdorf, Tanja; de Lacey, Antonio L; Buhrke, Thorsten; Scholte, Marcel; Fernandez, Victor M; Friedrich, Bärbel; Albracht, Simon P J

2006-03-01

Infrared (IR) spectra in combination with chemical analyses have recently shown that the active Ni-Fe site of the soluble NAD(+)-reducing [NiFe]-hydrogenase from Ralstonia eutropha contains four cyanide groups and one carbon monoxide as ligands. Experiments presented here confirm this result, but show that a variable percentage of enzyme molecules loses one or two of the cyanide ligands from the active site during routine purification. For this reason the redox conditions during the purification have been optimized yielding hexameric enzyme preparations (HoxFUYHI(2)) with aerobic specific H(2)-NAD(+) activities of 150-185 mumol/min/mg of protein (up to 200% of the highest activity previously reported in the literature). The preparations were highly homogeneous in terms of the active site composition and showed superior IR spectra. IR spectro-electrochemical studies were consistent with the hypothesis that only reoxidation of the reduced enzyme with dioxygen leads to the inactive state, where it is believed that a peroxide group is bound to nickel. Electron paramagnetic resonance experiments showed that the radical signal from the NADH-reduced enzyme derives from the semiquinone form of the flavin (FMN-a) in the hydrogenase module (HoxYH dimer), but not of the flavin (FMN-b) in the NADH-dehydrogenase module (HoxFU dimer). It is further demonstrated that the hexameric enzyme remains active in the presence of NADPH and air, whereas NADH and air lead to rapid destruction of enzyme activity. It is proposed that the presence of NADPH in cells keeps the enzyme in the active state.

Demonstration test of burner liner strain measurements using resistance strain gages

NASA Technical Reports Server (NTRS)

Grant, H. P.; Anderson, W. L.

1984-01-01

A demonstration test of burner liner strain measurements using resistance strain gages as well as a feasibility test of an optical speckle technique for strain measurement are presented. The strain gage results are reported. Ten Kanthal A-1 wire strain gages were used for low cycle fatigue strain measurements to 950 K and .002 apparent strain on a JT12D burner can in a high pressure (10 atmospheres) burner test. The procedure for use of the strain gages involved extensive precalibration and postcalibration to correct for cooling rate dependence, drift, and temperature effects. Results were repeatable within + or - .0002 to .0006 strain, with best results during fast decels from 950 K. The results agreed with analytical prediction based on an axisymmetric burner model, and results indicated a non-uniform circumferential distribution of axial strain, suggesting temperature streaking.

Diversity analysis of diazotrophic bacteria associated with the roots of tea (Camellia sinensis (L.) O. Kuntze).

PubMed

Gulati, Arvind; Sood, Swati; Rahi, Praveen; Thakur, Rishu; Chauhan, Sunita; Chawla, Isha

2011-06-01

The diversity elucidation by amplified ribosomal DNA restriction analysis and 16S rDNA sequencing of 96 associative diazotrophs, isolated from the feeder roots of tea on enriched nitrogen-free semisolid media, revealed the predominance of Gram-positive over Gram-negative bacteria within the Kangra valley in Himachal Pradesh, India. The Gram-positive bacteria observed belong to two taxonomic groupings; Firmicutes, including the genera Bacillus and Paenibacillus; and Actinobacteria, represented by the genus Microbacterium. The Gram-negative bacteria included alpha-Proteobacteria genera Brevundimonas, Rhizobium, and Mesorhizobium; gamma-Proteobacteria genera Pseudomonas and Stenotrophomonas; and beta-Proteobacteria genera Azospira, Burkholderia, Delftia, Herbaspirillum and Ralstonia. The low level of similarity of two isolates, with the type strains Paenibacillus xinjiangensis and Mesorhizobium albiziae, suggests the possibility of raising species novum. The bacterial strains of different phylogenetic groups exhibited distinct carbon-source utilization patterns and fatty acid methyl ester profiles. The strains differed in their nitrogenase activities with relatively high activity seen in the Gramnegative strains exhibiting the highest similarity to Azospira oryzae, Delftia lacustris and Herbaspirillum huttiense.

New Insights into PhaM-PhaC-Mediated Localization of Polyhydroxybutyrate Granules in Ralstonia eutropha H16

PubMed Central

Bresan, Stephanie

2017-01-01

ABSTRACT The formation and localization of polyhydroxybutyrate (PHB) granules in Ralstonia eutropha are controlled by PhaM, which interacts both with the PHB synthase (PhaC) and with the bacterial nucleoid. Here, we studied the importance of proline and lysine residues of two C-terminal PAKKA motifs in PhaM for their importance in attaching PHB granules to DNA by in vitro and in vivo methods. Substitution of the lysine residues but not of the proline residues resulted in detachment of formed PHB granules from the nucleoid. Instead, formation of PHB granule clusters at polar regions of the rod-shaped cells and an unequal distribution of PHB granules to daughter cells were observed. The formation of PHB granules was studied by the expression of chromosomally anchored gene fusions of fluorescent proteins with PhaM and PhaC in different backgrounds. PhaM and PhaC fusions showed a distinct colocalization at formed PHB granules in the nucleoid region of the wild type. In a ΔphaC background, PhaM and the catalytically inactive PhaCC319A protein were not able to form fluorescent foci, indicating that correct positioning requires the formation of PHB. Furthermore, time-lapse experiments revealed that PhaC and PhaM proteins detach from formed PHB granules at later stages, resulting in a nonhomogeneous population of PHB granules. This could explain why growth of individual PHB granules stops under PHB-permissive conditions at a certain size. IMPORTANCE PHB granules are storage compounds for carbon and energy in many prokaryotes. Equal distribution of accumulated PHB granules during cell division is therefore important for optimal fitness of the daughter cells. In R. eutropha, PhaM is responsible for maximal activity of PHB synthase, for initiation of PHB granule formation at discrete regions in the cells, and for association of formed PHB granules with the nucleoid. Here we found that four lysine residues of C-terminal PhaM sequence motifs are essential for association of

Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

PubMed

Nakagawa, Youji; Ogihara, Hiroyuki; Mochizuki, Chisato; Yamamura, Hideki; Iimura, Yuzuru; Hayakawa, Masayuki

2017-03-01

Previously reported self-cloning procedures for breeding of industrial yeast strains require DNA from other strains, plasmid DNA, or mutagenesis. Therefore, we aimed to construct a self-cloning baker's yeast strain that exhibits freeze tolerance via an improved self-cloning procedure. We first disrupted the URA3 gene of a prototrophic baker's yeast strain without the use of any marker gene, resulting in a Δura3 homozygous disruptant. Then, the URA3 gene of the parental baker's yeast strain was used as a selection marker to introduce the constitutive TDH3 promoter upstream of the PDE2 gene encoding high-affinity cyclic AMP phosphodiesterase. This self-cloning procedure was performed without using DNA from other Saccharomyces cerevisiae strains, plasmid DNA, or mutagenesis and was therefore designated an intra-strain self-cloning procedure. Using this self-cloning procedure, we succeeded in producing self-cloning baker's yeast strains that harbor the TDH3p-PDE2 gene heterozygously and homozygously, designated TDH3p-PDE2 hetero and TDH3p-PDE2 homo strains, respectively. These self-cloning strains expressed much higher levels of PDE2 mRNA than the parental strain and exhibited higher viability after freeze stress, as well as higher fermentation ability in frozen dough, when compared with the parental strain. The TDH3p-PDE2 homo strain was genetically more stable than the TDH3p-PDE2 hetero strain. These results indicate that both heterozygous and homozygous strains of self-cloning PDE2-overexpressing freeze-tolerant strains of industrial baker's yeast can be prepared using the intra-strain self-cloning procedure, and, from a practical viewpoint, the TDH3p-PDE2 homo strain constructed in this study is preferable to the TDH3p-PDE2 hetero strain for frozen dough baking. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Superlattice strain gage

DOEpatents

Noel, B.W.; Smith, D.L.; Sinha, D.N.

1988-06-28

A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element. 8 figs.

Measurement of high temperature strain by the laser-speckle strain gauge

NASA Technical Reports Server (NTRS)

Yamaguchi, I.

1984-01-01

By using the laser-speckle strain gauge, the strain of metal at the temperature lower than 250 C is measured. The principle of the gauge is to measure the expansion or contraction of the fine structures of surface by detecting the resultant speckle displacement in an optoelectronic way, whereby the effect of rigid-body motion is automatically cancelled out with the aid of a differential detection system. A transportable apparatus was built and a comparison experiment performed with a resistance strain gauge at room temperature. It has a strain sensitivity of .00002, a gauge length smaller than 1 mm, and no upper limit in a range of strain measurement. In the measurement of high-temperature strain it is free from the need for a dummy gauge and insensitive to an electric drift effect. As examples of strain measurement at high-temperature, thermal expansion and contraction of a top of a soldering iron are measured. The interval of the measurement can be made at shortest 1.6 sec. and the change in the strain is clearly followed until the ultimate stationary temperature is reached.

Resequencing of Capsicum annuum parental lines (YCM334 and Taean) for the genetic analysis of bacterial wilt resistance.

PubMed

Kang, Yang Jae; Ahn, Yul-Kyun; Kim, Ki-Taek; Jun, Tae-Hwan

2016-10-28

Bacterial wilt (BW) is a widespread plant disease that affects a broad range of dicot and monocot hosts and is particularly harmful for solanaceous plants, such as pepper, tomato, and eggplant. The pathogen responsible for BW is the soil-borne bacterium, Ralstonia solanacearum, which can adapt to diverse temperature conditions and is found in climates ranging from tropical to temperate. Resistance to BW has been detected in some pepper plant lines; however, the genomic loci and alleles that mediate this are poorly studied in this species. We resequenced the pepper cultivars YCM344 and Taean, which are parental recombinant inbred lines (RIL) that display differential resistance phenotypes against BW, with YCM344 being highly resistant to infection with this pathogen. We identified novel single nucleotide polymorphisms (SNPs) and insertions/deletions (Indels) that are only present in both parental lines, as compared to the reference genome and further determined variations that distinguish these two cultivars from one another. We then identified potentially informative SNPs that were found in genes related to those that have been previously associated with disease resistance, such as the R genes and stress response genes. Moreover, via comparative analysis, we identified SNPs located in genomic regions that have homology to known resistance genes in the tomato genomes. From our SNP profiling in both parental lines, we could identify SNPs that are potentially responsible for BW resistance, and practically, these may be used as markers for assisted breeding schemes using these populations. We predict that our analyses will be valuable for both better understanding the YCM334/Taean-derived populations, as well as for enhancing our knowledge of critical SNPs present in the pepper genome.

The phytopathogenic virulent effector protein RipI induces apoptosis in budding yeast Saccharomyces cerevisiae.

PubMed

Deng, Meng-Ying; Sun, Yun-Hao; Li, Pai; Fu, Bei; Shen, Dong; Lu, Yong-Jun

2016-10-01

Virulent protein toxins secreted by the bacterial pathogens can cause cytotoxicity by various molecular mechanisms to combat host cell defense. On the other hand, these proteins can also be used as probes to investigate the defense pathway of host innate immunity. Ralstonia solanacearum, one of the most virulent bacterial phytopathogens, translocates more than 70 effector proteins via type III secretion system during infection. Here, we characterized the cytotoxicity of effector RipI in budding yeast Saccharomyce scerevisiae, an alternative host model. We found that over-expression of RipI resulted in severe growth defect and arginine (R) 117 within the predicted integrase motif was required for inhibition of yeast growth. The phenotype of death manifested the hallmarks of apoptosis. Our data also revealed that RipI-induced apoptosis was independent of Yca1 and mitochondria-mediated apoptotic pathways because Δyca1 and Δaif1 were both sensitive to RipI as compared with the wild type. We further demonstrated that RipI was localized in the yeast nucleus and the N-terminal 1-174aa was required for the localization. High-throughput RNA sequencing analysis showed that upon RipI over-expression, 101 unigenes of yeast ribosome presented lower expression level, and 42 GO classes related to the nucleus or recombination were enriched with differential expression levels. Taken together, our data showed that a nuclear-targeting effector RipI triggers yeast apoptosis, potentially dependent on its integrase function. Our results also provided an alternative strategy to dissect the signaling pathway of cytotoxicity induced by the protein toxins. Copyright © 2016 Elsevier Ltd. All rights reserved.

Genome-wide identification and transcriptional expression analysis of mitogen-activated protein kinase and mitogen-activated protein kinase kinase genes in Capsicum annuum

PubMed Central

Liu, Zhiqin; Shi, Lanping; Liu, Yanyan; Tang, Qian; Shen, Lei; Yang, Sheng; Cai, Jinsen; Yu, Huanxin; Wang, Rongzhang; Wen, Jiayu; Lin, Youquan; Hu, Jiong; Liu, Cailing; Zhang, Yangwen; Mou, Shaoliang; He, Shuilin

2015-01-01

The tripartite mitogen-activated protein kinase (MAPK) signaling cascades have been implicated in plant growth, development, and environment adaptation, but a comprehensive understanding of MAPK signaling at genome-wide level is limited in Capsicum annuum. Herein, genome-wide identification and transcriptional expression analysis of MAPK and MAPK kinase (MAPKK) were performed in pepper. A total of 19 pepper MAPK (CaMAPKs) genes and five MAPKK (CaMAPKKs) genes were identified. Phylogenetic analysis indicated that CaMAPKs and CaMAPKKs could be classified into four groups and each group contains similar exon-intron structures. However, significant divergences were also found. Notably, five members of the pepper MAPKK family were much less conserved than those found in Arabidopsis, and 9 Arabidopsis MAPKs did not have orthologs in pepper. Additionally, 7 MAPKs in Arabidopsis had either two or three orthologs in the pepper genome, and six pepper MAPKs and one MAPKK differing in sequence were found in three pepper varieties. Quantitative real-time RT-PCR analysis showed that the majority of MAPK and MAPKK genes were ubiquitously expressed and transcriptionally modified in pepper leaves after treatments with heat, salt, and Ralstonia solanacearum inoculation as well as exogenously applied salicylic acid, methyl jasmonate, ethephon, and abscisic acid. The MAPKK-MAPK interactome was tested by yeast two-hybrid assay, the results showed that one MAPKK might interact with multiple MAPKs, one MAPK might also interact with more than one MAPKKs, constituting MAPK signaling networks which may collaborate in transmitting upstream signals into appropriate downstream cellular responses and processes. These results will facilitate future functional characterization of MAPK cascades in pepper. PMID:26442088

Application of Serratia marcescens RZ-21 significantly enhances peanut yield and remediates continuously cropped peanut soil.

PubMed

Ma, Hai-Yan; Yang, Bo; Wang, Hong-Wei; Yang, Qi-Yin; Dai, Chuan-Chao

2016-01-15

Continuous cropping practices cause a severe decline in peanut yield. The aim of this study was to investigate the remediation effect of Serratia marcescens on continuously cropped peanut soil. A pot experiment was conducted under natural conditions to determine peanut agronomic indices, soil microorganism characteristics, soil enzyme activities and antagonism ability to typical pathogens at different growth stages. Four treatments were applied to red soil as follows: an active fermentation liquor of S. marcescens (RZ-21), an equivalent sterilized fermentation liquor (M), an equivalent fermentation medium (P) and distilled water (CK). S. marcescens significantly inhibited the two typical plant pathogens Fusarium oxysporum A1 and Ralstonia solanacearum B1 and reduced their populations in rhizosphere soil. The RZ-21 treatment significantly increased peanut yield, vine dry weight, root nodules and taproot length by 62.3, 33, 72 and 61.4% respectively, followed by the M treatment. The P treatment also increased root nodules and root length slightly. RZ-21 also enhanced the activities of soil urease, sucrase and hydrogen peroxidase at various stages. In addition, RZ-21 and M treatments increased the average population of soil bacteria and decreased the average population of fungi in the three critical peanut growth stages, except for M in the case of the fungal population at flowering, thus balancing the structure of the soil microorganism community. This is the first report of S. marcescens being applied to continuously cropped peanut soil. The results suggest that S. marcescens RZ-21 has the potential to improve the soil environment and agricultural products and thus allow the development of sustainable management practices. © 2015 Society of Chemical Industry.

Recombinant Ralstonia eutropha engineered to utilize xylose and its use for the production of poly(3-hydroxybutyrate) from sunflower stalk hydrolysate solution.

PubMed

Kim, Hee Su; Oh, Young Hoon; Jang, Young-Ah; Kang, Kyoung Hee; David, Yokimiko; Yu, Ju Hyun; Song, Bong Keun; Choi, Jong-il; Chang, Yong Keun; Joo, Jeong Chan; Park, Si Jae

2016-06-03

Lignocellulosic raw materials have extensively been examined for the production of bio-based fuels, chemicals, and polymers using microbial platforms. Since xylose is one of the major components of the hydrolyzed lignocelluloses, it is being considered a promising substrate in lignocelluloses based fermentation process. Ralstonia eutropha, one of the most powerful and natural producers of polyhydroxyalkanoates (PHAs), has extensively been examined for the production of bio-based chemicals, fuels, and polymers. However, to the best of our knowledge, lignocellulosic feedstock has not been employed for R. eutropha probably due to its narrow spectrum of substrate utilization. Thus, R. eutropha engineered to utilize xylose should be useful in the development of microbial process for bio-based products from lignocellulosic feedstock. Recombinant R. eutropha NCIMB11599 expressing the E. coli xylAB genes encoding xylose isomerase and xylulokinase respectively, was constructed and examined for the synthesis of poly(3-hydroxybutyrate) [P(3HB)] using xylose as a sole carbon source. It could produce 2.31 g/L of P(3HB) with a P(3HB) content of 30.95 wt% when it was cultured in a nitrogen limited chemically defined medium containing 20.18 g/L of xylose in a batch fermentation. Also, recombinant R. eutropha NCIMB11599 expressing the E. coli xylAB genes produced 5.71 g/L of P(3HB) with a P(3HB) content of 78.11 wt% from a mixture of 10.05 g/L of glucose and 10.91 g/L of xylose in the same culture condition. The P(3HB) concentration and content could be increased to 8.79 g/L and 88.69 wt%, respectively, when it was cultured in the medium containing 16.74 g/L of glucose and 6.15 g/L of xylose. Further examination of recombinant R. eutropha NCIMB11599 expressing the E. coli xylAB genes by fed-batch fermentation resulted in the production of 33.70 g/L of P(3HB) in 108 h with a P(3HB) content of 79.02 wt%. The concentration of xylose could be maintained as high as 6 g/L, which is

The Effect of Ivermectin in Seven Strains of Aedes aegypti (Diptera: Culicidae) Including a Genetically Diverse Laboratory Strain and Three Permethrin Resistant Strains

PubMed Central

Deus, K. M.; Saavedra-rodriguez, K.; Butters, M. P.; Black, W. C.; Foy, B. D.

2014-01-01

Seven different strains of Aedes aegypti (L.), including a genetically diverse laboratory strain, three laboratory-selected permethrin-resistant strains, a standard reference strain, and two recently colonized strains were fed on human blood containing various concentrations of ivermectin. Ivermectin reduced adult survival, fecundity, and hatch rate of eggs laid by ivermectin-treated adults in all seven strains. The LC50 of ivermectin for adults and the concentration that prevented 50% of eggs from hatching was calculated for all strains. Considerable variation in adult survival after an ivermectin-bloodmeal occurred among strains, and all three permethrin-resistant strains were significantly less susceptible to ivermectin than the standard reference strain. The hatch rate after an ivermectin bloodmeal was less variable among strains, and only one of the permethrin-resistant strains differed significantly from the standard reference strain. Our studies suggest that ivermectin induces adult mortality and decreases the hatch rate of eggs through different mechanisms. A correlation analysis of log-transformed LC50 among strains suggests that permethrin and ivermectin cross-resistance may occur. PMID:22493855

Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains

PubMed Central

Gangaiah, Dharanesh; Webb, Kristen M.; Humphreys, Tricia L.; Fortney, Kate R.; Toh, Evelyn; Tai, Albert; Katz, Samantha S.; Pillay, Allan; Chen, Cheng-Yen; Roberts, Sally A.; Munson, Robert S.; Spinola, Stanley M.

2015-01-01

Background Although cutaneous ulcers (CU) in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU) and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin? Methodology/Principal Findings To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya) and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin. Conclusions/Significance These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions. PMID:26147869

Factors affecting finite strain estimation in low-grade, low-strain clastic rocks

NASA Astrophysics Data System (ADS)

Pastor-Galán, Daniel; Gutiérrez-Alonso, Gabriel; Meere, Patrick A.; Mulchrone, Kieran F.

2009-12-01

The computer strain analysis methods SAPE, MRL and DTNNM have permitted the characterization of finite strain in two different regions with contrasting geodynamic scenarios; (1) the Talas Ala Tau (Tien Shan, Kyrgyzs Republic) and (2) the Somiedo Nappe and Narcea Antiform (Cantabrian to West Asturian-Leonese Zone boundary, Variscan Belt, NW of Iberia). The performed analyses have revealed low-strain values and the regional strain trend in both studied areas. This study also investigates the relationship between lithology (grain size and percentage of matrix) and strain estimates the two methodologies used. The results show that these methods are comparable and the absence of significant finite strain lithological control in rocks deformed under low metamorphic and low-strain conditions.

To Be or Not To Be a Poly(3-Hydroxybutyrate) (PHB) Depolymerase: PhaZd1 (PhaZ6) and PhaZd2 (PhaZ7) of Ralstonia eutropha, Highly Active PHB Depolymerases with No Detectable Role in Mobilization of Accumulated PHB

PubMed Central

Sznajder, Anna

2014-01-01

The putative physiological functions of two related intracellular poly(3-hydroxybutyrate) (PHB) depolymerases, PhaZd1 and PhaZd2, of Ralstonia eutropha H16 were investigated. Purified PhaZd1 and PhaZd2 were active with native PHB granules in vitro. Partial removal of the proteinaceous surface layer of native PHB granules by trypsin treatment or the use of PHB granules isolated from ΔphaP1 or ΔphaP1-phaP5 mutant strains resulted in increased specific PHB depolymerase activity, especially for PhaZd2. Constitutive expression of PhaZd1 or PhaZd2 reduced or even prevented the accumulation of PHB under PHB-permissive conditions in vivo. Expression of translational fusions of enhanced yellow fluorescent protein (EYFP) with PhaZd1 and PhaZd2 in which the active-site serines (S190 and Ser193) were replaced with alanine resulted in the colocalization of only PhaZd1 fusions with PHB granules. C-terminal fusions of inactive PhaZd2(S193A) with EYFP revealed the presence of spindle-like structures, and no colocalization with PHB granules was observed. Chromosomal deletion of phaZd1, phaZd2, or both depolymerase genes had no significant effect on PHB accumulation and mobilization during growth in nutrient broth (NB) or NB-gluconate medium. Moreover, neither proteome analysis of purified native PHB granules nor lacZ fusion studies gave any indication that PhaZd1 or PhaZd2 was detectably present in the PHB granule fraction or expressed at all during growth on NB-gluconate medium. In conclusion, PhaZd1 and PhaZd2 are two PHB depolymerases with a high capacity to degrade PHB when artificially expressed but are apparently not involved in PHB mobilization in the wild type. The true in vivo functions of PhaZd1 and PhaZd2 remain obscure. PMID:24907326

To be or not to be a poly(3-hydroxybutyrate) (PHB) depolymerase: PhaZd1 (PhaZ6) and PhaZd2 (PhaZ7) of Ralstonia eutropha, highly active PHB depolymerases with no detectable role in mobilization of accumulated PHB.

PubMed

Sznajder, Anna; Jendrossek, Dieter

2014-08-01

The putative physiological functions of two related intracellular poly(3-hydroxybutyrate) (PHB) depolymerases, PhaZd1 and PhaZd2, of Ralstonia eutropha H16 were investigated. Purified PhaZd1 and PhaZd2 were active with native PHB granules in vitro. Partial removal of the proteinaceous surface layer of native PHB granules by trypsin treatment or the use of PHB granules isolated from ΔphaP1 or ΔphaP1-phaP5 mutant strains resulted in increased specific PHB depolymerase activity, especially for PhaZd2. Constitutive expression of PhaZd1 or PhaZd2 reduced or even prevented the accumulation of PHB under PHB-permissive conditions in vivo. Expression of translational fusions of enhanced yellow fluorescent protein (EYFP) with PhaZd1 and PhaZd2 in which the active-site serines (S190 and Ser193) were replaced with alanine resulted in the colocalization of only PhaZd1 fusions with PHB granules. C-terminal fusions of inactive PhaZd2(S193A) with EYFP revealed the presence of spindle-like structures, and no colocalization with PHB granules was observed. Chromosomal deletion of phaZd1, phaZd2, or both depolymerase genes had no significant effect on PHB accumulation and mobilization during growth in nutrient broth (NB) or NB-gluconate medium. Moreover, neither proteome analysis of purified native PHB granules nor lacZ fusion studies gave any indication that PhaZd1 or PhaZd2 was detectably present in the PHB granule fraction or expressed at all during growth on NB-gluconate medium. In conclusion, PhaZd1 and PhaZd2 are two PHB depolymerases with a high capacity to degrade PHB when artificially expressed but are apparently not involved in PHB mobilization in the wild type. The true in vivo functions of PhaZd1 and PhaZd2 remain obscure. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Sonication contribution to identifying prosthetic joint infection with Ralstonia pickettii: a case report and review of the literature.

PubMed

Birlutiu, Rares Mircea; Roman, Mihai Dan; Cismasiu, Razvan Silviu; Fleaca, Sorin Radu; Popa, Crina Maria; Mihalache, Manuela; Birlutiu, Victoria

2017-07-19

In the context of an increase number of primary and revision total hip and total knee arthroplasty performed yearly, an increased risk of complication is expected. Prosthetic joint infection (PJI) remains the most common and feared arthroplasty complication. Ralstonia pickettii is a Gram-negative bacterium, that has also been identified in biofilms. It remains an extremely rare cause of PJI. There is no report of an identification of R. pickettii on an extracted spacer loaded with antibiotic. We present the case of an 83-years-old Caucasian male patient, that underwent a right cemented total hip replacement surgery. The patient is diagnosed with an early PJI with no isolated microorganism. A debridement and change of mobile parts is performed. At the beginning of 2016, the patient in readmitted into the Orthopedic Department for sever, right abdominal and groin pain and elevated serum erythrocyte sedimentation rate and C-reactive protein. A joint aspiration is performed with a negative microbiological examination. A two-stage exchange with long interval management is adopted, and a preformed spacer loaded with gentamicin was implanted. In July 2016, based on the proinflammatory markers evolution, a shift a three-stage exchange strategy is decided. In September 2016, a debridement, and changing of the preformed spacer loaded with gentamicin with another was carried out. Bacteriological examination of the tissues sampled intraoperatively was positive for Pseudomonas aeruginosa. From the sonication fluid, no bacteria were isolated on culture or identified using the bbFISH assay. During the hospitalization period, the patient received i.v. ceftazidime 3x2g/day and p.o. ciprofloxacin 2x750mg/day, antibiotic therapy that was continued after discharge with p.o. ciprofloxacin 2x750mg/day for 6 weeks. In February 2017, a reimplantation of a revision prosthesis is performed. The retrieved spacer is sonicated, and after 4 days of incubation of the sonication fluid, R

Analysis of the tensile stress-strain behavior of elastomers at constant strain rates. I - Criteria for separability of the time and strain effects

NASA Technical Reports Server (NTRS)

Hong, S. D.; Fedors, R. F.; Schwarzl, F.; Moacanin, J.; Landel, R. F.

1981-01-01

A theoretical analysis of the tensile stress-strain relation of elastomers at constant strain rate is presented which shows that the time and the stress effect are separable if the experimental time scale coincides with a segment of the relaxation modulus that can be described by a single power law. It is also shown that time-strain separability is valid if the strain function is linearly proportional to the Cauchy strain, and that when time-strain separability holds, two strain-dependent quantities can be obtained experimentally. In the case where time and strain effect are not separable, superposition can be achieved only by using temperature and strain-dependent shift factors.

Hydrogen-induced structural changes at the nickel site of the regulatory [NiFe] hydrogenase from Ralstonia eutropha detected by X-ray absorption spectroscopy.

PubMed

Haumann, Michael; Porthun, Antje; Buhrke, Thorsten; Liebisch, Peter; Meyer-Klaucke, Wolfram; Friedrich, Bärbel; Dau, Holger

2003-09-23

For the first time, the nickel site of the hydrogen sensor of Ralstonia eutropha, the regulatory [NiFe] hydrogenase (RH), was investigated by X-ray absorption spectroscopy (XAS) at the nickel K-edge. The oxidation state and the atomic structure of the Ni site were investigated in the RH in the absence (air-oxidized, RH(ox)) and presence of hydrogen (RH(+H2)). Incubation with hydrogen is found to cause remarkable changes in the spectroscopic properties. The Ni-C EPR signal, indicative of Ni(III), is detectable only in the RH(+H2) state. XANES and EXAFS spectra indicate a coordination of the Ni in the RH(ox) and RH(+H2) that pronouncedly differs from the one in standard [NiFe] hydrogenases. Also, the changes induced by exposure to H(2) are unique. A drastic modification in the XANES spectra and an upshift of the K-edge energy from 8339.8 (RH(ox)) to 8341.1 eV (RH(+H2)) is observed. The EXAFS spectra indicate a change in the Ni coordination in the RH upon exposure to H(2). One likely interpretation of the data is the detachment of one sulfur ligand in RH(+H2) and the binding of additional (O,N) or H ligands. The following Ni oxidation states and coordinations are proposed: five-coordinated Ni(II)(O,N)(2)S(3) for RH(ox) and six-coordinated Ni((III))(O,N)(3)X(1)S(2) [X being either an (O,N) or H ligand] for RH(+H2). Implications of the structural features of the Ni site of the RH in relation to its function, hydrogen sensing, are discussed.

Biochemical characterization of Gram-positive and Gram-negative plant-associated bacteria with micro-Raman spectroscopy.

PubMed

Paret, Mathews L; Sharma, Shiv K; Green, Lisa M; Alvarez, Anne M

2010-04-01

Raman spectra of Gram-positive and Gram-negative plant bacteria have been measured with micro-Raman spectrometers equipped with 785 and 514.5 nm lasers. The Gram-positive bacteria Microbacterium testaceum, Paenibacillus validus, and Clavibacter michiganensis subsp. michiganensis have strong carotenoid bands in the regions 1155-1157 cm(-1) and 1516-1522 cm(-1) that differentiate them from other tested Gram-negative bacteria. In the Raman spectrum of Gram-positive bacteria Bacillus megaterium excited with 785 nm laser, the Raman bands at 1157 and 1521 cm(-1) are weak in intensity compared to other Gram-positive bacteria, and these bands did not show significant resonance Raman enhancement in the spectrum recorded with 514.5 nm laser excitation. The Gram-positive bacteria could be separated from each other based on the bands associated with the in-phase C=C (v(1)) vibrations of the polyene chain of carotenoids. None of the Gram-negative bacteria tested had carotenoid bands. The bacteria in the genus Xanthomonas have a carotenoid-like pigment, xanthomonadin, identified in Xanthomonas axonopodis pv. dieffenbachiae, and it is a unique Raman marker for the bacteria. The representative bands for xanthomonadin were the C-C stretching (v(2)) vibrations of the polyene chain at 1135-1136 cm(-1) and the in-phase C=C (v(1)) vibrations of the polyene chain at 1529-1531 cm(-1), which were distinct from the carotenoid bands of other tested bacteria. The tyrosine peak in the region 1170-1175 cm(-1) was the only other marker present in Gram-negative bacteria that was absent in all tested Gram-positives. A strong-intensity exopolysaccharide-associated marker at 1551 cm(-1) is a distinguishable feature of Enterobacter cloacae. The Gram-negative Agrobacterium rhizogenes and Ralstonia solanacearum were differentiated from each other and other tested bacteria on the basis of presence or absence and relative intensities of peaks. The principal components analysis (PCA) of the spectra

Geobacteraceae strains and methods

DOEpatents

Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

2015-07-07

Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

Highly Invasive Listeria monocytogenes Strains Have Growth and Invasion Advantages in Strain Competition

PubMed Central

Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N.

2015-01-01

Multiple Listeria monocytogenes strains can be present in the same food sample; moreover, infection with more than one L. monocytogenes strain can also occur. In this study we investigated the impact of strain competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor strains, whose growth was not (or only slightly) influenced by the presence of other strains and two weak competitor strains, which were outcompeted by other strains. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor strains showed high invasiveness. Moreover, invasion efficiency of the highly invasive strain was further increased in certain combinations by the presence of a low invasive strain. In all tested combinations, the less invasive strain was outcompeted by the higher invasive strain. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential. PMID:26529510

Characterization of the ZAT1p zinc transporter from Arabidopsis thaliana in microbial model organisms and reconstituted proteoliposomes.

PubMed

Bloss, Tanja; Clemens, Stephan; Nies, Dietrich H

2002-03-01

The ZAT1p zinc transporter from Arabidopsis thaliana (L.) Heynh. is a member of the cation diffusion facilitator (CDF) protein family. When heterologously expressed in Escherichia coli, ZAT1p bound zinc in a metal blot. Binding of zinc occurred mainly to the hydrophilic amino acid region from H182 to H232. A ZAT1p/ZAT1p*Delta(M1-I25) protein mixture was purified and reconstituted into proteoliposomes. Uptake of zinc into the proteoliposomes did not require a proton gradient across the liposomal membrane. ZAT1p did not transport cobalt, and transported cadmium at only 1% of the zinc transport rate. ZAT1p functioned as an uptake system for 65Zn2+ in two strains of the Gram-negative bacterium Ralstonia metallidurans, which were different in their content of zinc-efflux systems. The ZAT1 gene did not rescue increased zinc sensitivity of a Delta ZRC1single-mutant strain or of a Delta ZRC1 Delta COT1 double-mutant strain of Saccharomyces cerevisiae, but ZAT1 complemented this phenotype in a Delta SpZRC1 mutant strain of Schizosaccharomyces pombe.

Photothermal strain imaging

NASA Astrophysics Data System (ADS)

Choi, Changhoon; Ahn, Joongho; Jeon, Seungwan; Kim, Chulhong

2017-07-01

Vulnerable plaques are the major cause of cardiovascular disease, but they are difficult to detect with conventional intravascular imaging techniques. Techniques are needed to identify plaque vulnerability based on the presence of lipids in plaque. Thermal strain imaging (TSI) is an imaging technique based on ultrasound (US) wave propagation speed, which varies with the medium temperature. In TSI, the strain that occurs during tissue temperature change can be used for lipid detection because it has a different tendency depending on the type of tissue. Here, we demonstrate photothermal strain imaging (pTSI) using an intravascular ultrasound catheter. pTSI is performed by slightly and selectively heating lipid using a relatively inexpensive continuous laser source. We applied a speckle-tracking algorithm to US B-mode images for strain calculations. As a result, the strain produced in porcine fat was different from the strain produced in water-bearing gelatin phantom, which made it possible to distinguish the two. This suggests that pTSI could potentially be a way of differentiating lipids in coronary artery.

High temperature strain measurement with a resistance strain gage

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Fichtel, ED; Mcdaniel, Amos

1993-01-01

A PdCr based electrical resistance strain gage was demonstrated in the laboratory to be a viable sensor candidate for static strain measurement at high temperatures. However, difficulties were encountered while transferring the sensor to field applications. This paper is therefore prepared for recognition and resolution of the problems likely to be encountered with PdCr strain gages in field applications. Errors caused by the measurement system, installation technique and lead wire attachment are discussed. The limitations and some considerations related to the temperature compensation technique used for this gage are also addressed.

Investigation of the interface characteristics of Y2O3/GaAs under biaxial strain, triaxial strain, and non-strain conditions

NASA Astrophysics Data System (ADS)

Shi, Li-Bin; Liu, Xu-Yang; Dong, Hai-Kuan

2016-09-01

We investigate the interface behaviors of Y2O3/GaAs under biaxial strain, triaxial strain, and non-strain conditions. This study is performed by first principles calculations based on density functional theory (DFT). First of all, the biaxial strain is realized by changing the lattice constants in ab plane. Averaged electrostatic potential (AEP) is aligned by establishing Y2O3 and GaAs (110) surfaces. The band offsets of Y2O3/GaAs interface under biaxial strain are investigated by generalized gradient approximation and Heyd-Scuseria-Ernzerhof (HSE) functionals. The interface under biaxial strain is suitable for the design of metal oxide semiconductor (MOS) devices because the valence band offsets (VBO) and conduction band offsets (CBO) are larger than 1 eV. Second, the triaxial strain is applied to Y2O3/GaAs interface by synchronously changing the lattice constants in a, b, and c axis. The band gaps of Y2O3 and GaAs under triaxial strain are investigated by HSE functional. We compare the VBO and CBO under triaxial strain with those under biaxial strain. Third, in the absence of lattice strain, the formation energies, charge state switching levels, and migration barriers of native defects in Y2O3 are assessed. We investigate how they will affect the MOS device performance. It is found that VO+2 and Oi-2 play a very dangerous role in MOS devices. Finally, a direct tunneling leakage current model is established. The model is used to analyze current and voltage characteristics of the metal/Y2O3/GaAs.

The H(2) sensor of Ralstonia eutropha: biochemical and spectroscopic analysis of mutant proteins modified at a conserved glutamine residue close to the [NiFe] active site.

PubMed

Buhrke, Thorsten; Brecht, Marc; Lubitz, Wolfgang; Friedrich, Bärbel

2002-09-01

[NiFe] hydrogenases contain a highly conserved histidine residue close to the [NiFe] active site which is altered by a glutamine residue in the H(2)-sensing [NiFe] hydrogenases. In this study, we exchanged the respective glutamine residue of the H(2) sensor (RH) of Ralstonia eutropha, Q67 of the RH large subunit HoxC, by histidine, asparagine and glutamate. The replacement by histidine and asparagine resulted in slightly unstable RH proteins which were hardly affected in their regulatory and enzymatic properties. The exchange to glutamate led to a completely unstable RH protein. The purified wild-type RH and the mutant protein with the Gln/His exchange were analysed by continuous-wave and pulsed electron paramagnetic resonance (EPR) techniques. We observed a coupling of a nitrogen nucleus with the [NiFe] active site for the mutant protein which was absent in the spectrum of the wild-type RH. A combination of theoretical calculations with the experimental data provided an explanation for the observed coupling. It is shown that the coupling is due to the formation of a weak hydrogen bond between the protonated N(epsilon) nucleus of the histidine with the sulfur of a conserved cysteine residue which coordinates the metal atoms of the [NiFe] active site as a bridging ligand. The effect of this hydrogen bond on the local structure of the [NiFe] active site is discussed.

Direct measurement of intrinsic critical strain and internal strain in barrier films

NASA Astrophysics Data System (ADS)

Vellinga, W. P.; De Hosson, J. Th. M.; Bouten, P. C. P.

2011-08-01

Resistance measurements during uniaxial tensile deformation of very thin (10 nm) conducting oxide films deposited on 150 nm SiN films on polyethylene naphthalate are discussed. It is first shown that certain characteristics of resistance versus strain curves are representative for the fracture behavior of the SiN film and not for that of the thin conducting oxide film. Subsequently, it is shown that the hysteresis in curves of resistance as a function of strain offers a way to directly measure the intrinsic critical strain of the SiN film without the need to determine internal strains from independent (curvature) measurements that rely on knowledge of moduli and geometry. The method should be applicable, in general, to measure intrinsic critical strain and residual strains of thin brittle films on polymers. Advantages and limitations of the method are discussed.

Geodetic Strain Analysis Tool

NASA Technical Reports Server (NTRS)

Kedar, Sharon; Baxter, Sean C.; Parker, Jay W.; Webb, Frank H.; Owen, Susan E.; Sibthorpe, Anthony J.; Dong, Danan

2011-01-01

A geodetic software analysis tool enables the user to analyze 2D crustal strain from geodetic ground motion, and create models of crustal deformation using a graphical interface. Users can use any geodetic measurements of ground motion and derive the 2D crustal strain interactively. This software also provides a forward-modeling tool that calculates a geodetic velocity and strain field for a given fault model, and lets the user compare the modeled strain field with the strain field obtained from the user s data. Users may change parameters on-the-fly and obtain a real-time recalculation of the resulting strain field. Four data products are computed: maximum shear, dilatation, shear angle, and principal components. The current view and data dependencies are processed first. The remaining data products and views are then computed in a round-robin fashion to anticipate view changes. When an analysis or display parameter is changed, the affected data products and views are invalidated and progressively re-displayed as available. This software is designed to facilitate the derivation of the strain fields from the GPS and strain meter data that sample it to facilitate the understanding of the strengths and weaknesses of the strain field derivation from continuous GPS (CGPS) and other geodetic data from a variety of tectonic settings, to converge on the "best practices" strain derivation strategy for the Solid Earth Science ESDR System (SESES) project given the CGPS station distribution in the western U.S., and to provide SESES users with a scientific and educational tool to explore the strain field on their own with user-defined parameters.

Electronic strain-level counter

NASA Technical Reports Server (NTRS)

Pitts, F. L.; Spencer, J. L. (Inventor)

1973-01-01

An electronic strain level counter for obtaining structural strain data on in-flight aircraft is described. The device counts the number of times the strain at a point on an aircraft structural member exceeds each of several preset levels. A dead band is provided at each level to prohibit the counting of small strain variations around a given preset level.

Strain measurement based battery testing

DOEpatents

Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

2017-05-23

A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

Elevated temperature strain gages

NASA Technical Reports Server (NTRS)

Brittain, J. O.; Geslin, D.; Lei, J. F.

1985-01-01

Materials were evaluated that could be used in manufacturing electrical resistance strain gages for static strain measurements at temperatures at or above 1273 K. Strain gage materials must have a characteristic response to strain, temperature and time that is reproducible or that varies in a predictable manner within specified limits. Several metallic alloys were evaluated, as well as a series of transition metal carbides, nitrides and silicides.

Quantitative assessment of viable cells of Lactobacillus plantarum strains in single, dual and multi-strain biofilms.

PubMed

Fernández Ramírez, Mónica D; Kostopoulos, Ioannis; Smid, Eddy J; Nierop Groot, Masja N; Abee, Tjakko

2017-03-06

Biofilms of Lactobacillus plantarum are a potential source for contamination and recontamination of food products. Although biofilms have been mostly studied using single species or even single strains, it is conceivable that in a range of environmental settings including food processing areas, biofilms are composed of multiple species with each species represented by multiple strains. In this study six spoilage related L. plantarum strains FBR1-FBR6 and the model strain L. plantarum WCFS1 were characterised in single, dual and multiple strain competition models. A quantitative PCR approach was used with added propidium monoazide (PMA) enabling quantification of intact cells in the biofilm, representing the viable cell fraction that determines the food spoilage risk. Our results show that the performance of individual strains in multi-strain cultures generally correlates with their performance in pure culture, and relative strain abundance in multi-strain biofilms positively correlated with the relative strain abundance in suspended (planktonic) cultures. Performance of individual strains in dual-strain biofilms was highly influenced by the presence of the secondary strain, and in most cases no correlation between the relative contributions of viable planktonic cells and viable cells in the biofilm was noted. The total biofilm quantified by CV staining of the dual and multi-strain biofilms formed was mainly correlated to CV values of the dominant strain obtained in single strain studies. However, the combination of strain FBR5 and strain WCFS1 showed significantly higher CV values compared to the individual performances of both strains indicating that total biofilm formation was higher in this specific condition. Notably, L. plantarum FBR5 was able to outgrow all other strains and showed the highest relative abundance in dual and multi-strain biofilms. All the dual and multi-strain biofilms contained a considerable number of viable cells, representing a potential

Strain expansion-reduction approach

NASA Astrophysics Data System (ADS)

Baqersad, Javad; Bharadwaj, Kedar

2018-02-01

Validating numerical models are one of the main aspects of engineering design. However, correlating million degrees of freedom of numerical models to the few degrees of freedom of test models is challenging. Reduction/expansion approaches have been traditionally used to match these degrees of freedom. However, the conventional reduction/expansion approaches are only limited to displacement, velocity or acceleration data. While in many cases only strain data are accessible (e.g. when a structure is monitored using strain-gages), the conventional approaches are not capable of expanding strain data. To bridge this gap, the current paper outlines a reduction/expansion technique to reduce/expand strain data. In the proposed approach, strain mode shapes of a structure are extracted using the finite element method or the digital image correlation technique. The strain mode shapes are used to generate a transformation matrix that can expand the limited set of measurement data. The proposed approach can be used to correlate experimental and analytical strain data. Furthermore, the proposed technique can be used to expand real-time operating data for structural health monitoring (SHM). In order to verify the accuracy of the approach, the proposed technique was used to expand the limited set of real-time operating data in a numerical model of a cantilever beam subjected to various types of excitations. The proposed technique was also applied to expand real-time operating data measured using a few strain gages mounted to an aluminum beam. It was shown that the proposed approach can effectively expand the strain data at limited locations to accurately predict the strain at locations where no sensors were placed.

Effects of environmental parameters on the dual-species biofilms formed by Escherichia coli O157:H7 and Ralstonia insidiosa, a strong biofilm producer isolated from a fresh-cut produce processing plant.

PubMed

Liu, Nancy T; Nou, Xiangwu; Bauchan, Gary R; Murphy, Charles; Lefcourt, Alan M; Shelton, Daniel R; Lo, Y Martin

2015-01-01

Biofilm-forming bacteria resident to food processing facilities are a food safety concern due to the potential of biofilms to harbor foodborne bacterial pathogens. When cultured together, Ralstonia insidiosa, a strong biofilm former frequently isolated from produce processing environments, has been shown to promote the incorporation of Escherichia coli O157:H7 into dual-species biofilms. In this study, interactions between E. coli O157:H7 and R. insidiosa were examined under different incubating conditions. Under static culture conditions, the incorporation of E. coli O157:H7 into biofilms with R. insidiosa was not significantly affected by either low incubating temperature (10°C) or by limited nutrient availability. Greater enhancement of E. coli O157:H7 incorporation in dual-species biofilms was observed by using a continuous culture system with limited nutrient availability. Under the continuous culture conditions used in this study, E coli O157:H7 cells showed a strong tendency of colocalizing with R. insidiosa on a glass surface at the early stage of biofilm formation. As the biofilms matured, E coli O157:H7 cells were mostly found at the bottom layer of the dual-species biofilms, suggesting an effective protection by R. insidiosa in the mature biofilms.

Acidovorax anthurii sp. nov., a new phytopathogenic bacterium which causes bacterial leaf-spot of anthurium.

PubMed

Gardan, L; Dauga, C; Prior, P; Gillis, M; Saddler, G S

2000-01-01

The bacterial leaf-spot of anthurium emerged during the 1980s, in the French West Indies and Trinidad. This new bacterial disease is presently wide spread and constitutes a serious limiting factor for commercial anthurium production. Twenty-nine strains isolated from leaf-spots of naturally infected anthurium were characterized and compared with reference strains belonging to the Comamonadaceae family, the genera Ralstonia and Burkholderia, and representative fluorescent pseudomonads. From artificial inoculations 25 out of 29 strains were pathogenic on anthurium. Biochemical and physiological tests, fatty acid analysis, DNA-DNA hybridization, 16S rRNA gene sequence analysis, DNA-16S RNA hybridization were performed. The 25 pathogenic strains on anthurium were clustered in one phenon closely related to phytopathogenic strains of the genus Acidovorax. Anthurium strains were 79-99% (deltaTm range 0.2-1.6) related to the strain CFBP 3232 and constituted a discrete DNA homology group indicating that they belong to the same species. DNA-rRNA hybridization, 16S rRNA sequence and fatty acid analysis confirmed that this new species belongs to the beta-subclass of Proteobacteria and to rRNA superfamily III, to the family of Comamonadaceae and to the genus Acidovorax. The name Acidovorax anthurii is proposed for this new phytopathogenic bacterium. The type strain has been deposited in the Collection Française des Bactéries Phytopathogènes as CFBP 3232T.

Sb-induced strain fluctuations in a strained layer superlattice of InAs/InAsSb

NASA Astrophysics Data System (ADS)

Kim, Honggyu; Meng, Yifei; Klem, John F.; Hawkins, Samuel D.; Kim, Jin K.; Zuo, Jian-Min

2018-04-01

We show that Sb substitution for As in a MBE grown InAs/InAsSb strained layer superlattice (SLS) is accompanied by significant strain fluctuations. The SLS was observed using scanning transmission electron microscopy along the [100] zone axis where the cation and anion atomic columns are separately resolved. Strain analysis based on atomic column positions reveals asymmetrical transitions in the strain profile across the SLS interfaces. The averaged strain profile is quantitatively fitted to the segregation model, which yields a distribution of Sb in agreement with the scanning tunneling microscopy result. The subtraction of the calculated strain reveals an increase in strain fluctuations with the Sb concentration, as well as isolated regions with large strain deviations extending spatially over ˜1 nm, which suggest the presence of point defects.

Specific Responses of Salmonella enterica to Tomato Varieties and Fruit Ripeness Identified by In Vivo Expression Technology

PubMed Central

Noel, Jason T.; Arrach, Nabil; Alagely, Ali; McClelland, Michael; Teplitski, Max

2010-01-01

Background Recent outbreaks of vegetable-associated gastroenteritis suggest that enteric pathogens colonize, multiply and persist in plants for extended periods of time, eventually infecting people. Genetic and physiological pathways, by which enterics colonize plants, are still poorly understood. Methodology/Principal Findings To better understand interactions between Salmonella enterica sv. Typhimurium and tomatoes, a gfp-tagged Salmonella promoter library was screened inside red ripe fruits. Fifty-one unique constructs that were potentially differentially regulated in tomato relative to in vitro growth were identified. The expression of a subset of these promoters was tested in planta using recombinase-based in vivo expression technology (RIVET) and fitness of the corresponding mutants was tested. Gene expression in Salmonella was affected by fruit maturity and tomato cultivar. A putative fadH promoter was upregulated most strongly in immature tomatoes. Expression of the fadH construct depended on the presence of linoleic acid, which is consistent with the reduced accumulation of this compound in mature tomato fruits. The cysB construct was activated in the fruit of cv. Hawaii 7997 (resistant to a race of Ralstonia solanacearum) more strongly than in the universally susceptible tomato cv. Bonny Best. Known Salmonella motility and animal virulence genes (hilA, flhDC, fliF and those encoded on the pSLT virulence plasmid) did not contribute significantly to fitness of the bacteria inside tomatoes, even though deletions of sirA and motA modestly increased fitness of Salmonella inside tomatoes. Conclusions/Significance This study reveals the genetic basis of the interactions of Salmonella with plant hosts. Salmonella relies on a distinct set of metabolic and regulatory genes, which are differentially regulated in planta in response to host genotype and fruit maturity. This enteric pathogen colonizes tissues of tomatoes differently than plant pathogens, and relies

Airborne Signals from a Wounded Leaf Facilitate Viral Spreading and Induce Antibacterial Resistance in Neighboring Plants

PubMed Central

Dorokhov, Yuri L.; Komarova, Tatiana V.; Petrunia, Igor V.; Frolova, Olga Y.; Pozdyshev, Denis V.; Gleba, Yuri Y.

2012-01-01

Many plants release airborne volatile compounds in response to wounding due to pathogenic assault. These compounds serve as plant defenses and are involved in plant signaling. Here, we study the effects of pectin methylesterase (PME)-generated methanol release from wounded plants (“emitters”) on the defensive reactions of neighboring “receiver” plants. Plant leaf wounding resulted in the synthesis of PME and a spike in methanol released into the air. Gaseous methanol or vapors from wounded PME-transgenic plants induced resistance to the bacterial pathogen Ralstonia solanacearum in the leaves of non-wounded neighboring “receiver” plants. In experiments with different volatile organic compounds, gaseous methanol was the only airborne factor that could induce antibacterial resistance in neighboring plants. In an effort to understand the mechanisms by which methanol stimulates the antibacterial resistance of “receiver” plants, we constructed forward and reverse suppression subtractive hybridization cDNA libraries from Nicotiana benthamiana plants exposed to methanol. We identified multiple methanol-inducible genes (MIGs), most of which are involved in defense or cell-to-cell trafficking. We then isolated the most affected genes for further analysis: β-1,3-glucanase (BG), a previously unidentified gene (MIG-21), and non-cell-autonomous pathway protein (NCAPP). Experiments with Tobacco mosaic virus (TMV) and a vector encoding two tandem copies of green fluorescent protein as a tracer of cell-to-cell movement showed the increased gating capacity of plasmodesmata in the presence of BG, MIG-21, and NCAPP. The increased gating capacity is accompanied by enhanced TMV reproduction in the “receivers”. Overall, our data indicate that methanol emitted by a wounded plant acts as a signal that enhances antibacterial resistance and facilitates viral spread in neighboring plants. PMID:22496658

Hamstring strain - aftercare

MedlinePlus

Pulled hamstring muscle; Sprain - hamstring ... There are 3 levels of hamstring strains: Grade 1 -- mild muscle strain or pull Grade 2 -- partial muscle tear Grade 3 -- complete muscle tear Recovery time depends ...

Strain Gage

NASA Technical Reports Server (NTRS)

1995-01-01

HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.

Relationships of left ventricular strain and strain rate to wall stress and their afterload dependency.

PubMed

Murai, Daisuke; Yamada, Satoshi; Hayashi, Taichi; Okada, Kazunori; Nishino, Hisao; Nakabachi, Masahiro; Yokoyama, Shinobu; Abe, Ayumu; Ichikawa, Ayako; Ono, Kota; Kaga, Sanae; Iwano, Hiroyuki; Mikami, Taisei; Tsutsui, Hiroyuki

2017-05-01

Whether and how left ventricular (LV) strain and strain rate correlate with wall stress is not known. Furthermore, it is not determined whether strain or strain rate is less dependent on the afterload. In 41 healthy young adults, LV global peak strain and systolic peak strain rate in the longitudinal direction (LS and LSR, respectively) and circumferential direction (CS and CSR, respectively) were measured layer-specifically using speckle tracking echocardiography (STE) before and during a handgrip exercise. Among all the points before and during the exercise, all the STE parameters significantly correlated linearly with wall stress (LS: r = -0.53, p < 0.01, LSR: r = -0.28, p < 0.05, CS in the inner layer: r = -0.72, p < 0.01, CSR in the inner layer: r = -0.47, p < 0.01). Strain more strongly correlated with wall stress than strain rate (r = -0.53 for LS vs. r = -0.28 for LSR, p < 0.05; r = -0.72 for CS vs. r = -0.47 for CSR in the inner layer, p < 0.05), whereas the interobserver variability was similar between strain and strain rate (longitudinal 6.2 vs. 5.2 %, inner circumferential 4.8 vs. 4.7 %, mid-circumferential 7.9 vs. 6.9 %, outer circumferential 10.4 vs. 9.7 %), indicating that the differences in correlation coefficients reflect those in afterload dependency. It was thus concluded that LV strain and strain rate linearly and inversely correlated with wall stress in the longitudinal and circumferential directions, and strain more strongly depended on afterload than did strain rate. Myocardial shortening should be evaluated based on the relationships between these parameters and wall stress.

Sb-induced strain fluctuations in a strained layer superlattice of InAs/InAsSb

DOE PAGES

Kim, Honggyu; Meng, Yifei; Klem, John F.; ...

2018-04-28

Here, we show that Sb substitution for As in a MBE grown InAs/InAsSb strained layer superlattice (SLS) is accompanied by significant strain fluctuations. The SLS was observed using scanning transmission electron microscopy along the [100] zone axis where the cation and anion atomic columns are separately resolved. Strain analysis based on atomic column positions reveals asymmetrical transitions in the strain profile across the SLS interfaces. The averaged strain profile is quantitatively fitted to the segregation model, which yields a distribution of Sb in agreement with our scanning tunneling microscopy result. The subtraction of the calculated strain reveals an increase inmore » strain fluctuations with the Sb concentration, as well as isolated regions with large strain deviations extending spatially over ~1 nm, which suggest the presence of point defects.« less

Sb-induced strain fluctuations in a strained layer superlattice of InAs/InAsSb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Honggyu; Meng, Yifei; Klem, John F.

Here, we show that Sb substitution for As in a MBE grown InAs/InAsSb strained layer superlattice (SLS) is accompanied by significant strain fluctuations. The SLS was observed using scanning transmission electron microscopy along the [100] zone axis where the cation and anion atomic columns are separately resolved. Strain analysis based on atomic column positions reveals asymmetrical transitions in the strain profile across the SLS interfaces. The averaged strain profile is quantitatively fitted to the segregation model, which yields a distribution of Sb in agreement with our scanning tunneling microscopy result. The subtraction of the calculated strain reveals an increase inmore » strain fluctuations with the Sb concentration, as well as isolated regions with large strain deviations extending spatially over ~1 nm, which suggest the presence of point defects.« less

A new radial strain and strain rate estimation method using autocorrelation for carotid artery

NASA Astrophysics Data System (ADS)

Ye, Jihui; Kim, Hoonmin; Park, Jongho; Yeo, Sunmi; Shim, Hwan; Lim, Hyungjoon; Yoo, Yangmo

2014-03-01

Atherosclerosis is a leading cause of cardiovascular disease. The early diagnosis of atherosclerosis is of clinical interest since it can prevent any adverse effects of atherosclerotic vascular diseases. In this paper, a new carotid artery radial strain estimation method based on autocorrelation is presented. In the proposed method, the strain is first estimated by the autocorrelation of two complex signals from the consecutive frames. Then, the angular phase from autocorrelation is converted to strain and strain rate and they are analyzed over time. In addition, a 2D strain image over region of interest in a carotid artery can be displayed. To evaluate the feasibility of the proposed radial strain estimation method, radiofrequency (RF) data of 408 frames in the carotid artery of a volunteer were acquired by a commercial ultrasound system equipped with a research package (V10, Samsung Medison, Korea) by using a L5-13IS linear array transducer. From in vivo carotid artery data, the mean strain estimate was -0.1372 while its minimum and maximum values were -2.961 and 0.909, respectively. Moreover, the overall strain estimates are highly correlated with the reconstructed M-mode trace. Similar results were obtained from the estimation of the strain rate change over time. These results indicate that the proposed carotid artery radial strain estimation method is useful for assessing the arterial wall's stiffness noninvasively without increasing the computational complexity.

Complex strain fields

NASA Astrophysics Data System (ADS)

Bradshaw, P.

Computational techniques for accounting for extra strain rates, abnormal distributions of delta-U/delta-y, fluctuating strain rates, and the effects of body forces in modeling shear flows are discussed. Consideration is given to simple shears where the extra strain rate does not affect turbulence, thin shear layers, moderately thin shear layers, and strongly distorted flows. Attention is given to formulations based on the exact transport equations for Reynolds stress as derived from the time-averaged Navier-Stokes equations. Extra strain rates arise from curvature, lateral divergence, and bulk compression, with Coriolis forces accounting for the first, intensification of the spanwise vorticity for the second, and compression or dilation of the shear layer producing the third. The curvature forces, e.g., buoyancy and Coriolis forces, are responsible for hurricanes and tornadoes.

Thin film strain transducer

NASA Technical Reports Server (NTRS)

Rand, J. L. (Inventor)

1984-01-01

A strain transducer system and process for making the same is disclosed. A beryllium copper ring having four strain gages is electrically connected in Wheatstone bridge fashion to the output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of a ring which provides an electrical signal through the gages proportional to the surface strain. A photographic pattern of a one half ring segment as placed on a sheet of beryllium copper for chem-mill etch formation is illustrated.

Elevated temperature strain gages

NASA Technical Reports Server (NTRS)

Brittain, J. O.; Geslin, D.; Lei, J. F.

1986-01-01

One of the goals of the HOST Program is the development of electrical resistance strain gages for static strain measurements at temperatures equal to or greater than 1273 K. Strain gage materials must have a reproducible or predictable response to temperature, time and strain. It is the objective of this research to investigate criteria for the selection of materials for such applications through electrical properties studies. The results of the investigation of two groups of materials, refractory compounds and binary alloy solid solutions are presented.

Investigation of local strain distribution and linear electro-optic effect in strained silicon waveguides.

PubMed

Chmielak, Bartos; Matheisen, Christopher; Ripperda, Christian; Bolten, Jens; Wahlbrink, Thorsten; Waldow, Michael; Kurz, Heinrich

2013-10-21

We present detailed investigations of the local strain distribution and the induced second-order optical nonlinearity within strained silicon waveguides cladded with a Si₃N₄ strain layer. Micro-Raman Spectroscopy mappings and electro-optic characterization of waveguides with varying width w(WG) show that strain gradients in the waveguide core and the effective second-order susceptibility χ(2)(yyz) increase with reduced w(WG). For 300 nm wide waveguides a mean effective χ(2)(yyz) of 190 pm/V is achieved, which is the highest value reported for silicon so far. To gain more insight into the origin of the extraordinary large optical second-order nonlinearity of strained silicon waveguides numerical simulations of edge induced strain gradients in these structures are presented and discussed.

Solitary waves in morphogenesis: Determination fronts as strain-cued strain transformations among automatous cells

NASA Astrophysics Data System (ADS)

Cox, Brian N.; Landis, Chad M.

2018-02-01

We present a simple theory of a strain pulse propagating as a solitary wave through a continuous two-dimensional population of cells. A critical strain is assumed to trigger a strain transformation, while, simultaneously, cells move as automata to tend to restore a preferred cell density. We consider systems in which the strain transformation is a shape change, a burst of proliferation, or the commencement of growth (which changes the shape of the population sheet), and demonstrate isomorphism among these cases. Numerical and analytical solutions describe a strain pulse whose height does not depend on how the strain disturbance was first launched, or the rate at which the strain transformation is achieved, or the rate constant in the rule for the restorative cell motion. The strain pulse is therefore very stable, surviving the imposition of strong perturbations: it would serve well as a timing signal in development. The automatous wave formulation is simple, with few model parameters. A strong case exists for the presence of a strain pulse during amelogenesis. Quantitative analysis reveals a simple relationship between the velocity of the leading edge of the pulse in amelogenesis and the known speed of migration of ameloblast cells. This result and energy arguments support the depiction of wave motion as an automatous cell response to strain, rather than as a response to an elastic energy gradient. The theory may also contribute to understanding the determination front in somitogenesis, moving fronts of convergent-extension transformation, and mitotic wavefronts in the syncytial drosophila embryo.

Mycobacterium tuberculosis strains exhibit differential and strain-specific molecular signatures in pulmonary epithelial cells.

PubMed

Mvubu, Nontobeko Eunice; Pillay, Balakrishna; Gamieldien, Junaid; Bishai, William; Pillay, Manormoney

2016-12-01

Although pulmonary epithelial cells are integral to innate and adaptive immune responses during Mycobacterium tuberculosis infection, global transcriptomic changes in these cells remain largely unknown. Changes in gene expression induced in pulmonary epithelial cells infected with M. tuberculosis F15/LAM4/KZN, F11, F28, Beijing and Unique genotypes were investigated by RNA sequencing (RNA-Seq). The Illumina HiSeq 2000 platform generated 50 bp reads that were mapped to the human genome (Hg19) using Tophat (2.0.10). Differential gene expression induced by the different strains in infected relative to the uninfected cells was quantified and compared using Cufflinks (2.1.0) and MeV (4.0.9), respectively. Gene expression varied among the strains with the total number of genes as follows: F15/LAM4/KZN (1187), Beijing (1252), F11 (1639), F28 (870), Unique (886) and H37Rv (1179). A subset of 292 genes was commonly induced by all strains, where 52 genes were down-regulated while 240 genes were up-regulated. Differentially expressed genes were compared among the strains and the number of induced strain-specific gene signatures were as follows: F15/LAM4/KZN (138), Beijing (52), F11 (255), F28 (55), Unique (186) and H37Rv (125). Strain-specific molecular gene signatures associated with functional pathways were observed only for the Unique and H37Rv strains while certain biological functions may be associated with other strain signatures. This study demonstrated that strains of M. tuberculosis induce differential gene expression and strain-specific molecular signatures in pulmonary epithelial cells. Specific signatures induced by clinical strains of M. tuberculosis can be further explored for novel host-associated biomarkers and adjunctive immunotherapies. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Comparison of genotype characteristics between the circulating mumps virus strain in Beijing area and the vaccine strain].

PubMed

Chen, Meng; Zhang, Tie-gang; Chen, Li-juan; Wu, Jiang; Yang, Jie; Zhang, Wei

2009-11-01

To compare the genetic characteristics of mumps virus strain circulating in Beijing with vaccine strain and to preliminarily analysis the reasons of vaccine ineffectiveness. The following methods were used: Isolation and identification of the mumps virus which had been circulating in Beijing, immunization history analysis, SH gene sequence analysis and comparison genotype homology with reference strains and analysis of the key amino acid sites of HN variation. In 38 mumps cases that virus had been isolated from, another seven cases were IgM negative. In 2007 and 2008, the positive rates on virus isolation, RT-PCR and IgM-decreased significantly, while the cases with immunization history had an increase. Cases without histories of vaccination had both higher positive rates on virus isolation and IgM. Thirty-eight strains belonged to F genotype virus, but vaccine strain was A genotype. The circulating viruses showed 5.6% sequence divergence on SH gene nucleotide and 16.0% - 18.1% from vaccine strain. Conservative hydrophobic amino acids on SH protein of some Beijing strains had changed. For example, there were 6 strains, from No.8: L-->F. The circulating viruses showed 2.3% sequence divergence on HN protein amino acid sequences and 4.2% - 5.3% from vaccine strain. Amino acids sites, which deciding the ability of cross-neutralization of the Beijing strains and vaccine strains were different. At the 354 and 356 sites, all the Beijing strains were different from the vaccine strains. The N-glycosylation sites on HN of Beijing strains were also different from those on vaccine strains. Locations 464 - 466 appeared to be NCS on Beijing strain, but locations 464 - 466 were NCR on the vaccine strains. Another 18 unknown function amino acids sites of all Beijing strains were different from those on vaccine strains. In recent years, genotype F became the main genotype of circulating strains in Beijing without genotype variation, but larger difference was found between them

Flexible piezotronic strain sensor.

PubMed

Zhou, Jun; Gu, Yudong; Fei, Peng; Mai, Wenjie; Gao, Yifan; Yang, Rusen; Bao, Gang; Wang, Zhong Lin

2008-09-01

Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I- V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

Molecular typing of Brucella melitensis endemic strains and differentiation from the vaccine strain Rev-1.

PubMed

Noutsios, Georgios T; Papi, Rigini M; Ekateriniadou, Loukia V; Minas, Anastasios; Kyriakidis, Dimitrios A

2012-03-01

In the present study forty-four Greek endemic strains of Br. melitensis and three reference strains were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four strains were discriminated from the vaccine strain Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine strains are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine strain can be discriminated from endemic strains by allele's clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic strains. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic strains two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic strains due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic strains of Br. melitensis and differentiate them from vaccine strain Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.

Quantitative Residual Strain Analyses on Strain Hardened Nickel Based Alloy

NASA Astrophysics Data System (ADS)

Yonezawa, Toshio; Maeguchi, Takaharu; Goto, Toru; Juan, Hou

Many papers have reported about the effects of strain hardening by cold rolling, grinding, welding, etc. on stress corrosion cracking susceptibility of nickel based alloys and austenitic stainless steels for LWR pipings and components. But, the residual strain value due to cold rolling, grinding, welding, etc. is not so quantitatively evaluated.

The influence of strain rate and hydrogen on the plane-strain ductility of Zircaloy cladding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Link, T.M.; Motta, A.T.; Koss, D.A.

1998-03-01

The authors studied the ductility of unirradiated Zircaloy-4 cladding under loading conditions prototypical of those found in reactivity-initiated accidents (RIA), i.e.: near plane-strain deformation in the hoop direction (transverse to the cladding axis) at room temperature and 300 C and high strain rates. To conduct these studies, they developed a specimen configuration in which near plane-strain deformation is achieved in the gage section, and a testing methodology that allows one to determine both the limit strain at the onset of localized necking and the fracture strain. The experiments indicate that there is little effect of strain rate (10{sup {minus}3} tomore » 10{sup 2} s{sup {minus}1}) on the ductility of unhydrided Zircaloy tubing deformed under near plane-strain conditions at either room temperature or 300 C. Preliminary experiments on cladding containing 190 ppm hydrogen show only a small loss of fracture strain but no clear effect on limit strain. The experiments also indicate that there is a significant loss of Zircaloy ductility when surface flaws are present in the form of thickness imperfections.« less

Strain-specific reverse transcriptase PCR assay: means to distinguish candidate vaccine from wild-type strains of respiratory syncytial virus.

PubMed Central

Zheng, H; Peret, T C; Randolph, V B; Crowley, J C; Anderson, L J

1996-01-01

Candidate live-virus vaccines for respiratory syncytial virus are being developed and are beginning to be evaluated in clinical trials. To distinguish candidate vaccine strains from wild-type strains isolated during these trials, we developed PCR assays specific to two sets of candidate vaccine strains. The two sets were a group A strain (3A), its three attenuated, temperature-sensitive variant strains, a group B strain (2B), and its four attenuated, temperature-sensitive variant strains. The PCR assays were evaluated by testing 18 group A wild-type strains, the 3A strains, 9 group B wild-type strains, and the 2B strains. PCR specific to group A wild-type strains amplified only group A wild-type strains, and 3A-specific PCR amplified only 3A strains. PCR specific to group B wild-type strains amplified all group A and group B strains but gave a 688-bp product for group B wild-type strains, a 279-bp product for 2B strains, a 547-bp product for all group A strains, and an additional 688-bp product for some group A strains, including 3A strains. These types of PCR assays can, in conjunction with other methods, be used to efficiently distinguish candidate vaccine strains from other respiratory syncytial virus strains. PMID:8789010

Probiotic Potential of Lactobacillus Strains with Antimicrobial Activity against Some Human Pathogenic Strains

PubMed Central

Shokryazdan, Parisa; Sieo, Chin Chin; Kalavathy, Ramasamy; Liang, Juan Boo; Alitheen, Noorjahan Banu; Faseleh Jahromi, Mohammad; Ho, Yin Wan

2014-01-01

The objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic strains. One hundred and forty bacterial strains were isolated and, after initial identification and a preliminary screening for acid and bile tolerance, nine of the best isolates were selected and further identified using 16 S rRNA gene sequences. The nine selected isolates were then characterized in vitro for their probiotic characteristics and their antimicrobial activities against some human pathogens. Results showed that all nine isolates belonged to the genus Lactobacillus. They were able to tolerate pH 3 for 3 h, 0.3% bile salts for 4 h, and 1.9 mg/mL pancreatic enzymes for 3 h. They exhibited good ability to attach to intestinal epithelial cells and were not resistant to the tested antibiotics. They also showed good antimicrobial activities against the tested pathogenic strains of humans, and most of them exhibited stronger antimicrobial activity than the reference strain L. casei Shirota. Thus, the nine Lactobacillus strains could be considered as potential antimicrobial probiotic strains against human pathogens and should be further studied for their human health benefits. PMID:25105147

Novel Human Intervertebral Disc Strain Template to Quantify Regional Three-Dimensional Strains in a Population and Compare to Internal Strains Predicted by a Finite Element Model

PubMed Central

Showalter, Brent L.; DeLucca, John F.; Peloquin, John M.; Cortes, Daniel H.; Yoder, Jonathon H.; Jacobs, Nathan T.; Wright, Alexander C.; Gee, James C.; Vresilovic, Edward J.; Elliott, Dawn M.

2017-01-01

Tissue strain is an important indicator of mechanical function, but is difficult to noninvasively measure in the intervertebral disc. The objective of this study was to generate a disc strain template, a 3D average of disc strain, of a group of human L4–L5 discs loaded in axial compression. To do so, magnetic resonance images of uncompressed discs were used to create an average disc shape. Next, the strain tensors were calculated pixel-wise by using a previously developed registration algorithm. Individual disc strain tensor components were then transformed to the template space and averaged to create the disc strain template. The strain template reduced individual variability while highlighting group trends. For example, higher axial and circumferential strains were present in the lateral and posterolateral regions of the disc, which may lead to annular tears. This quantification of group-level trends in local 3D strain is a significant step forward in the study of disc biomechanics. These trends were compared to a finite element model that had been previously validated against the disc-level mechanical response. Depending on the strain component, 81–99% of the regions within the finite element model had calculated strains within one standard deviation of the template strain results. The template creation technique provides a new measurement technique useful for a wide range of studies, including more complex loading conditions, the effect of disc pathologies and degeneration, damage mechanisms, and design and evaluation of treatments. PMID:26694516

Heat strain in cold.

PubMed

Rintamäki, Hannu; Rissanen, Sirkka

2006-07-01

In spite of increased environmental cold stress, heat strain is possible also in a cold environment. The body heat balance depends on three factors: environmental thermal conditions, metabolic heat production and thermal insulation of clothing and other protective garments. As physical exercise may increase metabolic heat production from rest values by ten times or even more, the required thermal insulation of clothing may vary accordingly. However, in most outdoor work, and often in indoor cold work, too, the thermal insulation of clothing is impractical, difficult or impossible to adjust according to the changes in physical activity. This is especially true with whole body covering garments like chemical protective clothing. As a result of this imbalance, heat strain may develop. In cold all the signs of heat strain (core temperature above 38 degrees C, warm or hot thermal sensations, increased cutaneous circulation and sweating) may not be present at the same time. Heat strain in cold may be whole body heat strain or related only to torso or core temperature. Together with heat strain in torso or body core, there can be at the same time even cold strain in peripheral parts and/or superficial layers of the body. In cold environment both the preservation of insulation and facilitation of heat loss are important. Development of clothing design is still needed to allow easy adjustments of thermal insulation.

The mechanical consequences of load bearing in the equine third metacarpal across speed and gait: the nonuniform distributions of normal strain, shear strain, and strain energy density

PubMed Central

Rubin, Clinton T.; Seeherman, Howard; Qin, Yi-Xian; Gross, Ted S.

2013-01-01

Distributions of normal strain, shear strain, and strain energy density (SED) were determined across the midshaft of the third metacarpal (MCIII, or cannon bone) of 3 adult thoroughbred horses as a function of speed and gait. A complete characterization of the mechanical demands of the bone made through the stride and from mild through the extremes of locomotion was possible by using three 3-element rosette strain gauges bonded at the diaphyseal midshaft of the MCIII and evaluating the strain output with beam theory and finite element analysis. Mean ± sd values of normal strain, shear strain, and SED increased with speed and peaked during a canter (−3560±380 microstrain, 1760±470 microstrain, and 119±23 kPa, respectively). While the location of these peaks was similar across animals and gaits, the resulting strain distributions across the cortex were consistently nonuniform, establishing between a 73-fold (slow trot) to a 330-fold (canter) disparity between the sites of maximum and minimum SED for each gait cycle. Using strain power density as an estimate of strain history across the bone revealed a 154-fold disparity between peak and minimum at the walk but fell to ∼32-fold at the canter. The nonuniform, minimally varying, strain environment suggests either that bone homeostasis is mediated by magnitude-independent mechanical signals or that the duration of stimuli necessary to establish and maintain tissue integrity is relatively brief, and thus the vast majority of strain information is disregarded.—Rubin, C. T., Seeherman, H., Qin, Y.-X., Gross, T. S., The mechanical consequences of load bearing in the equine third metacarpal across speed and gait: the nonuniform distributions of normal strain, shear strain, and strain energy density. PMID:23355269

Strain Pattern in Supercooled Liquids

NASA Astrophysics Data System (ADS)

Illing, Bernd; Fritschi, Sebastian; Hajnal, David; Klix, Christian; Keim, Peter; Fuchs, Matthias

2016-11-01

Investigations of strain correlations at the glass transition reveal unexpected phenomena. The shear strain fluctuations show an Eshelby-strain pattern [˜cos (4 θ ) /r2 ], characteristic of elastic response, even in liquids, at long times. We address this using a mode-coupling theory for the strain fluctuations in supercooled liquids and data from both video microscopy of a two-dimensional colloidal glass former and simulations of Brownian hard disks. We show that the long-ranged and long-lived strain signatures follow a scaling law valid close to the glass transition. For large enough viscosities, the Eshelby-strain pattern is visible even on time scales longer than the structural relaxation time τ and after the shear modulus has relaxed to zero.

Mycobacterium tuberculosis strains induce strain-specific cytokine and chemokine response in pulmonary epithelial cells.

PubMed

Mvubu, Nontobeko E; Pillay, Balakrishna; McKinnon, Lyle R; Pillay, Manormoney

2018-04-01

M. tuberculosis F15/LAM4/KZN has been associated with high transmission rates of drug resistant tuberculosis in the KwaZulu-Natal province of South Africa. The current study elucidated the cytokine/chemokine responses induced by representatives of the F15/LAM4/KZN and other dominant strain families in pulmonary epithelial cells. Multiplex cytokine analyses were performed at 24, 48 and 72h post infection of the A549 pulmonary epithelial cell line with the F15/LAM4/KZN, F28, F11, Beijing, Unique and H37Rv strains at an MOI of ∼10:1. Twenty-three anti- and pro-inflammatory cytokines/chemokines were detected at all-time intervals. Significantly high concentrations of IL-6, IFN-γ, TNF-α and G-CSF at 48h, and IL-8, IFN-γ, TNF-α, G-CSF and GM-CSF at 72h, were induced by the F28 and F15/LAM4/KZN strains, respectively. Lower levels of cytokines/chemokines were induced by either the Beijing or Unique strains at all three time intervals. All strains induced up-regulation of pathogen recognition receptors (PRRs) (TLR3 and TLR5) while only the F15/LAM4/KZN, F11 and F28 strains induced significant differential expression of TLR2 compared to the Beijing, Unique and H37Rv strains. The low induction of cytokines in epithelial cells by the Beijing strain correlates with its previously reported hypervirulent properties. High concentrations of cytokines and chemokines required for early protection against M. tuberculosis infections induced by the F15/LAM4/KZN and F28 strains suggests a lower virulence of these genotypes compared to the Beijing strain. These findings demonstrate the high diversity in host cytokine/chemokine response to early infection of pulmonary epithelial cells by different strains of M. tuberculosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Strain: Fact or Fiction?

NASA Astrophysics Data System (ADS)

Heilbronner, Renée

2017-04-01

2017 marks the 50th anniversary of the publication of John Ramsay's well known textbook "Folding and Fracturing of Rocks" - ... and the 30th anniversary of the rejection of a rather less well known paper entitled "Strain: Fact or Fiction?" submitted by Renée Panozzo to the Journal of Structural Geology. The gist of the paper was simple and straight forward: it was argued that not every fabric that can be observed in deformed rocks is necessarily a measure of the amount of strain the rock incurred. A distinction was made between a general "fabric", i.e., the traceable geometry of grain boundaries, for example, and a so-called "strain fabric", i.e., the model geometry that would result from homogeneously straining an initially isotropic fabric and that would exhibit at least orthorhombic symmetry. To verify if a given fabric was indeed a strain fabric it was therefore suggested to use the SURFOR method (published by Panozzo) and to carry out a so-called strain test, i.e., a check of symmetry, before interpreting the results of a fabric analysis in terms of strain. The problem with the paper was that it was very obviously written out of frustration. The frustration came form having reviewed a number of manuscripts which tried to use the then novel SURFOR method for strain analysis without first checking if the the fabric was a indeed a "strain fabric" or not, and then blaming the SURFOR method for producing ambiguous results. As a result, the paper was not exactly well balanced and carefully thought out. It was considered "interesting but not scholarly" by one of the reviewers and down-right offensive by the second. To tell the truth, however, the paper was not formally rejected. The editor Sue Treagus strongly encouraged Panozzo to revise the paper, ... and 30 years later, I will follow her advise and offer a revised paper as a tribute to John Ramsay. To quote from the original manuscript: "We should be a little more impressed that strain works so well, and less

Biological assay of attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus.

PubMed

Mengeling, W L; Pejsak, Z; Paul, P S

1984-11-01

Attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus (PPV) were titrated in vivo and in vitro under similar conditions to provide a better understanding of some of the factors involved in virulence of PPV in causing maternal reproductive failure of swine. Both strains cause fetal death when they are injected directly into fetal fluids, but only strain NADL-8 does so when administered to pregnant swine. The strains were tested for their hemagglutinating activity (HA), median cell culture infective dose (CCID50), median fetal infective dose (FID50), and median fetal lethal dose (FLD50). The FID50 and FLD50 were determined by injecting virus directly into the amniotic fluid of fetuses in utero at 44 +/- 2 days of gestation and collecting the fetuses 15 +/- 1 days later. Both strains had an HA titer of 64, suggesting that there is a similar number of virions in stock preparations. However, other measurements differed markedly. The CCID50, FID50, and FLD50 were 10(5.5), 10(3.5), and 10(0.5), respectively, for strain NADL-2, and 10(4.5), 10(7.7), and 10(6.3), respectively, for strain NADL-8. Collectively, the values indicate that more than 10,000 times as much strain NADL-2 would need to reach the conceptus transplacentally to establish infection. These observations may help to explain the different consequences of oronasal exposure of pregnant swine to these strains of PPV.

Noninvasive characterization of carotid plaque strain.

PubMed

Khan, Amir A; Sikdar, Siddhartha; Hatsukami, Thomas; Cebral, Juan; Jones, Michael; Huston, John; Howard, George; Lal, Brajesh K

2017-06-01

Current risk stratification of internal carotid artery plaques based on diameter-reducing percentage stenosis may be unreliable because ischemic stroke results from plaque disruption with atheroembolization. Biomechanical forces acting on the plaque may render it vulnerable to rupture. The feasibility of ultrasound-based quantification of plaque displacement and strain induced by hemodynamic forces and their relationship to high-risk plaques have not been determined. We studied the feasibility and reliability of carotid plaque strain measurement from clinical B-mode ultrasound images and the relationship of strain to high-risk plaque morphology. We analyzed carotid ultrasound B-mode cine loops obtained in patients with asymptomatic ≥50% stenosis during routine clinical scanning. Optical flow methods were used to quantify plaque motion and shear strain during the cardiac cycle. The magnitude (maximum absolute shear strain rate [MASSR]) and variability (entropy of shear strain rate [ESSR] and variance of shear strain rate [VSSR]) of strain were combined into a composite shear strain index (SSI), which was assessed for interscan repeatability and correlated with plaque echolucency. Nineteen patients (mean age, 70 years) constituting 36 plaques underwent imaging; 37% of patients (n = 7) showed high strain (SSI ≥0.5; MASSR, 2.2; ESSR, 39.7; VSSR, 0.03) in their plaques; the remaining clustered into a low-strain group (SSI <0.5; MASSR, 0.58; ESSR, 21.2; VSSR, 0.002). The area of echolucent morphology was greater in high-strain plaques vs low-strain plaques (28% vs 17%; P = .018). Strain measurements showed low variability on Bland-Altman plots with cluster assignment agreement of 76% on repeated scanning. Two patients developed a stroke during 2 years of follow-up; both demonstrated high SSI (≥0.5) at baseline. Carotid plaque strain is reliably computed from routine B-mode imaging using clinical ultrasound machines. High plaque strain correlates with known

Strain preservation of experimental animals: vitrification of two-cell stage embryos for multiple mouse strains.

PubMed

Eto, Tomoo; Takahashi, Riichi; Kamisako, Tsutomu

2015-04-01

Strain preservation of experimental animals is crucial for experimental reproducibility. Maintaining complete animal strains, however, is costly and there is a risk for genetic mutations as well as complete loss due to disasters or illness. Therefore, the development of effective vitrification techniques for cryopreservation of multiple experimental animal strains is important. We examined whether a vitrification method using cryoprotectant solutions, P10 and PEPeS, is suitable for preservation of multiple inbred and outbred mouse strains. First, we investigated whether our vitrification method using cryoprotectant solutions was suitable for two-cell stage mouse embryos. In vitro development of embryos exposed to the cryoprotectant solutions was similar to that of fresh controls. Further, the survival rate of the vitrified embryos was extremely high (98.1%). Next, we collected and vitrified two-cell stage embryos of 14 mouse strains. The average number of embryos obtained from one female was 7.3-33.3. The survival rate of vitrified embryos ranged from 92.8% to 99.1%, with no significant differences among mouse strains. In vivo development did not differ significantly between fresh controls and vitrified embryos of each strain. For strain preservation using cryopreserved embryos, two offspring for inbred lines and one offspring for outbred lines must be produced from two-cell stage embryos collected from one female. The expected number of surviving fetuses obtained from embryos collected from one female of either the inbred or outbred strains ranged from 2.9 to 19.5. The findings of the present study indicated that this vitrification method is suitable for strain preservation of multiple mouse strains. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Two-dimensional surface strain measurement based on a variation of Yamaguchi's laser-speckle strain gauge

NASA Technical Reports Server (NTRS)

Barranger, John P.

1990-01-01

A novel optical method of measuring 2-D surface strain is proposed. Two linear strains along orthogonal axes and the shear strain between those axes is determined by a variation of Yamaguchi's laser-speckle strain gage technique. It offers the advantages of shorter data acquisition times, less stringent alignment requirements, and reduced decorrelation effects when compared to a previously implemented optical strain rosette technique. The method automatically cancels the translational and rotational components of rigid body motion while simplifying the optical system and improving the speed of response.

Colony Dimorphism in Bradyrhizobium Strains

PubMed Central

Sylvester-Bradley, Rosemary; Thornton, Philip; Jones, Peter

1988-01-01

Ten isolates of Bradyrhizobium spp. which form two colony types were studied; the isolates originated from a range of legume species. The two colony types differed in the amount of gum formed or size or both, depending on the strain. Whole 7-day-old colonies of each type were subcultured to determine the proportion of cells which had changed to the other type. An iterative computerized procedure was used to determine the rate of switching per generation between the two types and to predict proportions reached at equilibrium for each strain. The predicted proportions of the wetter (more gummy) or larger colony type at equilibrium differed significantly between strains, ranging from 0.9999 (strain CIAT 2383) to 0.0216 (strain CIAT 2469), because some strains switched faster from dry to wet (or small to large) and others switched faster from wet to dry (or large to small). Predicted equilibrium was reached after about 140 generations in strain USDA 76. In all but one strain (CIAT 3030) the growth rate of the wetter colony type was greater than or similar to that of the drier type. The mean difference in generation time between the two colony types was 0.37 h. Doubling times calculated for either colony type after 7 days of growth on the agar surface ranged from 6.0 to 7.3 h. The formation of two persistent colony types by one strain (clonal or colony dimorphism) may be a common phenomenon among Bradyrhizobium strains. Images PMID:16347599

Echocardiographic strain and strain-rate imaging: a new tool to study regional myocardial function.

PubMed

D'hooge, Jan; Bijnens, Bart; Thoen, Jan; Van de Werf, Frans; Sutherland, George R; Suetens, Paul

2002-09-01

Ultrasonic imaging is the noninvasive clinical imaging modality of choice for diagnosing heart disease. At present, two-dimensional ultrasonic grayscale images provide a relatively cheap, fast, bedside method to study the morphology of the heart. Several methods have been proposed to assess myocardial function. These have been based on either grayscale or motion (velocity) information measured in real-time. However, the quantitative assessment of regional myocardial function remains an important goal in clinical cardiology. To do this, ultrasonic strain and strain-rate imaging have been introduced. In the clinical setting, these techniques currently only allow one component of the true three-dimensional deformation to be measured. Clinical, multidimensional strain (rate) information can currently thus only be obtained by combining data acquired using different transducer positions. Nevertheless, given the appropriate postprocessing, the clinical value of these techniques has already been shown. Moreover, multidimensional strain and strain-rate estimation of the heart in vivo by means of a single ultrasound acquisition has been shown to be feasible. In this paper, the new techniques of ultrasonic strain rate and strain imaging of the heart are reviewed in terms of definitions, data acquisition, strain-rate estimation, postprocessing, and parameter extraction. Their clinical validation and relevance will be discussed using clinical examples on relevant cardiac pathology. Based on these examples, suggestions are made for future developments of these techniques.

Strain Insensitive Optical Phase Locked Loop

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliviera (Inventor); Rogowski, Robert S. (Inventor)

1996-01-01

An apparatus is provided to allow for quasi distributed sensing of strain within a test object. Strain insensitive fiber is used to deliver a light signal to a strain sensitive fiber in an optical phase locked loop sensor configuration. The use of strain insensitive delivery fiber allows for non-integrated measurements of strain without the use of expensive electronics such as those employed in ODTR techniques. The novelty of the present invention lies in the use of strain insensitive multimode fiber. The inventors had previously developed a similar sensor with strain insensitive fiber, however it was restricted to the use of single or few mode fibers. The use of an optical phase locked loop arrangement allows for the use of multimode strain insensitive fiber.

Strain improvement of chymosin-producing strains of Aspergillus niger var. awamori using parasexual recombination.

PubMed

Bodie, E A; Armstrong, G L; Dunn-Coleman, N S

1994-05-01

Parasexual recombination was used to obtain improved chymosin-producing strains and to perform genetic analysis on existing strains. Chlorate resistance was used to select for a variety of spontaneous nitrate assimilation pathway mutations in strains previously improved for chymosin production using classical strain improvement methods including mutation and screening, and selection for 2-deoxyglucose resistance (dgr). Diploids of these improved strains were generated via parasexual recombination and were isolated on selective media by complementation of nitrate assimilation mutations. A preliminary genetic analysis of diploid and haploid segregants indicated that the dgr trait, resulting in overexpression of chymosin, was recessive. Also, mutations in two different dgr genes resulted in an increased level of chymosin production. When these mutations were combined via parasexual recombination, the resulting haploid segregants produced about 15% more chymosin than either parental strain. CHEF gel electrophoresis was used to determine the chromosomal location of the integrated chymosin DNA sequences, and to verify diploidy in one case where the chromosome composition of two haploid parents differed.

Segregation of genes from donor strain during the production of recombinant congenic strains.

PubMed

van Zutphen, L F; Den Bieman, M; Lankhorst, A; Demant, P

1991-07-01

Recombinant congenic strains (RCS) constitute a set of inbred strains which are designed to dissect the genetic control of multigenic traits, such as tumour susceptibility or disease resistance. Each RCS contains a small fraction of the genome of a common donor strain, while the majority of genes stem from a common background strain. We tested at two stages of the inbreeding process in 20 RCS, derived from BALB/cHeA and STS/A, to see whether alleles from the STS/A donor strain are distributed over the RCS in a ratio as would theoretically be expected. Four marker genes (Pep-3; Pgm-1; Gpi-1 and Es-3) located at 4 different chromosomes were selected and the allelic distribution was tested after 3-4 and after 12 generations of inbreeding. The data obtained do not significantly deviate from the expected pattern, thus supporting the validity of the concept of RCS.

Thin film strain transducer. [suitable for in-flight measurement of scientific balloon strain

NASA Technical Reports Server (NTRS)

Rand, J. L. (Inventor)

1985-01-01

A strain transducer system and process for making same is disclosed wherein a beryllium-copper ring having four strain gages disposed thereon is electrically connected in Wheatstone bridge fashion to output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of the ring and providing an electrical signal through the gages proportional to the surface strain. A figure is provided which illustrates a pattern of a one-half ring segment as placed on a sheet of beryllium-copper for chem-mill etch formation, prior to bending and welding of a pair of the segments to form a ring structure.

Relationship of compressive stress-strain response of engineering materials obtained at constant engineering and true strain rates

DOE PAGES

Song, Bo; Sanborn, Brett

2018-05-07

In this paper, a Johnson–Cook model was used as an example to analyze the relationship of compressive stress-strain response of engineering materials experimentally obtained at constant engineering and true strain rates. There was a minimal deviation between the stress-strain curves obtained at the same constant engineering and true strain rates. The stress-strain curves obtained at either constant engineering or true strain rates could be converted from one to the other, which both represented the intrinsic material response. There is no need to specify the testing requirement of constant engineering or true strain rates for material property characterization, provided that eithermore » constant engineering or constant true strain rate is attained during the experiment.« less

Relationship of compressive stress-strain response of engineering materials obtained at constant engineering and true strain rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Sanborn, Brett

In this paper, a Johnson–Cook model was used as an example to analyze the relationship of compressive stress-strain response of engineering materials experimentally obtained at constant engineering and true strain rates. There was a minimal deviation between the stress-strain curves obtained at the same constant engineering and true strain rates. The stress-strain curves obtained at either constant engineering or true strain rates could be converted from one to the other, which both represented the intrinsic material response. There is no need to specify the testing requirement of constant engineering or true strain rates for material property characterization, provided that eithermore » constant engineering or constant true strain rate is attained during the experiment.« less

Synthesis and quantitative structure activity relationship (QSAR) of arylidene (benzimidazol-1-yl)acetohydrazones as potential antibacterial agents.

PubMed

El-Kilany, Yeldez; Nahas, Nariman M; Al-Ghamdi, Mariam A; Badawy, Mohamed E I; El Ashry, El Sayed H

2015-01-01

Ethyl (benzimidazol-1-yl)acetate was subjected to hydrazinolysis with hydrazine hydrate to give (benzimidazol-1-yl)acetohydrazide. The latter was reacted with various aromatic aldehydes to give the respective arylidene (1H-benzimidazol-1-yl)acetohydrazones. Solutions of the prepared hydrazones were found to contain two geometric isomers. Similarly (2-methyl-benzimidazol-1-yl)acetohydrazide was reacted with various aldehydes to give the corresponding hydrazones. The antibacterial activity was evaluated in vitro by minimum inhibitory concentration (MIC) against Agrobacterium tumefaciens (A. tumefaciens), Erwinia carotovora (E. carotovora), Corynebacterium fascians (C. fascians) and Pseudomonas solanacearum (P. solanacearum). MIC result demonstrated that salicylaldehyde(1H-benzimidazol-1-yl)acetohydrazone (4) was the most active compound (MIC = 20, 35, 25 and 30 mg/L against A. tumefaciens, C. fascians, E. carotovora and P. solanacearum, respectively). Quantitative structure activity relationship (QSAR) investigation using Hansch analysis was applied to find out the correlation between antibacterial activity and physicochemical properties. Various physicochemical descriptors and experimentally determined MIC values for different microorganisms were used as independent and dependent variables, respectively. pMICs of the compounds exhibited good correlation (r = 0.983, 0.914, 0.960 and 0.958 for A. tumefaciens, C. fascians, E. carotovora and P. solanacearum, respectively) with the prediction made by the model. QSAR study revealed that the hydrophobic parameter (ClogP), the aqueous solubility (LogS), calculated molar refractivity, topological polar surface area and hydrogen bond acceptor were found to have overall significant correlation with antibacterial activity. The statistical results of training set, correlation coefficient (r and r (2)), the ratio between regression and residual variances (f, Fisher's statistic), the standard error of estimates and

Hydrogen-driven asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol by Ralstonia eutropha transformant expressing alcohol dehydrogenase from Kluyveromyces lactis.

PubMed

Oda, Takahiro; Oda, Koji; Yamamoto, Hiroaki; Matsuyama, Akinobu; Ishii, Masaharu; Igarashi, Yasuo; Nishihara, Hirofumi

2013-01-10

Conversion of industrial processes to more nature-friendly modes is a crucial subject for achieving sustainable development. Utilization of hydrogen-oxidation reactions by hydrogenase as a driving force of bioprocess reaction can be an environmentally ideal method because the reaction creates no pollutants. We expressed NAD-dependent alcohol dehydrogenase from Kluyveromyces lactis in a hydrogen-oxidizing bacterium: Ralstonia eutropha. This is the first report of hydrogen-driven in vivo coupling reaction of the alcohol dehydrogenase and indigenous soluble NAD-reducing hydrogenase. Asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol, which is a commercial building block for antibacterial agents, was performed using the transformant as the microbial cell catalyst. The two enzymes coupled in vitro in vials without a marked decrease of reactivity during the 20 hr reaction because of the hydrogenase reaction, which generates no by-product that affects enzymes. Alcohol dehydrogenase was expressed functionally in R. eutropha in an activity level equivalent to that of indigenous NAD-reducing hydrogenase under the hydrogenase promoter. The hydrogen-driven in vivo coupling reaction proceeded only by the transformant cell without exogenous addition of a cofactor. The decrease of reaction velocity at higher concentration of hydroxyacetone was markedly reduced by application of an in vivo coupling system. Production of (R)-1,2-propanediol (99.8% e.e.) reached 67.7 g/l in 76 hr with almost a constant rate using a jar fermenter. The reaction velocity under 10% PH2 was almost equivalent to that under 100% hydrogen, indicating the availability of crude hydrogen gas from various sources. The in vivo coupling system enabled cell-recycling as catalysts. Asymmetric reduction of hydroxyacetone by a coupling reaction of the two enzymes continued in both in vitro and in vivo systems in the presence of hydrogen. The in vivo reaction system using R. eutropha transformant expressing

Forming limit strains for non-linear strain path of AA6014 aluminium sheet deformed at room temperature

NASA Astrophysics Data System (ADS)

Bressan, José Divo; Liewald, Mathias; Drotleff, Klaus

2017-10-01

Forming limit strain curves of conventional aluminium alloy AA6014 sheets after loading with non-linear strain paths are presented and compared with D-Bressan macroscopic model of sheet metal rupture by critical shear stress criterion. AA6014 exhibits good formability at room temperature and, thus, is mainly employed in car body external parts by manufacturing at room temperature. According to Weber et al., experimental bi-linear strain paths were carried out in specimens with 1mm thickness by pre-stretching in uniaxial and biaxial directions up to 5%, 10% and 20% strain levels before performing Nakajima testing experiments to obtain the forming limit strain curves, FLCs. In addition, FLCs of AA6014 were predicted by employing D-Bressan critical shear stress criterion for bi-linear strain path and comparisons with the experimental FLCs were analyzed and discussed. In order to obtain the material coefficients of plastic anisotropy, strain and strain rate hardening behavior and calibrate the D-Bressan model, tensile tests, two different strain rate on specimens cut at 0°, 45° and 90° to the rolling direction and also bulge test were carried out at room temperature. The correlation of experimental bi-linear strain path FLCs is reasonably good with the predicted limit strains from D-Bressan model, assuming equivalent pre-strain calculated by Hill 1979 yield criterion.

Dynamic Tensile Properties of Iron and Steels for a Wide Range of Strain Rates and Strain

NASA Astrophysics Data System (ADS)

Kojima, Nobusato; Hayashi, Hiroyuki; Yamamoto, Terumi; Mimura, Koji; Tanimura, Shinji

The tensile stress-strain curves of iron and a variety of steels, covering a wide range of strength level, over a wide strain rate range on the order of 10-3 ~ 103 s-1, were obtained systematically by using the Sensing Block Type High Speed Material Testing System (SBTS, Saginomiya). Through intensive analysis of these results, the strain rate sensitivity of the flow stress for the large strain region, including the viscous term at high strain rates, the true fracture strength and the true fracture strain were cleared for the material group of the ferrous metals. These systematical data may be useful to develop a practical constitutive model for computer codes, including a fracture criterion for simulations of the dynamic behavior in crash worthiness studies and of work-pieces subjected to dynamic plastic working for a wide strain rate range.

The Effect of Strain Rate on the Evolution of Plane Wakes Subjected to Irrotational Strains

NASA Technical Reports Server (NTRS)

Rogers, Michael M.; Merriam, Marshal (Technical Monitor)

1996-01-01

Direct numerical simulations of time-evolving turbulent plane wakes developing in the presence of irrotational plane strain applied at three different strain rates have been generated. The strain geometry is such that the flow is compressed in the streamwise direction and expanded in the cross-stream direction with the spanwise direction being unstrained. This geometry is the temporally evolving analogue of a spatially evolving wake in an adverse pressure gradient. A pseudospectral numerical method with up to 16 million modes is used to solve the equations in a reference frame moving with the irrotational strain. The initial condition for each simulation is taken from a previous turbulent self-similar plane wake direct numerical simulation at a velocity deficit Reynolds number, Re, of about 2,000. Although the evolutions of many statistics are nearly collapsed when plotted against total strain, there are some differences owing to the different strain rate histories. The impact of strain-rate on the wake spreading rate, the peak velocity deficit, the Reynolds stress profiles, and the flow structure is examined.

A tale of two mechanisms. Strain-softening versus strain-hardening in single crystals under small stressed volumes

DOE PAGES

Bei, Hongbin; Xia, Yuzhi; Barabash, Rozaliya; ...

2015-08-10

Pre-straining defect-free single crystals will introduce heterogeneous dislocation nucleation sources that reduce the measured strength from the theoretical value, while pre-straining bulk samples will lead to strain hardening. Their competition is investigated by nanoindentation pop-in tests on variously pre-strained Mo single crystals with several indenter radii (~micrometer). Pre-straining primarily shifts deformation mechanism from homogeneous dislocation nucleation to a stochastic behavior, while strain hardening plays a secondary role, as summarized in a master plot of pop-in strength versus normalized indenter radius.

Revealing Differences in Metabolic Flux Distributions between a Mutant Strain and Its Parent Strain Gluconacetobacter xylinus CGMCC 2955

PubMed Central

Liu, Miao; Yang, Xiao-Ning; Zhu, Hui-Xia; Jia, Yuan-Yuan; Jia, Shi-Ru; Piergiovanni, Luciano

2014-01-01

A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain. PMID:24901455

Mumps Hoshino and Torii vaccine strains were distinguished from circulating wild strains.

PubMed

Sawada, Akihito; Yamaji, Yoshiaki; Nakayama, Tetsuo

2013-06-01

Aseptic meningitis and acute parotitis have been observed after mumps vaccination. Mumps outbreaks have been reported in Japan because of low vaccine coverage, and molecular differentiation is required to determine whether these cases are vaccine associated. RT-nested PCR was performed in the small hydrophobic gene region, and viruses were differentiated by restriction fragment length polymorphism assay. A total of 584 nucleotides were amplified. The PCR product of the Hoshino strain was cut into two fragments (313 and 271 nucleotides) by MfeI; that of the Torii strain was digested with EcoT22I, resulting in 332- and 252-nucleotide fragments. Both strains were genotype B and had an XbaI site, resulting in two fragments: 299 and 285 nucleotides. Current circulating wild types were cut only by XbaI or MfeI. However, the MfeI site of the wild types was different from that of the Hoshino strain, resulting in 451- and 133-nucleotide fragments. Using three restriction enzymes, two mumps vaccine strains were distinguished from wild types, and this separation was applied to the identification of vaccine-related adverse events.

Isolation of As-tolerant bacteria and their potentials of reducing As and Cd accumulation of edible tissues of vegetables in metal(loid)-contaminated soils.

PubMed

Wang, Xiaohan; Nie, Zongwei; He, Linyan; Wang, Qi; Sheng, Xiafang

2017-02-01

In this study, three As-tolerant bacteria Ralstonia eutropha Q2-8, Rhizobium tropici Q2-13, and Exiguobacterium aurantiacum Q3-11 were isolated from the rhizosphere and bulk soils of Chinese cabbage. The strains were characterized for their production of indole-3-acetic acid (IAA) and siderophores, their effects on soil metal(loid) bioavailability and organic matter content, and their effects on the edible tissue growth and metal(loid) accumulation of Chinese cabbage and radish in the metal(loid)-contaminated soil. The strains produced IAA and siderophores and increased the edible tissue biomass (ranging from 74% to 124%) of the vegetables compared to the controls. Furthermore, strain Q2-8 reduced As contents (ranging from 22% to 50%), while strains Q2-13 and Q3-11 decreased Cd contents (ranging from 21% to 53%) of the edible tissues of the vegetables compared to the controls. Strains Q2-8, Q2-13, and Q3-11 decreased the DTPA-extractable Cd contents (ranging from 16% to 41%) and increased the organic matter contents of the rhizosphere soils compared to the controls. The results showed the effects of the strains on the increased edible tissue growth and reduced As and Cd uptake of the edible tissues and highlighted the possibility to develop a new bacterial-assisted technique for reduced metal(loid) uptake of vegetables in the metal(loid)-contaminated soils. Copyright © 2016 Elsevier B.V. All rights reserved.

Bone strain magnitude is correlated with bone strain rate in tetrapods: implications for models of mechanotransduction

PubMed Central

Aiello, B. R.; Iriarte-Diaz, J.; Blob, R. W.; Butcher, M. T.; Carrano, M. T.; Espinoza, N. R.; Main, R. P.; Ross, C. F.

2015-01-01

Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone strain magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level strain magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that osteocytes sense bone deformation by detecting fluid flow-induced drag in the bone's lacunar–canalicular porosity. This model suggests that the osteocyte's intracellular response depends on fluid-flow rate, a product of bone strain rate and gradient, but does not provide a mechanism for detection of strain magnitude. Such a mechanism is necessary for bone modelling to adapt to loads, because strain magnitude is an important determinant of skeletal fracture. Using strain gauge data from the limb bones of amphibians, reptiles, birds and mammals, we identified strong correlations between strain rate and magnitude across clades employing diverse locomotor styles and degrees of rhythmicity. The breadth of our sample suggests that this pattern is likely to be a common feature of tetrapod bone loading. Moreover, finding that bone strain magnitude is encoded in strain rate at the tissue level is consistent with the hypothesis that it might be encoded in fluid-flow rate at the cellular level, facilitating bone adaptation via mechanotransduction. PMID:26063842

Bacterial Metabolism of Chlorinated Dehydroabietic Acids Occurring in Pulp and Paper Mill Effluents

PubMed Central

Mohn, W. W.; Stewart, G. R.

1997-01-01

Chlorinated dehydroabietic acids are formed during the chlorine bleaching of wood pulp and are very toxic to fish. Thus, destruction of these compounds is an important function of biological treatment systems for pulp and paper mill effluents. In this study, 12 strains of diverse, aerobic resin acid-degrading bacteria were screened for the ability to grow on chlorinated dehydroabietic acids as sole organic substrates. All seven strains of the class Proteobacteria able to use dehydroabietic acid were also able to use a mixture of 12- and 14-chlorodehydroabietic acid (Cl-DhA). None of the strains used 12,14-dichlorodehydroabietic acid. Sphingomonas sp. strain DhA-33 grew best on Cl-DhA and simultaneously removed both Cl-DhA isomers. Ralstonia sp. strain BKME-6 was typical of most of the strains tested, growing more slowly on Cl-DhA and leaving higher residual concentrations of Cl-DhA than DhA-33 did. Strains DhA-33 and BKME-6 mineralized (converted to CO(inf2) plus biomass) 32 and 43%, respectively, of carbon in Cl-DhA consumed. Strain DhA-33 produced a metabolite from Cl-DhA, tentatively identified as 3-oxo-14-chlorodehydroabietin, and both strains produced dissolved organic carbon which may include unidentified metabolites. Cl-DhA removal was inducible in both DhA-33 and BKME-6, and induced DhA-33 cells also removed 12,14-dichlorodehydroabietic acid. Based on activities of strains DhA-33 and BKME-6, chlorinated DhAs, and potentially toxic metabolite(s) of these compounds, are relatively persistent in biological treatment systems and in the environment. PMID:16535663

Revisiting borehole strain, typhoons, and slow earthquakes using quantitative estimates of precipitation-induced strain changes

NASA Astrophysics Data System (ADS)

Hsu, Ya-Ju; Chang, Yuan-Shu; Liu, Chi-Ching; Lee, Hsin-Ming; Linde, Alan T.; Sacks, Selwyn I.; Kitagawa, Genshio; Chen, Yue-Gau

2015-06-01

Taiwan experiences high deformation rates, particularly along its eastern margin where a shortening rate of about 30 mm/yr is experienced in the Longitudinal Valley and the Coastal Range. Four Sacks-Evertson borehole strainmeters have been installed in this area since 2003. Liu et al. (2009) proposed that a number of strain transient events, primarily coincident with low-barometric pressure during passages of typhoons, were due to deep-triggered slow slip. Here we extend that investigation with a quantitative analysis of the strain responses to precipitation as well as barometric pressure and the Earth tides in order to isolate tectonic source effects. Estimates of the strain responses to barometric pressure and groundwater level changes for the different stations vary over the ranges -1 to -3 nanostrain/millibar(hPa) and -0.3 to -1.0 nanostrain/hPa, respectively, consistent with theoretical values derived using Hooke's law. Liu et al. (2009) noted that during some typhoons, including at least one with very heavy rainfall, the observed strain changes were consistent with only barometric forcing. By considering a more extensive data set, we now find that the strain response to rainfall is about -5.1 nanostrain/hPa. A larger strain response to rainfall compared to that to air pressure and water level may be associated with an additional strain from fluid pressure changes that take place due to infiltration of precipitation. Using a state-space model, we remove the strain response to rainfall, in addition to those due to air pressure changes and the Earth tides, and investigate whether corrected strain changes are related to environmental disturbances or tectonic-original motions. The majority of strain changes attributed to slow earthquakes seem rather to be associated with environmental factors. However, some events show remaining strain changes after all corrections. These events include strain polarity changes during passages of typhoons (a characteristic that is

An ultrasensitive strain sensor with a wide strain range based on graphene armour scales.

PubMed

Yang, Yi-Fan; Tao, Lu-Qi; Pang, Yu; Tian, He; Ju, Zhen-Yi; Wu, Xiao-Ming; Yang, Yi; Ren, Tian-Ling

2018-06-12

An ultrasensitive strain sensor with a wide strain range based on graphene armour scales is demonstrated in this paper. The sensor shows an ultra-high gauge factor (GF, up to 1054) and a wide strain range (ε = 26%), both of which present an advantage compared to most other flexible sensors. Moreover, the sensor is developed by a simple fabrication process. Due to the excellent performance, this strain sensor can meet the demands of subtle, large and complex human motion monitoring, which indicates its tremendous application potential in health monitoring, mechanical control, real-time motion monitoring and so on.

Large Strain Behaviour of ZEK100 Magnesium Alloy at Various Strain Rates

NASA Astrophysics Data System (ADS)

Lévesque, Julie; Kurukuri, Srihari; Mishra, Raja; Worswick, Michael; Inal, Kaan

A constitutive framework based on a rate-dependent crystal plasticity theory is employed to simulate large strain deformation in hexagonal closed-packed metals that deform by slip and twinning. The model allows the twinned zones and the parent matrix to rotate independently. ZEK100 magnesium alloy sheets which significant texture weakening compared to AZ31 sheets are investigated using the model. There is considerable in-plane anisotropy and tension compression asymmetry in the flow behavior of ZEK100. Simulations of uniaxial tension in different directions at various strain rates and the accompanying texture evolution are performed and they are in very good agreement with experimental measurements. The effect of strain rate on the activation of the various slip systems and twinning show that differences in the strain rate dependence of yield stress and Rvalues in ZEK100 have their origin in the activation of different deformation mechanisms.

Material approaches to stretchable strain sensors.

PubMed

Park, Jaeyoon; You, Insang; Shin, Sangbaie; Jeong, Unyong

2015-04-27

With the recent progress made in wearable electronics, devices now require high flexibility and stretchability up to large strain levels (typically larger than 30 % strain). Wearable strain sensors or deformable strain sensors have been gaining increasing research interest because of the rapid development of electronic skins and robotics and because of their biomedical applications. Conventional brittle strain sensors made of metals and piezoresistors are not applicable for such stretchable sensors. This Review summarizes recent advances in stretchable sensors and focuses on material aspects for high stretchability and sensitivity. It begins with a brief introduction to the Wheatstone bridge circuit of conventional resistive strain sensors. Then, studies on the manipulation of materials are reviewed, including waved structural approaches for making metals and semiconductors stretchable, the use of liquid metals, and conductive filler/elastomer composites by using percolation among the fillers. For capacitive strain sensors, the constant conductivity of the electrode is a key factor in obtaining reliable sensors. Possible approaches to developing capacitive strain sensors are presented. This Review concludes with a discussion on the major challenges and perspectives related to stretchable strain sensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Revision of the taxonomic status of type strains of Mesorhizobium loti and reclassification of strain USDA 3471T as the type strain of Mesorhizobiumerdmanii sp. nov. and ATCC 33669T as the type strain of Mesorhizobiumjarvisii sp. nov.

PubMed

Martínez-Hidalgo, Pilar; Ramírez-Bahena, Martha Helena; Flores-Félix, José David; Rivas, Raúl; Igual, José M; Mateos, Pedro F; Martínez-Molina, Eustoquio; León-Barrios, Milagros; Peix, Álvaro; Velázquez, Encarna

2015-06-01

The species Mesorhizobim loti was isolated from nodules of Lotus corniculatus and its type strain deposited in several collections. Some of these type strains, such as those deposited in the USDA and ATCC collections before 1990, are not coincident with the original strain, NZP 2213T, deposited in the NZP culture collection. The analysis of the 16S rRNA gene showed that strains USDA 3471T and ATCC 33669T formed independent branches from that occupied by Mesorhizobium loti NZP 2213T and related to those occupied by Mesorhizobium opportunistum WSM2075T and Mesorhizobium huakuii IFO 15243T, respectively, with 99.9 % similarity in both cases. However, the analysis of concatenated recA, atpD and glnII genes with similarities lower than 96, 98 and 94 %, respectively, between strains USDA 3471T and M. opportunistum WSM2075T and between strains ATCC 33669T and M. huakuii IFO 15243T, indicated that the strains USDA 3471T and ATCC 33669T represent different species of the genus Mesorhizobium. These results were confirmed by DNA-DNA hybridization experiments and phenotypic characterization. Therefore, the two strains were reclassified as representatives of the two species Mesorhizobium erdmanii sp. nov. (type strain USDA 3471T = CECT 8631T = LMG 17826t2T) and Mesorhizobium jarvisii sp. nov. (type strain ATCC 33669T = CECT 8632T = LMG 28313T).

Origin of the Strain Sensitivity for an Organic Heptazole Thin-Film and Its Strain Gauge Application

NASA Astrophysics Data System (ADS)

Bae, Heesun; Jeon, Pyo Jin; Park, Ji Hoon; Lee, Kimoon

2018-04-01

The authors report on the origin of the strain sensitivity for an organic C26H16N2 (heptazole) thinfilm and its application for the detection of tensile strain. From the electrical characterization on the thin-film transistor adopting a heptazole channel, heptazole film exhibits p-channel conduction with a relatively low value of field-effect mobility (0.05 cm2/Vs), suggesting a hopping conduction behavior via hole carriers. By analyzing the strain and temperature dependences of the electrical conductivity, we reveal that the electrical conduction for a heptazole thin-film is dominated by the variable range hopping process with quite a large energy separation (224.9 meV) between the localized states under a relatively long attenuation length (10.46 Å). This indicates that a change in the inter-grain spacing that is much larger than the attenuation length is responsible for the reversible modification of electrical conductivity depending on strain for the heptazole film. By utilizing our heptazole thin-film both as a strain sensitive passive resistor and an active semiconducting channel layer, we can achieve a strain gauge device exhibiting reversible endurance for tensile strains up to 2.12%. Consequently, this study advances the understanding of the fundamental strain sensing mechanism in a heptazole thin-film toward finding a promise material with a strain gauge for applications as potential flexible devices and/or wearable electronics.

Creep Strain and Strain Rate Response of 2219 Al Alloy at High Stress Levels

NASA Technical Reports Server (NTRS)

Taminger, Karen M. B.; Wagner, John A.; Lisagor, W. Barry

1998-01-01

As a result of high localized plastic deformation experienced during proof testing in an International Space Station connecting module, a study was undertaken to determine the deformation response of a 2219-T851 roll forging. After prestraining 2219-T851 Al specimens to simulate strains observed during the proof testing, creep tests were conducted in the temperature range from ambient temperature to 107 C (225 F) at stress levels approaching the ultimate tensile strength of 2219-T851 Al. Strain-time histories and strain rate responses were examined. The strain rate response was extremely high initially, but decayed rapidly, spanning as much as five orders of magnitude during primary creep. Select specimens were subjected to incremental step loading and exhibited initial creep rates of similar magnitude for each load step. Although the creep rates decreased quickly at all loads, the creep rates dropped faster and reached lower strain rate levels for lower applied loads. The initial creep rate and creep rate decay associated with primary creep were similar for specimens with and without prestrain; however, prestraining (strain hardening) the specimens, as in the aforementioned proof test, resulted in significantly longer creep life.

Strain-controlled nonvolatile magnetization switching

NASA Astrophysics Data System (ADS)

Geprägs, S.; Brandlmaier, A.; Brandt, M. S.; Gross, R.; Goennenwein, S. T. B.

2014-11-01

We investigate different approaches towards a nonvolatile switching of the remanent magnetization in single-crystalline ferromagnets at room temperature via elastic strain using ferromagnetic thin film/piezoelectric actuator hybrids. The piezoelectric actuator induces a voltage-controllable strain along different crystalline directions of the ferromagnetic thin film, resulting in modifications of its magnetization by converse magnetoelastic effects. We quantify the magnetization changes in the hybrids via ferromagnetic resonance spectroscopy and superconducting quantum interference device magnetometry. These measurements demonstrate a significant strain-induced change of the magnetization, limited by an inefficient strain transfer and domain formation in the particular system studied. To overcome these obstacles, we address practicable engineering concepts and use a model to demonstrate that a strain-controlled, nonvolatile magnetization switching should be possible in appropriately engineered ferromagnetic/piezoelectric actuator hybrids.

Attachment techniques for high temperature strain

NASA Astrophysics Data System (ADS)

Wnuk, Steve P., Jr.

1993-01-01

Attachment methods for making resistive strain measurements to 2500 F were studied. A survey of available strain gages and attachment techniques was made, and the results are compiled for metal and carbon composite test materials. A theoretical analysis of strain transfer into a bonded strain gage was made, and the important physical parameters of the strain transfer medium, the ceramic matrix, were identified. A pull tester to measure pull-out tests on commonly used strain gage cements indicated that all cements tested displayed adequate strength for good strain transfer. Rokide flame sprayed coatings produced significantly stronger bonds than ceramic cements. An in-depth study of the flame spray process produced simplified installation procedures which also resulted in greater reliability and durability. Application procedures incorporating improvements made during this program are appended to the report. Strain gages installed on carbon composites, Rene' 41, 316 stainless steel, and TZM using attachment techniques developed during this program were successfully tested to 2500 F. Photographs of installation techniques, test procedures, and graphs of the test data are included in this report.

Practical on-site measurement of heat strain with the use of a perceptual strain index.

PubMed

Chan, Albert P C; Yang, Y

2016-02-01

There have been increased interests in research on quantifying heat strain of construction workers and formulating corresponding guidelines for working in hot weather. The aim of this study was to validate a subjective measurement tool, the perceptual strain index (PeSI), for measuring heat strain in real-work settings. A total of sixteen construction workers were invited to participate in the field surveys. Empiric-based human monitoring was carried out with simultaneous micrometeorological (wet-bulb globe temperature, WBGT), physiological (heart rate, HR), and perceptual (perceived exertion, RPE; thermal sensation, TS) measurements throughout the test. The relative heart rate (RHR), the physiological strain index (PSIHR), and the PeSI were then calculated accordingly. The PeSI exhibited moderate correlations with WBGT and RHR (r = 0.42 and 0.40, respectively), which indicated the PeSI was sensitive to the variants of WBGT and RHR. The results of regression analysis indicated that the PeSI changed in the same general manner as the PSIHR, with a relatively large determination coefficient (R(2) = 0.67). The established perceptual strain zone illustrated that the PeSI ranging from 7 to 8 would be the exposure limit of construction workers in hot weather. The PeSI is a simple, robust, reliable, and user-friendly tool for heat strain assessment in occupational settings. The perceptual strain zone will provide practical guidelines for on-site heat strain monitoring for construction workers.

Turbulent Plane Wakes Subjected to Successive Strains

NASA Technical Reports Server (NTRS)

Rogers, Michael M.

2003-01-01

Six direct numerical simulations of turbulent time-evolving strained plane wakes have been examined to investigate the response of a wake to successive irrotational plane strains of opposite sign. The orientation of the applied strain field has been selected so that the flow is the time-developing analogue of a spatially developing wake evolving in the presence of either a favourable or an adverse streamwise pressure gradient. The magnitude of the applied strain rate a is constant in time t until the total strain e(sup at) reaches about four. At this point, a new simulation is begun with the sign of the applied strain being reversed (the original simulation is continued as well). When the total strain is reduced back to its original value of one, yet another simulation is begun with the sign of the strain being reversed again back to its original sign. This process is done for both initially "favourable" and initially "adverse" strains, providing simulations for each of these strain types from three different initial conditions. The evolution of the wake mean velocity deficit and width is found to be very similar for all the adversely strained cases, with both measures rapidly achieving exponential growth at the rate associated with the cross-stream expansive strain e(sup at). In the "favourably" strained cases, the wake widths approach a constant and the velocity deficits ultimately decay rapidly as e(sup -2at). Although all three of these cases do exhibit the same asymptotic exponential behaviour, the time required to achieve this is longer for the cases that have been previously adversely strained (by at approx. equals 1). These simulations confirm the generality of the conclusions drawn in Rogers (2002) regarding the response of plane wakes to strain. The evolution of strained wakes is not consistent with the predictions of classical self-similar analysis; a more general equilibrium similarity solution is required to describe the results. At least for the cases

Electronic and optical properties of strained graphene and other strained 2D materials: a review.

PubMed

Naumis, Gerardo G; Barraza-Lopez, Salvador; Oliva-Leyva, Maurice; Terrones, Humberto

2017-09-01

This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schrödinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

Enzyme markers in inbred rat strains: genetics of new markers and strain profiles.

PubMed

Adams, M; Baverstock, P R; Watts, C H; Gutman, G A

1984-08-01

Twenty-six inbred strains of the laboratory rat (Rattus norvegicus) were examined for electrophoretic variation at an estimated 97 genetic loci. In addition to previously documented markers, variation was observed for the enzymes aconitase, aldehyde dehydrogenase, and alkaline phosphatase. The genetic basis of these markers (Acon-1, Ahd-2, and Akp-1) was confirmed. Linkage analysis between 35 pairwise comparisons revealed that the markers Fh-1 and Pep-3 are linked. The strain profiles of the 25 inbred strains at 11 electrophoretic markers are given.

A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

PubMed

Szpara, Moriah L; Tafuri, Yolanda R; Parsons, Lance; Shamim, S Rafi; Verstrepen, Kevin J; Legendre, Matthieu; Enquist, L W

2011-10-01

Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1) and 2, and varicella zoster virus (VZV). These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV), causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs), a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit limited sequence

Tissue Doppler, strain, and strain rate echocardiography for the assessment of left and right systolic ventricular function

PubMed Central

Pellerin, D; Sharma, R; Elliott, P; Veyrat, C

2003-01-01

Tissue Doppler (TDE), strain, and strain rate echocardiography are emerging real time ultrasound techniques that provide a measure of wall motion. They offer an objective means to quantify global and regional left and right ventricular function and to improve the accuracy and reproducibility of conventional echocardiography studies. Radial and longitudinal ventricular function can be assessed by the analysis of myocardial wall velocity and displacement indices, or by the analysis of wall deformation using the rate of deformation of a myocardial segment (strain rate) and its deformation over time (strain). A quick and easy assessment of left ventricular ejection fraction is obtained by mitral annular velocity measurement during a routine study, especially in patients with poor endocardial definition or abnormal septal motion. Strain rate and strain are less affected by passive myocardial motion and tend to be uniform throughout the left ventricle in normal subjects. This paper reviews the underlying principles of TDE, strain, and strain rate echocardiography and discusses currently available quantification tools and clinical applications. PMID:14594870

Finite element simulation and comparison of a shear strain and equivalent strain during ECAP and asymmetric rolling

NASA Astrophysics Data System (ADS)

Pesin, A.; Pustovoytov, D.; Shveyova, T.; Vafin, R.

2017-12-01

The level of a shear strain and equivalent strain plays a key role in terms of the possibility of using the asymmetric rolling process as a method of severe plastic deformation. Strain mode (pure shear or simple shear) can affect very strongly on the equivalent strain and the grain refinement of the material. This paper presents the results of FEM simulations and comparison of the equivalent strain in the aluminium alloy 5083 processed by a single-pass equal channel angular pressing (simple shear), symmetric rolling (pure shear) and asymmetric rolling (simultaneous pure and simple shear). The nonlinear effect of rolls speed ratio on the deformation characteristics during asymmetric rolling was found. Extremely high equivalent strain up to e=4.2 was reached during a single-pass asymmetric rolling. The influence of the shear strain on the level of equivalent strain is discussed. Finite element analysis of the deformation characteristics, presented in this study, can be used for optimization of the asymmetric rolling process as a method of severe plastic deformation.

HIGH-RATE FORMABILITY OF HIGH-STRENGTH ALUMINUM ALLOYS: A STUDY ON OBJECTIVITY OF MEASURED STRAIN AND STRAIN RATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyay, Piyush; Rohatgi, Aashish; Stephens, Elizabeth V.

2015-02-18

Al alloy AA7075 sheets were deformed at room temperature at strain-rates exceeding 1000 /s using the electrohydraulic forming (EHF) technique. A method that combines high speed imaging and digital image correlation technique, developed at Pacific Northwest National Laboratory, is used to investigate high strain rate deformation behavior of AA7075. For strain-rate sensitive materials, the ability to accurately model their high-rate deformation behavior is dependent upon the ability to accurately quantify the strain-rate that the material is subjected to. This work investigates the objectivity of software-calculated strain and strain rate by varying different parameters within commonly used commercially available digital imagemore » correlation software. Except for very close to the time of crack opening the calculated strain and strain rates are very consistent and independent of the adjustable parameters of the software.« less

Hydrogen production from microbial strains

DOEpatents

Harwood, Caroline S; Rey, Federico E

2012-09-18

The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

Bacteriocin-like inhibitory activities of seven Lactobacillus delbrueckii subsp. bulgaricus strains against antibiotic susceptible and resistant Helicobacter pylori strains.

PubMed

Boyanova, L; Gergova, G; Markovska, R; Yordanov, D; Mitov, I

2017-12-01

The aim of the study was to detect anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains by four cell-free supernatant (CFS) types. Activity of non-neutralized and non-heat-treated (CFSs1), non-neutralized and heat-treated (CFSs2), pH neutralized, catalase-treated and non-heat-treated (CFSs3), or neutralized, catalase- and heat-treated (CFSs4) CFSs against 18 H. pylori strains (11 of which with antibiotic resistance) was evaluated. All GLB strains produced bacteriocin-like inhibitory substances (BLISs), the neutralized CFSs of two GLB strains inhibited >81% of test strains and those of four GLB strains were active against >71% of antibiotic resistant strains. Two H. pylori strains were BLIS resistant. The heating did not reduce the CFS activity. Briefly, all GLB strains evaluated produced heat-stable BLISs, although GLB and H. pylori strain susceptibility patterns exhibited differences. Bacteriocin-like inhibitory substance activity can be an advantage for the probiotic choice for H. pylori infection control. In this study, anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains was evaluated by four cell-free supernatant (CFS) types. The GLB strains produced heat-stable bacteriocin-like inhibitory substances (BLISs) with a strong anti-H. pylori activity and some neutralized, catalase- and heat-treated CFSs inhibited >83% of the test strains. Bacteriocin-like inhibitory substance production of GLB strains can render them valuable probiotics in the control of H. pylori infection. © 2017 The Society for Applied Microbiology.

Strain screen and haplotype association mapping of wheel running in inbred mouse strains.

PubMed

Lightfoot, J Timothy; Leamy, Larry; Pomp, Daniel; Turner, Michael J; Fodor, Anthony A; Knab, Amy; Bowen, Robert S; Ferguson, David; Moore-Harrison, Trudy; Hamilton, Alicia

2010-09-01

Previous genetic association studies of physical activity, in both animal and human models, have been limited in number of subjects and genetically homozygous strains used as well as number of genomic markers available for analysis. Expansion of the available mouse physical activity strain screens and the recently published dense single-nucleotide polymorphism (SNP) map of the mouse genome (approximately 8.3 million SNPs) and associated statistical methods allowed us to construct a more generalizable map of the quantitative trait loci (QTL) associated with physical activity. Specifically, we measured wheel running activity in male and female mice (average age 9 wk) in 41 inbred strains and used activity data from 38 of these strains in a haplotype association mapping analysis to determine QTL associated with activity. As seen previously, there was a large range of activity patterns among the strains, with the highest and lowest strains differing significantly in daily distance run (27.4-fold), duration of activity (23.6-fold), and speed (2.9-fold). On a daily basis, female mice ran further (24%), longer (13%), and faster (11%). Twelve QTL were identified, with three (on Chr. 12, 18, and 19) in both male and female mice, five specific to males, and four specific to females. Eight of the 12 QTL, including the 3 general QTL found for both sexes, fell into intergenic areas. The results of this study further support the findings of a moderate to high heritability of physical activity and add general genomic areas applicable to a large number of mouse strains that can be further mined for candidate genes associated with regulation of physical activity. Additionally, results suggest that potential genetic mechanisms arising from traditional noncoding regions of the genome may be involved in regulation of physical activity.

Temperature and strain registration by fibre-optic strain sensor in the polymer composite materials manufacturing

NASA Astrophysics Data System (ADS)

Matveenko, V. P.; Kosheleva, N. A.; Shardakov, I. N.; Voronkov, A. A.

2018-04-01

The presence of process-induced strains induced by various manufacturing and operational factors is one of the characteristics of polymer composite materials (PCM). Conventional methods of registration and evaluation of process-induced strains can be laborious, time-consuming and demanding in terms of technical applications. The employment of embedded fibre-optic strain sensors (FOSS) offers a real prospect of measuring residual strains. This paper demonstrates the potential for using embedded FOSS for recording technological strains in a PCM plate. The PCM plate is manufactured from prepreg, using the direct compression-moulding method. In this method, the prepared reinforcing package is placed inside a mould, heated, and then exposed to compaction pressure. The examined technology can be used for positioning FOSS between the layers of the composite material. Fibre-optic sensors, interacting with the material of the examined object, make it possible to register the evolution of the strain process during all stages of polymer-composite formation. FOSS data were recorded with interrogator ASTRO X 327. The obtained data were processed using specially developed algorithms.

Sensitivity Enhancement of FBG-Based Strain Sensor.

PubMed

Li, Ruiya; Chen, Yiyang; Tan, Yuegang; Zhou, Zude; Li, Tianliang; Mao, Jian

2018-05-17

A novel fiber Bragg grating (FBG)-based strain sensor with a high-sensitivity is presented in this paper. The proposed FBG-based strain sensor enhances sensitivity by pasting the FBG on a substrate with a lever structure. This typical mechanical configuration mechanically amplifies the strain of the FBG to enhance overall sensitivity. As this mechanical configuration has a high stiffness, the proposed sensor can achieve a high resonant frequency and a wide dynamic working range. The sensing principle is presented, and the corresponding theoretical model is derived and validated. Experimental results demonstrate that the developed FBG-based strain sensor achieves an enhanced strain sensitivity of 6.2 pm/με, which is consistent with the theoretical analysis result. The strain sensitivity of the developed sensor is 5.2 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The dynamic characteristics of this sensor are investigated through the finite element method (FEM) and experimental tests. The developed sensor exhibits an excellent strain-sensitivity-enhancing property in a wide frequency range. The proposed high-sensitivity FBG-based strain sensor can be used for small-amplitude micro-strain measurement in harsh industrial environments.

Sensitivity Enhancement of FBG-Based Strain Sensor

PubMed Central

Chen, Yiyang; Tan, Yuegang; Zhou, Zude; Mao, Jian

2018-01-01

A novel fiber Bragg grating (FBG)-based strain sensor with a high-sensitivity is presented in this paper. The proposed FBG-based strain sensor enhances sensitivity by pasting the FBG on a substrate with a lever structure. This typical mechanical configuration mechanically amplifies the strain of the FBG to enhance overall sensitivity. As this mechanical configuration has a high stiffness, the proposed sensor can achieve a high resonant frequency and a wide dynamic working range. The sensing principle is presented, and the corresponding theoretical model is derived and validated. Experimental results demonstrate that the developed FBG-based strain sensor achieves an enhanced strain sensitivity of 6.2 pm/με, which is consistent with the theoretical analysis result. The strain sensitivity of the developed sensor is 5.2 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The dynamic characteristics of this sensor are investigated through the finite element method (FEM) and experimental tests. The developed sensor exhibits an excellent strain-sensitivity-enhancing property in a wide frequency range. The proposed high-sensitivity FBG-based strain sensor can be used for small-amplitude micro-strain measurement in harsh industrial environments. PMID:29772826

Haemophilus ducreyi Cutaneous Ulcer Strains Diverged from Both Class I and Class II Genital Ulcer Strains: Implications for Epidemiological Studies

PubMed Central

Gangaiah, Dharanesh

2016-01-01

Background Haemophilus ducreyi has emerged as a major cause of cutaneous ulcers (CU) in yaws-endemic regions of the tropics in the South Pacific, South East Asia and Africa. H. ducreyi was once thought only to cause the genital ulcer (GU) disease chancroid; GU strains belong to 2 distinct classes, class I and class II. Using whole-genome sequencing of 4 CU strains from Samoa, 1 from Vanuatu and 1 from Papua New Guinea, we showed that CU strains diverged from the class I strain 35000HP and that one CU strain expressed β-lactamase. Recently, the Center for Disease Control and Prevention released the genomes of 11 additional CU strains from Vanuatu and Ghana; however, the evolutionary relationship of these CU strains to previously-characterized CU and GU strains is unknown. Methodology/Principal Findings We performed phylogenetic analysis of 17 CU and 10 GU strains. Class I and class II GU strains formed two distinct clades. The class I strains formed two subclades, one containing 35000HP and HD183 and the other containing the remainder of the class I strains. Twelve of the CU strains formed a subclone under the class I 35000HP subclade, while 2 CU strains formed a subclone under the other class I subclade. Unexpectedly, 3 of the CU strains formed a subclone under the class II clade. Phylogenetic analysis of dsrA-hgbA-ncaA sequences yielded a tree similar to that of whole-genome phylogenetic tree. Conclusions/Significance CU strains diverged from multiple lineages within both class I and class II GU strains. Multilocus sequence typing of dsrA-hgbA-ncaA could be reliably used for epidemiological investigation of CU and GU strains. As class II strains grow relatively poorly and are relatively more susceptible to vancomycin than class I strains, these findings have implications for methods to recover CU strains. Comparison of contemporary CU and GU isolates would help clarify the relationship between these entities. PMID:28027326

Haemophilus ducreyi Cutaneous Ulcer Strains Diverged from Both Class I and Class II Genital Ulcer Strains: Implications for Epidemiological Studies.

PubMed

Gangaiah, Dharanesh; Spinola, Stanley M

2016-12-01

Haemophilus ducreyi has emerged as a major cause of cutaneous ulcers (CU) in yaws-endemic regions of the tropics in the South Pacific, South East Asia and Africa. H. ducreyi was once thought only to cause the genital ulcer (GU) disease chancroid; GU strains belong to 2 distinct classes, class I and class II. Using whole-genome sequencing of 4 CU strains from Samoa, 1 from Vanuatu and 1 from Papua New Guinea, we showed that CU strains diverged from the class I strain 35000HP and that one CU strain expressed β-lactamase. Recently, the Center for Disease Control and Prevention released the genomes of 11 additional CU strains from Vanuatu and Ghana; however, the evolutionary relationship of these CU strains to previously-characterized CU and GU strains is unknown. We performed phylogenetic analysis of 17 CU and 10 GU strains. Class I and class II GU strains formed two distinct clades. The class I strains formed two subclades, one containing 35000HP and HD183 and the other containing the remainder of the class I strains. Twelve of the CU strains formed a subclone under the class I 35000HP subclade, while 2 CU strains formed a subclone under the other class I subclade. Unexpectedly, 3 of the CU strains formed a subclone under the class II clade. Phylogenetic analysis of dsrA-hgbA-ncaA sequences yielded a tree similar to that of whole-genome phylogenetic tree. CU strains diverged from multiple lineages within both class I and class II GU strains. Multilocus sequence typing of dsrA-hgbA-ncaA could be reliably used for epidemiological investigation of CU and GU strains. As class II strains grow relatively poorly and are relatively more susceptible to vancomycin than class I strains, these findings have implications for methods to recover CU strains. Comparison of contemporary CU and GU isolates would help clarify the relationship between these entities.

Molecular characterization of the probiotic strain Bacillus cereus var. toyoi NCIMB 40112 and differentiation from food poisoning strains.

PubMed

Klein, Günter

2011-07-01

Bacillus cereus var. toyoi strain NCIMB 40112 (Toyocerin), a probiotic authorized in the European Union as feed additive for swine, bovines, poultry, and rabbits, was characterized by DNA fingerprinting applying pulsed-field gel electrophoresis and multilocus sequence typing and was compared with reference strains (of clinical and environmental origins). The probiotic strain was clearly characterized by pulsed-field gel electrophoresis using the restriction enzymes Apa I and Sma I resulting in unique DNA patterns. The comparison to the clinical reference strain B. cereus DSM 4312 was done with the same restriction enzymes, and again a clear differentiation of the two strains was possible by the resulting DNA patterns. The use of the restriction enzymes Apa I and Sma I is recommended for further studies. Furthermore, multilocus sequence typing analysis revealed a sequence type (ST 111) that was different from all known STs of B. cereus strains from food poisoning incidents. Thus, a strain characterization and differentiation from food poisoning strains for the probiotic strain was possible. Copyright ©, International Association for Food Protection

Retaining large and adjustable elastic strains of kilogram-scale Nb nanowires [Better Superconductor by Elastic Strain Engineering: Kilogram-scale Free-Standing Niobium Metal Composite with Large Retained Elastic Strains

DOE PAGES

Hao, Shijie; Cui, Lishan; Wang, Hua; ...

2016-02-10

Crystals held at ultrahigh elastic strains and stresses may exhibit exceptional physical and chemical properties. Individual metallic nanowires can sustain ultra-large elastic strains of 4-7%. However, retaining elastic strains of such magnitude in kilogram-scale nanowires is challenging. Here, we find that under active load, ~5.6% elastic strain can be achieved in Nb nanowires in a composite material. Moreover, large tensile (2.8%) and compressive (-2.4%) elastic strains can be retained in kilogram-scale Nb nanowires when the composite is unloaded to a free-standing condition. It is then demonstrated that the retained tensile elastic strains of Nb nanowires significantly increase their superconducting transitionmore » temperature and critical magnetic fields, corroborating ab initio calculations based on BCS theory. This free-standing nanocomposite design paradigm opens new avenues for retaining ultra-large elastic strains in great quantities of nanowires and elastic-strain-engineering at industrial scale.« less

Optical Fibers Would Sense Local Strains

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1994-01-01

Proposed fiber-optic transducers measure local strains. Includes lead-in and lead-out lengths producing no changes in phase shifts, plus short sensing length in which phase shift is sensitive to strain. Phase shifts in single-mode fibers vary with strains. In alternative version, multiple portions of optical fiber sensitive to strains characteristic of specific vibrational mode of object. Same principle also used with two-mode fiber.

Simultaneous measurement of absolute strain and differential strain based on fiber Bragg grating Fabry-Perot sensor

NASA Astrophysics Data System (ADS)

Wang, Kuiru; Wang, Bo; Yan, Binbin; Sang, Xinzhu; Yuan, Jinhui; Peng, Gang-Ding

2013-10-01

We present a fiber Bragg grating Fabry-Perot (FBG-FP) sensor using the fast Fourier transform (FFT) demodulation for measuring the absolute strain and differential strain simultaneously. The amplitude and phase characteristics of Fourier transform spectrum have been studied. The relation between the amplitude of Fourier spectrum and the differential strain has been presented. We fabricate the fiber grating FP cavity sensor, and carry out the experiment on the measurement of absolute strain and differential strain. Experimental results verify the demodulation method, and show that this sensor has a good accuracy in the scope of measurement. The demodulating method can expand the number of multiplexed sensors combining with wavelength division multiplexing and time division multiplexing.

40 CFR 180.1209 - Bacillus subtilis strain QST 713 and strain QST 713 variant soil; exemption from the requirement...

Code of Federal Regulations, 2013 CFR

2013-07-01

... strain QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... strain QST 713 and strain QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis strain QST 713 and strain QST 713 variant soil when used in or on all food commodities...

40 CFR 180.1209 - Bacillus subtilis strain QST 713 and strain QST 713 variant soil; exemption from the requirement...

Code of Federal Regulations, 2014 CFR

2014-07-01

... strain QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... strain QST 713 and strain QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis strain QST 713 and strain QST 713 variant soil when used in or on all food commodities...

Identification of a multifunctional protein, PhaM, that determines number, surface to volume ratio, subcellular localization and distribution to daughter cells of poly(3-hydroxybutyrate), PHB, granules in Ralstonia eutropha H16.

PubMed

Pfeiffer, Daniel; Wahl, Andreas; Jendrossek, Dieter

2011-11-01

A two-hybrid approach was applied to screen for proteins with the ability to interact with PHB synthase (PhaC1) of Ralstonia eutropha. The H16_A0141 gene (phaM) was identified in the majority of positive clones. PhaM (26.6 kDa) strongly interacted with PhaC1 and with phasin PhaP5 but not with PhaP1 or other PHB granule-associated proteins. A ΔphaM mutant accumulated only one or two large PHB granules instead of three to six medium-sized PHB granules of the wild type, and distribution of granules to daughter cells was disordered. All three phenotypes (number, size and distribution of PHB granules) were reversed by reintroduction of phaM. Purified PhaM revealed DNA-binding properties in gel mobility shift experiments. Expression of a fusion of the yellow fluorescent protein (eYfp) with PhaM resulted in formation of many small fluorescent granules that were bound to the nucleoid region. Remarkably, an eYfp-PhaP5 fusion localized at the cell poles in a PHB-negative background and overexpression of eYfp-PhaP5 in the wild type conferred binding of PHB granules to the cell poles. In conclusion, subcellular localization of PHB granules in R. eutropha depends on a concerted expression of at least three PHB granule-associated proteins, namely PhaM, PhaP5 and PHB synthase PhaC1. © 2011 Blackwell Publishing Ltd.

Strain gage system evaluation program

NASA Technical Reports Server (NTRS)

Dolleris, G. W.; Mazur, H. J.; Kokoszka, E., Jr.

1978-01-01

A program was conducted to determine the reliability of various strain gage systems when applied to rotating compressor blades in an aircraft gas turbine engine. A survey of current technology strain gage systems was conducted to provide a basis for selecting candidate systems for evaluation. Testing and evaluation was conducted in an F 100 engine. Sixty strain gage systems of seven different designs were installed on the first and third stages of an F 100 engine fan. Nineteen strain gage failures occurred during 62 hours of engine operation, for a survival rate of 68 percent. Of the failures, 16 occurred at blade-to-disk leadwire jumps (84 percent), two at a leadwire splice (11 percent), and one at a gage splice (5 percent). Effects of erosion, temperature, G-loading, and stress levels are discussed. Results of a post-test analysis of the individual components of each strain gage system are presented.

Decolorization of sulfonated azo dye Metanil Yellow by newly isolated bacterial strains: Bacillus sp. strain AK1 and Lysinibacillus sp. strain AK2.

PubMed

Anjaneya, O; Souche, S Yogesh; Santoshkumar, M; Karegoudar, T B

2011-06-15

Two different bacterial strains capable of decolorizing a highly water soluble azo dye Metanil Yellow were isolated from dye contaminated soil sample collected from Atul Dyeing Industry, Bellary, India. The individual bacterial strains Bacillus sp. AK1 and Lysinibacillus sp. AK2 decolorized Metanil Yellow (200 mg L(-1)) completely within 27 and 12h respectively. Various parameters like pH, temperature, NaCl and initial dye concentrations were optimized to develop an economically feasible decolorization process. The maximum concentration of Metanil Yellow (1000 mg L(-1)) was decolorized by strains AK2 and AK1 within 78 and 84 h respectively. These strains could decolorize Metanil Yellow over a broad pH range 5.5-9.0; the optimum pH was 7.2. The decolorization of Metanil Yellow was most efficient at 40°C and confirmed by UV-visible spectroscopy, TLC, HPLC and GC/MS analysis. Further, both the strains showed the involvement of azoreductase in the decolorization process. Phytotoxicity studies of catabolic products of Metanil Yellow on the seeds of chick pea and pigeon pea revealed much reduction in the toxicity of metabolites as compared to the parent dye. These results indicating the effectiveness of strains AK1 and AK2 for the treatment of textile effluents containing azo dyes. Copyright © 2011 Elsevier B.V. All rights reserved.

Probing the prodigious strain fringes from Lourdes

NASA Astrophysics Data System (ADS)

Aerden, Domingo G. A. M.; Sayab, Mohammad

2017-12-01

We investigate the kinematics of classic sigmoidal strain fringes from Lourdes (France) and review previous genetic models, strain methods and strain rates for these microstructures. Displacement controlled quartz and calcite fibers within the fringes yield an average strain of 195% with the technique of Ramsay and Huber (1983). This agrees well with strains measured from boudinaged pyrite layers and calcite veins in the same rocks, but conflicts with ca. ∼675% strain in previous analogue models for the studied strain fringes produced by progressive simple shear. We show that the detailed geometry and orientation of fiber patterns are insufficiently explained by simple shear but imply two successive, differently oriented strain fields. Although all strain fringes have the same overall asymmetry, considerable morphological variation resulted from different amounts of rotation of pyrite grains and fringes. Minor rotation led to sharply kinked fibers that record a ca. 70° rotation of the kinematic frame. Larger (up to 145°) rotations, accommodated by antithetic sliding on pyrite-fringe contacts, produced more strongly and smoothly curved fibers. Combined with published Rb-Sr ages for the studied microstructures, our new strain data indicate an average strain rate of 1.41 10-15 s-1 during ca. 37 Myr. continuous growth.

Taxonomic and Strain-Specific Identification of the Probiotic Strain Lactobacillus rhamnosus 35 within the Lactobacillus casei Group▿

PubMed Central

Coudeyras, Sophie; Marchandin, Hélène; Fajon, Céline; Forestier, Christiane

2008-01-01

Lactobacilli are lactic acid bacteria that are widespread in the environment, including the human diet and gastrointestinal tract. Some Lactobacillus strains are regarded as probiotics because they exhibit beneficial health effects on their host. In this study, the long-used probiotic strain Lactobacillus rhamnosus 35 was characterized at a molecular level and compared with seven reference strains from the Lactobacillus casei group. Analysis of rrn operon sequences confirmed that L. rhamnosus 35 indeed belongs to the L. rhamnosus species, and both temporal temperature gradient gel electrophoresis and ribotyping showed that it is closer to the probiotic strain L. rhamnosus ATCC 53103 (also known as L. rhamnosus GG) than to the species type strain. In addition, L. casei ATCC 334 gathered in a coherent cluster with L. paracasei type strains, unlike L. casei ATCC 393, which was closer to L. zeae; this is evidence of the lack of relatedness between the two L. casei strains. Further characterization of the eight strains by pulsed-field gel electrophoresis repetitive DNA element-based PCR identified distinct patterns for each strain, whereas two isolates of L. rhamnosus 35 sampled 40 years apart could not be distinguished. By subtractive hybridization using the L. rhamnosus GG genome as a driver, we were able to isolate five L. rhamnosus 35-specific sequences, including two phage-related ones. The primer pairs designed to amplify these five regions allowed us to develop rapid and highly specific PCR-based identification methods for the probiotic strain L. rhamnosus 35. PMID:18326671

High temperature static strain measurement with an electrical resistance strain gage

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen

1992-01-01

An electrical resistance strain gage that can supply accurate static strain measurement for NASP application is being developed both in thin film and fine wire forms. This gage is designed to compensate for temperature effects on substrate materials with a wide range of thermal expansion coefficients. Some experimental results of the wire gage tested on one of the NASP structure materials, i.e., titanium matrix composites, are presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckert, C. A.; Sullivan, R.; Johnson, C.

CO2 and H2 are promising feedstocks for production of valuable biocompounds. Ralstonia eutropha utilizes these feedstocks to generate energy (ATP) and reductant (NAD(P)H) via oxidation of H2 by a membrane-bound (MBH) and a soluble hydrogenase (SH) for CO2 fixation by the Calvin-Benson-Bassham (CBB) cycle. Increased expression of the enzyme that fixes CO2 (RubisCO) resulted in 6-fold activity improvement in vitro, while increased expression of the MBH operon or the SH operon plus MBH operon maturation factors necessary for activity resulted in a 10-fold enhancement. Current research involves genetic manipulation of two endogenous cbb operons for increased expression, analysis of expressionmore » and activity of CBB/MBH/SH, cofactor ratios, and downstream products during autotrophic growth in control versus enhanced strains, and development of strategies for long-term, optimal overexpression. These studies will improve our understanding of autotrophic metabolism and provide a chassis strain for autotrophic production of biodiesel and other valuable carbon biocompounds.« less

A Bioluminescent Whole-Cell Reporter for Detection of 2,4-Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol in Soil

PubMed Central

Hay, Anthony G.; Rice, James F.; Applegate, Bruce M.; Bright, Nathan G.; Sayler, Gary S.

2000-01-01

A bioreporter was made containing a tfdRPDII-luxCDABE fusion in a modified mini-Tn5 construct. When it was introduced into the chromosome of Ralstonia eutropha JMP134, the resulting strain, JMP134-32, produced a sensitive bioluminescent response to 2,4-dichlorophenoxyacetic acid (2,4-D) at concentrations of 2.0 μM to 5.0 mM. This response was linear (R2 = 0.9825) in the range of 2.0 μM to 1.1 × 102 μM. Saturation occurred at higher concentrations, with maximal bioluminescence occurring in the presence of approximately 1.2 mM 2,4-D. A sensitive response was also recorded in the presence of 2,4-dichlorophenol at concentrations below 1.1 × 102 μM; however, only a limited bioluminescent response was recorded in the presence of 3-chlorobenzoic acid at concentrations below 1.0 mM. A significant bioluminescent response was also recorded when strain JMP134-32 was incubated with soils containing aged 2,4-D residues. PMID:11010925

Brucella abortus Strain 2308 Wisconsin Genome: Importance of the Definition of Reference Strains

PubMed Central

Suárez-Esquivel, Marcela; Ruiz-Villalobos, Nazareth; Castillo-Zeledón, Amanda; Jiménez-Rojas, César; Roop II, R. Martin; Comerci, Diego J.; Barquero-Calvo, Elías; Chacón-Díaz, Carlos; Caswell, Clayton C.; Baker, Kate S.; Chaves-Olarte, Esteban; Thomson, Nicholas R.; Moreno, Edgardo; Letesson, Jean J.; De Bolle, Xavier; Guzmán-Verri, Caterina

2016-01-01

Brucellosis is a bacterial infectious disease affecting a wide range of mammals and a neglected zoonosis caused by species of the genetically homogenous genus Brucella. As in most studies on bacterial diseases, research in brucellosis is carried out by using reference strains as canonical models to understand the mechanisms underlying host pathogen interactions. We performed whole genome sequencing analysis of the reference strain B. abortus 2308 routinely used in our laboratory, including manual curated annotation accessible as an editable version through a link at https://en.wikipedia.org/wiki/Brucella#Genomics. Comparison of this genome with two publically available 2308 genomes showed significant differences, particularly indels related to insertional elements, suggesting variability related to the transposition of these elements within the same strain. Considering the outcome of high resolution genomic techniques in the bacteriology field, the conventional concept of strain definition needs to be revised. PMID:27746773

Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients.

PubMed

Zhan, Xiao-Yong; Hu, Chao-Hui; Zhu, Qing-Yi

2016-04-01

Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains, respectively. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Distribution frequencies of these genes in reference L. pneumophila strains were similar to those in environmental L. pneumophila strains. In contrast, environmental non-L. pneumophila maintained higher frequencies of these genes compared to those found in reference non-L. pneumophila strains. This study illustrates the association of virulence genes with Legionella pathogenicity and reveals the possible virulence evolution of non-L. pneumophia strains isolated from environmental water.

Strains and Sprains Are a Pain

MedlinePlus

... for Educators Search English Español Strains and Sprains Are a Pain KidsHealth / For Kids / Strains and Sprains ... sports. Let's find out more about them. What Are Strains and Sprains? Muscles contract and relax (almost ...

Determination of Dynamic Recrystallization Process by Equivalent Strain

NASA Astrophysics Data System (ADS)

Qin, Xiaomei; Deng, Wei

Based on Tpнoвckiй's displacement field, equivalent strain expression was derived. And according to the dynamic recrystallization (DRX) critical strain, DRX process was determined by equivalent strain. It was found that equivalent strain distribution in deformed specimen is inhomogeneous, and it increases with increasing true strain. Under a certain true strain, equivalent strains at the center, demisemi radius or on tangential plane just below the surface of the specimen are higher than the true strain. Thus, micrographs at those positions can not exactly reflect the true microstructures under the certain true strain. With increasing strain rate, the initial and finish time of DRX decrease. The frozen microstructures of 20Mn23AlV steel with the experimental condition validate the feasibility of predicting DRX process by equivalent strain.

Chitinase producing Bt strains

Treesearch

Haim B. Gunner; Matthew Zimet; Sarah Berger

1985-01-01

Screening of 402 strains of more than 18 varieties of Bacillus thuringiensis showed chitinase to be inducible in virtually every serovar tested. Though the chitinase titre varied among strains, there was a strong correlation between enhanced lethality to spruce budworm, Choristoneura fumiferana (Clemens), and an increase in...

Specific identification of Bacillus anthracis strains

NASA Astrophysics Data System (ADS)

Krishnamurthy, Thaiya; Deshpande, Samir; Hewel, Johannes; Liu, Hongbin; Wick, Charles H.; Yates, John R., III

2007-01-01

Accurate identification of human pathogens is the initial vital step in treating the civilian terrorism victims and military personnel afflicted in biological threat situations. We have applied a powerful multi-dimensional protein identification technology (MudPIT) along with newly generated software termed Profiler to identify the sequences of specific proteins observed for few strains of Bacillus anthracis, a human pathogen. Software termed Profiler was created to initially screen the MudPIT data of B. anthracis strains and establish the observed proteins specific for its strains. A database was also generated using Profiler containing marker proteins of B. anthracis and its strains, which in turn could be used for detecting the organism and its corresponding strains in samples. Analysis of the unknowns by our methodology, combining MudPIT and Profiler, led to the accurate identification of the anthracis strains present in samples. Thus, a new approach for the identification of B. anthracis strains in unknown samples, based on the molecular mass and sequences of marker proteins, has been ascertained.

Job strain and male fertility.

PubMed

Hjollund, Niels Henrik I; Bonde, Jens Peter E; Henriksen, Tine Brink; Giwercman, Aleksander; Olsen, Jørn

2004-01-01

Job strain, defined as high job demands and low job control, has not previously been explored as a possible determinant of male fertility. We collected prospective data on job strain among men, and describe the associations with semen quality and probability of conceiving a clinical pregnancy during a menstrual cycle. Danish couples (N = 399) who were trying to become pregnant for the first time were followed for up to 6 menstrual periods. All men collected semen samples, and a blood sample was drawn from both partners. Job demand and job control were measured by a self-administered questionnaire at entry, and in each cycle the participants recorded changes in job control or job demand during the previous 30 days. In adjusted analyses, no associations were found between any semen characteristic or sexual hormones and any job strain variable. The odds for pregnancy were not associated with job strain. Psychologic job strain encountered in normal jobs in Denmark does not seem to affect male reproductive function.

Potential for plant growth promotion by a consortium of stress-tolerant 2,4-dinitrotoluene-degrading bacteria: isolation and characterization of a military soil

PubMed Central

Thijs, Sofie; Weyens, Nele; Sillen, Wouter; Gkorezis, Panagiotis; Carleer, Robert; Vangronsveld, Jaco

2014-01-01

The presence of explosives in soils and the interaction with drought stress and nutrient limitation are among the environmental factors that severely affect plant growth on military soils. In this study, we seek to isolate and identify the cultivable bacteria of a 2,4-dinitrotoluene (DNT) contaminated soil (DS) and an adjacent grassland soil (GS) of a military training area aiming to isolate new plant growth-promoting (PGP) and 2,4-DNT-degrading strains. Metabolic profiling revealed disturbances in Ecocarbon use in the bare DS; isolation of cultivable strains revealed a lower colony-forming-unit count and a less diverse community associated with DS in comparison with GS. New 2,4-DNT-tolerant strains were identified by selective enrichments, which were further characterized by auxanography for 2,4-DNT use, resistance to drought stress, cold, nutrient starvation and PGP features. By selecting multiple beneficial PGP and abiotic stress-resistant strains, efficient 2,4-DNT-degrading consortia were composed. After inoculation, consortium UHasselt Sofie 3 with seven members belonging to Burkholderia, Variovorax, Bacillus, Pseudomonas and Ralstonia species was capable to successfully enhance root length of Arabidopsis under 2,4-DNT stress. After 9 days, doubling of main root length was observed. Our results indicate that beneficial bacteria inhabiting a disturbed environment have the potential to improve plant growth and alleviate 2,4-DNT stress. PMID:24467368

Inoculating Helianthus annuus (sunflower) grown in zinc and cadmium contaminated soils with plant growth promoting bacteria--effects on phytoremediation strategies.

PubMed

Marques, Ana P G C; Moreira, Helena; Franco, Albina R; Rangel, António O S S; Castro, Paula M L

2013-06-01

Plant growth promoting bacteria (PGPR) may help reducing the toxicity of heavy metals to plants in polluted environments. In this work the effects of inoculating metal resistant and plant growth promoting bacterial strains on the growth of Helianthus annuus grown in Zn and Cd spiked soils were assessed. The PGPR strains Ralstonia eutropha (B1) and Chrysiobacterium humi (B2) reduced losses of weight in metal exposed plants and induced changes in metal bioaccumulation and bioconcentration - with strain B2 decreasing up to 67% Zn accumulation and by 20% Zn bioconcentration factor (BCF) in the shoots, up to 64% Zn uptake and 38% Zn BCF in the roots, and up to 27% Cd uptake and 27% Cd BCF in plant roots. The impact of inoculation on the bacterial communities in the rhizosphere of the plant was also assessed. Bacterial community diversity decreased with increasing levels of metal contamination in the soil, but in rhizosphere soil of plants inoculated with the PGPR strains, a higher bacterial diversity was kept throughout the experimental period. Inoculation of sunflower, particularly with C. humi (B2), appears to be an effective way of enhancing the short term stabilization potential of the plant in metal contaminated land, lowering losses in plant biomass and decreasing aboveground tissue contamination. Copyright © 2013 Elsevier Ltd. All rights reserved.

A magnetically actuated cellular strain assessment tool for quantitative analysis of strain induced cellular reorientation and actin alignment

NASA Astrophysics Data System (ADS)

Khademolhosseini, F.; Liu, C.-C.; Lim, C. J.; Chiao, M.

2016-08-01

Commercially available cell strain tools, such as pneumatically actuated elastomer substrates, require special culture plates, pumps, and incubator setups. In this work, we present a magnetically actuated cellular strain assessment tool (MACSAT) that can be implemented using off-the-shelf components and conventional incubators. We determine the strain field on the MACSAT elastomer substrate using numerical models and experimental measurements and show that a specific region of the elastomer substrate undergoes a quasi-uniaxial 2D stretch, and that cells confined to this region of the MACSAT elastomer substrate undergo tensile, compressive, or zero axial strain depending on their angle of orientation. Using the MACSAT to apply cyclic strain on endothelial cells, we demonstrate that actin filaments within the cells reorient away from the stretching direction, towards the directions of minimum axial strain. We show that the final actin orientation angles in strained cells are spread over a region of compressive axial strain, confirming previous findings on the existence of a varied pre-tension in the actin filaments of the cytoskeleton. We also demonstrate that strained cells exhibit distinctly different values of actin alignment coherency compared to unstrained cells and therefore propose that this parameter, i.e., the coherency of actin alignment, can be used as a new readout to determine the occurrence/extent of actin alignment in cell strain experiments. The tools and methods demonstrated in this study are simple and accessible and can be easily replicated by other researchers to study the strain response of other adherent cells.

[Biodiversity of phosphate-dissolving and plant growth--promoting endophytic bacteria of two crops].

PubMed

Huang, Jing; Sheng, Xiafang; He, Linyan

2010-06-01

We isolated and characterized phosphate-dissolving endophytic bacteria from two commonly cultivated crops. Phosphate-dissolving endophytic bacteria were isolated by plating and screening from interior tissues of rape and maize plants on NBRIP medium with tricalcium phosphate as sole phosphate source. Bacteria were characterized regarding characteristics that may be relevant for a beneficial plant-microbe interaction-indoleacetic acid, siderophore and 1-aminocyclopropane-1-carboxylic acid deaminase production,and further classified by restriction analysis of 16S rDNA. Eleven typical strains were identified by 16S rDNA sequence analysis. Thirty-two phosphate-dissolving endophytic bacteria were isolated from maize and rape plants and classified by restriction analysis of 16S rDNA in 8 different taxonomic groups at the similarity level of 76%. All the isolates could release phosphate from tricalcium phosphate and decrease the pH of the medium. The maximum phosphate content (537.6 mg/L) in the solution was obtained with strain M1L5. Thirteen isolates isolated from rape produced indoleacetic acid and siderophore, 68.4% and 63.2% of the strains isolated from maize produced indoleacetic acid and siderophore,respectively. 63.2% of the strains isolated from maize were able to grow on 1-aminocyclopropane-1-carboxylic acid as the sole nitrogen source. The eleven strains belonged to five different genera including Pantoea, Pseudomonas, Burkholderia, Acinetobacter and Ralstonia. Phosphate-dissolving endophytic bacteria isolated from rape and maize plants have abundant characteristics relative to promoting plant growth and genetic diversity.

Metal(loid)-resistant bacteria reduce wheat Cd and As uptake in metal(loid)-contaminated soil.

PubMed

Wang, Xiao-Han; Luo, Wei-Wei; Wang, Qi; He, Lin-Yan; Sheng, Xia-Fang

2018-06-05

This study characterized the effect of the metal(loid)-resistant bacteria Ralstonia eutropha Q2-8 and Exiguobacterium aurantiacum Q3-11 on Cd and As accumulation in wheat grown in Cd- and As-polluted soils (1 mg kg -1 of Cd + 40 mg kg -1 of As and 2 mg kg -1 of Cd + 60 mg kg -1 of As). The influence of strains Q2-8 and Q3-11 on water-soluble Cd and As and NH 4 + concentration and pH in the soil filtrate were also analyzed. Inoculation with these strains significantly reduced wheat plant Cd (12-32%) and As (9-29%) uptake and available Cd (15-28%) and As (22-38%) contents in rhizosphere soils compared to the controls. Furthermore, these strains significantly increased the relative abundances of the arsM bacterial As metabolism gene and of Fe- and Mn-oxidizing Leptothrix species in rhizosphere soils. Notably, these strains significantly reduced water-soluble Cd and As concentrations and increased pH and NH 4 + concentration in the soil filtrate. These results suggest that these strains increased soil pH and the abundance of genes possibly involved in metal(loid) unavailability, resulting in reduced wheat Cd and As accumulation and highlight the possibility of using bacteria for in situ remediation and safe production of wheat or other food crops in metal(loid)-polluted soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Altering thermal transport by strained-layer epitaxy

NASA Astrophysics Data System (ADS)

Majdi, Tahereh; Pal, Souvik; Hafreager, Anders; Murad, Sohail; Sahu, Rakesh P.; Puri, Ishwar K.

2018-05-01

Since strain changes the interatomic spacing of matter and alters electron and phonon dispersion, an applied strain can modify the thermal conductivity k of a material. We show how the strain induced by heteroepitaxy is a passive mechanism to change k in a thin film. Molecular dynamics simulations of the deposition and epitaxial growth of ZnTe thin films provide insights into the role of interfacial strain in the conductivity of a deposited film. ZnTe films grow strain-free on lattice-matched ZnTe substrates, but similar thin films grown on a lattice-mismatched CdTe substrate exhibit ˜6% biaxial in-plane tensile strain and ˜7% uniaxial out-of-plane compressive strain. In the T = 700 K-1100 K temperature range, the conductivities of strained ZnTe layers decrease to ˜60% of their unstrained values. The resulting understanding of dk/dT shows that strain engineering can be used to alter the performance of a thermal rectifier and also provides a framework for enhancing thermoelectric devices.

Thin film strain transducer. [in-flight measurement of stress or strain in walls of high altitude balloons

NASA Technical Reports Server (NTRS)

Rand, J. L.

1981-01-01

Previous attempts to develop an appropriate sensor for measuring the stress or strain of high altitude balloons during flight are reviewed as well as the various conditions that must be met by such a device. The design, development and calibration of a transducer which promises to satisfy the necessary design constraints are described. The thin film strain transducer has a low effective modulus so as not to interfere with the strain that would naturally occur in the balloon. In addition, the transducer has a high sensitivity to longitudinal strain (7.216 mV/V/unit strain) which is constant for all temperature from room temperature to -80 C and all strains from 5 percent compression to 10 percent tensile strain. At the same time, the sensor is relatively insensitive (0.27 percent) to transverse forces. The device has a standard 350 ohm impedance which is compatible with available bridge balance, amplification and telemetry instrumentation now available for balloon flight. Recommendations are included for improved coatings to provide passive thermal control as well as model, tethered and full scale flight testing.

Thick film wireless and powerless strain sensor

NASA Astrophysics Data System (ADS)

Jia, Yi; Sun, Ke

2006-03-01

The development of an innovative wireless strain sensing technology has a great potential to extend its applications in manufacturing, civil engineering and aerospace industry. This paper presents a novel wireless and powerless strain sensor with a multi-layer thick film structure. The sensor employs a planar inductor (L) and capacitive transducer (C) resonant tank sensing circuit, and a strain sensitive material of a polarized polyvinylidene fluoride (PVDF) piezoelectric thick film to realize the wireless strain sensing by strain to frequency conversion and to receive radio frequency electromagnetic energy for powering the sensor. The prototype sensor was designed and fabricated. The results of calibration on a strain constant cantilever beam show a great linearity and sensitivity about 0.0013 in a strain range of 0-0.018.

Strains and Stressors: An Analysis of Touchscreen Learning in Genetically Diverse Mouse Strains

PubMed Central

Graybeal, Carolyn; Bachu, Munisa; Mozhui, Khyobeni; Saksida, Lisa M.; Bussey, Timothy J.; Sagalyn, Erica; Williams, Robert W.; Holmes, Andrew

2014-01-01

Touchscreen-based systems are growing in popularity as a tractable, translational approach for studying learning and cognition in rodents. However, while mouse strains are well known to differ in learning across various settings, performance variation between strains in touchscreen learning has not been well described. The selection of appropriate genetic strains and backgrounds is critical to the design of touchscreen-based studies and provides a basis for elucidating genetic factors moderating behavior. Here we provide a quantitative foundation for visual discrimination and reversal learning using touchscreen assays across a total of 35 genotypes. We found significant differences in operant performance and learning, including faster reversal learning in DBA/2J compared to C57BL/6J mice. We then assessed DBA/2J and C57BL/6J for differential sensitivity to an environmental insult by testing for alterations in reversal learning following exposure to repeated swim stress. Stress facilitated reversal learning (selectively during the late stage of reversal) in C57BL/6J, but did not affect learning in DBA/2J. To dissect genetic factors underlying these differences, we phenotyped a family of 27 BXD strains generated by crossing C57BL/6J and DBA/2J. There was marked variation in discrimination, reversal and extinction learning across the BXD strains, suggesting this task may be useful for identifying underlying genetic differences. Moreover, different measures of touchscreen learning were only modestly correlated in the BXD strains, indicating that these processes are comparatively independent at both genetic and phenotypic levels. Finally, we examined the behavioral structure of learning via principal component analysis of the current data, plus an archival dataset, totaling 765 mice. This revealed 5 independent factors suggestive of “reversal learning,” “motivation-related late reversal learning,” “discrimination learning,” “speed to respond,” and �

Strains and stressors: an analysis of touchscreen learning in genetically diverse mouse strains.

PubMed

Graybeal, Carolyn; Bachu, Munisa; Mozhui, Khyobeni; Saksida, Lisa M; Bussey, Timothy J; Sagalyn, Erica; Williams, Robert W; Holmes, Andrew

2014-01-01

Touchscreen-based systems are growing in popularity as a tractable, translational approach for studying learning and cognition in rodents. However, while mouse strains are well known to differ in learning across various settings, performance variation between strains in touchscreen learning has not been well described. The selection of appropriate genetic strains and backgrounds is critical to the design of touchscreen-based studies and provides a basis for elucidating genetic factors moderating behavior. Here we provide a quantitative foundation for visual discrimination and reversal learning using touchscreen assays across a total of 35 genotypes. We found significant differences in operant performance and learning, including faster reversal learning in DBA/2J compared to C57BL/6J mice. We then assessed DBA/2J and C57BL/6J for differential sensitivity to an environmental insult by testing for alterations in reversal learning following exposure to repeated swim stress. Stress facilitated reversal learning (selectively during the late stage of reversal) in C57BL/6J, but did not affect learning in DBA/2J. To dissect genetic factors underlying these differences, we phenotyped a family of 27 BXD strains generated by crossing C57BL/6J and DBA/2J. There was marked variation in discrimination, reversal and extinction learning across the BXD strains, suggesting this task may be useful for identifying underlying genetic differences. Moreover, different measures of touchscreen learning were only modestly correlated in the BXD strains, indicating that these processes are comparatively independent at both genetic and phenotypic levels. Finally, we examined the behavioral structure of learning via principal component analysis of the current data, plus an archival dataset, totaling 765 mice. This revealed 5 independent factors suggestive of "reversal learning," "motivation-related late reversal learning," "discrimination learning," "speed to respond," and "motivation during

Strains

MedlinePlus

... the first 3 days. After 3 days, either heat or ice may be helpful if you still have pain. Rest the pulled muscle for at least a day. If possible, keep the pulled muscle raised above your heart. Try not to use a strained muscle while ...

Reduction of petroleum hydrocarbons and toxicity in refinery wastewater by bioremediation.

PubMed

Płaza, Grazyna A; Jangid, Kamlesh; Lukasik, Krystyna; Nałecz-Jawecki, Grzegorz; Berry, Christopher J; Brigmon, Robin L

2008-10-01

The aim of the study was to investigate petroleum waste remediation and toxicity reduction by five bacterial strains: Ralstonia picketti SRS (BP-20), Alcaligenes piechaudii SRS (CZOR L-1B), Bacillus subtilis (I'-1a), Bacillus sp. (T-1), and Bacillus sp. (T'-1), previously isolated from petroleum-contaminated soils. Petroleum hydrocarbons were significantly degraded (91%) by the mixed bacterial cultures in 30 days (reaching up to 29% in the first 72 h). Similarly, the toxicity of the biodegraded petroleum waste decreased 3-fold after 30 days. This work shows the influence of bacteria on hydrocarbon degradation and associated toxicity, and its dependence on the specific microorganisms present. The ability of these mixed cultures to degrade hydrocarbons and reduce toxicity makes them candidates for environmental restoration applications at other hydrocarbon-contaminated environments.

Genetic analysis of Saccharomyces cerevisiae strains isolated from palm wine in eastern Nigeria. Comparison with other African strains.

PubMed

Ezeronye, O U; Legras, J-L

2009-05-01

To study the yeast diversity of Nigerian palm wines by comparison with other African strains. Twenty-three Saccharomyces cerevisiae strains were obtained from palm wine samples collected at four locations in eastern Nigeria, and characterized using different molecular techniques: internal transcribed spacer restriction fragment length polymorphism and sequence analysis, pulsed field gel electrophoresis, inter delta typing and microsatellite multilocus analysis. These techniques revealed that palm wine yeasts represent a group of closely related strains that includes other West African isolates (CBS400, NCYC110, DVPG6044). Population analysis revealed an excess of homozygote strains and an allelic richness similar to wine suggestive of local domestication. Several other African yeast strains were not connected to this group. Ghana sorghum beer strains and other African strains (DBVPG1853 and MUCL28071) displayed strikingly high relatedness with European bread, beer or wine strains, and the genome of strain MUCL30909 contained African and wine-type alleles, indicating its hybrid origin. Nigerian palm wine yeast represents a local specific yeast flora, whereas a European origin or hybrid was suspected for several other Africa isolates. This study presents the first genetic characterization of an autochthonous African palm wine yeast population and confirms the idea that human intervention has favoured yeast migration.

Strain, strain rate, and the force frequency relationship in patients with and without heart failure.

PubMed

Mak, Susanna; Van Spall, Harriette G C; Wainstein, Rodrigo V; Sasson, Zion

2012-03-01

The aim of this study was to examine the effect of heart rate (HR) on indices of deformation in adults with and without heart failure (HF) who underwent simultaneous high-fidelity catheterization of the left ventricle to describe the force-frequency relationship. Right atrial pacing to control HR and high-fidelity recordings of left ventricular (LV) pressure were used to inscribe the force-frequency relationship. Simultaneous two-dimensional echocardiographic imaging was acquired for speckle-tracking analysis. Thirteen patients with normal LV function and 12 with systolic HF (LV ejection fraction, 31 ± 13%) were studied. Patients with HF had depressed isovolumic contractility and impaired longitudinal strain and strain rate. HR-dependent increases in LV+dP/dt(max), the force-frequency relationship, was demonstrated in both groups (normal LV function, baseline to 100 beats/min: 1,335 ± 296 to 1,564 ± 320 mm Hg/sec, P < .0001; HF, baseline to 100 beats/min: 970 ± 207 to 1,083 ± 233 mm Hg/sec, P < .01). Longitudinal strain decreased significantly (normal LV function, baseline to 100 beats/min: 18.0 ± 3.5% to 10.8 ± 6.0%, P < .001; HF: 9.4 ± 4.1% to 7.5 ± 3.4%, P < .01). The decrease in longitudinal strain was related to a decrease in LV end-diastolic dimensions. Strain rate did not change with right atrial pacing. Despite the inotropic effect of increasing HR, longitudinal strain decreases in parallel with stroke volume as load-dependent indices of ejection. Strain rate did not reflect the modest HR-related changes in contractility; on the other hand, the use of strain rate for quantitative stress imaging is also less likely to be confounded by chronotropic responses. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

Nanoscale strain mapping in battery nanostructures

NASA Astrophysics Data System (ADS)

Ulvestad, A.; Cho, H. M.; Harder, R.; Kim, J. W.; Dietze, S. H.; Fohtung, E.; Meng, Y. S.; Shpyrko, O. G.

2014-02-01

Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi0.5Mn1.5O4-δ cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn3+. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process.

Biochemical Characterization of Prion Strains in Bank Voles

PubMed Central

Pirisinu, Laura; Marcon, Stefano; Di Bari, Michele Angelo; D’Agostino, Claudia; Agrimi, Umberto; Nonno, Romolo

2013-01-01

Prions exist as different strains exhibiting distinct disease phenotypes. Currently, the identification of prion strains is still based on biological strain typing in rodents. However, it has been shown that prion strains may be associated with distinct PrPSc biochemical types. Taking advantage of the availability of several prion strains adapted to a novel rodent model, the bank vole, we investigated if any prion strain was actually associated with distinctive PrPSc biochemical characteristics and if it was possible to univocally identify strains through PrPSc biochemical phenotypes. We selected six different vole-adapted strains (three human-derived and three animal-derived) and analyzed PrPSc from individual voles by epitope mapping of protease resistant core of PrPSc (PrPres) and by conformational stability and solubility assay. Overall, we discriminated five out of six prion strains, while two different scrapie strains showed identical PrPSc types. Our results suggest that the biochemical strain typing approach here proposed was highly discriminative, although by itself it did not allow us to identify all prion strains analyzed. PMID:25437201

Strain effects on oxygen migration in perovskites.

PubMed

Mayeshiba, Tam; Morgan, Dane

2015-01-28

Fast oxygen transport materials are necessary for a range of technologies, including efficient and cost-effective solid oxide fuel cells, gas separation membranes, oxygen sensors, chemical looping devices, and memristors. Strain is often proposed as a method to enhance the performance of oxygen transport materials, but the magnitude of its effect and its underlying mechanisms are not well-understood, particularly in the widely-used perovskite-structured oxygen conductors. This work reports on an ab initio prediction of strain effects on migration energetics for nine perovskite systems of the form LaBO3, where B = [Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga]. Biaxial strain, as might be easily produced in epitaxial systems, is predicted to lead to approximately linear changes in migration energy. We find that tensile biaxial strain reduces the oxygen vacancy migration barrier across the systems studied by an average of 66 meV per percent strain for a single selected hop, with a low of 36 and a high of 89 meV decrease in migration barrier per percent strain across all systems. The estimated range for the change in migration barrier within each system is ±25 meV per percent strain when considering all hops. These results suggest that strain can significantly impact transport in these materials, e.g., a 2% tensile strain can increase the diffusion coefficient by about three orders of magnitude at 300 K (one order of magnitude at 500 °C or 773 K) for one of the most strain-responsive materials calculated here (LaCrO3). We show that a simple elasticity model, which assumes only dilative or compressive strain in a cubic environment and a fixed migration volume, can qualitatively but not quantitatively model the strain dependence of the migration energy, suggesting that factors not captured by continuum elasticity play a significant role in the strain response.

Nanocomposite Strain Gauges Having Small TCRs

NASA Technical Reports Server (NTRS)

Gregory, Otto; Chen, Ximing

2009-01-01

Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

Two-Dimensional Laser-Speckle Surface-Strain Gauge

NASA Technical Reports Server (NTRS)

Barranger, John P.; Lant, Christian

1992-01-01

Extension of Yamaguchi's laser-speckle surface-strain-gauge method yields data on two-dimensional surface strains in times as short as fractions of second. Laser beams probe rough spot on surface of specimen before and after processing. Changes in speckle pattern of laser light reflected from spot indicative of changes in surface strains during processing. Used to monitor strains and changes in strains induced by hot-forming and subsequent cooling of steel.

[Phylogenetic relationship of street rabies virus strains and their antigenic reactivity with antibodies induced by vaccine strains. I. Analysis of phylogenetic relationship of street rabies virus strains isolated in Poland].

PubMed

Sadkowska-Todys, M

2000-01-01

The aims of these studies were: genetic characteristic of street rabies virus strains isolated from different animal species in Poland and determination of phylogenetic relationships to reference laboratory strains of the street rabies viruses belonging to genotype 1 and 5. The variability of rabies isolates and their phylogenetic relationship were studied by comparing the nucleotide sequence of the virus genome fragment. The Polish strains of genotype 1 belong to four phylogenetic groups (NE, CE, NEE, EE) corresponding to four variants: fox-racoon dog (F-RD); European fox 1 (F1); European fox 2 (F2) and European fox 3 (F3). On the Polish territories there are no rabies strains representing the variant dog-wolf and typical for arctic fox variant. The similarity of nucleotide and amino acid sequences of street rabies strains belonging to genotype 1 and laboratory strain CVS is very high. It is about 91% similarity at nucleotide level and 95% at amino acid level. Rabies strain CVS is similar to genotype 5 bat strains (EBL 1) only in about 69% and 74% at nucleotide and amino acid level, respectively. The genetic divergence of rabies strains circulating in Poland raised the need of permanent epidemiological and virological surveillance. The genotype and variant of isolated strains should be determined (using PCR and RLFP methods).

Ultra High Strain Rate Nanoindentation Testing.

PubMed

Sudharshan Phani, Pardhasaradhi; Oliver, Warren Carl

2017-06-17

Strain rate dependence of indentation hardness has been widely used to study time-dependent plasticity. However, the currently available techniques limit the range of strain rates that can be achieved during indentation testing. Recent advances in electronics have enabled nanomechanical measurements with very low noise levels (sub nanometer) at fast time constants (20 µs) and high data acquisition rates (100 KHz). These capabilities open the doors for a wide range of ultra-fast nanomechanical testing, for instance, indentation testing at very high strain rates. With an accurate dynamic model and an instrument with fast time constants, step load tests can be performed which enable access to indentation strain rates approaching ballistic levels (i.e., 4000 1/s). A novel indentation based testing technique involving a combination of step load and constant load and hold tests that enables measurement of strain rate dependence of hardness spanning over seven orders of magnitude in strain rate is presented. A simple analysis is used to calculate the equivalent uniaxial response from indentation data and compared to the conventional uniaxial data for commercial purity aluminum. Excellent agreement is found between the indentation and uniaxial data over several orders of magnitude of strain rate.

Use of colony-based bacterial strain typing for tracking the fate of Lactobacillus strains during human consumption

PubMed Central

2009-01-01

Background The Lactic Acid Bacteria (LAB) are important components of the healthy gut flora and have been used extensively as probiotics. Understanding the cultivable diversity of LAB before and after probiotic administration, and being able to track the fate of administered probiotic isolates during feeding are important parameters to consider in the design of clinical trials to assess probiotic efficacy. Several methods may be used to identify bacteria at the strain level, however, PCR-based methods such as Random Amplified Polymorphic DNA (RAPD) are particularly suited to rapid analysis. We examined the cultivable diversity of LAB in the human gut before and after feeding with two Lactobacillus strains, and also tracked the fate of these two administered strains using a RAPD technique. Results A RAPD typing scheme was developed to genetically type LAB isolates from a wide range of species, and optimised for direct application to bacterial colony growth. A high-throughput strategy for fingerprinting the cultivable diversity of human faeces was developed and used to determine: (i) the initial cultivable LAB strain diversity in the human gut, and (ii) the fate of two Lactobacillus strains (Lactobacillus salivarius NCIMB 30211 and Lactobacillus acidophilus NCIMB 30156) contained within a capsule that was administered in a small-scale human feeding study. The L. salivarius strain was not cultivated from the faeces of any of the 12 volunteers prior to capsule administration, but appeared post-feeding in four. Strains matching the L. acidophilus NCIMB 30156 feeding strain were found in the faeces of three volunteers prior to consumption; after taking the Lactobacillus capsule, 10 of the 12 volunteers were culture positive for this strain. The appearance of both Lactobacillus strains during capsule consumption was statistically significant (p < 0.05). Conclusion We have shown that genetic strain typing of the cultivable human gut microbiota can be evaluated using a high

Strain-induced three-photon effects

NASA Astrophysics Data System (ADS)

Jeong, Jae-Woo; Shin, Sung-Chul; Lyubchanskii, I. L.; Varyukhin, V. N.

2000-11-01

Strain-induced three-photon effects such as optical second-harmonic generation and hyper-Rayleigh light scattering, characterized by electromagnetic radiation at the double frequency of an incident light, are phenomenologically investigated by adopting a nonlinear photoelastic interaction. The relations between the strain and the nonlinear optical susceptibility for crystal surfaces with point symmetries of 4mm and 3m are described by a symmetry analysis of the nonlinear photoelastic tensor. We theoretically demonstrate a possibility of determining the strain components by measuring the rotational anisotropy of radiation at the second-harmonic frequency. Hyper-Rayleigh light scattering by dislocation strain is also described using a nonlinear photoelastic tensor. The angular dependencies of light scattered at the double frequency of an incident light for different scattering geometries are analyzed.

AN ORGANOTYPIC UNIAXIAL STRAIN MODEL USING MICROFLUIDICS

PubMed Central

Dollé, Jean-Pierre; Morrison, Barclay; Schloss, Rene R.; Yarmush, Martin L.

2012-01-01

Traumatic brain injuries are the leading cause of disability each year in the US. The most common and devastating consequence is the stretching of axons caused by shear deformation that occurs during rotational acceleration of the brain during injury. The injury effects on axonal molecular and functional events are not fully characterized. We have developed a strain injury model that maintains the three dimensional cell architecture and neuronal networks found in vivo with the ability to visualize individual axons and their response to a mechanical injury. The advantage of this model is that it can apply uniaxial strains to axons that make functional connections between two organotypic slices and injury responses can be observed in real-time and over long term. This uniaxial strain model was designed to be capable of applying an array of mechanical strains at various rates of strain, thus replicating a range of modes of axonal injury. Long term culture, preservation of slice and cell orientation, and slice-slice connection on the device was demonstrated. The device has the ability to strain either individual axons or bundles of axons through the control of microchannel dimensions. The fidelity of the model was verified by observing characteristic responses to various strain injuries which included axonal beading, delayed elastic effects and breakdown in microtubules. Microtubule breakdown was shown to be dependent on the degree of the applied strain field, where maximal breakdown was observed at peak strain and minimal breakdown is observed at low strain. This strain injury model could be a powerful tool in assessing strain injury effects on functional axonal connections. PMID:23233120

Optical fiber sensor technique for strain measurement

DOEpatents

Butler, Michael A.; Ginley, David S.

1989-01-01

Laser light from a common source is split and conveyed through two similar optical fibers and emitted at their respective ends to form an interference pattern, one of the optical fibers having a portion thereof subjected to a strain. Changes in the strain cause changes in the optical path length of the strain fiber, and generate corresponding changes in the interference pattern. The interference pattern is received and transduced into signals representative of fringe shifts corresponding to changes in the strain experienced by the strained one of the optical fibers. These signals are then processed to evaluate strain as a function of time, typical examples of the application of the apparatus including electrodeposition of a metallic film on a conductive surface provided on the outside of the optical fiber being strained, so that strains generated in the optical fiber during the course of the electrodeposition are measurable as a function of time. In one aspect of the invention, signals relating to the fringe shift are stored for subsequent processing and analysis, whereas in another aspect of the invention the signals are processed for real-time display of the strain changes under study.

Dependence of the Brillouin gain spectrum on linear strain distribution for optical time-domain reflectometer-type strain sensors

NASA Astrophysics Data System (ADS)

Naruse, Hiroshi; Tateda, Mitsuhiro; Ohno, Hiroshige; Shimada, Akiyoshi

2002-12-01

We theoretically derive the shape of the Brillouin gain spectrum, that is, the Brillouin backscattered-light power spectrum, produced in an optical fiber under conditions of a strain distribution that changes linearly with a constant slope. The modeled measurement system is an optical time-domain reflectometer-type strain sensor system. The linear strain distribution is one of the fundamental distributions and is produced in, for example, a beam to which a concentrated load is applied. By analyzing a function that expresses the shape of the derived Brillouin gain spectrum, we show that the strain calculated from the frequency at which the spectrum has a peak value coincides with that at the center of the effective pulsed light. In addition, the peak value and the full width at half-maximum of the Brillouin gain spectrum are both influenced by the strain difference between the two ends of the effective pulse. We investigate this influence in detail and obtain the relationship between strain difference and strain measurement error.

Two-dimensional strain echocardiography technology for evaluation of myocardial strain in swimming athletes after high-intensity exercise.

PubMed

Liang, Chen; Ma, Yun; Gao, Can; Zhang, Jianhong; Yang, Min; Chen, Gen; Fu, Shan; Zhu, Tiangang

2017-02-01

The aim of this study was to investigate the change in myocardial strain in swimming athletes before and after high-intensity exercise using two-dimensional strain echocardiography (2DSE) technology. To assess whether the local and overall myocardial function and myocardial injury are accurately measured using 2DSE technology, 15 swimming athletes were selected as research objects. We applied 2DSE technology to track the 2D ultrasound images of the apical four chambers, the apical two chambers, and the apical long axis before and after high-intensity, increasing-load exercise. We recorded indices such as the left ventricular global strain (GS) and the left ventricular segmental wall longitudinal peak systolic strain (PS) in 18 systoles and analyzed the myocardial strain change before and after exercise. After high-intensity exercise, the overall myocardial strain decreased, especially the strain of the posterior wall, posterior divider, lateral wall, lower wall, and the basal and middle segments of the anterior wall. The influence of exercise on myocardial strain was greater on the basal and middle segments than on the apical segment. One-time intensive exercise negatively affected the myocardial muscle. Myocardial muscles in the apical segment and the myocardial wall were more sensitive to intensive exercise. The 2DSE technology can precisely position the motion-sensitive areas and help locate myocardial injury. © 2017, Wiley Periodicals, Inc.

Strain engineering of van der Waals heterostructures.

PubMed

Vermeulen, Paul A; Mulder, Jefta; Momand, Jamo; Kooi, Bart J

2018-01-18

Modifying the strain state of solids allows control over a plethora of functional properties. The weak interlayer bonding in van der Waals (vdWaals) materials such as graphene, hBN, MoS 2 , and Bi 2 Te 3 might seem to exclude strain engineering, since strain would immediately relax at the vdWaals interfaces. Here we present direct observations of the contrary by showing growth of vdWaals heterostructures with persistent in-plane strains up to 5% and we show that strain relaxation follows a not yet reported process distinctly different from strain relaxation in three-dimensionally bonded (3D) materials. For this, 2D bonded Bi 2 Te 3 -Sb 2 Te 3 and 2D/3D bonded Bi 2 Te 3 -GeTe multilayered films are grown using Pulsed Laser Deposition (PLD) and their structure is monitored in situ using Reflective High Energy Electron Diffraction (RHEED) and post situ analysis is performed using Transmission Electron Microscopy (TEM). Strain relaxation is modeled and found to solely depend on the layer being grown and its initial strain. This insight demonstrates that strain engineering of 2D bonded heterostructures obeys different rules than hold for epitaxial 3D materials and opens the door to precise tuning of the strain state of the individual layers to optimize functional performance of vdWaals heterostructures.

StrainSeeker: fast identification of bacterial strains from raw sequencing reads using user-provided guide trees.

PubMed

Roosaare, Märt; Vaher, Mihkel; Kaplinski, Lauris; Möls, Märt; Andreson, Reidar; Lepamets, Maarja; Kõressaar, Triinu; Naaber, Paul; Kõljalg, Siiri; Remm, Maido

2017-01-01

Fast, accurate and high-throughput identification of bacterial isolates is in great demand. The present work was conducted to investigate the possibility of identifying isolates from unassembled next-generation sequencing reads using custom-made guide trees. A tool named StrainSeeker was developed that constructs a list of specific k -mers for each node of any given Newick-format tree and enables the identification of bacterial isolates in 1-2 min. It uses a novel algorithm, which analyses the observed and expected fractions of node-specific k -mers to test the presence of each node in the sample. This allows StrainSeeker to determine where the isolate branches off the guide tree and assign it to a clade whereas other tools assign each read to a reference genome. Using a dataset of 100 Escherichia coli isolates, we demonstrate that StrainSeeker can predict the clades of E. coli with 92% accuracy and correct tree branch assignment with 98% accuracy. Twenty-five thousand Illumina HiSeq reads are sufficient for identification of the strain. StrainSeeker is a software program that identifies bacterial isolates by assigning them to nodes or leaves of a custom-made guide tree. StrainSeeker's web interface and pre-computed guide trees are available at http://bioinfo.ut.ee/strainseeker. Source code is stored at GitHub: https://github.com/bioinfo-ut/StrainSeeker.

Differentiation of Mycoplasma gallisepticum vaccine strains ts-11 and 6/85 from commonly used Mycoplasma gallisepticum challenge strains by PCR.

PubMed

Evans, J D; Leigh, S A

2008-09-01

Mycoplasma gallisepticum (MG) is an important avian pathogen causing significant economic losses within the poultry industry. In an effort to develop tools to aid in MG research and diagnostics, we have compared sequences of the attenuated MG vaccine strain ts-11 to those of commonly used pathogenic challenge strains in search of a simple means of differentiation. Via gapA sequence alignments and comparisons, we have identified and designed primers facilitating strain differentiation. When applied to conventional polymerase chain reaction (PCR) assay at low annealing temperature, the primer sets allow for the differentiation of MG attenuated vaccine strains ts-11 as well as the attenuated MG vaccine strain 6/85 from the commonly utilized MG challenge strains R(low), R, and S6. Conventional PCR differentiation is based on the visualization of sole products with the attenuated MG strains ts-11 and 6/85 and the lack of the corresponding products from MG strains R(low), R, and S6. When applied to MG strain F, product visualization varies with the applied primer set. The differentiation of MG strains ts-11 and 6/85 from the pathogenic challenge strains was also accomplished via real-time analyses, however, the primer sets were not able to differentiate MG strains ts-11 and 6/85 from selected MG field isolates.

The effect of simulated microgravity on bacteria from the mir space station

NASA Astrophysics Data System (ADS)

Baker, Paul W.; Leff, Laura

2004-03-01

The effects of simulated microgravity on two bacterial isolates, Sphingobacterium thalpophilium and Ralstonia pickettii (formerly Burkholderia pickettii), originally recovered from water systems aboard the Mir space station were examined. These bacteria were inoculated into water, high and low concentrations of nutrient broth and subjected to simulated microgravity conditions. S. thalpophilium (which was motile and had flagella) showed no significant differences between simulated microgravity and the normal gravity control regardless of the method of enumeration and medium. In contrast, for R. pickettii (that was non-motile and lacked flagella), there were significantly higher numbers in high nutrient broth under simulated microgravity compared to normal gravity. Conversely, when R. pikkettii was inoculated into water (i.e., starvation conditions) significantly lower numbers were found under simulated microgravity compared to normal gravity. Responses to microgravity depended on the strain used (e.g., the motile strain exhibited no response to microgravity, while the non-motile strain did), the method of enumeration, and the nutrient concentration of the medium. Under oligotrophic conditions, non-motile cells may remain in geostationary orbit and deplete nutrients in their vicinity, while in high nutrient medium, resources surrounding the cell may be sufficient so that high growth is observed until nutrients becoming limiting.

The effect of simulated microgravity on bacteria from the Mir space station.

PubMed

Baker, Paul W; Leff, Laura

2004-01-01

The effects of simulated microgravity on two bacterial isolates, Sphingobacterium thalpophilium and Ralstonia pickettii (formerly Burkholderia pickettii), originally recovered from water systems aboard the Mir space station were examined. These bacteria were inoculated into water, high and low concentrations of nutrient broth and subjected to simulated microgravity conditions. S. thalpophilium (which was motile and had flagella) showed no significant differences between simulated microgravity and the normal gravity control regardless of the method of enumeration and medium. In contrast, for R. pickettii (that was non-motile and lacked flagella), there were significantly higher numbers in high nutrient broth under simulated microgravity compared to normal gravity. Conversely, when R. pikkettii was inoculated into water (i.e., starvation conditions) significantly lower numbers were found under simulated microgravity compared to normal gravity. Responses to microgravity depended on the strain used (e.g., the motile strain exhibited no response to microgravity, while the non-motile strain did), the method of enumeration, and the nutrient concentration of the medium. Under oligotrophic conditions, non-motile cells may remain in geostationary orbit and deplete nutrients in their vicinity, while in high nutrient medium, resources surrounding the cell may be sufficient so that high growth is observed until nutrients becoming limiting.

The effect of simulated microgravity on bacteria from the Mir space station

NASA Technical Reports Server (NTRS)

Baker, Paul W.; Leff, Laura

2004-01-01

The effects of simulated microgravity on two bacterial isolates, Sphingobacterium thalpophilium and Ralstonia pickettii (formerly Burkholderia pickettii), originally recovered from water systems aboard the Mir space station were examined. These bacteria were inoculated into water, high and low concentrations of nutrient broth and subjected to simulated microgravity conditions. S. thalpophilium (which was motile and had flagella) showed no significant differences between simulated microgravity and the normal gravity control regardless of the method of enumeration and medium. In contrast, for R. pickettii (that was non-motile and lacked flagella), there were significantly higher numbers in high nutrient broth under simulated microgravity compared to normal gravity. Conversely, when R. pikkettii was inoculated into water (i.e., starvation conditions) significantly lower numbers were found under simulated microgravity compared to normal gravity. Responses to microgravity depended on the strain used (e.g., the motile strain exhibited no response to microgravity, while the non-motile strain did), the method of enumeration, and the nutrient concentration of the medium. Under oligotrophic conditions, non-motile cells may remain in geostationary orbit and deplete nutrients in their vicinity, while in high nutrient medium, resources surrounding the cell may be sufficient so that high growth is observed until nutrients becoming limiting.

Strain distributions and their influence on electronic structures of WSe2-MoS2 laterally strained heterojunctions

NASA Astrophysics Data System (ADS)

Zhang, Chendong; Li, Ming-Yang; Tersoff, Jerry; Han, Yimo; Su, Yushan; Li, Lain-Jong; Muller, David A.; Shih, Chih-Kang

2018-02-01

Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p-n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe2-MoS2, offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe2-MoS2 lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe2-MoS2 lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding.

Effect of Static Strains on Diffusion

NASA Technical Reports Server (NTRS)

Girifalco, L. A.; Grimes, H. H.

1961-01-01

A theory is developed that gives the diffusion coefficient in strained systems as an exponential function of the strain. This theory starts with the statistical theory of the atomic jump frequency as developed by Vineyard. The parameter determining the effect of strain on diffusion is related to the changes in the inter-atomic forces with strain. Comparison of the theory with published experimental results for the effect of pressure on diffusion shows that the experiments agree with the form of the theoretical equation in all cases within experimental error.

Early Assessment of Right Ventricular Function in Systemic Lupus Erythematosus Patients using Strain and Strain Rate Imaging.

PubMed

Luo, Runlan; Cui, Hongyan; Huang, Dongmei; Sun, Lihua; Song, Shengda; Sun, Mengyao; Li, Guangsen

2018-06-11

Right ventricular function is a crucial factor of the prognosis of systemic lupus erythematosus (SLE). To evaluate the right ventricular function in SLE patients with different degrees of pulmonary hypertension (PH) by strain and strain rate imaging. A total of 102 SLE patients and 30 healthy volunteers were studied between October 2015 and May 2016. Patients were divided into three groups according to pulmonary artery systolic pressure (PASP) estimated by echocardiography: group control (A); PASP ≤ 30 mmHg (group B, n = 37); PASP 30-50 mmHg (mild PH; group C, n = 34); and PASP ≥ 50 mmHg (moderate-to-severe PH; group D, n = 31). Longitudinal peak systolic strain (ε) and strain rate (SR), including systolic strain rate (SRs), early diastolic strain rate (SRe) and late diastolic strain rate (SRa) were measured in the basal, middle and apical segments of the right ventricular free wall in participants by two-dimensional speckle tracking echocardiography (2D-STE) from the apical four-chamber view. A p < 0.05 was set for statistical significance. The parameters of ε, SRs, SRe, and SRa were significantly decreased in groups C and D compared with groups A and B. The ε of each segments was significantly lower in group D than in group C, while there were no differences in SRs, SRe and SRa between groups C and D. Strain and strain rate imaging could early detect the right ventricular dysfunction in SLE patients with PH, and provide important value for clinical therapy and prognosis of these patients. (Arq Bras Cardiol. 2018; [online].ahead print, PP.0-0).

Effects of C and Si on strain aging of strain-based API X60 pipeline steels

NASA Astrophysics Data System (ADS)

Sung, Hyo Kyung; Lee, Dong Ho; Lee, Sunghak; Lee, Byeong-Joo; Hong, Seung-Pyo; Kim, Young-Woon; Yoo, Jang Yong; Hwang, Byoungchul; Shin, Sang Yong

2017-05-01

Four types of strain-based API X60 pipeline steels were fabricated by varying the C and Si contents, and the effects of C and Si on strain aging were investigated. The 0.05 wt% C steels consisted mainly of polygonal ferrite (PF), whereas the 0.08 wt% C steels consisted of acicular ferrite (AF). The volume fraction of AF increased with increasing C content because C is an austenite stabilizer element. The volume fractions of bainitic ferrite (BF) of the 0.15 wt% Si steels were higher than those of the 0.25 wt% Si steels, whereas the volume fractions of the secondary phases were lower. From the tensile properties before and after the aging process of the strainbased API X60 pipeline steels, the yield strength increased and the uniform and total elongation decreased, which is the strain aging effect. The strain aging effect in the strain-based API X60 pipeline steels was minimized when the volume fraction of AF was increased and secondary phases were distributed uniformly. On the other hand, an excessively high C content formed fine precipitates, and the strain aging effect occurred because of the interactions among dislocations and fine precipitates.

Interplay between strain, quantum confinement, and ferromagnetism in strained ferromagnetic semiconductor (In,Fe)As thin films

NASA Astrophysics Data System (ADS)

Sasaki, Daisuke; Anh, Le Duc; Nam Hai, Pham; Tanaka, Masaaki

2014-04-01

We systematically investigated the influence of strain on the electronic structure and ferromagnetism of (In,Fe)As thin films. It is found that while the shift of the critical point energies of compressive-strained (In,Fe)As layers grown on (In1-y,Gay)As (y = 0.05, 0.1) buffer layers can be explained by the hydrostatic deformation effect (HDE) alone, those of tensile-strained (In,Fe)As layers grown on (Ga1-z,Alz)Sb (z = 0, 0.5, 1) buffer layers can be explained by the combination of HDE and the quantum confinement effect (QCE). The Curie temperature TC of the (In,Fe)As layers strongly depends on the strain, and shows a maximum for the (In,Fe)As layer grown on a GaSb buffer layer. The strain dependence of TC can be explained by the s-d exchange mechanism taking into account HDE and QCE.

5-Fluorouracil-resistant strain of Methanobacterium thermoautotrophicum.

PubMed

Nagle, D P; Teal, R; Eisenbraun, A

1987-09-01

Growth of Methanobacterium thermoautotrophicum Marburg is inhibited by the pyrimidine, 5-fluorouracil (FU). It was shown previously that methanogenesis is not inhibited to the same extent as growth. A spontaneously occurring FU-resistant strain (RTAE-1) was isolated from a culture of strain Marburg. The growth of both strains was inhibited by 5-fluorodeoxyuridine but not 5-fluorocytosine, and the wild type was more susceptible to inhibition by 5-azauracil and 6-azauracil than was strain RTAE-1. The cellular targets for the pyrimidine analogs are not known. When the accumulation of 14C-labeled uracil or FU by the two strains was compared, the wild type took up 15-fold more radiolabel per cell than did the FU-resistant strain. In the wild type, radiolabel from uracil was incorporated into the soluble pool, RNA, and DNA. The metabolism of uracil appeared to involve a uracil phosphoribosyltransferase activity. Strain Marburg extracts contained this enzyme, whereas FU-resistant strain RTAE-1 extracts had less than 1/10 as much activity. Although it is possible that a change in permeability to the compounds plays a role in the stable resistance of strain RTAE-1, the fact that it lacks the ability to metabolize pyrimidines to nucleotides is sufficient to account for its phenotype.

5-Fluorouracil-resistant strain of Methanobacterium thermoautotrophicum.

PubMed Central

Nagle, D P; Teal, R; Eisenbraun, A

1987-01-01

Growth of Methanobacterium thermoautotrophicum Marburg is inhibited by the pyrimidine, 5-fluorouracil (FU). It was shown previously that methanogenesis is not inhibited to the same extent as growth. A spontaneously occurring FU-resistant strain (RTAE-1) was isolated from a culture of strain Marburg. The growth of both strains was inhibited by 5-fluorodeoxyuridine but not 5-fluorocytosine, and the wild type was more susceptible to inhibition by 5-azauracil and 6-azauracil than was strain RTAE-1. The cellular targets for the pyrimidine analogs are not known. When the accumulation of 14C-labeled uracil or FU by the two strains was compared, the wild type took up 15-fold more radiolabel per cell than did the FU-resistant strain. In the wild type, radiolabel from uracil was incorporated into the soluble pool, RNA, and DNA. The metabolism of uracil appeared to involve a uracil phosphoribosyltransferase activity. Strain Marburg extracts contained this enzyme, whereas FU-resistant strain RTAE-1 extracts had less than 1/10 as much activity. Although it is possible that a change in permeability to the compounds plays a role in the stable resistance of strain RTAE-1, the fact that it lacks the ability to metabolize pyrimidines to nucleotides is sufficient to account for its phenotype. PMID:3624203

Complete Genomic Sequences of H3N8 Equine Influenza Virus Strains Used as Vaccine Strains in Japan

PubMed Central

Yamanaka, Takashi; Bannai, Hiroshi; Tsujimura, Koji; Kokado, Hiroshi

2018-01-01

ABSTRACT We sequenced the eight segments of influenza A virus strains A/equine/Ibaraki/1/2007 and A/equine/Yokohama/aq13/2010, which are strains of the Florida sublineage clades 1 and 2 of the H3N8 subtype equine influenza virus. These strains have been used as vaccine strains in Japan since 2016 in accordance with World Organization for Animal Health (OIE) recommendations. PMID:29567739

Complete Genomic Sequences of H3N8 Equine Influenza Virus Strains Used as Vaccine Strains in Japan.

PubMed

Nemoto, Manabu; Yamanaka, Takashi; Bannai, Hiroshi; Tsujimura, Koji; Kokado, Hiroshi

2018-03-22

We sequenced the eight segments of influenza A virus strains A/equine/Ibaraki/1/2007 and A/equine/Yokohama/aq13/2010, which are strains of the Florida sublineage clades 1 and 2 of the H3N8 subtype equine influenza virus. These strains have been used as vaccine strains in Japan since 2016 in accordance with World Organization for Animal Health (OIE) recommendations. Copyright © 2018 Nemoto et al.

Improved Hardware for Higher Spatial Resolution Strain-ENCoded (SENC) Breast MRI for Strain Measurements

PubMed Central

Harouni, Ahmed A.; Hossain, Jakir; Jacobs, Michael A.; Osman, Nael F.

2012-01-01

Introduction Early detection of breast lesions using mammography has resulted in lower mortality-rates. However, some breast lesions are mammography occult and magnetic resonance imaging (MRI) is recommended, but has lower specificity. It is possible to achieve higher specificity by using Strain-ENCoded (SENC) MRI and/or magnetic resonance elastography(MRE). SENC breast MRI can measure the strain properties of breast tissue. Similarly, MRE is used to measure elasticity (i.e., shear stiffness) of different tissue compositions interrogating the tissue mechanical properties. Reports have shown that malignant tumors are 3–13 times stiffer than normal tissue and benign tumors. Methods We have developed a Strain-ENCoded (SENC) breast hardware device capable of periodically compressing the breast, thus allowing for longer scanning time and measuring the strain characteristics of breast tissue. This hardware enabled us to use SENC MRI with high spatial resolution (1×1×5mm3) instead of Fast SENC(FSENC). Simple controls and multiple safety measures were added to ensure accurate, repeatable and safe in-vivo experiments. Results Phantom experiments showed that SENC breast MRI has higher SNR and CNR than FSENC under different scanning resolutions. Finally, the SENC breast device reproducibility measurements resulted in a difference of less than one mm with a 1% strain difference. Conclusion SENC breast MR images have higher SNR and CNR than FSENC images. Thus, combining SENC breast strain measurements with diagnostic breast MRI to differentiate benign from malignant lesions could potentially increase the specificity of diagnosis in the clinical setting. PMID:21440464

Finite Strain Behavior of Polyurea for a Wide Range of Strain Rates

DTIC Science & Technology

2010-02-01

dimensional dynamic compressive behavior of EPDM rubber ," Journal of Engineering Materials and Technology, Transaction of the ASME, 125:294-301. [97] Song, B...and Chen, W. (2004) "Dynamic compressive behavior of EPDM rubber un- der nearly uniaxial strain conditions," Journal of Engineering Materials and... rubber elastic springs to describe the steep initial stiffness of virgin butadiene rubber under tensile and compressive loading at intermediate strain