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Environmental Strains (environmental + strain)
Selected AbstractsIron uptake is essential for Escherichia coli survival in drinking waterLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2006D. Grandjean Abstract Aims:, The aim of this study was to elucidate if the need for iron for Escherichia coli to remain cultivable in a poorly nutritive medium such as the drinking water uses the iron transport system via the siderophores. Methods and Results:, Environmental strains of E. coli (isolated from a drinking water network), referenced strains of E. coli and mutants deficient in TonB, an essential protein for iron(III) acquisition, were incubated for 3 weeks at 25°C, in sterile drinking water with and without lepidocrocite (, -FeOOH), an insoluble iron corrosion product. Only cells with a functional iron transport system were able to survive throughout the weeks. Conclusions:, The iron transport system via protein TonB plays an essential role on the survival of E. coli in a weakly nutritive medium like drinking water. Significance and Impacts of the Study:, Iron is a key parameter involved in coliform persistence in drinking water distribution systems. [source] Investigating Burkholderia cepacia complex populations recovered from Italian maize rhizosphere by multilocus sequence typingENVIRONMENTAL MICROBIOLOGY, Issue 7 2007Claudia Dalmastri Summary The Burkholderia cepacia complex (BCC) comprises at least nine closely related species of abundant environmental microorganisms. Some of these species are highly spread in the rhizosphere of several crop plants, particularly of maize; additionally, as opportunistic pathogens, strains of the BCC are capable of colonizing humans. We have developed and validated a multilocus sequence typing (MLST) scheme for the BCC. Although widely applied to understand the epidemiology of bacterial pathogens, MLST has seen limited application to the population analysis of species residing in the natural environment; we describe its novel application to BCC populations within maize rhizospheres. 115 BCC isolates were recovered from the roots of different maize cultivars from three different Italian regions over a 9-year period (1994,2002). A total of 44 sequence types (STs) were found of which 41 were novel when compared with existing MLST data which encompassed a global database of 1000 clinical and environmental strains representing nearly 400 STs. In this study of rhizosphere isolates approximately 2.5 isolates per ST was found, comparable to that found for the whole BCC population. Multilocus sequence typing also resolved inaccuracies associated with previous identification of the maize isolates based on recA gene restriction fragment length polymorphims and species-specific polymerase chain reaction. The 115 maize isolates comprised the following BCC species groups, B. ambifaria (39%), BCC6 (29%), BCC5 (10%), B. pyrrocinia (8%), B. cenocepacia IIIB (7%) and B. cepacia (6%), with BCC5 and BCC6 potentially constituting novel species groups within the complex. Closely related clonal complexes of strains were identified within B. cepacia, B. cenocepacia IIIB, BCC5 and BCC6, with one of the BCC5 clonal complexes being distributed across all three sampling sites. Overall, our analysis demonstrates that the maize rhizosphere harbours a massive diversity of novel BCC STs, so that their addition to our global MLST database increased the ST diversity by 10%. [source] Repetitive elements sequence (REP/ERIC)-PCR based genotyping of clinical and environmental strains of Yersinia enterocolitica biotype 1A reveal existence of limited number of clonal groupsFEMS MICROBIOLOGY LETTERS, Issue 2 2004Pooja Sachdeva Abstract REP- and ERIC-PCR genotyping were used to assess genetic heterogeneity among 81 strains of Yersinia enterocolitica biotype 1A isolated from India, Germany, France and the USA. Although both gave comparable results, ERIC fingerprints discriminated the strains better. The rep- (REP and ERIC) PCR genotyping showed that strains having different serotypes produced identical rep-profiles indicating their limited genetic diversity. The concatenated dendrogram of REP- and ERIC-PCR fingerprints clustered the biotype 1A strains into two major groups. In each group, majority of the Indian, European and American strains exhibited similarities ranging from 85% to >95%. Similarity of rep-PCR fingerprints amongst strains isolated from widely separated geographical regions revealed existence of a limited number of clonal groups of Y. enterocolitica biotype 1A. The present study failed to reveal unequivocal relationships between rep-PCR genotypes and the source of isolation. However, the clinical serotype O:6,30-6,31 strains formed a tight cluster and the aquatic O:6,30-6,31 strains formed a yet another tight cluster. [source] Distribution of type III secretion systems in Vibrio parahaemolyticus from the northern Gulf of MexicoJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2010N.F. Noriea III Abstract Aims:, Two well-characterized Vibrio parahaemolyticus pathogenicity factors , thermostable direct haemolysin (TDH) and TDH - related haemolysin , are produced by strains containing the tdh and trh genes, respectively. Most strains of V. parahaemolyticus contain two nonredundant type III secretion systems (T3SS), T3SS1 and T3SS2, both of which contribute to pathogenicity. Furthermore, a recent study has revealed two distinct lineages of the V. parahaemolyticus T3SS2: T3SS2, and T3SS2,. The aim of this study was to determine the incidence of these pathogenicity factors in environmental isolates of V. parahaemolyticus. Methods and Results:, We collected 130 V. parahaemolyticus isolates (TCBS agar) containing tdh and/or trh (determined by colony hybridization) from sediment, oyster and water in the northern Gulf of Mexico and screened them and 12 clinical isolates (PCR and agarose gel electrophoresis) for pathogenicity factors tdh, trh, T3SS1, T3SS2, and T3SS2,. The majority of potential pathogens were detected in the sediment, including all tdh,/trh+ isolates. T3SS2, components were detected in all tdh+/trh, isolates and zero of 109 trh+ isolates. One T3SS2, gene, vopB2, was found in all tdh+/trh, clinical strains but not in any of the 130 environmental strains. Fluorescence in situ hybridization adapted for individual gene recognition (RING-FISH) was used to confirm the presence/absence of vopB2. T3SS2, was found in all tdh,/trh+ isolates and in no tdh+/trh, isolates. Conclusions:, The combination of haemolysins found in each isolate consistently corresponded to the presence and type of T3SS detected. The vopB2 gene may represent a novel marker for identifying increased virulence among strains. Significance and Impact of the Study:, This is the first study to confirm the presence of T3SS2, genes in V. parahaemolyticus strains isolated from the Gulf of Mexico and one of the few that examines the distribution and co-existence of tdh, trh, T3SS1, T3SS2, and T3SS2, in a large collection of environmental strains. [source] Evidence for dose-dependent effects on plant growth by Stenotrophomonas strains from different originsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2003I. Suckstorff Abstract Aims: To assess the influence of Stenotrophomonas on plants, the interaction of 16 Stenotrophomonas strains from clinical and environmental sources with strawberry plant seedlings was analysed. Methods and Results:In vitro, all Stenotrophomonas strains influenced plant growth when applied to seedlings. Whereas most of the Stenotrophomonas strains promoted root growth and hair development, a statistically significantly negative influence on the length of stem was found. Although strains from a clinical origin also showed statistically significant effects on plants, this was generally lower when compared with environmental strains. For three selected strains, a strong dose-dependent effect was observed for all parameters. In vitro, a correlation was found between plant growth promotion and production of a plant growth hormone, indole-3-acetic acid (IAA). Xanthomonas campestris, a phylogenetically very closely related species to Stenotrophomonas, was used as a phytopathogenic control. It too confirmed the reduction of plant growth in this in vitro system. Conclusions: Independent of their origin, Stenotrophomonas strains can produce IAA in vitro and subsequently, influence plant growth. The effect of Stenotrophomonas presence on plants was dose-dependent. Significance and Impact of the Study: The dose-dependent effect of Stenotrophomonas, a bacterium of both biotechnological and medical interest, is of great interest for biocontrol applications of plant-associated strains. This paper is the first report that clearly demonstrates the phytopathogenic capacity of Stenotrophomonas. [source] Determination of the toxic potential of Bacillus cereus isolates by quantitative enterotoxin analysesFEMS MICROBIOLOGY LETTERS, Issue 2 2006Maximilian Moravek Abstract Haemolysin BL (HBL) and nonhaemolytic enterotoxin (Nhe), each consisting of three components, represent the major enterotoxins produced by Bacillus cereus. To evaluate the expression of these toxins, a set of 100 B. cereus strains was examined. Molecular biological characterization showed that 42% of the strains harboured the genes for HBL and 99% for Nhe. The production of all Nhe and HBL components were analyzed using specific antibodies and, in culture supernatants, detectable levels of HBL and Nhe were found for 100% of hbl- positive and 96% of nhe -positive strains. The concentrations of the HBL,L2 and NheB component ranged from 0.02 to 5.6 ,g mL,1 and from 0.03 to 14.2 ,g mL,1, respectively. Comparison of the amount of NheB produced by food poisoning and food/environmental strains revealed that the median value for all food poisoning strains was significantly higher than for the food/environmental isolates. The data presented in this study provide evidence that specific and quantitative determination of the enterotoxins is necessary to evaluate the toxic potential of B. cereus. In particular, the level of Nhe seems to explain most of the cytotoxic activity of B. cereus isolates and may indicate a highly diarrheic potential. [source] | ||||||||||