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Butyrate-producing bacteria are promising probiotic candidates to target microbial dysbiosis in gastrointestinal disorders like inflammatory bowel diseases. Butyricicoccus pullicaecorum 25-3T, a butyrate-producing clostridial cluster IV strain, is such a candidate. Little is known about its abundance in the colon microbiota and its butyrogenic properties. We used the M-SHIMER® , an in vitro simulator for the human intestinal microbial ecosystem, to study the effect of supplementing a single dose of B. pullicaecorum 25-3T on lumen- and mucus-associated microbiota of eight individuals. Butyricicoccus pullicaecorum was more abundant in mucus-associated microbiota compared with lumen microbiota. Supplementation with a single dose of B. pullicaecorum 25-3T resulted in a temporary increase in B. pullicaecorum bacteria in lumen compartment of all individuals. In two cases, the responders, an increased butyrate production was observed as compared with the control. 16S rRNA gene amplicon sequencing revealed the microbiota of responders to be different as compared to non-responder microbiota. We can conclude that B. pullicaecorum 25-3T is a mucus-associated bacterium whose potency to stimulate butyrate production is characterized by a large interindividual variability in terms of composition of the receiving microbial community. [ABSTRACT FROM AUTHOR]

In drinking water (DW) and the distribution systems, bacterial growth and biofilm formation have to be controlled both for limiting taste or odour development and preventing clogging or biocorrosion problems. After a contamination with undesired bacteria, factors like nutrient availability and temperature will influence the survival of these invaders. Understanding the conditions enabling invaders to proliferate is essential for a holistic approach towards microbial risk assessment in DW. Pseudomonas putida was used as a model invader because this easy-growing bacterium can use a wide range of substrates. Invasion experiments in oligo- to eutrophic waters showed the requirement of both a carbon and phosphate source for survival of P. putida in DW. Addition of C, N and P enabled P. putida to grow in DW from 5.80 × 104 to 1.84 × 108 cells mL−1 and survive for at least 12 days. However, in surface water with similar nutrient concentrations, P. putida did not survive, indicating the concomitant importance of the present indigenous microbial community of the specific water sample. Either extensive carbon or phosphate limitation can be used in water treatment design in order to obtain a DW which is not susceptible for unwanted bacterial growth. [ABSTRACT FROM AUTHOR]

Bacillus cereus comprises a highly versatile group of bacteria, which are of particular interest because of their capacity to cause disease. Emetic food poisoning is caused by the toxin cereulide produced during the growth of emetic B. cereus in food, while diarrhoeal food poisoning is the result of enterotoxin production by viable vegetative B. cereus cells in the small intestine, probably in the mucus layer and/or attached to the host's intestinal epithelium. The numbers of B. cereus causing disease are highly variable, depending on diverse factors linked to the host (age, diet, physiology and immunology), bacteria (cellular form, toxin genes and expression) and food (nutritional composition and meal characteristics). Bacillus cereus group strains show impressive ecological diversity, ranging from their saprophytic life cycle in soil to symbiotic (commensal and mutualistic) lifestyles near plant roots and in guts of insects and mammals to various pathogenic ones in diverse insect and mammalian hosts. During all these different ecological lifestyles, their toxins play important roles ranging from providing competitive advantages within microbial communities to inhibition of specific pathogenic organisms for their host and accomplishment of infections by damaging their host's tissues. [ABSTRACT FROM AUTHOR]

Life in hypersaline environments is typically limited by bioenergetic constraints. Microbial activity at the thermodynamic edge, such as the anaerobic oxidation of methane ( AOM) coupled to sulphate reduction ( SR), is thus unlikely to thrive in these environments. In this study, carbon and sulphur cycling was investigated in the extremely hypersaline cold seep sediments of Mercator mud volcano. AOM activity was partially inhibited but still present at salinity levels of 292 g L−1 ( c. eightfold sea water concentration) with rates of 2.3 nmol cm−3 day−1 and was even detectable under saturated conditions. Methane and evaporite-derived sulphate comigrated in the ascending geofluids, which, in combination with a partial activity inhibition, resulted in AOM activity being spread over unusually wide depth intervals. Up to 79% of total cells in the AOM zone were identified by fluorescence in situ hybridization ( FISH) as anaerobic methanotrophs of the ANME-1. Most ANME-1 cells formed monospecific chains without any attached partner. At all sites, AOM activity co-occurred with SR activity and sometimes significantly exceeded it. Possible causes of these unexpected results are discussed. This study demonstrates that in spite of a very low energy yield of AOM, microorganisms carrying this reaction can thrive in salinity up to halite saturation. [ABSTRACT FROM AUTHOR]

The mucus layer in the colon, acting as a barrier to prevent invasion of pathogens, is thinner and discontinuous in patients with ulcerative colitis ( UC). A recent developed in vitro dynamic gut model, the M- SHIME, was used to compare long-term colonization of the mucin layer by the microbiota from six healthy volunteers ( HV) and six UC patients and thus distinguish the mucin adhered from the luminal microbiota. Although under the same nutritional conditions, short-chain fatty acid production by the luminal communities from UC patients showed a tendency toward a lower butyrate production. A more in-depth community analysis of those microbial groups known to produce butyrate revealed that the diversity of the C lostridium coccoides/ E ubacterium rectale and C lostridium leptum group, and counts of F aecalibacterium prausnitzii were lower in the luminal fractions of the UC samples. Counts of R oseburia spp. were lower in the mucosal fractions of the UC samples. q PCR analysis for butyryl- Co A:acetate Co A transferase, responsible for butyrate production, displayed a lower abundance in both the luminal and mucosal fractions of the UC samples. The M- SHIME model revealed depletion in butyrate producing microbial communities not restricted to the luminal but also in the mucosal samples from UC patients compared to HV. [ABSTRACT FROM AUTHOR]

Poly-β-hydroxybutyrate ( PHB) is a natural polymer that can be depolymerized into water-soluble short-chain fatty acid monomers. These monomers can act as microbial control agents. In this study, the effects of partially replacing the diet of Siberian sturgeon fingerlings with 2% and 5% PHB were investigated. Replacing 2% of the diet with PHB improved weight gain, specific growth rate ( SGR) and survival in the sturgeon fingerlings during the 10-week experimental period. Community-level physiological profiling and PCR-denaturing gradient gel electrophoresis ( PCR- DGGE) were used to analyze the microbial community diversity and community organization in the sturgeon gastrointestinal tract. DGGE analysis revealed that PHB affected the intestinal microbial species richness and diversity. The highest species richness was observed with 2% PHB. DNA sequencing of the dominant bands in 2% and 5% PHB treatments revealed that PHB stimulated bacteria belonging to the genera B acillus and R uminococcaceae. Principal component analysis, Lorenz curves and the Shannon index of Biolog™ Ecoplate data revealed that aerobic metabolic potential of the bacterial community was different in the PHB-treated fishes as compared with the control situation. Overall, our results indicate that PHB act as microbial control agents and replacement of 2% of Siberian sturgeon fingerling diet with PHB has beneficial effects. [ABSTRACT FROM AUTHOR]

A poly-β-hydroxybutyrate (PHB)-accumulating enrichment culture was obtained using activated sludge from a polyphosphate-accumulating reactor as inoculum. PHB accumulated by the enrichment culture significantly enhanced the survival of Artemia nauplii, infected with the virulent pathogen Vibrio campbellii LMG 21363. A strain was isolated from the enrichment culture, based on its ability to accumulate PHB, and 16S rRNA gene sequencing of the isolate revealed 99% sequence similarity to Brachymonas denitrificans AS-P1. The isolate, named PHB2, showed good PHB-accumulating activity (up to 32% of the cell dry weight). PHB accumulated by isolate PHB2 was able to protect Artemia completely from the V. campbellii strain. Our data indicate that PHB-accumulating bacteria, such as B. denitrificans PHB2, could be used as an an effective and economically interesting alternative strategy to control infections in aquaculture. [ABSTRACT FROM AUTHOR]

Abstract: The prebiotic potential of native chicory inulin was assessed in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) by monitoring microbial community from the colon compartments, its metabolic activity and community structure. Inulin addition selected for a higher short chain fatty acid production with shifts towards propionic and butyric acid. Conventional culture-based techniques and PCR-denaturing gradient gel electrophoresis analysis showed no remarkable changes in the overall microbial community from the colon compartments of the SHIME, whereas selective effects were seen for lactic acid bacteria. Quantitative PCR with bifidobacteria-specific primers revealed a significant increase with more than 1 log CFU ml−1 from the proximal to distal colon, in contrast to culture-based techniques, which only showed a minor bifidogenic effect in the ascending colon. Our results indicate that inulin purports prebiotic effects from the proximal to distal colon and that real-time PCR is a more precise technique to detect differences in bifidobacterial populations whereas conventional culturing techniques are much more variable. [Copyright &y& Elsevier]

The mucus layer in the colon, acting as a barrier to prevent invasion of pathogens, is thinner and discontinuous in patients with ulcerative colitis (UC). A recent developed in vitro dynamic gut model, the M-SHIME, was used to compare long-term colonization of the mucin layer by the microbiota from six healthy volunteers (HV) and six UC patients and thus distinguish the mucin adhered from the luminal microbiota. Although under the same nutritional conditions, short-chain fatty acid production by the luminal communities from UC patients showed a tendency toward a lower butyrate production. A more in-depth community analysis of those microbial groups known to produce butyrate revealed that the diversity of the Clostridium coccoides/Eubacterium rectale and Clostridium leptum group, and counts of Faecalibacterium prausnitzii were lower in the luminal fractions of the UC samples. Counts of Roseburia spp. were lower in the mucosal fractions of the UC samples. qPCR analysis for butyryl-CoA:acetate CoA transferase, responsible for butyrate production, displayed a lower abundance in both the luminal and mucosal fractions of the UC samples. The M-SHIME model revealed depletion in butyrate producing microbial communities not restricted to the luminal but also in the mucosal samples from UC patients compared to HV., (© 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

Poly-β-hydroxybutyrate (PHB) is a natural polymer that can be depolymerized into water-soluble short-chain fatty acid monomers. These monomers can act as microbial control agents. In this study, the effects of partially replacing the diet of Siberian sturgeon fingerlings with 2% and 5% PHB were investigated. Replacing 2% of the diet with PHB improved weight gain, specific growth rate (SGR) and survival in the sturgeon fingerlings during the 10-week experimental period. Community-level physiological profiling and PCR-denaturing gradient gel electrophoresis (PCR-DGGE) were used to analyze the microbial community diversity and community organization in the sturgeon gastrointestinal tract. DGGE analysis revealed that PHB affected the intestinal microbial species richness and diversity. The highest species richness was observed with 2% PHB. DNA sequencing of the dominant bands in 2% and 5% PHB treatments revealed that PHB stimulated bacteria belonging to the genera Bacillus and Ruminococcaceae. Principal component analysis, Lorenz curves and the Shannon index of Biolog Ecoplate data revealed that aerobic metabolic potential of the bacterial community was different in the PHB-treated fishes as compared with the control situation. Overall, our results indicate that PHB act as microbial control agents and replacement of 2% of Siberian sturgeon fingerling diet with PHB has beneficial effects.

A poly-beta-hydroxybutyrate (PHB)-accumulating enrichment culture was obtained using activated sludge from a polyphosphate-accumulating reactor as inoculum. PHB accumulated by the enrichment culture significantly enhanced the survival of Artemia nauplii, infected with the virulent pathogen Vibrio campbellii LMG 21363. A strain was isolated from the enrichment culture, based on its ability to accumulate PHB, and 16S rRNA gene sequencing of the isolate revealed 99% sequence similarity to Brachymonas denitrificans AS-P1. The isolate, named PHB2, showed good PHB-accumulating activity (up to 32% of the cell dry weight). PHB accumulated by isolate PHB2 was able to protect Artemia completely from the V. campbellii strain. Our data indicate that PHB-accumulating bacteria, such as B. denitrificans PHB2, could be used as an an effective and economically interesting alternative strategy to control infections in aquaculture.