Project description:Although the major food-borne pathogen Campylobacter jejuni has been isolated from diverse animal, human and environmental sources, our knowledge of genomic diversity in C. jejuni is based exclusively on human or human food-chain-associated isolates. Studies employing multilocus sequence typing have indicated that some clonal complexes are more commonly associated with particular sources. Using comparative genomic hybridization on a collection of 80 isolates representing diverse sources and clonal complexes, we identified a separate clade comprising a group of water/wildlife isolates of C. jejuni with multilocus sequence types uncharacteristic of human food-chain-associated isolates. By genome sequencing one representative of this diverse group (C. jejuni 1336), and a representative of the bank-vole niche specialist ST-3704 (C. jejuni 414), we identified deletions of genomic regions normally carried by human food-chain-associated C. jejuni. Several of the deleted regions included genes implicated in chicken colonization or in virulence. Novel genomic insertions contributing to the accessory genomes of strains 1336 and 414 were identified. Comparative analysis using PCR assays indicated that novel regions were common but not ubiquitous among the water/wildlife group of isolates, indicating further genomic diversity among this group, whereas all ST-3704 isolates carried the same novel accessory regions. While strain 1336 was able to colonize chicks, strain 414 was not, suggesting that regions specifically absent from the genome of strain 414 may play an important role in this common route of Campylobacter infection of humans. We suggest that the genomic divergence observed constitutes evidence of adaptation leading to niche specialization. Data is also available from <ahref=http://bugs.sgul.ac.uk/E-BUGS-95 target=_blank>BuG@Sbase</a>
2011-04-15 | E-BUGS-95 | biostudies-arrayexpress
Project description:Multidrug-resistant pathogens in the food chain
Project description:Bifidobacterium longum subsp. infantis (B. infantis) resides in the human infant gut and helps with the utilization of human milk-derived nutrient components. While its utilization of various carbohydrate sources has been studied extensively, mechanisms behind utilization of nitrogen components from human milk remain largely unknown. In this study, we present B. infantis growth profiles on the N-containing human milk oligosaccharides (HMO) as nitrogen sources, namely, lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT). Dietary 2-Oxoglutarate (2-OG) in known in mice model for its protective effects against intestinal inflammation and colitis development. In this study, we have shown that B. infantis had increased 2-OG concentration when utilizes LNT or LNnT as a primary nitrogen source. As LNT and LNnT are the isomers of HMO core structures, N-acetyl glucosamine (NAG), the N-containing monosaccharide, was regarded as the nitrogen provider of the HMO core structures. Differentially expressed gene patterns in B. infantis were analyzed under the less efficient nitrogen conditions (HMOs and NAG) relative to the complex nitrogen controls. Proteomics analysis of B. infantis using 15N-labeled NAG revealed that NAG nitrogen was incorporated into B. infantis metabolism. Transcriptomics results of B. infantis in LNT, LNnT and NAG nitrogen were consistent with the proteomics results. This further indicated that B. infantis metabolism was affected by NAG nitrogen in nitrogen assimilation, HMO catabolism, NAD cofactor biosynthesis and regeneration, and peptidoglycan biosynthesis pathways. In summary, B. infantis can use NAG-containing HMO as a nitrogen source and incorporate NAG nitrogen into metabolism pathways.
Project description:Bifidobacterium infantis is associated with the gut microbiota of breast-fed infants. B. infantis promotes intestinal barrier and immune function through several proposed mechanisms, including interactions between their surface polysaccharides, the host, and other gut microorganisms. Dairy foods and ingredients are some of the most conspicuous food-based niches for this species and may provide benefits for their delivery and efficacy in the gut. Milk phospholipid (MPL)-rich ingredients have been increasingly recognized for their versatile benefits to health, including interactions with the gut microbiota and intestinal cells. Therefore, our objective was to investigate the capacity for MPL to promote survival of B. infantis during simulated digestion and to modulate bacterial polysaccharide production. To achieve these aims, B. infantis was incubated with or without 0.5% MPL in de Man, Rogosa, and Sharpe (MRS) media at 37 °C under anaerobiosis. Survival across the oral, gastric, and intestinal phases using in vitro digestion was measured using plate count, along with adhesion to goblet-like intestinal cells. MPL increased B. infantis survival at the end of the intestinal phase by at least 7% and decreased adhesion to intestinal cells. The bacterial surface characteristics, which may contribute to these effects, were assessed by ζ-potential, changes in surface proteins using comparative proteomics, and production of bound polysaccharides. MPL decreased the surface charge of the bifidobacteria from –17 to –24 mV and increased a 50 kDa protein (3-fold) that appears to be involved in protection from stress. The production of bound polysaccharides was measured using FTIR, HPLC, and TEM imaging. These techniques all suggest an increase in bound polysaccharide production at least 1.7-fold in the presence of MPL. Our results show that MPL treatment is positively correlated with increased survival during simulated digestion, a stress resistance surface protein, and bound polysaccharide production of B. infantis, suggesting its use as a functional ingredient to enhance probiotic and postbiotic effects.
2023-05-15 | PXD042186 | Pride
Project description:Listeria monocytogenes strains isolated from two food-processing plants in Central Italy
Project description:Eosinophilia–myalgia syndrome (EMS) is characterized by subacute onset of myalgias and peripheral eosinophilia, followed by chronic neuropathy and skin induration. The EMS epidemic in 1989 was linked to L-tryptophan consumption originating from a single source. Following the Food and Drug Administration (FDA) ban on the sale of L-tryptophan, the incidence of EMS declined rapidly. Moreover, no new cases have been published since the FDA ban was lifted in 2005. We report the clinical, histopathological and immunogenetic features of a new case of L-tryptophan-associated EMS along with evidence of activated transforming growth factor-ß and interleukin-4 signaling in the lesional skin. 6 samples were analyzed to include EMS patient and two replicates along with three normal controls
Project description:Human milk oligosaccharides (HMOs) enrich beneficial bifidobacteria in the infant gut microbiome which produce molecules that impact development and physiology. 2´fucosyllactose (2´FL) is a highly abundant fucosylated HMO which is utilized by Bifidobacterium longum subsp. infantis, despite limited scientific understanding of the underlying mechanism. Moreover, there is not a current consensus on whether free fucose could be metabolized when not incorporated in a larger oligosaccharide structure. Based on metabolic and genomic analyses, we hypothesize that B. infantis catabolizes both free fucose and fucosyl oligosaccharide residues to produce 1,2-propanediol (1,2-PD). Accordingly, systems-level approaches including transcriptomics and proteomics support this metabolic path. Co-fermentation of fucose and limiting lactose or glucose was found to promote significantly higher biomass and 1,2-PD concentrations than individual substrates, suggesting a synergistic effect. In addition, and during growth on 2´FL, B. infantis achieves significantly higher biomass corresponding to increased 1,2-PD. These findings support a singular fucose catabolic pathway in B. infantis that is active on both free and HMO-derived fucose and intimately linked with central metabolism. The impact of fucose and 2´FL metabolism on B. infantis physiology provides insight into the role of fucosylated HMOs in influencing host- and microbe-microbe interactions within the infant gut microbiome.
Project description:Antimicrobials have been shown to select for changes in biofilm formation and multidrug susceptibility in common human pathogens. We investigated whether common food preservatives selected for these changes in the food pathogen Salmonella enterica serovar Typhimurium. Bacteria were exposed to four food preservatives in either planktonic cultures or biofilms grown on stainless steel beads. Cultures were passaged into fresh media supplemented with the food preservative every 72 hours. Following approximately 1000 generations of continuous preservative exposure, populations were sequenced to determine the single nucleotide polymorphisms that were selected for over evolutionary time.