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Probiotics are recognized for outcompeting pathogenic bacteria by competitive receptor-mediated colonization and secretion of functional metabolites which are antimicrobial against certain microbes as well as improving host’s gut health and immunity. Recently, we have constructed a bioactive Lactobacillus casei (LC) strain, LC+mcra, by inserting mcra (myosin cross-reactive antigen) gene, which stimulates the conversion of conjugated linoleic acids. In this study, we evaluated the modulation of gut microbiome and protective roles of LC+mcra against pathogenic Salmonella enterica serovar Typhimurium (ST) and enterohemorrhagic E. coli (EHEC) infections in BALB/cJ mice. We observed that LC+mcra colonized efficiently in mice gut intestine and competitively reduced the infection with ST and EHEC in various locations of small and large intestine, specifically cecum, jejunum, and ileum (p

Olea europaea L. was known associated with health benefits, however the role of single bioactive component remains to be elucidated. This study was to investigate the operational feasibility of maslinic/oleanolic acid, hydroxytyrosol, and oleuropein from olive in control and alleviation of enteric pathogen infections. Our results indicated that the growth of Lactobacillus was stimulated by maslinic/oleanolic acid up to 4% (w/v) in dose-dependent manner. Hydroxytyrosol (>0.05%) and oleuropein (>0.5%) significantly reduced Salmonella Typhimurium/EHEC within 12 h, altered their physicochemical properties, influenced host cell-pathogen interactions, and especially 0.6–6.0 folds down-regulated the virulence gene expressions. Further molecular analysis revealed that these olive compounds up-regulated anti-inflammatory cytokine IL-10 gene by 3.0–8.0 folds and down-regulated multiple inflammation related genes at various levels. These results suggest that polyphenols in olive may serve as potential preservatives in post-harvest food processing while tri-terpenoids may assist in modulation of gut microflora and reduction of enteric pathogen colonization.

Olea europaea L. was known associated with health benefits, however the role of single bioactive component remains to be elucidated. This study was to investigate the operational feasibility of maslinic/oleanolic acid, hydroxytyrosol, and oleuropein from olive in control and alleviation of enteric pathogen infections. Our results indicated that the growth of Lactobacillus was stimulated by maslinic/oleanolic acid up to 4% (w/v) in dose-dependent manner. Hydroxytyrosol (>0.05%) and oleuropein (>0.5%) significantly reduced Salmonella Typhimurium/EHEC within 12 h, altered their physicochemical properties, influenced host cell-pathogen interactions, and especially 0.6–6.0 folds down-regulated the virulence gene expressions. Further molecular analysis revealed that these olive compounds up-regulated anti-inflammatory cytokine IL-10 gene by 3.0–8.0 folds and down-regulated multiple inflammation related genes at various levels. These results suggest that polyphenols in olive may serve as potential preservatives in post-harvest food processing while tri-terpenoids may assist in modulation of gut microflora and reduction of enteric pathogen colonization. [ABSTRACT FROM AUTHOR]

Abstract: The study describes a rapid approach for detection of common enteric bacterial pathogens, which involves partial amplification of the 16S rRNA gene by PCR using a colony from selective medium followed by restriction enzyme (RE) digestion using the EcoRI, HindIII and SalI enzymes. On the basis of RE digestion analysis different genera namely, Escherichia, Salmonella, Shigella, Vibrio, Campylobacter, Arcobacter, Yesinia and Listeria were differentiated. [Copyright &y& Elsevier]

Probiotics are recognized for outcompeting pathogenic bacteria by competitive receptor-mediated colonization and secretion of functional metabolites which are antimicrobial against certain microbes as well as improving host's gut health and immunity. Recently, we have constructed a bioactive Lactobacillus casei (LC) strain, LC + mcra , by inserting mcra (myosin cross-reactive antigen) gene, which stimulates the conversion of conjugated linoleic acids. In this study, we evaluated the modulation of gut microbiome and protective roles of LC + mcra against pathogenic Salmonella enterica serovar Typhimurium (ST) and enterohemorrhagic E. coli (EHEC) infections in BALB/cJ mice. We observed that LC + mcra colonized efficiently in mice gut intestine and competitively reduced the infection with ST and EHEC in various locations of small and large intestine, specifically cecum, jejunum, and ileum ( p < 0.05). Positive modulation of the cecal microbiota, for example, higher relative abundances of Firmicutes, lower relative abundances of Proteobacteria, and increased bacterial species diversity/richness, was detected in ST-challenged mice pretreated with LC + mcra based on 16S metagenomic sequencing. Cytokine gene expression analysis indicated that mice pretreated with LC + mcra associated with attenuated bacterial pathogen-induced gut inflammation. Furthermore, mice fed daily with LC + mcra for one week could protect themselves from the impairments caused by enteric infections with ST or EHEC. These impairments include weight loss, negative hematological changes, intestinal histological alterations, and potential death. This in vivo study suggests that daily consumption of novel conjugated linoleic acids over-producing probiotic effectively improves intestinal microbiota composition and prevents/combats foodborne enteric bacterial infections with pathogenic Salmonella and diarrheagenic E. coli .

The genetic code expansion strategy has become an elegant method for site-specific incorporation of noncanonical amino acids with diverse functionalities into proteins of interest in bacteria, yeast, mammalian cells, and even animals. This technique allows precise labeling as well as manipulation of a given protein to dissect its physiological and/or pathological roles under living conditions. Here, we demonstrate the extension of a recently emerged pyrrolysine-based genetic code expansion strategy for encoding noncanonical amino acids into enteric bacterial pathogens.