The aim of this study was to evaluate the phenotypic and genotypic properties of Salmonella enterica serovar Typhimurium (ST) in the presence of lethal and sublethal concentrations (SLC2LOG) of blackberry (Rubus fruticosus) and blueberry (Vaccinium corymbosum) pomace extracts. Antimicrobial susceptibility, physicochemical properties, motility, biofilm formation ability, virulence gene expression patterns, and the ability of ST to colonize in chick cecum were evaluated in the presence of these bioactive extracts. HPLC-MS analysis indicated that the phenolics in the berry pomace extracts consisted, but not limited to, flavan, flavanone, flavones, glucuronides, glucosides, quinolones, catechol, coumarin, phenols, luteolines, tannins, quercetin, chlorogenic acid, ellagic acid, gallic acid, and xanthoxic acid. The SLC2LOG of both berry pomace extracts increased the rates of injured ST by ~50%; significantly decreased the hydrophobicity, auto-aggregation, cellular motility, and invasion into cultured INT407, HD11, and DF1 cells. The relative expression of type III secretion system regulated genes, hilA, hilC, invA, invF, sirA, and sirB was significantly downregulated in ST. In addition, natural colonization ability of Salmonella in chick cecum was reduced by more than two logs in the presence of 0.5 and 1.0gGallicAcidEquivalent/L berry pomace extracts when provided as water supplement. Findings from this study reveal the high potential of phenolic extracts from berry pomaces as a green antimicrobial against enteric pathogen Salmonella and application in the reduction of pre-harvest colonization level of Salmonella in poultry gut.
Keywords: Antimicrobials; Gene expression; In vivo; Phenolics; Salmonella.
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