Research – Effect of phenolic compounds and cold shock on survival and virulence of Escherichia coli pathotypes

Wiley Online

Phenolic compounds (PC) affect many metabolic processes of microbes; however, there is no information about their effectiveness when these act in combination with low temperatures for the control of Escherichia coli pathotypes. In this study, four PC, (tannic acid [TA], gallic acid [GA], methyl gallate [MG], and epigallocatechin gallate [EG]) in combination with cold shock (CS, 10°C) were evaluated for their effect on growth, swarming motility, biofilm formation, and expression of selected virulence-related genes of E. coli pathotypes [enteropathogenic (EPEC), enterohemorrhagic (EHEC), and enterotoxigenic (ETEC)]. Sub-inhibitory concentrations of the PC were used alone (37°C) or in combination with CS. For CS assays, E. coli strains were grown at 37°C until mid-log phase and then subjected to 10°C for 4 hr. Membrane damage was determined by flow cytometry; swarming motility was measured on soft-LB agar, biofilm formation was analyzed by crystal violet staining, and gene expression of CS, biofilm, and swarming motility related-genes was determined by qPCR. Sub-inhibitory concentrations of the PC did not affect the viability of the strains. The combination of CS + TA provoked the highest (p ≤ .05) mortality in all pathotypes. CS + GA inhibited (100%) the motility of EHEC and ETEC. PC and CS + PC reduced (p ≤ .05) biofilm formation. The combination of PC and CS affected virulence factors and their gene expression of pathogenic E. coli presenting a novel alternative for its control in foods.

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