The prevalence of Yersinia enterocolitica in retail pre-prepared dishes in Xi'an and the antibacterial activity and mechanism of ε-polylysine against it

Abstract

This study comprehensively evaluated the antimicrobial efficacy and mechanisms of ε-polylysine (ε-PL) against Yersinia enterocolitica (Y. enterocolitica) contamination in pre-prepared meat products. Surveillance data from retail pork and beef samples collected in Xi'an, China (May 2024 to April 2025) revealed a 50.0 % (48/96) prevalence of Y. enterocolitica. In terms of antimicrobial activity against Y. enterocolitica, ε-PL exhibited significant inhibitory effects, with a minimum inhibitory concentration (MIC) of 200 μg/mL and a minimum bactericidal concentration (MBC) of 400 μg/mL. Mechanistic studies revealed that ε-PL exerts its antimicrobial effects through multiple pathways: (1) disruption of bacterial cell membrane integrity, resulting in the leakage of intracellular proteins, nucleic acids, and ATP; (2) induction of reactive oxygen species accumulation; (3) significant inhibition of bacterial motility; and (4) interference with biofilm formation (inhibition rate of 42.29 ± 0.81 %) and removal of pre-formed biofilms (removal rate of 56.31 ± 8.19 %). Animal experiments further demonstrated that ε-PL treatment effectively reduced the intestinal load of Y. enterocolitica and mortality rate in infected mice (from 100 % to 37.5 %), significantly alleviated pathological damage in the liver, spleen, and intestines, and improved intestinal barrier function by reducing the inhibitory effect of Y. enterocolitica on the expression of tight junction proteins (ZO-1 and Occludin). In practical applications, ε-PL treatment reduced the viable count of Y. enterocolitica in pre-prepared pork and beef (reduce 2.55–3.62 log CFU/g). These results indicate that ε-PL, as a multi-target antimicrobial agent, holds significant potential for the safety control and preservation of pre-prepared meat products.