Inactivation and Subsequent Growth Kinetics of Listeria monocytogenes After Various Mild Bactericidal Treatments.

Taisong Fang,Hongmei Li,Qingli Dong,Yangtai Liu,Yufan Wu,Linjun Sun,Xiaojie Qin,Xiang Wang,Yani Xie

doi:10.3389/fmicb.2021.646735

Abstract

This study was carried out to investigate the effects of mild heat, lactic acid, benzalkonium chloride and nisin treatments on the inactivation, sublethal injury, and subsequent growth of Listeria monocytogenes. Results showed that the Bigelow model successfully described the thermal inactivation kinetics, while the Log-linear model with tail consistently offered the most accurate fit to LA, BC, and nisin inactivation curves of cells. Differential plating indicated that percentage of sublethal injury for nisin treated cells was significantly higher than that for the other three treatments. Compared to non-treated cells, significant extension of lag time was observed for all treated cells. The longer exposures to heat treatment contributed to the extended lag time of the survivors. While for LA, BC and nisin treated cells, the longest lag time was not observed at the most severe treatment conditions. The correlation analysis of sublethal injury percentage on the duration of lag time revealed that only heat treatment showed the significant correlation. Overall, the lag time analysis could evaluate a wide range of bacterial injury. Lag time of treated cells was significantly influenced by stress treatments and temperatures of recovery, however, there were not any significant changes in the maximum specific growth rate between treated and non-treated cells under isothermal recovery conditions. The information generated from this study is valuable for utilizing intervention strategies in the elimination or growth inhibition of L. monocytogenes.

Highlights

Listeria monocytogenes is the causative agent of human listeriosis, a life threatening foodborne disease commonly associated with consumption of contaminated food products, especially readyto-eat (RTE) foods (Swaminathan and Gerner-Smidt, 2007)
We investigated the effects of three types of treatments with heat, lactic acid (LA), benzalkonium chloride (BC) and nisin on the inactivation, sublethal injury, and subsequent growth of L. monocytogenes
This study sought to evaluate the effects of four mild bactericidal treatments on the inactivation, sublethal injury, and subsequent growth of L. monocytogenes cells, and the growth parameters at different recovery temperatures (20, 25, 30, and 37◦C) were further determined

Summary

Introduction

Listeria monocytogenes is the causative agent of human listeriosis, a life threatening foodborne disease commonly associated with consumption of contaminated food products, especially readyto-eat (RTE) foods (Swaminathan and Gerner-Smidt, 2007). Compared to reliable information on the maximum specific growth rate, the lag time is usually difficult to be predicted accurately due to poor understanding of initial physiological state of cells and/or repair of injured cell structures (D’Arrigo et al, 2006). The mild process may result in surviving L. monocytogenes cell populations, which most likely exhibited the state of sublethal injury This suboptimal physiological state of cells could considerably extend the duration of lag time because of self-repairing process of injured cells in the appropriate growth environments (Yuste et al, 2004). Injury induced by exposure to the mild bactericidal treatments influences the growth behavior of surviving cells This emphasizes the importance of understanding the growth of L. monocytogenes after different mild bactericidal treatments

Methods

Results

Conclusion