Study on the Viable but Non-culturable (VBNC) State Formation of Staphylococcus aureus and Its Control in Food System.

Yanmei Li,Teng-Yi Huang,Yuzhu Mao,Junyan Liu,Jinxuan Chen,Caiying Bai,Fan Shi,Ruixin Peng,Yanni Chen,Ling Chen,Kan Wang,Lei Yuan

doi:10.3389/fmicb.2020.599739

Abstract

A Viable but non-culturable (VBNC) state is a bacterial survival strategy under reverse conditions. It poses a significant challenge for public health and food safety. In this study, the effect of external environmental conditions including acid, nutrition, and salt concentrations on the formation of S. aureus VBNC states at low temperatures were investigated. Different acidity and nutritional conditions were then applied to food products to control the VBNC state formation. Four different concentration levels of each factor (acid, nutrition, and salt) were selected in a total of 16 experimental groups. Nutrition showed the highest influence on the VBNC state formation S. aureus, followed by acid and salt. The addition of 1% acetic acid could directly kill S. aureus cells and inhibit the formation of the VBNC state with a nutrition concentration of 25, 50, and 100%. A propidium monoazide-polymerase chain reaction (PMA-PCR) assay was applied and considered as a rapid and sensitive method to detect S. aureus in VBNC state with the detection limit of 104 CFU/mL.

Highlights

Food-borne pathogens can cause diseases by contaminating food products and are the cause of serious concerns in public health and food safety
Nutrition showed the highest influence on the Viable but Non-culturable (VBNC) state formation S. aureus, followed by acid and salt
This study aimed to investigate the effect of nutrition, acid, and salt concentrations on the viability and culturability of S. aureus at low temperature (4 and −20◦C) to obtain a better understanding of the conditions of the formation of the VBNC state in food systems and to enable us to control it

Summary

Introduction

Food-borne pathogens can cause diseases by contaminating food products and are the cause of serious concerns in public health and food safety. Staphylococcus aureus is widely distributed in the environment including air, water, and the surface of the skin, and has been found in raw meat, milk and dairy products, frozen products, and cooked foods (Xu et al, 2012a,b; Bao et al, 2017a,c) It is the source of major concern in the food industry due to its multi-drug resistance and virulence (Miao et al, 2017c; Jia et al, 2018). Foodborne outbreaks with vomiting cases caused by S. aureus have been frequently reported in recent years (Bennett et al, 2013) It can produce Staphylococcus enterotoxins (SEs) including SEA, SEB, SEC, SED, and SEE which can cause severe food poisoning incidents (Xu et al, 1982). PantonValentine leukocidin (PVL) can cause food poisoning with a high mortality rate (Kraushaar and Fetsch, 2014; Liu et al, 2019)

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