Comparison on the Growth Variability of Vibrio parahaemolyticus Coupled With Strain Sources and Genotypes Analyses in Simulated Gastric Digestion Fluids.

Yangmei Wang,Yong Zhao,Yingjie Pan,Haiquan Liu

doi:10.3389/fmicb.2020.00212

Abstract

Vibrio parahaemolyticus is a food-borne pathogen that causes pathogenic symptoms such as diarrhea and abdominal pain. Currently no studies have shown that either pathogenic and non-pathogenic V. parahaemolyticus possess growth heterogeneity in a human environment, such as in gastric and intestinal fluids. The tlh gene is present in both pathogenic and non-pathogenic V. parahaemolyticus strains, while the tdh and trh genes are only present in pathogenic strains. This study firstly applied simulated human gastric fluids to explore growth variability of 50 strains of V. parahaemolyticus at 37°C. The bacterial growth curves were fitted by primary modified Gompertz model, and the maximum growth rate (μmax), lag time (LT), and their CV values were calculated to compare the stress response of pathogenic and non-pathogenic V. parahaemolyticus to simulated human gastric fluids. Results showed that the simulated human gastric fluids treatment significantly increased the μmax of pathogenic strains and shortened the lag time, while decreased the μmax of non-pathogenic strains and prolonged the lag time. Meanwhile, the CV values of genotypes (tlh+/tdh+/trh–) evidently increased, showing that the pathogenic genotype (tlh+/tdh+/trh–) strains had strong activity to simulated gastric fluids. All of the results indicated that the V. parahaemolyticus strains exhibited a great stress-resistant variability and growth heterogeneity to the simulated gastric fluids, which provides a novel insight to unlock the efficient control of pathogenic V. parahaemolyticus.

Highlights

Vibrio parahaemolyticus is a gram-negative non-spore halophilic bacteria, which inhabits primarily coastal marine and estuarine environments and is widely found in various marine products (Alonsohernando et al, 2013)
The results showed that the coefficient of variation (CV) value of μmax of VPE5 was the largest, which revealed the largest growth heterogeneity in the gastric fluids environment, and there was growth heterogeneity between the various strains of V. parahaemolyticus after SGF treatment
The growth kinetics characteristics of 50 pathogenic and non-pathogenic V. parahaemolyticus strains with different genotypes and from different sources were determined in simulated gastric fluids

Summary

Introduction

Vibrio parahaemolyticus is a gram-negative non-spore halophilic bacteria, which inhabits primarily coastal marine and estuarine environments and is widely found in various marine products (Alonsohernando et al, 2013). Heterogeneity of Vibrio parahaemolyticus in SGF is a common food-borne pathogen, which can cause pathogenic symptoms such as diarrhea, vomiting, acute gastroenteritis, dehydration, shock, and even death after the ingestion of the bacteria (Baker-Austin et al, 2010). V. parahaemolyticus has become the major pathogen causing food-borne infection in many countries and coastal areas, such as Japan, Southeast Asia, the United States, and Taiwan (Yamasaki et al, 2009). The detection of tdh and trh genes as pathogenic isolates is the main cause of human food-borne diseases (Letchumanan et al, 2015)

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Conclusion