iTRAQ-based proteomic analysis of the viable but nonculturable state of Vibrio parahaemolyticus ATCC 17802 induced by food preservative and low temperature

Vibrio parahaemolyticus is a significant food-borne pathogen which can cause serious acute gastroenteritis. The viable but nonculturable (VBNC) state is a survival strategy of some bacteria when they are exposed to environmental stresses. In this study, V. parahaemolyticus ATCC 17802 was induced into VBNC state by food preservative at low temperature and oligotrophic condition, and the aim of the study is to compare differentially expressed proteins (DEPs) between the VBNC state and the exponential phase of V. parahaemolyticus ATCC 17802 using isobaric tags for relative and absolute quantitation (iTRAQ) technique. Functional annotations were carried out using protein sequence similarity, GO and KEGG pathway analysis. The results showed that V. parahaemolyticus ATCC 17802 was induced into the VBNC state at 4°C in seawater containing 10 mmol/L potassium sorbate within 40 days. A total of 1139 proteins were identified,1088 proteins were quantified. Of the DEPs under the VBNC state, 36 were significantly down-regulated and 15 up-regulated. The remarkable down-regulated proteins were type III secretion host injection and negative regulator protein, polar flagellin protein, ribosomal proteins, multidrug efflux pump component MtrF, and other key components involved in metabolism. The notable up-regulated proteins were mainly focused on transporter proteins, outer membrane protein, ferritin and amino acid synthase. The majorities of the significant DEPs were associated with translation, structural constituent of ribosome, rRNA binding, siderophore transmembrane transporter activity, receptor activity, and bacterial-type flagellum organization. This study contributes to a better understanding of the adaptation mechanism of the VBNC state of V. parahaemolyticus under food processing and environmental stresses.