The TCA Pathway is an Important Player in the Regulatory Network Governing Vibrio alginolyticus Adhesion Under Adversity.

Lixing Huang,Yingxue Qin,Xiaojin Xu,Mao Lin,Qingpi Yan,Jiang Zheng,Li Huang,Ying Ma

doi:10.3389/fmicb.2016.00040

Abstract

Adhesion is a critical step in the initial stage of Vibrio alginolyticus infection; therefore, it is important to understand the underlying mechanisms governing the adhesion of V. alginolyticus and determine if environmental factors have any effect. A greater understanding of this process may assist in developing preventive measures for reducing infection. In our previous research, we presented the first RNA-seq data from V. alginolyticus cultured under stress conditions that resulted in reduced adhesion. Based on the RNA-seq data, we found that the Tricarboxylic acid cycle (TCA pathway) might be closely related to adhesion. Environmental interactions with the TCA pathway might alter adhesion. To validate this, bioinformatics analysis, quantitative Real-Time PCR (qPCR), RNAi, and in vitro adhesion assays were performed, while V. alginolyticus was treated with various stresses including temperature, pH, salinity, and starvation. The expression of genes involved in the TCA pathway was confirmed by qPCR, which reinforced the reliability of the sequencing data. Silencing of these genes was capable of reducing the adhesion ability of V. alginolyticus. Adhesion of V. alginolyticus is influenced substantially by environmental factors and the TCA pathway is sensitive to some environmental stresses, especially changes in pH and starvation. Our results indicated that (1) the TCA pathway plays a key role in V. alginolyticus adhesion: (2) the TCA pathway is sensitive to environmental stresses.

Highlights

Vibrio alginolyticus is an important opportunistic pathogen for marine organisms (Patterson et al, 1988)
It involves adherence to specific receptors within the mucus or epithelial cell surface receptors and the bacterial attraction to the mucosal surface. This means that bacteria sense and respond to a chemical stimulus, flagella assembly, energy production, and biosynthesis; and other biological processes are involved in the regulation of adhesion
These biological processes are tightly regulated by protein coding genes and ncRNAs

Summary

Introduction

Vibrio alginolyticus is an important opportunistic pathogen for marine organisms (Patterson et al, 1988). V. alginolyticus is an ubiquitous organism in seawater and has been associated with several epidemics of vibriosis in cultivated marine animals, including fish, shellfish, crustaceans (Wang et al, 2012), and coral reefs (Xie et al, 2013). Large yellow croaker (Pseudosciaena crocea) is an economically important cultivated marine species in China. V. alginolyticus is the main pathogenic bacterium of the cultured large yellow croaker, which has led to considerable economic losses (Yan et al, 2007; Huang et al, 2008). The temperature (Yeh et al, 2010), salinity (López-Hernández et al, 2015), TCA pathway regulates bacterial adhesion pH (Li and Chen, 2008), and starvation (Yi et al, 2008) are the primary environmental factors of epidemic vibriosis in aquaculture

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