Mechanisms Underlying the Virulence Regulation of Vibrio alginolyticus ND-01 pstS and pstB with a Transcriptomic Analysis

Xin Yi; Xiaojin Xu; Xin Qi; Yunong Chen; Zhiqin Zhu; Genhuang Xu; Huiyao Li; Emma-Katharine Kraco; Haoyang Shen; Mao Lin; Jiang Zheng; Yingxue Qin; Xinglong Jiang

doi:10.3390/microorganisms10112093

Mechanisms Underlying the Virulence Regulation of Vibrio alginolyticus ND-01 pstS and pstB with a Transcriptomic Analysis

Microorganisms. 2022 Oct 22;10(11):2093. doi: 10.3390/microorganisms10112093.

Authors

Affiliations

¹ Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China.
² Fisheries Research Institute of Fujian, Xiamen 361013, China.
³ School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 East Greenfield Avenue, Milwaukee, WI 53204, USA.

Abstract

Vibrio alginolyticus is a common opportunistic pathogen of fish, shrimp, and shellfish, and many diseases it causes can result in severe economic losses in the aquaculture industry. Causing host disease was confirmed by several virulence factors of V. alginolyticus. To date, there have been no reports on the effect of the pstS gene on its virulence regulation of V. alginolyticus. The virulence mechanism of target genes regulating V. alginolyticus is worthy of further study. Previous studies found that Fructus schisandrae (30 mg/mL) inhibited the growth of V. alginolyticus ND-01 (OD₆₀₀ = 0.5) for 4 h, while the expressions of pstS and pstB were significantly affected by F. schisandrae stress. So, we speculated that pstS and pstB might be the virulence genes of V. alginolyticus, which were stably silenced by RNAi to construct the silencing strains pstS-RNAi and pstB-RNAi, respectively. After the expression of pstS or pstB gene was inhibited, the adhesion capacity and biofilm formation of V. alginolyticus were significantly down-regulated. The chemotaxis and biofilm formation ability of pstS-RNAi was reduced by 33.33% and 68.13% compared with the wild-type strain, respectively. Sequence alignment and homology analysis showed that pstS was highly conserved, which suggested that pstS played a vital role in the secretion system of V. alginolyticus. The pstS-RNAi with the highest silencing efficiency was selected for transcriptome sequencing. The Differentially Expressed Genes (DEGs) and GO terms were mapped to the reference genome of V. alginolyticus, including 1055 up-regulated genes and 1134 down-regulated genes. The functions of the DEGs were analyzed by GO and categorized into different enriched functional groups, such as ribosome synthesis, organelles, biosynthesis, pathogenesis, and secretion. These DEGs were then mapped to the reference KEGG pathways of V. alginolyticus and enriched in commonalities in the metabolic, ribosomal, and bacterial secretion pathways. Therefore, pstS and pstB could regulate the bacterial virulence of V. alginolyticus by affecting its adhesion, biofilm formation ability, and motility. Understanding the relationship between the expressions of pstS and pstB with bacterial virulence could provide new perspectives to prevent bacterial diseases.

Keywords: RNAi; Vibrio alginolyticus; homology analysis; pstB; pstS; transcriptome; virulence.

Grants and funding

This research was supported by the Natural Science Foundation of Fujian Province (No. 2020J01673, 2019J01695, No. MinKeNong [2019] No. 11, [2020] No. 32, No. 2018N2005, 2017L3019), Jimei University National Fund cultivation program project [2020] No. 32, ZP2021001, the Scientific Research Fund of Engineering Research Center of the Modern Industry Technology for Eel Ministry of Education (No. RE202108). Xiamen Ocean and Fishery Development Special Fund (21CZP007HJ07). the National Key Research and Development Plan (No. 2020YFD0900102), the NSFC (General Program No. 31702384), the Scientific Research Fund of Fujian Provincial Department of Education (No. JA15292), and the open fund of the Fujian Province Key Laboratory of Special Aquatic Formula Feed (Fujian Tianma Science and Technology Group Co., Ltd.) (No. TMKJZ1907). the National Key Research and Development Program of China (NO. 2018YFC1406305), the Foreign Cooperation Project of Fujian Province (No. 2019I1008).