cheA, cheB, cheR, cheV, and cheY Are Involved in Regulating the Adhesion of Vibrio harveyi

Diseases caused by <i>Vibrio harveyi</i> lead to severe economic losses in the aquaculture industry. Adhesion is an important disease-causing factor observed in bacteria with chemotactic activity. In our study, we measured the adhesion of <i>V. harveyi</i> by subjecting the bacteria to stress using Cu²⁺, Pb²⁺, Hg²⁺, and Zn²⁺. The genes responsible for chemotaxis (<i>cheA</i>, <i>cheB</i>, <i>cheR</i>, <i>cheV</i>, and <i>cheY</i>), which are also crucial for adhesion, were identified and silenced <i>via</i> RNAi. We observed that a decrease in chemotactic gene expression reduced the ability of the organism to demonstrate adhesion, motility, chemotaxis, and biofilm formation. Upon comparing the <i>cheA</i>-RNAi bacteria to the wild-type strain, we observed that the transcriptome of <i>V. harveyi</i> was significantly altered. Additionally, the expression of key genes and the adhesion ability were affected by the pH (pH of 5, 6, 7, 8, and 9), salinity (NaCl at concentrations of 0.8, 1.5, 2.5, 3.5, or 4.5%), and temperature (4, 15, 28, 37, and 44°C) of the medium. Based on these results, the following conclusions were made: (1) The chemotactic genes <i>cheA</i>, <i>cheB</i>, <i>cheR</i>, <i>cheV</i>, and <i>cheY</i> may regulate the adhesion ability of <i>V. harveyi</i> by affecting bacterial motility, and participate in the regulation of adhesion at different temperatures, salinities, and pH values; (2) stable silencing of <i>cheA</i> could alter the transcriptional landscape of <i>V. harveyi</i> and regulate the expression of genes associated with its adhesion mechanisms.