DataSheet_1_cheA, cheB, cheR, cheV, and cheY Are Involved in Regulating the Adhesion of Vibrio harveyi.docx

Diseases caused by Vibrio harveyi 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 V. harveyi by subjecting the bacteria to stress using Cu2+, Pb2+, Hg2+, and Zn2+. The genes responsible for chemotaxis (cheA, cheB, cheR, cheV, and cheY), which are also crucial for adhesion, were identified and silenced via 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 cheA-RNAi bacteria to the wild-type strain, we observed that the transcriptome of V. harveyi 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 cheA, cheB, cheR, cheV, and cheY may regulate the adhesion ability of V. harveyi by affecting bacterial motility, and participate in the regulation of adhesion at different temperatures, salinities, and pH values; (2) stable silencing of cheA could alter the transcriptional landscape of V. harveyi and regulate the expression of genes associated with its adhesion mechanisms.

哈维弧菌（Vibrio harveyi）引发的病害会给水产养殖业造成严重的经济损失。对于具备趋化活性的细菌来说，黏附（adhesion）是其重要的致病因子之一。本研究中，我们利用Cu²+、Pb²+、Hg²+及Zn²+对哈维弧菌施加胁迫，以此测定其黏附能力。我们对与趋化相关且同样对黏附至关重要的基因（cheA、cheB、cheR、cheV及cheY）进行了鉴定，并通过RNA干扰（RNA interference, RNAi）技术对其进行了沉默。研究发现，趋化基因表达量的下调会削弱哈维弧菌的黏附、运动、趋化以及生物被膜形成（biofilm formation）能力。将cheA-RNAi沉默菌株与野生型菌株（wild-type strain）进行对比后发现，哈维弧菌的转录组（transcriptome）发生了显著变化。此外，培养基的pH值（5、6、7、8、9）、盐度（salinity，氯化钠浓度分别为0.8%、1.5%、2.5%、3.5%或4.5%）以及温度（4℃、15℃、28℃、37℃和44℃）会影响关键基因的表达量与哈维弧菌的黏附能力。基于上述研究结果，本研究得出以下结论：(1) 趋化基因cheA、cheB、cheR、cheV及cheY可能通过影响细菌的运动性来调控哈维弧菌的黏附能力，并参与不同温度、盐度及pH值条件下的黏附调控过程；(2) 稳定沉默cheA基因可改变哈维弧菌的转录图谱（transcriptional landscape），并调控与其黏附机制相关的基因表达。