Qin Y X, Yan Q P, Mao X X, Chen Z, Su Y Q
Fisheries College, Jimei University, Xiamen, Fujian, China.
Fisheries College, Jimei University, Xiamen, Fujian, China
Genet Mol Res. 2014 Oct 31;13(4):8982-96. doi: 10.4238/2014.October.31.13.
Biofilm formation of pathogen bacterium is currently one of the most widely studied topics; however, little is known regarding pathogen bacteria biofilms in aquaculture. Aeromonas hydrophila is a representative species of the genus Aeromonas, which has been recognized as a common pathogen, is associated with many diseases in aquatic animals, and causes significant mortality. The objectives of this study are i) to confirm that A. hydrophila can form biofilms on abiotic substrates and construct a biofilm growth curve for this bacterium; ii) to identify the genes that play crucial roles in A. hydrophila biofilm formation. The biofilm growth curve of A. hydrophila was constructed using a crystal violet assay, which showed that biofilm formation for this bacterium is a dynamic process. Next, a mutant library of pathogenic A. hydrophila B11 was constructed using the mini-Tn10 transposon mutagenesis system. A total of 861 mutants were screened, and 5 mutants were stably deficient in biofilm formation. Molecular analysis of the mutant B112 revealed that the open reading frame that encodes the protein MshQ was disrupted. Comparison of biological characteristics including growth, motility, and adhesion between the mutant B112 and the wild-type strain B11 suggested that MshQ is necessary for mannose-sensitive hemagglutinin pilus biosynthesis of A. hydrophila, and that these pili play crucial roles in A.hydrophila adherence to a solid surface during the early stages of biofilm formation.
病原菌的生物膜形成是目前研究最为广泛的课题之一；然而，关于水产养殖中病原菌生物膜的情况却知之甚少。嗜水气单胞菌是气单胞菌属的代表性菌种，它已被公认为一种常见病原菌，与水生动物的多种疾病相关，并导致大量死亡。本研究的目的是：i）确认嗜水气单胞菌能在非生物基质上形成生物膜，并构建该细菌的生物膜生长曲线；ii）鉴定在嗜水气单胞菌生物膜形成中起关键作用的基因。采用结晶紫测定法构建了嗜水气单胞菌的生物膜生长曲线，结果表明该细菌的生物膜形成是一个动态过程。接下来，利用mini-Tn10转座子诱变系统构建了致病性嗜水气单胞菌B11的突变体文库。共筛选出861个突变体，其中5个突变体在生物膜形成方面稳定缺陷。对突变体B112的分子分析表明，编码蛋白MshQ的开放阅读框被破坏。突变体B112与野生型菌株B11在生长、运动性和黏附性等生物学特性方面的比较表明，MshQ是嗜水气单胞菌甘露糖敏感血凝素菌毛生物合成所必需的，并且这些菌毛在生物膜形成早期嗜水气单胞菌黏附到固体表面过程中起关键作用。
