IV型菌毛(T4P)是介导多种细菌过程的多功能蛋白质突起,包括附着力,运动性,和生物膜的形成。嗜水气单胞菌,革兰氏阴性兼性厌氧菌,在广泛的宿主中引起疾病。以前,我们报告了一个独特的IV型C类菌毛的存在,称为紧密粘附(Tad),毒力嗜水气单胞菌(vAh)。在本研究中,我们试图将Tad菌毛在嗜水菌ML09-119的致病性中的作用功能化。通过对170个嗜水气单胞菌基因组的全面比较基因组学分析,证实了vAh分离株中Tad操纵子的保守存在,表明其对致病性的潜在贡献。在这里,将整个Tad操纵子从嗜水A.hydrophilaML09-119中敲除,以阐明其在嗜水A.hydrophila毒力中的特定作用。Tad操纵子的缺失不会影响cat鱼种的生长动力学,但会显着降低毒力,强调Tad操纵子在感染过程中的重要作用。在Tad操纵子缺失物中,嗜水气单胞菌ML09-119的生物膜形成显着降低。缺乏Tad操纵子对其他环境压力源的敏感性没有影响,包括过氧化氢,渗透压,碱度,和温度;然而,它对低pH条件更敏感。扫描电子显微镜显示,Tad突变体在对数期生长过程中具有比野生型菌株更粗糙的表面结构,表明Tad的缺失会影响细胞分裂过程中vAh的外表面,其生物学后果是未知的。这些发现强调了Tad在vAh发病机理和生物膜形成中的作用,表明T4P在细菌感染中的重要性。
Type IV pili (T4P) are versatile proteinaceous protrusions that mediate diverse bacterial processes, including adhesion, motility, and biofilm formation. Aeromonas hydrophila, a Gram-negative facultative anaerobe, causes disease in a wide range of hosts. Previously, we reported the presence of a unique Type IV class C pilus, known as tight adherence (Tad), in virulent Aeromonas hydrophila (vAh). In the present study, we sought to functionalize the role of Tad pili in the pathogenicity of A. hydrophila ML09-119. Through a comprehensive comparative genomics analysis of 170 A. hydrophila genomes, the conserved presence of the Tad operon in vAh isolates was confirmed, suggesting its potential contribution to pathogenicity. Herein, the entire Tad operon was knocked out from A. hydrophila ML09-119 to elucidate its specific role in A. hydrophila virulence. The absence of the Tad operon did not affect growth kinetics but significantly reduced virulence in catfish fingerlings, highlighting the essential role of the Tad operon during infection. Biofilm formation of A. hydrophila ML09-119 was significantly decreased in the Tad operon deletant. Absence of the Tad operon had no effect on sensitivity to other environmental stressors, including hydrogen peroxide, osmolarity, alkalinity, and temperature; however, it was more sensitive to low pH conditions. Scanning electron microscopy revealed that the Tad mutant had a rougher surface structure during log phase growth than the wildtype strain, indicating the absence of Tad impacts the outer surface of vAh during cell division, of which the biological consequences are unknown. These findings highlight the role of Tad in vAh pathogenesis and biofilm formation, signifying the importance of T4P in bacterial infections.