Studies on bioflim formation and survival mechanisms of Campylobacter species in foods

我们观察到空肠弯曲菌菌株81-176，一个强大的粘液生产者，显示扩展和高度粘液样菌落在血琼脂平板上，并在布鲁氏菌肉汤中静止培养后在玻璃烧瓶底部形成生物膜。本研究旨在探讨C.空肠粘附在光滑表面上。当将布鲁氏菌肉汤中的细菌悬液在微孔板孔中孵育时，孵育后2 h在盖玻片上形成小菌落。6 h时，小菌落逐渐生长，形成网状连接的生物膜。透射电子显微镜检查表明，大量的细胞外物质掩盖了细胞表面和结合钌红，表明多糖部分的存在。扫描电子显微镜观察表明，鞭毛起桥梁作用，在生物体之间形成网状连接。为了确定与生物膜形成相关的基因，通过自然转化介导的等位基因交换从菌株81-176构建了几个突变体。作为aflagellate（flaAB和flbA）和鞭毛虫，但nonmotile（pflA和motA）突变体没有形成一个生物膜所表现出的野生型菌株，即使在细胞表面上表达的荚膜样多糖。相比之下，kpsM和peb 1突变体，缺乏荚膜样多糖和外膜蛋白，分别保留了生物膜形成的能力。这些发现表明，鞭毛介导的运动，而不是荚膜样多糖和PEB 1蛋白是需要在体外生物膜形成。

We observed that Campylobacter jejuni strain 81-176, a strong slime producer, showed spreading and highly mucoid colonies on blood agar plates, and formed biofilm on the bottom of a glass flask after stationary cultivation in Brucella broth. The present study was performed to examine the mode of C. jejuni adherence to a smooth surface. When bacterial suspensions in Brucella broth were incubated in a microplate well, microcolonies were formed on the coverslip by 2 h after incubation. The microcolonies gradually grew and formed a biofilm of net-like connections by 6 h. Transmission electron microscopy indicated that massive amounts of extracellular material were masking the cell surface and bound ruthenium red, suggesting the presence of a poiysaccharide moiety. Scanning electron microscopy indicated that the flagella acted as bridges, forming a net-like connection between the organisms. To determine the genes associated with biofilm formation, several mutants were constructed from strain 81-176 by natural transformation-madiated allelic exchange. As aflagellate (flaAB and flbA) and flagellate but nonmotile (pflA and motA) mutants did not form a biofilm exhibited by the wild type strain even though capsular-like polysaccharide was expressed on the cell surface. In contrast, kpsM and peb1 mutants which lack capsular-like polysaccharide and a outer membrane protein, respectively, retained the ability of biofilm formation. These findings suggest that flagella-mediated motility but not capsular-like polysaccharide and PEB 1 protein is needed for biofilm formation in vitro.