Study on the mode of biofilm formation of Campylobacter jejuni and its biological functions

结果表明，空肠弯曲杆菌81-176菌株是一种强黏液产生菌，经布鲁氏菌肉汤固定培养后，在血琼脂平板上呈现出扩散和高度黏液菌落，并在玻璃烧瓶底部形成生物膜。本研究以菌株81-176为材料，通过自然转化介导的等位基因交换，构建了8个与生物膜形成相关的基因。作为鞭毛型（flaA^- b ^-和flbA^-）和鞭毛型但不运动型（pflA^-和motA^-）突变体，即使在细胞表面表达荚膜样多糖，也没有形成野生型菌株所表现出的生物膜。相比之下，分别缺乏荚膜样多糖和外膜蛋白的kpsM和peb1突变体保留了形成生物膜的能力。此外，luxS和cheY突变体分别与细胞间信号传导和趋化性相关，不影响生物膜的形成能力。这些发现表明鞭毛介导的运动是体外生物膜形成所必需的。利用生物膜形成菌株及其缺乏突变体（motA^-）或浮游细胞，研究了空肠梭菌在非生长条件下的存活情况。这些生物被钉在纸浆盘上，或用热、消毒剂或抗生素处理。通过非选择性血琼脂板上可培养细胞的数量来确定存活率。在所有的实验中，形成生物膜的空肠梭菌细胞比不形成生物膜的突变体或浮游细胞存活的时间更长，这表明生物膜的形成对在没有宿主的环境条件下存活很重要。

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 determine the genes associated with biofilm formation, eight mutants were constructed from strain 81-176 by natural transformation-madiated allelic exchange. As aflagellate (flaA^-B^- 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 an outer membrane protein, respectively, retained the ability of biofilm formation. Furthermore, luxS and cheY mutants which were associated with cell to cell signaling and chemotaxis, respectively, did not affect the ability of biofilm formation. These findings suggest that flagella-mediated motility is required for biofilm formation in vitro.Survival of C.jejuni in the environment under non-growth conditions was examined using a biofilm-forming strain and its lacked mutant (motA^-) or planktonic cells. The organisms were spiked on pulp disks or treated with heat, sanitizers, or antibiotics. Survival was determined by the number of culturable cells on non-selective blood agar plates. In all the experiments, biofilm forming cells of C.jejuni can survive longer than biofilm non-forming mutant or planktonik cells, suggesting that biofilm formation is important to survive under environment conditions without hosts.