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

我们观察到产粘性较强的空肠弯曲杆菌81-176菌株在血液琼脂平板上表现出铺展的高粘液性菌落，在布鲁氏菌肉汤中静止培养后在玻璃瓶底部形成生物膜。为了确定与生物膜形成相关的基因，从81-176菌株通过自然转化和等位基因交换的方法构建了8个突变体。有鞭毛但不活动的突变株(FlaA^-B^-和flbA^-)和鞭毛状但不活动的突变株(pflA^-和Mota^-)没有形成野生型菌株所表现出的生物膜，尽管细胞表面表达了囊状多糖。相反，分别缺乏囊状多糖和外膜蛋白的kpsM和peb1突变体保留了生物被膜形成的能力。此外，分别与细胞间信号转导和趋化作用相关的LuxS和Chey突变体不影响生物被膜的形成能力。这些发现表明，在体外生物膜的形成需要鞭毛介导的运动。利用一株形成生物膜的菌株及其缺失的突变株(Mota^-)或浮游细胞，研究了空肠弯曲菌在非生长条件下在环境中的存活。这些微生物被添加到纸浆盘上，或者用加热、消毒剂或抗生素处理。存活率由非选择性血液琼脂平板上可培养细胞的数量决定。在所有的实验中，空肠弯曲菌的生物膜形成细胞比未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于在无宿主的环境条件下的生存是重要的。

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.