中文摘要：

生物膜法被广泛用于污水处理领域,而污水中含有的重金属离子会严重影响生物被膜的稳定性,降低污水处理效率。该研究以污水处理系统中常见的枯草芽孢杆菌（Bacillus subtilis）为研究对象,分析了菌体在液体生物被膜形成过程中对镉离子的耐受性。结果表明,枯草芽孢杆菌胞外基质合成的抑制因子Sin R缺失后,突变株耐受Cd2＋离子的能力明显增强,说明胞外基质能够提高菌体对Cd2＋的耐受性;△eps G突变株比△tas A突变株对Cd2＋更敏感,说明胞外多糖比胞外蛋白起到更显著的保护作用;同时发现△eps G突变株和△tas A突变株可以共享分别产生的胞外蛋白和多糖;该研究还首次发现硬水软化剂EDTA-2Na能够提高菌株形成生物被膜过程中对Cd2＋的耐受性。该研究对于提高污水处理系统中生物被膜的初始驯化速度和生物被膜稳定性具有一定的理论指导和实践意义。

英文摘要：

Biofilm has been widely applied in wastewater treatment. Heavy metals contained in wastewater, always decrease the biofilm stability and thus reduce the efficiency of wastewater treatment. In this study, Bacillus subtilis was used as modal strain to investigate the resistance of Bacillus subtilis to Cd^2＋. The results showed that the deletion of SinR, a major inhibitor for the matrix synthesis, increased the resistance to Cd^2＋, indicating that the biofilm matrix can protect the cells from Cd^2＋. AepsG mutant was more sensitive to Cd^2＋ than AtasA, suggesting that extracellular polysaccharides play a predominant role in the resistance to Cd^2＋. At the same time, it was found that AepsG and AtasA mutants can share the extracellular proteins and polysaccharides produced separately. In addition, Na-EDTA can improve the resistance of biofilm to Cd^2＋. Therefore, this study has some theoretical guidance and practical significance for promoting the initial formation and stability of the biofilm in the wastewater treatment system.