土壤蜡样芽孢杆菌M4耐镉代谢产物及其作用机制

Bacillus cereus, known as plant growth-promoting rhizobacteria and biocontrol bacteria, were wildly used in microbial agent and microbiological fertilizer. But with the rapidly increase of cadmium pollution, it is particularly important to study on the Cd-tolerance of Bacillus cereus. Rhizosphere microbes Bacillus cereus M4 with Cd-tolerance and nitrogen fixation activity was isolated from heavy metal polluted farmland soil. In this study, various of extracting methods and chromatographic means were used to separate and purify metabolites with tolerance to cadmium from Bacillus cereus M4. After structural identification, these metabolites were tested by subcellular localization and infrared spectroscopy in order to analyze the interreactions with cadmium preliminarily. Furthermore, the differences of genome, RNA transcription and protein translation among various strain or cadmium stress were studied by genomics, transcriptomics and proteomics. On this basis, the functions of differential gene were speculated by bioinformatics to find new Cd-tolerance functional genes and explain the response mechanism of cadmium stress in Bacillus cereus at the molecular level. Meanwhile, the metabolites downstream of differential gene speculated by bioinformatics were also compared to the separation result of Cd-tolerance metabolites in order to find new Cd-tolerance functional genes specifically. This project will not only develop the theoretic study, but also lay the foundation for genetically engineering of microbial agents and microbial remediation used in cadmium polluted farmland soil.

蜡样芽孢杆菌具有植物促生和生防作用，作为微生物菌剂肥料应用广泛，但随着农田土壤重金属镉污染问题日益突出，其耐镉性显得更为重要。本项目以从重金属污染农田水稻根际土壤中分离的具有强耐镉性和固氮活性的蜡样芽孢杆菌M4为材料，采用不同的提取方法和层析手段，对菌株中各类耐镉代谢产物进行分离纯化鉴定，利用亚细胞定位和红外光谱等手段，初步分析其与镉的互作方式；进一步利用基因组学、转录组学和蛋白组学手段，检测不同镉敏感型菌株或不同镉胁迫条件下基因组、RNA转录和蛋白产物的差异，利用生物信息学分析推测差异基因或蛋白功能与菌株耐镉性的关系，从而在分子水平上阐释其镉胁迫响应机制；推测目标差异基因下游代谢产物，并与分离纯化实验结果比对，从而更有针对性的克隆鉴定菌株M4中新的耐镉基因。该项目不但能完善理论研究，也为镉污染农田微生物菌剂基因工程改造及其改良应用奠定基础，同时在微生物修复镉污染土壤方面也具有重要应用价值