海洋细菌还原铬基因与耐盐特性的关联研究

The mechanism(s) under the correlation between chromium (VI)-reduction genes and salt-tolerance will be explored. Researches have showed that the chromium(VI)-reduction process of microbiology is very complex，and many factors involved in the mechanism have been testified. However, the correlation between chromium (VI)-reduction and salt-tolerance has remained to be be described. In prepared works, chrR gene encoding chromate reductase was mutated, leading to the decreasing of salt-tolerance ability of the strain. In this study, a marine chromium(VI)- tolerance bacterial stain Proteus sp. H24 isolated from seawater samples of an inlet of the East Sea long-term receiving industrial chromium-containing wastewaters will be used to probe the correlation between chromium(VI)-reduction genes and salt-tolerance ability. Chromium-tolerance bacteria are mutated through the insertion of transposon Tn5. Then the regulatory role of chromium(VI)-reduction genes on salt-tolerance will be explored by using PCR technique, gene cloning, protein expression, promoter analysis, mRNA detections and observations of electronic microscopy, etc. The results will reveal that the special mechanisms of bacteria and its role on marine eco-system. This study will provide more information with the mechanism of salt-tolerance along with the reduction of chromium(VI) to chromium(III) by the strain, and also some new theoretical explanation for microbial treatment of industrial chromate(VI) containing wastewaters.

本研究拟在揭示海洋细菌铬还原基因与耐盐性状具有相关性的机理。研究表明微生物还原六价铬的过程异常复杂，已证实与很多因子有关，但对于菌株在还原六价铬过程中与其耐盐特性相关联的机理认识还是一片空白。本项研究在发现铬还原酶基因（chrR）失活导致菌株耐盐性能下降的现象的工作基础上，以一株从工业废水污染的东海近海水域中分离的海洋耐铬细菌Proteus sp. H24作为材料，采用转座子Tn5插入菌株引起铬还原基因突变以筛选铬还原性状和耐盐性状发生改变的方法，再结合PCR技术、基因克隆、蛋白表达、启动子分析、mRNA检测和电镜观察等手段来探讨菌株还原铬基因与耐盐特性的关联性，揭示该菌特殊的生命机理和在海洋生态系统中的作用，为探索微生物将六价铬还原为三价的同时能耐受其它金属盐的生物机制提供更多信息，也将为微生物处理工业含铬废水提供新的理论基础。

微生物还原六价铬过程比较复杂，海洋细菌H24还原铬与其海水环境中的盐发生关联，对其机理研究会为探索海洋细菌特殊的生命特性提供更多信息。本研究采用转座子插入突变海洋细菌Proteus sp.H24得到目标性状变化的突变株，对相关基因进行克隆与分析，结合不同样品中铬还原率比较等实验结果，推测菌株的铬还原和耐盐的关联性及相关机理。结果表明菌株H24虽已适应海洋的高盐环境，可以在高盐下还原六价铬，但高盐不是它还原铬的必要条件。转座子突变研究也说明两者关联性并不十分紧密，只存在于少数基因中，如编码膜蛋白的基因等。研究还证实了该菌还原铬可以受到生长初级代谢和次级代谢活动中多个环节影响，如心磷脂合成酶和Mg2+转运ATP酶等众多类型的基因参与调节，类似基因调节至今还未见有报道。这说明研究的H24菌株在其生命演化过程中获得的功能特性与很多因素相关联，它赋予了海洋细菌在海洋生态系统中积极而开放的角色。同时该研究也为海洋细菌对六价铬生物治理的应用提供了有价值的理论参考，值得我们进一步探索。

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