砷对生物体具有较明显的毒害作用，许多生物仅能耐受较低浓度的砷。自然环境中的砷多数与金等矿石伴生，含砷难处理金矿中含有的大量砷阻碍了多数浸矿微生物的正常生长和对矿石的氧化预处理。目前，除了在大肠杆菌等微生物中证实了arsRDABC和arsRBC等典型的砷抗性操纵子以外，还陆续在能耐受较高浓度砷的菌株中发现了一些新的抗砷基因和抗砷机制。关于极端嗜酸硫杆菌在微生物浸矿中的抗砷行为和机制的报道为数不多，尚未见关于嗜酸氧化硫硫杆菌抗砷机制的报道，微生物的抗砷机制至今仍未被完全解释。在我们的前期工作中，分离得到了若干株嗜酸氧化亚铁硫杆菌和嗜酸氧化硫硫杆菌，研究发现它们的抗砷浓度超过了目前已有报道的所有浸矿微生物。在本项目中，拟通过对比不同来源的抗性菌株之间抗砷机理的差异，考证传统的砷抗性操纵子、转座子模型的保守性以及是否存在新的抗砷基因及抗砷机制。

Arsenic has obvious toxic effect to organisms. Many organisms can only tolerate very low dosage of arsenic. Arsenic in the environment is always found to be associated with several sulfide minerals like gold ore. However, high concentration of arsenic compounds existed in the arsenic-bearing refractory gold ores inhibits growth of a large number of bioleaching microorganisms and impedes the oxidation pretreatments of ores. Until now, some novel arsenic resistance genes and mechanisms have been proved to play key roles in certain microorganism strains which could resist high concentration of arsenic, besides those typical arsenic resistance operons such as arsRDABC and arsRBC found in Escherichia coli and other common strains. On the other hand, there have been only a few reports about arsenic resistance behaviors and mechanisms of Acidithiobacillus spp. in the bioleaching, and no paper on arsenic resistance mechanisms of Acidithiobacillus thiooxidans has been reported. Therefore, arsenic resistance mechanisms of microorganisms have not been illuminated completely. In our previous work, several strains of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were successfully isolated and applicated in the oxidation pretreatments of arsenic-bearing refractory gold ores, and it was demonstrated that the arsenic resistance concentrations were higher than those of all the bioleaching microorganisms reported. In this study, differences between arsenic resistance mechanisms from different sources will be compared among arsenic resistance behaviors and mechanisms of several resistant strains of Acidithiobacillus spp. Furthermore, the hereditary conservations of ars operon and transposons, and whether there are some unknown arsenic resistance genes or mechanisms will be examined.