| Biomining is a mineral pretreatment approach. Comparing with chemical approaches, the bioleaching method displays great advantages of cost-saving and environmental-friendly, particularly in dealing with the low grade ores and hard mining ores. The enhancement in activity and adaptability of the biomining microorganisms will increase the efficiency of biomining process and biomining industrial.In the certified reserves goldmine all over the world, the arsenic bearing goldmine takes a huge part and there are about 5% goldmine's arsenic/gold ratio are more than 2000:1 (Liu siqing and Song huanbin,1998). The biooxidation process were dominated by Acidilhiobacillus caldus, Leptospirillum ferriphilum and Acidithiobacillus ferrooxidans. L. ferriphilum is important in bioleaching. In real applications, it is under heavy stresses of heavy metal ions and high oxygen reduction potential (ORP). This bacterial can oxidize the iron(â…¡) to iron(â…¢) and generate energy. As the metabolism product of L. ferriphilum, iron(â…¢) also is a key oxidizer in bioleaching. So the oxidize activity and physiological activity will effect the biooxidize efficiency of arsenic bearing goldore's process. If the arsenic concentration exceed the arsenic tolerance ability of L. ferriphilum. Biooxidize of this arsenic bearing gold ore will not works. So the study of the detoxicity and tolerance mechanism were needed. The results of these researches will provide some useful guidance for further microbiology strain breeding works.Because the genetic background and physiological mechanisms of L. ferriphilum are still not very clear. The research of this bacteria can not based on the directly genetic analyze and physiological studies. So, the investigation about the arsenic tolerance and detoxification mechanism of L. ferriphilum will be conducted from a global aspect by the differential proteomic research approaches such as Two-dimensional-electrophoresis (2-DE) and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS).Two-dimensional-electrophoresis (2-DE) and comparative proteomic analysis are useful to investigate the responses of L. ferriphilum to environmental stresses. But,2-DE analysis for L. ferriphilum is not successful as the samples of L. ferriphilum contain low protein concentration, complex composition, high salt concentration, and many other interfering components, which make it difficult for 2-DE analysis. In this research, optimizations on the sample preparation and purification methods, sample volume, sample loading methods for isoelectric focusing (IEF), and gel visualization methods were made. More than 629 Coomassie stained spots in single gel were obtained. The image quality and protein concentration in most of the spots met the requirements for both differential spots analysis and mass-spectrum analysis. The 2-DE protocol for L. ferriphilum was successfully developed for the first time.Based on the 2-DE technic and proteomic research strategy, the response of Leptospirillum ferriphilum ML-04 under arsenic stress was analyzed using two-dimensional-electrophoresis (2-DE), matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS), and bio-informatics research methods.65 differential expressed protein were fond by 2-DE analysis (t-test, p<0.05).38 arsenic response proteins were highly identified. The arsenic resistant or tolerant mechanisms of these arsenic response proteins were studied and elucidated. In addition, some arsenic-resistance-system (ARS) member proteins were identified from these 38 arsenic response proteins. With the help of the genomic analysis, two ars operon like structures were discovered in the chromosome of this strain. One is a arsRC-arsB type LfML04Ars1 cluster. The other one is arsRDABC type cluster named LfFL04Ars2. Comparing with the former reported other arsRDABC type clusters, the LfML04Ars 2 contains a more gene ORF, which encodes a component protein of the Pst phosphate specific transfer system, the PstS like protein. This result indicats that there maybe a linkage relationship between the Ars arsenic resistance system and phosphate specific transfer system in this strain. The gene structure feature and possible function of these ars operon like structures were analyzed.
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