The Proteomics Study of Leptospirillum Ferriphilum under Arsenic Stress
|Keywords||Cleek Pylori case Bioleaching Arsenic stress Biohydrometallurgy Resistance to arsenic Bioleaching microorganisms Bioleaching bacteria Bioleaching Arsenopyrite Proteomics Trivalent arsenic ions Biological oxidation Phosphate starvation Bacterial leaching Iron - oxidizing bacteria Doctoral Dissertation Arsenic gold mine Thiobacillus Arsenic minerals|
Biological process metallurgy and other physical chemical metallurgy method compared with a low-cost, environmentally friendly, and suitable for mining lean ore smelting ore difficult. Improve the bioleaching microorganisms bioactivity and adaptability, will improve the efficiency of the production of bio-metallurgical process. Has proven gold resources, arsenic gold deposit account for a large proportion of which arsenic gold than 5% of the total proven reserves of gold resources 2000:1 (Liu Siqing of Influence, 1998). Arsenic is a semi-metal toxic and carcinogenic substances. Bioleaching' dissertation">Bioleaching process often have to deal with arsenopyrite and arsenic ore. Arsenopyrite bio-oxidation process mainly by sulfur-oxidizing bacteria the Thiobacillus caldus the (to Acidithiobacillus caldus), iron-oxidizing bacteria (Acidithiobacillus ferrooxidans) the tropic the the the iron hook end pylori (Leptospirillum ferriphilum) and iron-sulfur-oxidizing bacteria Thiobacillus ferrooxidans mixed carried out. Stenotrophomonas the cleek end pyroli (Leptospirillum ferriphilum) bioleaching reaction major iron-oxidizing microorganisms, especially in bio-oxidation treatment process in the late high redox potential conditions, is in a dominant status of the iron-oxidizing bacteria. The bacteria mainly oxide Fe2 Fe3 gain energy and Fe3 bioleaching process oxidant. Addicted to the oxidation of iron hook end pylori activity and vitality will directly affect the efficiency of bioleaching of arsenic-containing minerals. Bioleaching will be difficult to deal with arsenic poisoning ion concentration in the samples exceeded addicted the cleek end pylori arsenic tolerance levels. Therefore, in-depth understanding of the arsenic tolerance pylori addicted iron hook end, arsenic resistance mechanisms will provide theoretical guidance for the further breeding of microorganisms. But little addicted to the cleek end pylori genetic background, physiological and metabolic research, you can not directly starting from the bacteria existing physiological regulatory mechanisms and the genetic basis of the bacteria arsenic resistance mechanisms. Therefore, the use of comparative proteomics research strategy and the introduction of two-dimensional electrophoresis proteomics technology, global bacteria arsenic tolerance mechanism is a viable method. Two-dimensional electrophoresis (Two dimensional electrophoresis ,2-DE) is a global, high-throughput study of microbial protein expression differences, high-resolution, high-sensitivity display and separation of proteins differentially expressed in the analysis of complex mixtures and proteomics research in key technologies. Microbial interaction with the external environment and the biological response is often accomplished through comprehensive coordination of multiple systems, involving a variety of enzymes and regulation system changes, the focus is proteomics. Therefore, building a 2-DE analysis of L. ferriphilum technology platform, and proteomics technology based on to L. ferriphilum arsenic resistance, resistance the arsenic mechanisms is a scientific and rational choice. The L. ferriphilum the extremely acidophilic obligate chemoautotrophic Gram-negative bacteria. Were able to determine the cell density of bacteria cultures in ways, a variety of soluble ion impurity concentration. 2-DE technology is required to sample a higher protein concentration, the impurity concentration, particularly in a variety of soluble ion impurity concentration as low as possible. Therefore, the ordinary 2-DE programs can not get good separation, point rich L. ferriphilum 2-DE map, at home and abroad about L. ferriphilum global protein 2-DE experiments reported. In this study, by sample preparation for 2-DE, the removal of impurities on the sampling method, focusing parameter selection, staining methods of the key aspects of comparative experiment to develop a set of 2-DE experiment to L. ferriphilum the program, for the first time lattice clear, stable reproduce, the the gaining independence colloidal Coomassie staining protein spots to reach more than 600 L. ferriphilum 2-DE map. On this basis, in order to carry out differential proteomics study the Lf of arsenic under stress conditions, the study by domesticated and cultured with a higher resistance to arsenic performance Lf strains by 2D electrophoresis technology, arsenic resistant strains and bacterial control strains proteins are compared to determine differences in protein, by MALDI-TOF MS / MS technology and related biological informatics retrieval than tools of differential protein analysis. A more comprehensive understanding of L.f of resistance to arsenic mechanism. Currently known microbial resistance to arsenic arsenic resistance system is widespread Arsenic Resistance System, Ars systems. Recently reported arsenic stress conditions, some of the heat shock protein (HSP protein) capacity associated protein metabolism will also increase the amount of plasma membrane anion channel protein expression. Arsenic stress conditions, the cell discharge toxic ions in an attempt to improve the energy supply, improve the stability of the protein, and other ways to maintain the normal physiological and biochemical activities. Digitized by the original strain of L. ferriphilum ML-04 resistant to arsenic strain and ordinary protein 2-DE maps comparison and analysis, 65 protein spots appear more than three times the amount of expression changes (t-test, p lt; 0.05). Get a high score matching and recognition 38 proteins, including 25 proteins matching confirm the specific biological functions. A lot of protein helps to increase the tolerance of cells to arsenic, including the promotion of trivalent arsenic ions discharged in order to protect the stability of some important protein; protect and promote the repair chromosome protect the chromosome replication process; avoid important sulfur, phosphorus element waste; keep some important arsenic tolerance activity of the protein, etc.. Moreover, in order to more effectively protect the cells, improve the arsenic tolerance L. ferriphilumML-04 also be adjusted by changing the amount of the expression of some of the key enzymes in the metabolic pathway of the intracellular pathway, for example, carbohydrate metabolism, energy metabolism, amino acid metabolism. In addition, the proteomics research also detected two sets Ars arsenic resistance system. Set is the type of arsRC-arsB LJML04Ars1 gene cluster set arsRDABC the type LfML04Ars2 gene cluster. Compared with the the previously reported arsRDABC gene cluster, LfML04Ars2 gene cluster more than a coding frame, encoding a the Pst-type-specific phosphate transporter system PstS protein. Pst phosphate transport system the PstS protein belongs cells respond to phosphate starvation and anti the pentavalent arsenic poisoning ion system. The system is composed of protein appear in arsenic resistance system, suggesting addicted iron hook end pylori ML-04 strain, arsenic resistance system linkage relationship with some phosphate starvation response system. Due to arsenic poisoning ions can cause cell phosphate starvation, and can interfere with the cells within a variety of phosphorylation reaction process, the linkage of the the this arsenic Resistance system with the phosphate starvation response system can make the ML-04 to obtain greater arsenic tolerance. 2-DE technology platform and research strategies addicted to the cleek end pylori established in this study, can be applied to research addicted the cell adaptive mechanism of the the cleek end pylori on a variety of other environmental conditions change, such as bioleaching close other metal toxic ion resistance and tolerance mechanisms, changes in energy metabolism, pH disturbance heat shock response, physiological and biochemical processes, for the actual bacterial leaching process optimization, efficient bioleaching bacteria microbial breeding have important reference value and theoretical significance.