| Arsenic in nature as a kind of metalloid element, is widely used in terms of medicine, pesticides, herbicides, wood preservatives, pesticides, and other semiconductor materials as well as metal alloys. Because arsenic and its compounds have strong toxicity, long-term excessive exposure to arsenic, causing serious damage to human health, leading to chronic or acute poisoning and even cancer. In recent years, with the rapid development of China’s industrialization process, environmental arsenic contamination issues are also increasingly prominent,"cancer villages" and some other environmental problems caused by water pollution with arsenic and other heavy metals have attracted the attention of the community. Currently, the method of arsenic contaminated water treatment abroad mainly chemical, physical, and biological method. Chemical and physical methods which exist mostly complex processes, high operating costs, easy to produce large amounts of waste and cause secondary pollution problems, however, biological method as a new arsenic pollution control technology with high efficiency, low investment, no secondary pollution advantages been widespread concern. The present study was designed to isolate strains of microorganisms resistant to arsenic from arsenic contamination of the environment, and the separated arsenic-resistant strains were resistant to arsenic gradient test, the purpose of screening out high strain resistant strain as a follow-up experiment arsenic, and arsenic-resistant strains of high growth characteristics and performance in addition to arsenic-related research.The main contents and conclusions were as follows:(1) In this paper, soil bacteria and Yunnan Yangzonghai and old Datun sea arsenic contaminated areas for the study, in the beef extract peptone medium plus arsenic source conditions, through enrichment, coating separation and purification methods such as preliminary from the soil isolated the21arsenic-resistant strains, in turn named Gl, G2…G21. Further separated arsenic resistant strains were resistant to arsenic gradient test, three strains of selected strains with high resistance to arsenic in nature, which G1strains for tolerance As3+1000mg/L, G2and G8strains As3+tolerance was800mg/L. (2) By cell morphology, physiological and biochemical characteristics as well as research16S rRNA gene identification, determine Cook G1strains of bacteria Kocuria carniphila, G2as Proteobacteria Achromobacter insolitus and G8bacteria Bacillus Lysinibacillus xylanilyticus. Three height arsenic-resistant strains of the best growing conditions results showed high arsenic resistant strains G1, G2and G8pH optimum growth were5,6,7, optimal culture temperatures of30℃,40℃and30℃, rotation optimal shaker150r/min. Secondly, magnesium arsenic-resistant strains of high growth have certain promote optimal Mg2+concentration is about40mg/L, G1and G2phosphate on the growth of bacteria resistant to arsenic can promote optimal PO43-concentration in60about mg/L, the growth of the strain on the G8no role.(3) At different pH, contact time, initial concentration under As3+preliminary inquiry and other conditions of high arsenic resistant strains G1, G2and G8arsenic removal properties, and found three strains of high anti arsenic removal As3+the best solution pH was8,4and6; removing As3+the best reaction time and maximum average removal rate of about1h; high resistance to low concentrations of arsenic strain As3+removal is high concentration of As3+removal significantly better; G1bacteria BN/W is1:2, the removal efficiency reaches a maximum, G2bacteria BN/W is about1:1when the arsenic removal reaches a maximum, and stabilized, G8bacteria is as bacterial cells increased removal rate increases; overall, high resistance to arsenic strains screened (G1, G2and G8) arsenic removal effect is not ideal, and the removal of As (Ⅲ) most resistant strains of G1effect but not as tolerant of weaker G2and G8bacteria, arsenic-resistant strains of high arsenic removal need further optimization to improve performance.In summary, by applying arsenic source filter arsenic out of high resistance to bacteria, for As3+has a high tolerance and certain arsenic removal effect. This study microbial remediation of arsenic contaminated water has a certain practical significance. |
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