中文摘要：

以胶质芽孢杆菌CGMCC11和环状芽孢杆菌CGMCC12为出发菌株,采用亚硝酸钠对其进行诱变育种与浸矿研究。结果表明：菌株CGMCC11和CGMCC12的最适生长温度分别为28和30℃,最适pH值分别为7.2和8.3。采用40和60 mg/L亚硝酸钠分别处理出发菌株CGMCC11和CGMCC12,致死率分别为87%和85%,正突变率分别为18%和20%;筛选获得两株突变菌CGMCC11KP和CGMCC12KP,其达到生长稳定期的时间分别比对应的出发菌株达到生长稳定期的时间缩短了48和24 h,且具有更大的菌体密度、产酸和产大分子胞外聚合物的能力。浸矿15 d,与对应的出发菌株相比,突变菌株CGMCC11KP和CGMCC12KP溶出的SiO2量分别提高了30.47%和29.57%,且达到浸出终点的时间分别提前了5和3 d;混合诱变菌株浸出液中SiO2的量分别比对应的诱变菌株浸出液中SiO2的量提高了20.0%和37.5%,且达到浸出终点的时间比出发菌株达到浸出终点的时间提前了6 d。SEM和XRD结果表明：混合诱变菌株对铝土矿的溶蚀分解最为明显,混合浸出15 d后,诱变前后胶质芽孢杆菌CGMCC11和环状芽孢杆菌CGMCC12的菌落个数比由1：1变为10：1。

英文摘要：

The original strains, Bacillus mucilaginosus CGMCC 11 and Bacillus circulans CGMCC 12, were treated by sodium nitrite to induce mutagenesis and investigate bioleaching of bauxite. The results show that the optimum temperature and pH value are 28 ℃ and 7.2 for B-MCGMCCll, and 30℃ and 8.3 for B.C CGMCC12. The lethal rates of B.M CGMCC11 and B.C CGMCC12 are 87% and 85%, and the positive mutant rates are 18% and 20% after being treated by 40 and 60 mg/L sodium nitrite culturing, respectively. The two mutants, B.M CGMCCllKP and B＇C CGMCC 12KP, screened from positive mutant strains reach stationary stages by 48 and 24 h ahead of the corresponding original strains, and have higher bacterial concentrations and higher ability of producing organic acids and macromolecule extracellular polymers than the original strains. After leaching for 15 d, the SiO2 concentrations in supernatants of the mutant stains of B.M CGMCC11KP and B·C CGMCC12KP are improved by 30.47% and 29.57%, and the leaching time of 5 and 3 d shorter, respectively, than those of the two corresponding original strains. After bioleaching with the mixture ofB.M CGMCC11KP and B＇C CGMCC12KP, the SiO2 concentration of the supernatant is 20.0% and 37.5% higher than those of the corresponding mutants, and the mixture can shorten the leaching time by 6 d in comparison with the original strains. The SEM and XRD analyses of bauxite surfaces before and after leaching show thatthe mixture of B.M CGMCC 11KP and B·C CGMCC 12KP has the greatest corrosion and decomposition ability on bauxite. After bioleaching for 15 d, the proportion of cell density in the supematants of B·M CGMCC1 l and B.C CGMCC 12 is changed from 1 ： 1 to approximately 10 ： 1.