从青海某化工厂水溶态C(rⅥ)含量为248.17 mg/kg的表层土壤中,利用平板划线法,分离纯化出一株菌株。形态学观察该菌株为杆状的革兰氏阳性菌,16S rDNA序列分析结果显示,为芽孢杆菌属。生长条件实验表明,该菌株能在pH值为7~9,温度30~50℃条件下生长,是一株较为罕见的耐高温菌株。静态批实验表明,C(rⅥ)对该菌的生长有抑制作用,且抑制作用随着C(rⅥ)浓度的升高而增强;该菌株在48、72、168 h内,可将C(rⅥ)浓度为25、50、100 mg/L的溶液中99%以上的C(rⅥ)还原;还原过程呈现延滞期、对数期和稳定期3个阶段;在稳定期,培养基pH值上升速率随C(rⅥ)浓度的增大而降低,可能是由于细胞浓度不同、还原产物C(rⅢ)的水解作用导致。
For the purpose of bio-remediation of contaminated soil by Cr(Ⅵ),bench scale experiments were conducted involving the Cr(Ⅵ)reducing strain isolation and characterization using the sequence analysis of 16S rDNA which showed the strain belonged to Bacillus. The study on its growth condition suggested the strain’s adaption to the rather high temperature range 30~50 ℃. Results of static state experiment in the aqueous solution showed the Cr(Ⅵ) reducing strain was able to reduce C(rⅥ)by 99%,and the reduction process undergone could fall into three phases such as lag phase,logarithmic phase and the stationary phase. Besides,during the stationary phase pH value of the medium dropped when Cr(Ⅵ) concentration increased,which may be caused by the difference of bacterial cells concentrations as well as the hydrolytic action of the reduction products.