Cr(Ⅵ)抗性菌株的筛选及其Cr(Ⅵ)去除特性研究

Isolation and characterization of bacteria with chromium(Ⅵ) removal capacity from chromium-contaminated tannery sludge

采用微生物分离纯化方法,从制革厂含铬污泥中筛选分离Cr(Ⅵ)抗性菌株,并研究菌株对Cr(Ⅵ)的去除能力。共分离得到对50mg/LCr(Ⅵ)去除率大于50%的菌株20株,16S rRNA基因测序结果表明这些细菌主要属于Acinetobacter、Microbacterium、Leucobacter、Ochrobactrum和Brachymonas属。对其中7株细菌,考察了菌株生长期、pH值和Cr(Ⅵ)浓度对菌株去除Cr(Ⅵ)效果的影响,结果表明,细胞在有较高代谢活性的条件下具较高的Cr(Ⅵ)去除能力;pH值对菌株去除Cr(Ⅵ)的能力具有显著影响,在50mg/LCr(Ⅵ)、pH值为7～8的条件下,Microbacterium属16号和21号菌株在36h时对Cr(Ⅵ)的去除率达80%～95%;高浓度的Cr(Ⅵ)抑制菌株对Cr(Ⅵ)的去除能力,其中21号菌株在110mg/L的Cr(Ⅵ)浓度下去除效果最佳,Cr(Ⅵ)去除率达80%。

Bacteria strains with Cr （Ⅵ） tolerant capacity were isolated from chromium-contaminated tannery sludge and the Cr （Ⅵ） removal characteristics of these isolates were studied. Twenty strains with the Cr （Ⅵ） removal efficiency greater than 50% under the condition of 50 mg/L Cr （Ⅵ） were obtained. These strains were closely related to species in the genera Acinetobacter,Microbacterium,Leucobacter,Ochrobactrum and Brachymonas by their 16S rRNA gene sequences. The effects of growth phase,pH and Cr （Ⅵ） concentration on the Cr （Ⅵ） reducing capacity for seven isolates were investigated. Cells with high activity showed higher Cr （Ⅵ） removal efficiency. pH affected the Cr （Ⅵ） removal capacity of these strains remarkably. The Cr （Ⅵ） removal efficiencies of strain No. 16 and No. 21,closely related to the species in the genus Microbacterium,were over 80% at the pH of 7～8 under the condition of 50 mg/L of Cr （Ⅵ）. High concentration of Cr （Ⅵ） repressed the Cr （Ⅵ） removal capacity. However,strain No.21 showed a removal efficiency of about 80% when the initial Cr （Ⅵ） concentration was 110 mg/L.