菌株Enterobacter sp. L6异化Fe(Ⅲ)还原及Cr(Ⅵ)还原的性质分析

Characterization of dissimilatory iron reduction and Cr(Ⅵ) reduction by Enterobacter sp. L6

Cr(Ⅵ)是一种毒性极强的重金属,利用微生物还原Cr(Ⅵ)为Cr(Ⅲ)是解决Cr(Ⅵ)污染的一条有效途径。菌株Enterobacter sp. L6是一株分离自海洋沉积物中的异化铁还原细菌。接种时细胞密度A600为(0.25±0.03),培养12 h,A600达到(1.04±0.05),累积产生Fe(Ⅱ)浓度为(0.80±0.03)mmol/L;随着培养时间的延长,细胞密度A600和累积产生Fe(Ⅱ)浓度开始下降;培养36 h时,细胞密度A600为(0.81±0.04),累积Fe(Ⅱ)浓度(0.63±0.01)mmol/L。在厌氧培养过程中,菌株L6细胞生长与异化还原Fe(Ⅲ)性质存在明显的偶联关系。利用菌株L6的异化铁还原性质还原Cr(Ⅵ)的实验结果表明,在Cr(Ⅵ)浓度0~24 mg/L范围内,异化铁还原细菌L6都能进行细胞生长并还原Cr(Ⅵ)。Cr(Ⅵ)浓度为4、8和12 mg/L时,菌株L6对Cr(Ⅵ)还原率可达到100%,当Cr(Ⅵ)浓度为16 mg/L时,Cr(Ⅵ)还原率是参比[未添加Fe(Ⅲ)]的2.11倍。Cr(Ⅵ)浓度为20、24 mg/L时,仍能够还原Cr(Ⅵ)。以Fe(Ⅲ)为电子受体的异化铁还原细菌能明显提高Cr(Ⅵ)还原率,这为利用微生物修复Cr(Ⅵ)污染提供实验数据支持。

Cr(Ⅵ) is a highly toxic heavy metal. Reducing Cr(Ⅵ) to Cr(Ⅲ) by microorganism is an effective way to solve Cr(Ⅵ) pollution. Enterobacter sp. L6 was a dissimilatory iron-reducing bacterium isolated from marine sediments, A600 is(0.25±0.03) when inoculated, after fermentation for 12 h, the cell density A600 reached(1.04±0.05), the Fe(Ⅱ) concentration of culture was(0.80±0.03) mmol/L. As the processing of fermentation,A600 and the cumulative Fe(Ⅱ) concentration began to decrease. After 36 hours, the cell density A600 was(0.81±0.04) and Fe(Ⅱ) concentration was(0.63±0.01) mmol/L respectively. In the process of anaerobic fermentation, there was a significant coupling relationship between cell growth and dissimilatory reduction of Fe(Ⅲ). The results of Cr(Ⅵ) reduction by the dissimilatory iron-reducing bacterium L6 showed that strain L6 could grow and reduce Cr(Ⅵ) within the Cr(Ⅵ) concentration of 0~24 mg/L. When Cr(Ⅵ) concentration was4, 8 and 12 mg/L, the reduction rate of Cr(Ⅵ) could reach 100%. When Cr(Ⅵ) concentration was 16 mg/L, the Cr(Ⅵ) reduction rate was 2.11 times that of control [no Fe(Ⅲ) added]. When Cr(Ⅵ) concentration was20 mg/L or 24 mg/L, Cr(Ⅵ) could still be reduced. The results showed that the iron-reducing bacteria using Fe(Ⅲ) as electron acceptor could significantly improve the reduction rate of Cr(Ⅵ), which provides experimental data support for microbial remediation of Cr(Ⅵ) pollution.