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

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。

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

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 was 4, 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 was 20 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.