菌藻混合体系去除Cr(Ⅵ)的条件优化及Cr(Ⅵ)还原酶活性的测定

Optimization of Chromium(Ⅵ)Removal by Mixture of Bacteriamicroalgae and Determination of Chromium(Ⅵ)Reductase Activities

为了高效去除废水中的 Cr(Ⅵ),从天津某印染场印染废水中筛选出两株高效除 Cr(Ⅵ)细菌,探究了菌藻混合体系去除 Cr(Ⅵ)的效果及优化条件,并测定了 Cr(Ⅵ)还原酶活性。基于 16S rRNA 序列比对进行菌种鉴定。通过 Placket-Burman、最陡爬坡试验、Box-Behnken 实验设计及响应面法分析各因素交互作用。此外,对两株细菌 Cr(Ⅵ)还原酶进行了活性测定。两株细菌属于沙雷氏菌属(Serratia)和代尔夫特菌属(Delftia)。最终确定菌藻混合体系去除 Cr(Ⅵ)的最优条件为:温度29.74℃,Cu2+27.65 mg/L,葡萄糖含量 2.41%(W/V),丙酮酸钠 2%(W/V),接菌量 7%,pH7.0,NaCl 浓度为 0,优化后菌藻混合体系 24 h 对 Cr(Ⅵ)去除率达到 97.89%。细菌 S-3 和 D-7 的 Cr(Ⅵ)还原酶的最适温度为 30℃,菌株 S-3 的 Cr(Ⅵ)还原酶的最适 pH 值为 6.0,酶促反应动力学常数 Km=86.94 μmol/L,Vmax=2.71 μmol/(L min)。菌株 D-7 中 Cr(Ⅵ)还原酶最适 pH 值为 7.0,酶促反应动力学常数 Km=103.18 μmol/L,Vmax=3.38 μmol/(L min)。菌藻混合体系通过响应面法优化后不但能提高 Cr(Ⅵ)的去除率,也能缩短处理时间,在含铬废水处理方面具有良好的应用前景。

In order to efficiently remove Cr(VI)from industry wastewater,two strains of bacteria that remarkably reduced Cr(VI) were isolated from the wastewater in a dyeing factory of Tianjin. The effect of removing Cr(VI)by the mixture of bacteria-microalgae system and the optimized conditions were studied,as well as the activity of Cr(VI)reductase was determined. 16S rRNA gene sequence alignment was used to identify the bacterial isolates,and Placket-Burman,the Steepest Ascent,Box-Behnken experimental design and response surface methodology were conducted to analyze the interactions among each factor. In addition,the Cr(VI)reductase activities of two bacteria were determined. The result showed that two strains of Cr(VI)reducing bacteria belonged to the genus Serratia and the genus Delftia. The optimal conditions for removing Cr(VI)by the mixture of bacteria-microalgae were as follows :the temperature was 29.74℃,the Cu 2+ concentration was 27.65 mg/L,the glucose content was 2.41%(W/V),the sodium pyruvate content was 2%(W/V),the inoculum was 7%,and the pH was 7.0,and no NaCl,respectively. Under the optimized conditions,the removal rate of Cr(VI)by the mixture of bacteria-microalgae reached 97.89% in 24 h. The optimal temperature of the Cr(VI)reductase for two strains S-3 and D-7 was 30℃. The optimal pH of the Cr(VI) reductase for the strain S-3 was 6.0,and the kinetic constant of the enzymatic reaction was Km=86.94 μmol/L,Vmax=2.71 μmol/(L min). The optimal pH of the Cr(VI)reductase for the strain D-7 was 7.0,and the kinetic constant of the enzymatic reaction was Km=103.18 μmol/L,Vmax=3.38 μmol/(L·min). In conclusion,the optimized mixture of bacteria-microalgae may not only increase the removal rate of Cr(VI), but also shorten the treatment time,and it has a promising application prospect in the treatment of chromium-containing wastewater.