School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, P. R. China.
Environ Sci Technol. 2021 Feb 2;55(3):2121-2131. doi: 10.1021/acs.est.0c07442. Epub 2021 Jan 25.
Whereas prospects of bioremediation for a vanadium(V) [V(V)]-contaminated environment are widely recognized, reported functional species are extremely limited, with the vast majority of Gram-negative bacteria in Proteobacteria. Herein, the effectiveness of V(V) reduction is proved for the first time by , a Gram-positive bacterium in Firmicutes. The V(V) removal efficiency was 86.5 ± 2.17% during 10-d operation, with an average removal rate of 4.32 ± 0.28 mg/L·d in a citrate-fed system correspondingly. V(V) was bio-reduced to insoluble vanadium(IV) and distributed both inside and outside the cells. Nitrite reductase encoded by gene mainly catalyzed intracellular V(V) reduction, revealing a previously unrecognized pathway. Oxidative stress induced by reactive oxygen species from dissimilatory V(V) reduction was alleviated through strengthened superoxide dismutase and catalase activities. Extracellular polymeric substances with chemically reactive hydroxyl (-OH) and carboxyl (-COO) groups also contributed to V(V) binding and reduction as well as ROS scavenging. This study can improve the understanding of Gram-positive bacteria for V(V) bio-detoxification and offer microbial resources for bioremediation of a V(V)-polluted environment.
尽管生物修复 V(V)[五价钒(V)]污染环境的前景已得到广泛认可，但目前报道的功能物种极为有限，绝大多数为变形菌门中的革兰氏阴性菌。本文首次证明了厚壁菌门中的革兰氏阳性菌 能够还原 V(V)。在 10 天的实验中，V(V)去除效率达到 86.5±2.17%，相应的在柠檬酸盐喂养系统中 V(V)的平均去除速率为 4.32±0.28mg/L·d。V(V)被生物还原为不溶性的四价钒，分布在细胞内外。主要由基因 编码的亚硝酸盐还原酶催化细胞内 V(V)还原，揭示了一条以前未被识别的途径。通过增强超氧化物歧化酶和过氧化氢酶的活性，缓解了由异化 V(V)还原产生的活性氧引起的氧化应激。具有反应性羟基(-OH)和羧基(-COO)基团的细胞外聚合物物质也有助于 V(V)的结合和还原以及 ROS 的清除。本研究可以增进对革兰氏阳性菌进行 V(V)生物解毒的理解，并为 V(V)污染环境的生物修复提供微生物资源。
