Fan H, Su C, Wang Y, Yao J, Zhao K, Wang Y, Wang G
State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.
J Appl Microbiol. 2008 Aug;105(2):529-39. doi: 10.1111/j.1365-2672.2008.03790.x. Epub 2008 Apr 7.
Shanyin County is one of the most severe endemic arsenism affected areas in China but micro-organisms that potentially release arsenic from sediments to groundwater have not been studied. Our aim was to identify bacteria with the potential to metabolize or transform arsenic in the sediments.
Culture and nonculture-based molecular methods were performed to identify arsenite-oxidizing bacteria, arsenate-reducing bacteria and arsenite oxidase genes. Arsenite-oxidizing bacteria were identified only from the land surface to 7 m underground that were affiliated to alpha- and beta-Proteobacteria. Arsenate-reducing bacteria were found in almost all the sediment samples with different depths (0-41 m) and mainly belong to gamma-Proteobacteria. Several novel arsenite oxidase genes (aoxBs) were identified from the upper layers of the sediments (0-7 m) and were found to be specific for arsenite-oxidizing bacteria.
The distribution of arsenite-oxidizing bacteria in upper layers and arsenate-reducing bacteria in different depths of the sediments may impact the arsenic release into the nearby tubewell groundwater.
This study provides valuable sources of micro-organisms (and genes) that may contribute to groundwater arsenic abnormality and may be useful to clean arsenic contaminated groundwater.
山阴县是中国地方性砷中毒最严重的地区之一，但尚未对可能将沉积物中的砷释放到地下水中的微生物进行研究。我们的目的是鉴定沉积物中具有代谢或转化砷潜力的细菌。
采用基于培养和非培养的分子方法鉴定亚砷酸盐氧化细菌、砷酸盐还原细菌和亚砷酸盐氧化酶基因。仅在地表至地下7米处鉴定出亚砷酸盐氧化细菌，它们隶属于α-和β-变形菌纲。在几乎所有不同深度（0 - 41米）的沉积物样本中都发现了砷酸盐还原细菌，且主要属于γ-变形菌纲。从沉积物上层（0 - 7米）鉴定出了几个新的亚砷酸盐氧化酶基因（aoxBs），并且发现它们对亚砷酸盐氧化细菌具有特异性。
沉积物上层中亚砷酸盐氧化细菌和不同深度处砷酸盐还原细菌的分布可能会影响砷向附近管井地下水中的释放。
本研究提供了可能导致地下水砷异常的微生物（和基因）的宝贵来源，可能有助于净化受砷污染的地下水。
