Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands.
Appl Environ Microbiol. 2011 Jul;77(13):4437-45. doi: 10.1128/AEM.01940-10. Epub 2011 May 13.
The diffuse pollution by chlorinated organic compounds in river basins is a concern, due to their potential adverse effects on human health and the environment. Organohalides, like hexachlorobenzene (HCB), are recalcitrant to aerobic microbial degradation, and "Dehalococcoides" spp. are the only known microorganisms capable of anaerobic transformation of these compounds coupled to their growth. In this study, sediments from four European rivers were studied in order to determine their HCB dechlorination capacities and the role of Dehalococcoides spp. in this process. Only a weak correlation was observed between Dehalococcoides species abundance and HCB transformation rates from different locations. In one of these locations, in the Ebro River sediment, HCB dechlorination could be linked to Dehalococcoides species growth and activity by 16S rRNA-based molecular methods. Furthermore, HCB dechlorination activity in this sediment was found over the full range of ambient temperatures that this sediment can be exposed to during different seasons throughout the year. The sediment contained several reductive dehalogenase (rdh) genes, and analysis of their transcription revealed the dominance of cbrA, previously shown to encode a trichlorobenzene reductive dehalogenase. This study investigated the role of Dehalococcoides spp. in HCB dechlorination in river sediments and evaluated if the current knowledge of rdh genes could be used to assess HCB bioremediation potential.
流域中氯化有机化合物的扩散污染令人担忧，因为它们可能对人类健康和环境造成不利影响。卤代有机物，如六氯苯（HCB），难以被好氧微生物降解，而“脱卤球菌”属是唯一已知能够在厌氧条件下将这些化合物转化并与之生长偶联的微生物。本研究对来自欧洲四条河流的沉积物进行了研究，以确定它们的 HCB 脱氯能力以及脱卤球菌属在这一过程中的作用。不同地点的脱卤球菌属丰度与 HCB 转化速率之间仅观察到微弱的相关性。在其中一个地点，即埃布罗河沉积物中，16S rRNA 分子方法将 HCB 脱氯与脱卤球菌属的生长和活性联系起来。此外，在该沉积物中，HCB 脱氯活性在全年不同季节该沉积物可能暴露的环境温度范围内均可检测到。该沉积物中含有几种还原脱卤酶（rdh）基因，对其转录的分析表明 cbrA 的优势，cbrA 先前被证明编码三氯苯还原脱卤酶。本研究调查了脱卤球菌属在河流沉积物中 HCB 脱氯中的作用，并评估了当前关于 rdh 基因的知识是否可用于评估 HCB 生物修复潜力。
