Bioremediation is an active process for the detoxification of polluted ambient media employing the metabolism of microbes, while natural attenuation relies on physical, chemical and biological processes occurring without human intervention. A shallow aquifer (A0) was treated using a bioremediation approach through the amendment of whey to detoxify the most abundant contaminants: 1,1,2,2- tetrachloroethane (1,1,2,2-TeCA), perchloroethene (PCE) and trichloroethene (TCE). A deeper aquifer (A1), showing lower concentration of the contaminants, was left untreated. In A0, a concomitant decrease of more chlorinated molecules 1,1,2,2-TeCA, PCE and TCE and an increase of less halogenated molecules such as trichloroethane (1,1,2-TCA), cis-dichloroethene (cis-DCE) and vinyl chloride (VC) were observed, suggesting that a reductive dechlorination took place. In contrast, the aquifer A1 did not show a significant decrease of contaminants during this period. A metagenomic approach (shot gun and 16S rRNA gene) was then used to investigate the microbial population of the two aquifers. A massive presence of the dehalogenator Dehalococcoides mccartyi (D. mccartyi) and a spectrum of different Geobacter species were detected in A0, after the treatment. The metagenome assembly of shotgun (SG) data further indicated a significant presence of methanogenic archaea, most likely from class Methanomassiliicoccales, at a level comparable to that of D. mccartyi. Instead, A1 was characterized by the species Burkholderia, Curvibacter and Flavobacterium. These results indicate that the autochthonous microbial consortia reflected the geochemistry of the two aquifers, with a dominant population thriving in an anoxic and nutrient rich environment implicated in reductive dehalogenation in A0 and a more diverse population, not able to decompose the pollutants, in A1.

中文翻译：

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污染地下水的生物修复：通过下一代测序处理和未处理含水层的微生物群落比较

生物修复是利用微生物代谢对受污染的环境介质进行解毒的积极过程，而自然衰减依赖于在没有人为干预的情况下发生的物理、化学和生物过程。使用生物修复方法对浅层含水层 (A0) 进行处理，通过改良乳清来解毒最丰富的污染物：1,1,2,2-四氯乙烷 (1,1,2,2-TeCA)、全氯乙烯 (PCE) 和三氯乙烯（TCE）。较深的含水层 (A1) 显示出较低的污染物浓度，未进行处理。在 A0 中，同时减少更多的氯化分子 1,1,2,2-TeCA、PCE 和 TCE，而减少卤化分子如三氯乙烷 (1,1,2-TCA)、顺式二氯乙烯 (cis-DCE) ) 和氯乙烯 (VC)，表明发生了还原脱氯。相比之下，含水层 A1 在此期间没有显示出污染物的显着减少。然后使用宏基因组方法（霰弹枪和 16S rRNA 基因）来研究两个含水层的微生物种群。大量存在脱卤剂处理后，在 A0 中检测到Dehalococcoides mccartyi ( D. mccartyi ) 和一系列不同的Geobacter物种。霰弹枪（SG）数据的宏基因组组装进一步表明产甲烷古菌的显着存在，很可能来自Methanomassiliicoccales类，其水平与D. mccartyi 相当。相反，A1 的特征是伯克霍尔德菌属、弯曲杆菌属和黄杆菌属. 这些结果表明，本土微生物群落反映了两个含水层的地球化学，主要种群在缺氧和营养丰富的环境中繁衍生息，与 A0 中的还原脱卤有关，而在 A1 中，更多样化的种群不能分解污染物。