Potential Microbial Indicators for Better Bioremediation of an Aquifer Contaminated with Vinyl Chloride or 1,1-Dichloroethene
2020
Chen, Tzu-Wen | Chang, Shu-Chi
Trichloroethene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA) are notorious pollutants in groundwater. The biodegradation of them yields more toxic vinyl chloride (VC) and 1,1-dichloroethene (1,1-DCE). Although their biodegradation is highly feasible in the lab, field remediation still faces huge challenges. One challenge of them is the lack of good microbial indicators and consequently, monitoring famous species can cause the prediction of project time span and related expenses to fail. Here, in this study, we offer a solution by integrating predominance, correlation, and principal component analysis on the testing results of the biodegradation of VC and 1,1-DCE under seven different nutrient-amendment conditions. The inoculum was from a contaminated site with accumulated 1,1-DCE and VC. Next-generation sequencing (NGS) was applied to 15 microbial communities. Traditional analysis relying predominance on NGS data may be misleading due to the variation of copy number per cell for different microorganisms. By considering predominance, correlation between copy number and removal efficiency, and PCA loading factors of the principle component analysis, bacteria of the Ruminococcaceae family, Syntrophomonas sp., Pseudomonas stutzuri, Candidatus Methanoregula, and Methanospirillum sp. could be microbial indicators for removing 1,1-DCE and VC in biodegradation. The results suggested a variety of combinations of bacteria and archaeal species can effectively remove 1,1-DCE but less so for VC. The influence of archaeal species in the natural environment on bioremediation of chlorinated solvents cannot be neglected.
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