bacteria communities degrading PCE. soil metagenome

Precise characterisation of a contaminated site is essential to apply isotope enrichment factors for monitored natural attenuation to expect the grade of biodegradation. The aim of this study was to fortify site characterisation by compound specific isotope analysis of an anaerobic microcosm study to obtain isotope enrichment factors with 16S-rDNA analysis, degradation kinetic analysis and the influence of adsorption on the degradation process. The microcosm study comprised of eleven sediment samples taken from a geologically homogeneously looking site. Results showed two groups of isotope enrichment factors for PCE (-1.2‰, -6.4‰) and cis-DCE (-15.4‰, -28.2‰) besides one factor for TCE (-6.0‰) and VC (-27.8‰). Questioning the two groups suggested different microbial consortia consisting at least of Dehalogenimonas sp., Sedimentbacter sp., Desulfuromonas sp., Geobacter sp. and Pseudomonas sp., which were, as reported in literature, responsible for the partly complete degradation of PCE and its metabolites. In addition an increasing soil-water partitioning coefficient showed indication for enhancing the degradation of PCE.

精准表征污染场地，是利用同位素富集因子（isotope enrichment factors）开展监测自然衰减（monitored natural attenuation）研究以预判生物降解程度的必要前提。本研究旨在通过对厌氧微宇宙实验（anaerobic microcosm study）进行化合物特异性同位素分析，结合16S核糖体DNA（16S rDNA）分析、降解动力学分析以及吸附作用对降解过程的影响研究，完善场地表征工作。本次微宇宙实验共采集了11份采自地质特征均一场地的沉积物样品。研究结果表明，四氯乙烯（PCE）与顺式二氯乙烯（cis-DCE）各对应两组同位素富集因子，数值分别为-1.2‰、-6.4‰与-15.4‰、-28.2‰；而三氯乙烯（TCE）与氯乙烯（VC）则各对应单一富集因子，数值分别为-6.0‰与-27.8‰。针对这两组富集因子的溯源分析表明，其背后存在至少包含脱卤单胞菌属（Dehalogenimonas sp.）、沉积物杆菌属（Sedimentbacter sp.）、脱硫单胞菌属（Desulfuromonas sp.）、地杆菌属（Geobacter sp.）与假单胞菌属（Pseudomonas sp.）的不同微生物群落——正如文献报道所述，这些菌群负责四氯乙烯及其代谢产物的部分乃至完全降解。此外，土壤-水分配系数的升高提示其可促进四氯乙烯的降解过程。