Literature on microbiome of landfill leachate-contaminated aquifers is scarce despite groundwater contaminations from landfills being common globally. In this study, a combination of microbiological techniques was applied to groundwater samples from an aquifer contaminated by a municipal landfill and undergoing intrinsic bioremediation. Groundwater samples were obtained from three multilevel sampling wells placed along the groundwater flow path in the contaminated aquifer and additionally from a background well located in a nearby uncontaminated aquifer. The samples were subjected to chemical analysis, microbial culturing and characterisation, cell counting by fluorescence microscopy and 16S rRNA metabarcoding. Good concordance was realised with the results from the different microbiological techniques. Samples from the uncontaminated aquifer had both lower cell density and lower microbial diversity compared to samples from the contaminated aquifer. Among the wells located in the contaminated aquifer, microbial diversity increased between the well closest to the landfill and the intermediate well, but was lower at the most distant well. The majority of the cultured microbes represented taxa frequently recovered from contaminated environments, with 47% belonging to taxa with previously documented bioremediation potential. Multivariate redundancy analysis showed that microbial composition was most similar in wells located closer to the landfill, although beta diversity analysis indicated a significant difference in microbial composition across the wells. Taken together with the results of cell counting, culture and metabarcoding, these findings illustrate the effect of landfill leachate on the microbial community and indicate that it promoted the growth of a community dominated by culturable heterotrophic bacteria.

中文翻译：

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进行内在修复的垃圾填埋场承压含水层中细菌群落的特征

尽管全球范围内普遍存在垃圾填埋场对地下水的污染，但有关垃圾渗滤液被含水层微生物组的文献却很少。在这项研究中，微生物技术的组合应用于来自市政垃圾填埋场并进行了内在生物修复的含水层的地下水样品。地下水样品是从沿污染水层中地下水流动路径布置的三个多级采样井获得的，另外还从附近未污染水层中的背景井中获得。对样品进行化学分析，微生物培养和鉴定，通过荧光显微镜和16S rRNA元条形码的细胞计数。不同微生物技术的结果实现了良好的一致性。与来自受污染含水层的样品相比，来自未污染含水层的样品具有较低的细胞密度和较低的微生物多样性。在位于受污染的含水层中的各井中，最接近垃圾填埋场的井与中间井之间的微生物多样性增加，而最远处的井则较低。大多数培养的微生物代表经常从受污染的环境中回收的分类单元，其中47％属于具有先前记录的生物修复潜力的分类单元。多变量冗余度分析表明，靠近填埋场的井中微生物组成最相似，尽管β多样性分析表明各井之间的微生物组成存在显着差异。结合细胞计数，培养和元条形码的结果，