Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America.
Marshall University, Biological Sciences, Huntington, West Virginia, United States of America.
PLoS One. 2018 Mar 20;13(3):e0194663. doi: 10.1371/journal.pone.0194663. eCollection 2018.
Using in-field bioreactors, we investigated the influence of exogenous microorganisms in groundwater planktonic and biofilm microbial communities as part of the Integrated Field Research Challenge (IFRC). After an acclimation period with source groundwater, bioreactors received either filtered (0.22 μM filter) or unfiltered well groundwater in triplicate and communities were tracked routinely for 23 days after filtration was initiated. To address geochemical influences, the planktonic phase was assayed periodically for protein, organic acids, physico-/geochemical measurements and bacterial community (via 16S rRNA gene sequencing), while biofilms (i.e. microbial growth on sediment coupons) were targeted for bacterial community composition at the completion of the experiment (23 d). Based on Bray-Curtis distance, planktonic bacterial community composition varied temporally and between treatments (filtered, unfiltered bioreactors). Notably, filtration led to an increase in the dominant genus, Zoogloea relative abundance over time within the planktonic community, while remaining relatively constant when unfiltered. At day 23, biofilm communities were more taxonomically and phylogenetically diverse and substantially different from planktonic bacterial communities; however, the biofilm bacterial communities were similar regardless of filtration. These results suggest that although planktonic communities were sensitive to groundwater filtration, bacterial biofilm communities were stable and resistant to filtration. Bioreactors are useful tools in addressing questions pertaining to microbial community assembly and succession. These data provide a first step in understanding how an extrinsic factor, such as a groundwater inoculation and flux of microbial colonizers, impact how microbial communities assemble in environmental systems.
我们使用野外生物反应器,研究了外源微生物对地下水浮游生物和生物膜微生物群落的影响,这是综合野外研究挑战 (IFRC) 的一部分。在以源地下水适应一段时间后,生物反应器以三重复进行过滤(0.22 μM 过滤器)或未过滤的井水,在过滤开始后 23 天内定期跟踪群落。为了解决地球化学影响,浮游相定期进行蛋白质、有机酸、物理/地球化学测量和细菌群落(通过 16S rRNA 基因测序)分析,而生物膜(即沉积物上的微生物生长)则在实验结束时(23 天)针对细菌群落组成进行靶向分析。基于 Bray-Curtis 距离,浮游细菌群落组成随时间和处理方式(过滤、未过滤生物反应器)而变化。值得注意的是,过滤导致浮游生物群落中Zoogloea 属的相对丰度随时间增加,而在未过滤时相对稳定。在第 23 天,生物膜群落在分类学和系统发育上更加多样化,与浮游细菌群落有很大的不同;然而,无论是否过滤,生物膜细菌群落都相似。这些结果表明,尽管浮游生物群落对地下水过滤敏感,但细菌生物膜群落稳定且能抵抗过滤。生物反应器是解决与微生物群落组装和演替相关问题的有用工具。这些数据为了解外生因素(如地下水接种和微生物定植者通量)如何影响微生物群落在环境系统中的组装提供了第一步的认识。