Department of Biotechnology Engineering, Faculty of Engineering Science, Ben-Gurion University of Negev, Beer-Sheva, Israel.
ISME J. 2010 Mar;4(3):327-36. doi: 10.1038/ismej.2009.118. Epub 2009 Nov 19.
Changes in the microbial community composition of a full-scale membrane bioreactor treating industrial wastewater were studied over a period of 462 days using a series of 16S rRNA gene clone libraries. Frequent changes in the relative abundance of specific taxonomic groups were observed, which could not be explained by changes in the reactor's conditions or wastewater composition. Phage activity was proposed to drive some of the observed changes. Bacterial hosts were isolated from a biomass sample obtained towards the end of the study period, and specific phage counts were carried out for some of the isolated hosts using stored frozen biomass samples as the phage inocula. Plaque-forming unit concentrations were shown to change frequently over the study period, in correlation with changes in the relative abundance of taxonomic groups closely related by 16S rRNA gene sequence to the isolated strains. Quantitative PCR was used to verify changes in the abundance of a taxonomic group closely related to one of the isolated hosts, showing good agreement with the changes in relative abundance in the clone libraries of that group. The emerging pattern was consistent with the 'killing the winner' hypothesis, although alternative interaction mechanisms could not be ruled out. This is the first time that phage-host interactions in a complex microbial community are demonstrated over an extended period, and possibly the first in situ demonstration of 'killing the winner' stochastic behavior.
采用一系列 16S rRNA 基因克隆文库，研究了处理工业废水的全规模膜生物反应器中微生物群落组成的变化。在 462 天的时间内，观察到特定分类群相对丰度的频繁变化，这些变化无法用反应器条件或废水成分的变化来解释。提出噬菌体活性驱动了一些观察到的变化。从研究末期获得的生物量样本中分离出细菌宿主，并使用储存的冷冻生物量样本作为噬菌体接种物，对一些分离出的宿主进行特定噬菌体计数。在研究期间，噬菌斑形成单位浓度频繁变化，与通过 16S rRNA 基因序列与分离菌株密切相关的分类群的相对丰度变化相关。使用定量 PCR 验证了与一个分离宿主密切相关的分类群的丰度变化，与该组克隆文库中的相对丰度变化吻合良好。这种新兴模式与“杀死赢家”假说一致，尽管不能排除替代的相互作用机制。这是首次在较长时间内证明复杂微生物群落中的噬菌体-宿主相互作用，也可能是首次在原位证明“杀死赢家”的随机行为。
