US Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA.
Water Res. 2010 Mar;44(5):1353-60. doi: 10.1016/j.watres.2009.11.008. Epub 2009 Nov 14.
Intracellular RNA is rapidly degraded in stressed cells and is more unstable outside of the cell than DNA. As a result, RNA-based methods have been suggested to study the active microbial fraction in environmental matrices. The aim of this study was to identify bacterial populations in drinking water by analyzing 16S rRNA-based clone libraries. Hollow-fiber ultrafiltration was used to concentrate bacterial communities from 40l of tap water collected at 12 different times during three different summer months from a single point-of-use. Total RNA was extracted from the microbial concentrates and used to develop 16S rRNA-based clone libraries. Phylogenetic analyses of 1231 partial 16S rRNA gene sequences showed that difficult-to-classify bacterial sequences were the most predominant clones, representing 57.6% of the sequences analyzed. Within these unclassified clades, most sequences were closely related to sequences retrieved from previous DNA- and RNA-based drinking water studies. Other bacterial groups represented in this study included Proteobacteria, cyanobacteria, Actinobacteria, Bacteroidetes, and Planctomycetes. Overall, the results suggest that these bacterial groups are amongst potentially active bacteria in drinking water. Diversity analyses of clones generated show that while overall diversity is similar amongst the different months, membership changes with respect to time. The results from this study further improve our understanding of the molecular diversity and bacterial population dynamics of drinking water microbial communities. Moreover, these results provide the sequence foundation for the development of molecular assays that target active drinking water bacteria.
细胞内的 RNA 在应激细胞中迅速降解，并且在细胞外比 DNA 更不稳定。因此，人们提出了基于 RNA 的方法来研究环境基质中活跃的微生物部分。本研究的目的是通过分析基于 16S rRNA 的克隆文库来鉴定饮用水中的细菌种群。中空纤维超滤用于浓缩来自单个用水点在三个不同夏季的 12 个不同时间收集的 40L 自来水的细菌群落。从微生物浓缩物中提取总 RNA，并用于开发基于 16S rRNA 的克隆文库。对 1231 个部分 16S rRNA 基因序列的系统发育分析表明，难以分类的细菌序列是最主要的克隆，占分析序列的 57.6%。在这些未分类的分支中，大多数序列与先前基于 DNA 和 RNA 的饮用水研究中检索到的序列密切相关。本研究中还代表了其他细菌群，包括变形菌门、蓝细菌、放线菌门、拟杆菌门和浮霉菌门。总体而言，结果表明这些细菌群是饮用水中潜在活跃的细菌。克隆生成的多样性分析表明，尽管不同月份的总体多样性相似，但成员随时间而变化。本研究的结果进一步提高了我们对饮用水微生物群落的分子多样性和细菌种群动态的理解。此外，这些结果为开发针对活跃饮用水细菌的分子检测方法提供了序列基础。
