Kaushik Rajni, Balasubramanian Rajasekhar, Dunstan Hugh
Singapore-Delft Water Alliance, National University of Singapore, Singapore, Singapore; Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore.
School of Environmental and Life Sciences, The University of Newcastle, Callahan, NSW, Australia.
PLoS One. 2014 Jun 30;9(6):e100737. doi: 10.1371/journal.pone.0100737. eCollection 2014.
The impact of rainwater on the microbial quality of a tropical freshwater reservoir through atmospheric wet deposition of microorganisms was studied for the first time. Reservoir water samples were collected at four different sampling points and rainwater samples were collected in the immediate vicinity of the reservoir sites for a period of four months (January to April, 2012) during the Northeast monsoon period. Microbial quality of all fresh rainwater and reservoir water samples was assessed based on the counts for the microbial indicators: Escherichia coli (E. coli), total coliforms, and Enterococci along with total heterotrophic plate counts (HPC). The taxonomic richness and phylogenetic relationship of the freshwater reservoir with those of the fresh rainwater were also assessed using 16 S rRNA gene clone library construction. The levels of E. coli were found to be in the range of 0 CFU/100 mL-75 CFU/100 mL for the rainwater, and were 10-94 CFU/100 mL for the reservoir water. The sampling sites that were influenced by highway traffic emissions showed the maximum counts for all the bacterial indicators assessed. There was no significant increase in the bacterial abundances observed in the reservoir water immediately following rainfall. However, the composite fresh rainwater and reservoir water samples exhibited broad phylogenetic diversity, including sequences representing Betaproteobacteria, Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Lentisphaerae and Bacteriodetes. Members of the Betaproteobacteria group were the most dominant in both fresh rainwater and reservoir water, followed by Alphaproteobacteria, Sphingobacteria, Actinobacteria and Gammaproteobacteria.
首次研究了雨水通过大气中微生物的湿沉降对热带淡水水库微生物质量的影响。在东北季风期（2012年1月至4月）的四个月内，在四个不同的采样点采集水库水样，并在水库站点附近采集雨水样本。基于微生物指标（大肠杆菌、总大肠菌群、肠球菌以及总异养平板计数）的计数，评估所有新鲜雨水和水库水样的微生物质量。还使用16S rRNA基因克隆文库构建评估淡水水库与新鲜雨水的分类丰富度和系统发育关系。发现雨水中大肠杆菌水平在0 CFU/100 mL至75 CFU/100 mL范围内，水库水中为10 - 94 CFU/100 mL。受公路交通排放影响的采样点，所有评估的细菌指标计数最高。降雨后立即观察到水库水中细菌丰度没有显著增加。然而，新鲜雨水和水库水的复合样本表现出广泛的系统发育多样性，包括代表β-变形菌纲、α-变形菌纲、γ-变形菌纲、放线菌纲、浮霉菌门和拟杆菌门的序列。β-变形菌纲组的成员在新鲜雨水和水库水中都是最主要的，其次是α-变形菌纲、鞘脂杆菌纲、放线菌纲和γ-变形菌纲。
