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Title: Bacterial community composition and structure in an urban river impacted by different pollutant sources

Author
item Ibekwe, Abasiofiok - Mark
item MA, JINCAI - Jilin Agricultural University
item MURINDA, SHELTON - California Polytechnic State University

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2011
Publication Date: 6/3/2016
Citation: Ibekwe, A.M., Ma, J., Murinda, S.E. 2016. Bacterial community composition and structure in an urban river impacted by different pollutant sources. Science of the Total Environment. 566-567:1176-1185. doi: 10.1016/jscitotenv.2016.05.168.

Interpretive Summary: The Santa Ana River (SAR) in southern Californian is impacted by one of the highest concentration of cattle in the United States. The watershed is undergoing drastic changes. In general, the varying land uses in the middle SAR (Chino Basin) watershed include agriculture, open space, and rapidly growing urban areas with many waste water treatment plants. In order to address changes in water quality within the middle Santa Ana River watershed, a comparative study of bacterial population in the surface waters and sediment was performed. These communities were also examined to understand how different environmental factors (pH, salinity, turbidity, dissolved oxygen, and temperature may influence the microbial population and their densities throughout the watershed. Our data showed that the use of deep sequencing technology provided the best opportunity to differentiate between bacterial populations from the different sources than the standard cloning method. This research will directly benefit water quality managers, water utility agencies, and the public.

Technical Abstract: Microbial communities in terrestrial fresh water are diverse and dynamic in composition due to different environmental factors. The goal of this study was to undertake a comprehensive analysis of bacterial composition along different rivers and creeks and correlate these to land-use practices and pollutant sources. Here we used 454 pyrosequencing to determine the total bacterial community composition, and bacterial communities that are potentially of fecal origin, and of relevance to water quality assessment. The results were analyzed using UniFrac coupled with principal coordinate analysis (PCoA) to compare diversity, abundance, and community composition. Detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to correlate bacterial composition in streams and creeks to different environmental parameters impacting bacterial communities in the sediment and surface water within the watershed. Bacteria were dominated by the phyla Proteobacteria, Bacteroidetes, Acidobacteria, and Actinobacteria, with Bacteroidetes significantly (P < 0.001) higher in all water samples than sediment, where as Acidobacteria and Actinobacteria where significantly higher (P < 0.05) in all the sediment samples than surface water. Overall results, using the ß diversity measures, coupled with PCoA and DCA showed that bacterial composition in sediment and surface water was significantly different (P < 0.001). Also, there were differences in bacterial community composition between agricultural runoff and urban runoff based on parsimony tests using 454 pyrosequencing data. Fecal indicator bacteria in surface water along different creeks and channels were significantly correlated with pH (P < 0.01), NO2 (P < 0.03), and NH4N (P < 0.005); and in the sediment with NO3 (P < 0.015). Our results suggest that microbial community compositions were influenced by several environmental factors, and pH, NO2, and NH4 were the major environmental factors driving FIB in surface water based on CCA analysis, while NO3 was the only factor in sediment.