Anaerobic methane-oxidizing bacterial communities in sediments of a drinking reservoir, Beijing, China

Abstract

Purpose: Nitrate/nitrite-dependent anaerobic methane oxidation (N-DAMO) connects the global cycle of carbon and nitrogen in aquatic ecosystems. The aims of this study were to investigate the spatiotemporal variation of N-DAMO bacteria and its driving factors in a drinking reservoir which are strongly affected by human consumption. Methods: Cloning analyses were used to study the pmoA and 16S rRNA genes of N-DAMO bacteria. Sequencing and phylogenetic analyses were used to investigate the bacterial composition and structure. Redundancy analyses (RDA) and spearman’s correlations analyses were applied to analyze the relationships between bacterial distribution and environmental factors. Result: There were remarkable spatial variations of N-DAMO bacteria in winter. Shannon biodiversity of 16S rRNA genes was higher in winter than that in summer. Compared with other freshwater ecosystems, there was higher diversity of N-DAMO bacteria in Miyun Reservoir. The N-DAMO bacterial communities (16S rRNA and pmoA genes) in sampling sites near to dam were different from the bacterial communities in other sampling sites. The N-DAMO bacterial community structure in dam areas may be associated with the water column depth in front of the dam. Moreover, Spearman’s correlations revealed that DO, NO3− -N, NO2−-N, and NH4+-N in interstitial water and sediment were potential determinant factors influencing the diversity of N-DAMO bacteria (16S rRNA and pmoA genes). Conclusion: There were distinct seasonal variations in 16S rRNA and spatial variations in pmoA genes. N-DAMO bacterial communities contained novel Methylomirabilis oxyfera-like pmoA genes in Miyun Reservoir. Nitrogen (NO2−-N, NO3−-N, and NH4+-N) were the dominant factor influencing the N-DAMO bacterial community structure in the drinking reservoir. N-DAMO bacterial community structure in dam areas indicates that water depth and DO might be the dominant factor influencing the N-DAMO bacterial communities in the reservoir.