Abstract
PurposeNitrate/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.MethodsCloning 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.ResultThere 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).ConclusionThere 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.
Highlights
Methane (CH4) is the second most important greenhouse gas, which plays a key role in the carbon cycle (Shen et al 2014a)
nitrite-dependent anaerobic methane oxidation (N-DAMO) bacterial community structure A total of 697 16S rRNA sequences were obtained from Miyun Reservoir
The pmoA genes in Miyun Reservoir were different from Candidatus M. oxyfera bacteria which are observed in other ecosystems
Summary
Methane (CH4) is the second most important greenhouse gas, which plays a key role in the carbon cycle (Shen et al 2014a). Previous studies revealed that approximately 76 ~ 90% of the CH4 consumption relied on microbial oxidation by aerobic or anaerobic methanotrophic bacteria and archaea (Yan et al 2015, Wang et al 2016). CH4 oxidation is the key process that can mitigate the methane emission production in anoxic sediment layers (Liu et al 2015). M. oxyfera bacteria is an intra-aerobic methanotroph that performs methane oxidizing through the “intra-aerobic” pathway which is a dismutation process with nitric oxide changes into dinitrogen gas and oxygen, and the oxygen can be used by the bacteria to oxidize methane with catalysis by the methane monooxygenase enzyme complex (Ettwig et al 2010, Zhu et al 2012, Ho et al 2013, Liu et al 2015). With the worldwide increasing in nitrogen pollution, N-DAMO has the potential to mitigate the release of methane in freshwater ecosystems
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