水库与河流沉积物中好氧甲烷氧化菌群落差异性研究

甲烷在自然生态系统碳循环过程中起着重要作用，氮素形态的差异影响了甲烷氧化菌的氧化作用.选取北京市密云水库和北运河两类不同污染类型的水体作为研究区域，采用克隆文库分子生物学的方法，探究氮素形态及其来源的差异对MOB细菌群落特征的影响.结果表明：密云水库与北运河沉积物中氮素形态有显著差异，水库中氮素以NO₃^--N为主，河流中氮素以NH₄⁺-N为主；氮素形态的差异影响了MOB细菌的系统发育，密云水库沉积物中MOB细菌的高同源性菌群主要来自湖泊生态系统，与NO₃^--N有较强的响应关系，北运河沉积物中MOB细菌高同源性菌群主要来自污水处理厂废水和活性淤泥，与NH₄⁺-N有较强的响应关系，不同环境中氮素对MOB细菌的影响主要依赖于氮素的主要存在形态及其主要来源.北运河等重污染河流中MOB细菌群落的联系更紧密更趋于模块化，对环境变化的敏感程度更高，微生物更脆弱，更容易受到水质变化以及人类活动的干扰.北运河沉积物中NH₄⁺-N对MOB细菌氧化速率的抑制性强于密云水库沉积物中NO₃^--N对甲烷氧化的抑制作用.重污染的城市河流中高浓度的NH₄⁺-N通过抑制甲烷氧化速率和促进产甲烷产生速率的双重作用影响了河流沉积物中甲烷的产生.

Microbial communities differences between aerobic methanotrophs in Miyun Reservoir and North Canal

The aerobic methanotrophs play an important role in mitigating methane emissions and promoting the carbon-nitrogen cycle in the freshwater ecosystems. In this study, the influences of different water pollutant on aerobic methanotrophs were analyzed between the Miyun Reservoir and the North Canal at the Beijing Metropolitan. The results showed that differences of physiochemical between Miyun Reservoir and the North Canal were significantly, especially the main form of nitrogen. The main form of nitrogen in Miyun Reservoir was NO₃^--N, while NH₄⁺-N dominated in the North Canal. The physicochemical differences caused significantly influences on the MOB bacterial phylogenetic. Phylogenetic analyses revealed that the upstream freshwater highly contribute to the MOB sequences in Miyun Reservoir, and MOB has closely relationship with NO₃^--N. However, MOB sequences were mainly from activated sludge and wastewater in the North Canal, and MOB closely related with NH₄⁺-N. The different form of nitrogen in these two ecosystems showed significant influences not only on the MOB serious, but also the sources of MOB. Furthermore, the MOB OTUs showed higher modular microbial network in the North Canal than the Miyun Reservoir. The tightly connected species of MOB communities indicated that bacterial community composition was more vulnerable and sensitive to the various disturbances in the North Canal. The different forms of nitrogen influenced the MOB oxidation and MOB inhibitant activity in different extent, the influence of NH₄⁺-N on MOB was stronger than the influence of NO₃^--N on the Miyun Reservoir. The high concentration of NH₄⁺-N in the city river that would not only inhibitant the MOB bacteria oxidation but also promote the CH₄ release.