人类活动对河流沉积物中反硝化厌氧甲烷氧化菌群落特征的影响

河流生态系统是陆地生态系统输出营养盐和有机质的主要接收器,是水-气界面CO2和CH4全球碳循环的重要环节.人类活动导致大量未经处理的硝酸盐和有机物质汇入河流,影响了N-DAMO(N-DAMO,Nitrate/nitrite-dependent anaerobic methane oxidation,反硝化厌氧甲烷氧化菌)细菌的群落特征.本文选取北运河作为研究区域,通过对比分析北运河中游和下游沉积物理化参数和N-DAMO细菌群落特征的差异性,探究由于人类活动的影响,河流沉积物中N-DAMO细菌的群落组成结构特征,及其与沉积物中NH+4-N、NO-3-N的响应关系.结果表明,北运河沉积物中NH+4-N为中游和下游氮素的主要形态,且下游NH+4-N浓度显著高于中游;人类活动对N-DAMO细菌16S rRNA和pmo A功能基因群落分布有影响,16S rRNA和pmo A功能基因均分别聚为中游和下游两类;系统发育树分析显示,人类活动影响北运河N-DAMO细菌高同源性菌群的来源,其高同源性菌群来源与北运河主要污染物氨氮的来源一致;RDA分析显示,人类活动影响N-DAMO细菌相关环境因子,沉积物中高浓度的NH+4-N、NO-3-N与16S rRNA和pmo A功能基因有显著的响应关系.沉积物N-DAMO细菌16S rRNA和pmo A功能基因的共生关系分析显示,北运河下游沉积物中N-DAMO细菌彼此之间的共存关系更强,细菌群落形成的模块化程度较高,其对环境变化的敏感程度更高,受人类活动的影响更大.

Influences of Anthropogenic Activities on the Community Structure of N-DAMO Bacteria in the North Canal

Stream ecosystems are the primary receivers of nutrients and organic carbon exported from terrestrial ecosystems and are profoundly influenced by the land of the surrounding landscape. Anthropogenic activities increased the nutrient and organic carbon levels in both stream and benthic biofilms, which are closely related to the differences in the N-DAMO (Nitrate/nitrite-dependent anaerobic methane oxidation) bacterial communities. We studied N-DAMO bacterial communities in streams flowing through anthropogenic land in the city of Beijing. The results showed that anthropogenic activities increase the nutrient and organic carbon levels both midstream and downstream; these are closely related to the difference in the N-DAMO bacterial communities. Phylogenetic analysis revealed that most of the cloned 16S rRNA and pmoA sequences in the North Canal were similar to those recovered from activated sludge and wastewater. The effect of nitrogen on N-DAMO bacteria in the North Canal mainly depended on the main form of available nitrogen and the source of pollutant. Moreover, N-DAMO bacteria present downstream of the North Canal, had a more connected and modular microbial network than those present midstream, where bacterial communities with tightly connected species that were shown to be more vulnerable and sensitive to various disturbances were found.