内蒙古高原干涸湖泊反硝化及甲烷氧化细菌的群落分析

Community structures of denitrifying bacteria and methanotrophs in wetland soils of dry-up lake in the Inner Mongolia Plateau

以内蒙古高原半干旱草原区干涸湖泊为研究对象,应用末端限制性片段长度多态性(T-RFLP)技术对湿地土壤中的反硝化和甲烷氧化关联菌群的关键功能基因nosZ和pmoA进行了研究,根据末端限制性片段(T-RFs)分析了两种菌群的群落结构及多样性变化,以及环境因素所产生的影响,并探讨了土壤微生物群落对湖泊干涸的响应机制.结果表明:干涸湖泊的湖心、湖底土壤反硝化和甲烷氧化细菌多样性指数较高,群落结构较复杂;而较早干涸的湖坡以及相邻草原对照区,两个菌群多样性指数较低,群落结构相对单一.从湖心到相邻草原,反硝化和甲烷氧化细菌的群落相似度逐渐降低,显示两个菌群处于动态演替中.湖泊干涸过程中,水分含量和有机质含量对反硝化和甲烷氧化细菌的群落结构影响显著;高pH值和高铵态氮分别对反硝化和甲烷氧化细菌有抑制作用.随着湖泊干涸,土壤微生物群落因环境扰动而受到胁迫,这一过程会加剧CO2等温室气体的排放.

The method of terminal restriction fragment length polymorphism（T-RFLP） was used to study the community structures and diversities of denitrifying bacteria and aerobic methanotrophs by two key functional genes nosZ and pmoA in the wetland soils of dry-up lake in the Inner Mongolia Plateau.And the effects of soil factors on them were also evaluated,then the mechanism of microbiological communities in wetland soils response to the dry-up lake were discussed.The results showed that the diversity indices of denitrifying bacteria and aerobic methanotrophs were higher,and community structures appeared more complicated at the later dry-up plots.The opposite results were shown at the earlier dry-up plot and the adjacent steppe.Their similarity coefficients gradually declined from the middle of the lake to the adjacent steppe,indicating communities dynamic succession.During drying process,soil moisture and organic matter content had significant influence on both of them.In addition,high pH value and high NH4＋-N had inhibitory effects on denitrifying bacteria and the aerobic methanotrophs,respectively.The microbial communities were under the stress of dry-up process,which led to more emission of carbon dioxide and other greenhouse-gas from wetland soils.