辉腾锡勒草原干涸湖泊中氨氧化微生物群落结构分析

【目的】以内蒙古辉腾锡勒草原九十九泉湿地为对象,研究湖泊干涸过程中氨氧化微生物的群落结构及其变化。【方法】通过MPN-PCR定量测定氨氧化古菌(AOA)和氨氧化细菌(AOB)的数量;构建amoA基因克隆文库,进行系统发育分析;结合土壤环境因子,探讨湿地退化过程中影响氨氧化微生物的潜在因素。【结果】依湖泊湿地退水梯度的不同样点中,有75%的样点AOB的数量高于AOA,AOB与AOA的数量比率为0.3-18.1。从湖心到湖岸草原带,AOA和AOB的数量有明显增加,但生物多样性呈降低趋势,二者没有呈现正相关。研究发现,AOB的数量与土壤中NH 4+-N的变化存在良好响应。系统发育分析显示,退化湖泊湿地AOA克隆序列均来自于泉古菌门(Crenarchaeota);AOB的amoA基因的克隆序列大部分与亚硝化单胞菌属(Nitrosomonas)有一定同源性,较少部分与亚硝化螺菌属(Nitrosospira)有一定同源性。【结论】湖泊退水过程增加了湿地土壤氨氧化微生物的数量,而氨氧化微生物的种群丰度有所降低。AOA和AOB群落对湖泊湿地的退化过程做出了响应,其中AOB的响应较为明显,氧化条件和土壤铵浓度的改变可能是促成这种响应的重要原因。

Community structure of ammonia-oxidizing prokaryotes at the dry-up lake in Huitengxile grassland

Objective]To investigate the structure of ammonia-oxidation microbial communities in the wetlands to dry-up process at 99 degraded lakes of the Huitengxile grassland in the Inner Mongolia Plateau.Methods]The microbial quantity of ammonia-oxidizing archaea(AOA) and ammonia oxidizing bacteria(AOB) were examined by most probable number-polymerase chain reaction(MPN-PCR).The clone libraries of amoA were constructed and phylogenetics were analyzed.With analysis of the soil properties,we evaluated the effects of wetlands degradation on ammonia-oxidation microbes communities.Results] In 75% of the samples,the quantity of AOB communities was higher than that of AOA;moreover,quantity of bacterial were up to 18.1-fold more abundant than Archaea’s.The AOB microbial quantity was strongly correlated with NH4+-N content in the soil.Phylogenetic analyses of the amoA gene fragments showed that most AOB sequences from degraded wetlands were affiliated with Nitrosomonas-like species and a few close to Nitrosospira.All AOA sequences belonged to the kingdom Crenarchaeote.Conclusion] Experimental results showed that quantity of ammonia-oxidation microbes increased but community diversity declined during wetlands degradation,and oxidation conditions and ammonium concentration in the soil might play important roles in the community structure of both the AOA and AOB.