Effects Of The Dry-Up Natural Lake On Community Structure Of Ammonia-Oxidizing Prokaryotes In Huitengxile Grassland

To investigate the structure of ammonia-oxidation microbial communities in the wetlands to dry-up process at99degraded lakes of the Huitengxile grassland in the Inner Mongolia Plateau. 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. The quantity of AOB communities was higher than that of AOA in all samples except in lakebed, moreover, quantity of bacterial were up to18.1-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 lakebed were affiliated with Nitrosomonas-like species and most AOB sequences from grassland on lake shores were close to Nitrosospira. All AOA sequences belonged to the kingdom Crenarchaeote. 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.