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.