Seasonal and spatial distribution of ammonia-oxidizing microorganism communities in surface sediments from the East China Sea

Ammonia oxidation plays a significant role in the nitrogen cycle in marine sediments. Seasonal and spatial distribution of ammonia-oxidizing archaea (AOA) and betaproteobacteria (beta-AOB) in surface sediments from the East China Sea (ECS) were investigated using ammonia monooxygenase alpha subunit (amoA) gene. In order to characterize the community of AOA and beta-AOB, real-time quantitative polymerase chain reaction (qPCR) was carried out in this study, along with environmental parameters. The abundance of beta-AOB amoA gene (2.17x10(6)-4.54x10(7) copy numbers per gram wet weight sediment) was always greater than that of AOA amoA gene (2.18x10(5)-9.89x10(6) copy numbers per gram wet weight sediment) in all sampling stations. The qPCR results were correlated with environmental parameters. AOA amoA gene copy numbers in April were positively related to temperature and nitrite concentration (rho < 0.05). beta-AOB amoA gene copy numbers in August correlated negatively with salinity (rho < 0.01), and correlated positively with ammonium concentration (rho < 0.05). With the increase of salinity, the amoA gene copy ratio of AOB to AOA had a tendency to decrease, which suggested beta-AOB dominated in the area of high level ammonium and AOA preferred high salinity area.