Diversity and Activity of Ammonia Oxidizing Archaea and Bacteria at Estuary Ecosystem

Abstract

Ammonia oxidation is a key part of nitrogen transformation in the estuary ecosystem. It is essential to understand the distributions of ammonia oxidizing archaea and bacteria in these sediments and how they respond to changes in chemical properties along the river (freshwater-marine). Here, we investigated the distribution and abundance of bacterial and archaeal amoA genes in estuarine sediments in winter and summer. The abundance of bacterial amoA genes by qPCR was greater than the of archaeal amoA genes in all sites. Pyrosequencing data of bacterial and archaeal amoA revealed that the bacterial amoA OTUs were clearly different at terrestrial and tidal sediments. The Nitrosospira lineages 1, 3a, 3b, and 4 were dominated at terrestrial sediments, while Nitrosospira 15-like lineages were dominated at tidal sediments without season. However, archaeal amoA OTUs related with Nitrososphaera, Nitrosopumilis, and Nitrosotalea clusters were co-existed at terrestrial and tidal sediments. Salinity and pH strongly affected the AOB community. The results implied that AOB might play a more important role in estuary sediments.