Distinct distribution patterns of ammonia-oxidizing archaea and bacteria in sediment and water column of the Yellow River estuary

Mingcong Li,Xiaoyun Wang,Zheng Gao,Han Li,Wenchong Shi,Zhongtao Sun,Guangshan Wei

doi:10.1038/s41598-018-20044-6

Abstract

Ammonia oxidation is a critical process of estuarine nitrogen cycling involving ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the distribution patterns of ammonia-oxidizing microorganisms (AOMs) between different habitats in the same area remain unclear. The present study investigated the AOMs’ abundance and community compositions in both sediment and water habitats of the Yellow River estuary. Quantitative PCR (qPCR) revealed that AOA showed significant higher abundance than AOB both in sediment and water samples. AOA and AOB abundance distribution trends were consistent in sediment but distinct in water along the sampling sites. Clone library-based analyses showed that AOA sequences were affiliated with Nitrososphaera, Nitrosopumilus and Nitrosotalea clusters. Generally, Nitrososphaera was predominant in sediment, while Nitrosopumilus and Nitrosotalea dominated in water column. AOB sequences were classified into genera Nitrosospira and Nitrosomonas, and Nitrosospira dominated in both habitats. Principal coordinate analysis (PCoA) also indicated AOA community structures exhibited significant differences between two habitats, while AOB were not. Ammonium and carbon contents were the potential key factors to influence AOMs’ abundance and compositions in sediment, while no measured variables were determined to have major influences on communities in water habitat. These findings increase the understanding of the AOMs’ distribution patterns in estuarine ecosystems.

Highlights

Ammonia oxidation, the first and rate limiting step of nitrification process, which can remove a substantial percentage (10–80%) of anthropogenic nitrogen pollution and reduce the risk of eutrophication in estuaries when coupled with denitrification[1,2,3]
Little was known about the different distribution patterns of ammonia-oxidizing microorganisms (AOMs) between sediment and water habitats in estuarine environments[33]
Our quantitative PCR results revealed that the archaeal amoA gene performed significant higher copy numbers than that of Ammonia-oxidizing bacteria (AOB) in both sediment and water habitats (P < 0.01)

Summary

Introduction

The first and rate limiting step of nitrification process, which can remove a substantial percentage (10–80%) of anthropogenic nitrogen pollution and reduce the risk of eutrophication in estuaries when coupled with denitrification[1,2,3]. Large number of researches investigated on the abundance, diversity and community structure of AOA and AOB in various environments, indicating their widely distributions in both marine and terrestrial ecosystems[12,13]. More active ammonia oxidizers in N-rich grassland soil[18], Qinghai Lake[19] and Yangtze Estuary[20] These differences may be due to the distinct habitat types and the effect of environmental factors. Salinity is another important factor can affect the structure and abundance of ammonia oxidizing microbial community, in estuary ecosystem[22,23]. Most published surveys have only conducted on estuary sediment or water ecosystem, and the different distribution patterns of AOA and AOB between sediment and water column remain unclear

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Conclusion