Organic Matter Regulates Ammonia-Oxidizing Bacterial and Archaeal Communities in the Surface Sediments of Ctenopharyngodon idellus Aquaculture Ponds.

Lili Dai,Gu Li,Liqin Yu,Chaofeng Song,Liang Peng,Ling Tao,Chengqing Liu,Xiaoli Li

doi:10.3389/fmicb.2018.02290

Abstract

Ammonia-oxidizing bacteria (AOB) and archaea (AOA) play important roles in nitrogen removal in aquaculture ponds, but their distribution and the environmental factors that drive their distribution are largely unknown. In this study, we collected surface sediment samples from Ctenopharyngodon idellus ponds in three different areas in China that practice aquaculture. The community structure of AOB and AOA and physicochemical characteristics in the ponds were investigated. The results showed that AOA were more abundant than AOB in all sampling ponds except one, but sediment AOB and AOA numbers varied greatly between ponds. Correlation analyses indicated a significant correlation between the abundance of AOB and arylsulfatase, as well as the abundance of AOA and total nitrogen (TN) and arylsulfatase. In addition, AOB/AOA ratio was found to be significantly correlated with the microbial biomass carbon. AOB were grouped into seven clusters affiliated to Nitrosospira and Nitrosomonas, and AOA were grouped into six clusters affiliated to Nitrososphaera, Nitrososphaera sister group, and Nitrosopumilus. AOB/AOA diversity in the surface sediments of aquaculture ponds varied according to the levels of total organic carbon (TOC), and AOB and AOA diversity was significantly correlated with arylsulfatase and β-glucosidase, respectively. The compositions of the AOB communities were also found to be significantly influenced by sediment eutrophic status (TOC and TN levels), and pH. In addition, concentrations of acid phosphatase and arylsulfatase in surface sediments were significantly correlated with the prominent bacterial amoA genotypes, and concentrations of TOC and urease were found to be significantly correlated with the prominent archaeal amoA genotype compositions. Taken together, our results indicated that AOB and AOA communities in the surface sediments of Ctenopharyngodon idellus aquaculture ponds are regulated by organic matter and its availability to the microorganisms.

Highlights

Aquaculture has been continuously growing in the past 50 years to around 73.8 million tons in 2014 (FAO, 2016)
This study revealed that Ammonia-oxidizing bacteria (AOB) and Ammonia-Oxidizing Archaeal (AOA) were abundant in Ctenopharyngodon idellus aquaculture pond sediments
The predominance of AOB or AOA varied between the sediments of different aquaculture ponds according to the levels of total organic carbon (TOC)

Summary

Introduction

Aquaculture has been continuously growing in the past 50 years to around 73.8 million tons (not including aquatic plants) in 2014 (FAO, 2016). According to the Bureau of Fisheries, 31.79 million tons of freshwater aquaculture products were generated in China in 2016, with an estimated value of US$91.51 billion (Bureau of Fisheries, 2017). Along with these remarkable achievements, concerns have been raised about the negative environmental effects of increasing productivity which is largely based on highdensity pond cultivation. Fertilizers and supplementary feedstuffs are largely used in intensive aquaculture to achieve higher productivity, resulting in the accumulation of nitrogen in pond sediments owing to both the excrements of the species cultivated and excessive residual matter (Avnimelech and Ritvo, 2003). The removal of excess nitrogen from the pond systems of high-density aquaculture is of great importance

Methods

Results

Discussion

Conclusion