Comparison of Community and Function of Dissimilatory Nitrate Reduction to Ammonium (DNRA) Bacteria in Chinese Shallow Lakes with Different Eutrophication Degrees

Xiaowen Li,Chunlei Song,Zijun Zhou,Yiyong Zhou,Siyang Wang,Jian Xiao,Xiuyun Cao,Liu Yang

doi:10.3390/w12010174

Abstract

Dissimilatory nitrate reduction to ammonium (DNRA) plays an important role in controlling nitrogen (N) loading in lake ecosystems. However, studies on the linkage between DNRA bacterial community structure and lake eutrophication remain unclear. We examined the community and abundance of DNRA bacteria at six basins of four shallow lakes with different degrees of eutrophication in China. Measurements of the different forms of N and phosphorus (P) in the water column and interstitial water as well as total organic carbon (TOC) and sulfide in the sediments in summer (July 2016) were performed. The nutritional status of Lake Chaohu was more serious than that of the lakes in Wuhan, including Lake Qingling, Lake Houguan, and Lake Zhiyin by comparing geochemical and physical parameters. We found a higher abundance of the nrfA gene, which is a function gene of DNRA bacteria in sediments with higher contents of TOC and sulfide. Moreover, nitrate was a significant factor influencing the DNRA bacterial community structure. A significant difference of the DNRA bacterial community structure between Lake Chaohu and the lakes in Wuhan was discovered. Furthermore, DNRA bacterial abundance and community positively correlated with NH4+ and Chl a concentrations in Lake Chaohu, in which a percent abundance of dominant populations varied along eutrophication gradients. Overall, the abundance and community structure of the DNRA bacteria might be important regulators of eutrophication and cyanobacteria bloom in Lake Chaohu.

Highlights

Eutrophication has become a serious environmental issue in the world [1]
In Lake Qingling, different from the south basin, which was dominated by hydrophytes, significantly higher concentrations of N, P, and Chlorophyll a (Chl a) were recorded in the north basin dominated by algae (Figure 2)
This study reveals that variability in the abundance and community structure of Dissimilatory nitrate reduction to ammonium (DNRA) bacteria was largely driven by environmental factors

Summary

Introduction

Eutrophication has become a serious environmental issue in the world [1]. Nitrogen (N)is one of the key biogenic elements affecting the eutrophication of the shallow lake ecosystem.An excessive input of N into lakes typically may cause environmental problems such as harmful algae blooms [2]. Eutrophication has become a serious environmental issue in the world [1]. Is one of the key biogenic elements affecting the eutrophication of the shallow lake ecosystem. An excessive input of N into lakes typically may cause environmental problems such as harmful algae blooms [2]. DNRA has been reported mostly be a heterotrophic fermentation process, with an electron carbon as the electron donor, it can be chemolithoautotrophic by using sulfide [6,7,8,9,10]. DNRA in sediments is affected by the interaction of various factors, mainly the concentrations of NO3 − , iron, sulfide, organic carbon, temperature, and pH [11,12,13]. Previous studies have suggested that in the estuarine sediments, DNRA may prefer in conditions of low NO3 −

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