Metagenomics reveals microbial community differences lead to differential nitrate production in anammox reactors with differing nitrogen loading rates

Wei Li; Jin-Long Zhuang; Yuan-Yuan Zhou; Fan-Gang Meng; Da Kang; Ping Zheng; James P Shapleigh; Yong-di Liu

doi:10.1016/j.watres.2019.115279

Metagenomics reveals microbial community differences lead to differential nitrate production in anammox reactors with differing nitrogen loading rates

Water Res. 2020 Feb 1:169:115279. doi: 10.1016/j.watres.2019.115279. Epub 2019 Nov 9.

Authors

Wei Li¹, Jin-Long Zhuang², Yuan-Yuan Zhou², Fan-Gang Meng³, Da Kang⁴, Ping Zheng⁴, James P Shapleigh⁵, Yong-di Liu⁶

Affiliations

¹ National Engineering Laboratory for Industrial Wastewater Treatment, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University), Guangdong, China.
² National Engineering Laboratory for Industrial Wastewater Treatment, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China.
³ Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University), Guangdong, China.
⁴ Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University, Hangzhou, China.
⁵ Department of Microbiology, Cornell University, Ithaca, USA. Electronic address: jps2@cornell.edu.
⁶ National Engineering Laboratory for Industrial Wastewater Treatment, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China. Electronic address: ydliu@ecust.edu.cn.

PMID: 31734392
DOI: 10.1016/j.watres.2019.115279

Abstract

Nitrate production during anammox can decrease total nitrogen removal efficiency, which will negatively impact its usefulness for the removal of nitrogen from waste streams. However, neither the performance characteristics nor physiological shifts associated with nitrate accumulation in anammox reactors under different nitrogen loading rates (NLRs) is well understood. Consequently, these parameters were studied in a lower NLR anammox reactor, termed R1, producing higher than expected levels of nitrate and compared with a higher NLR reactor, termed R2, showing no excess nitrate production. While both reactors showed high NH₄⁺-N removal efficiencies (>90%), the total nitrogen removal efficiency (<60%) was much lower in R1 due to higher nitrate production. Metagenomic analysis found that the number of reads derived from anammox bacteria were significantly higher in R2. Another notable trend in reads occurrence was the relatively higher levels of reads from genes predicted to be nitrite oxidoreductases (nxr) in R1. Binning yielded 27 high quality draft genomes from the two reactors. Analysis of bin occurrence found that R1 showing both a decrease in anammox bacteria and an unexpected increase in nxr. In-situ assays confirmed that R1 had higher rates of nitrite oxidation to nitrate and suggested that it was not solely due to obligate NOB, but other nxr-containing bacteria are important contributors as well. Our results demonstrate that nitrate accumulation can be a serious operational concern for the application of anammox technology to low-strength wastewater treatment and provide insight into the community changes leading to this outcome.

Keywords: Anammox; Metagenomics; Nitrate accumulation; Nitrite oxidoreductase.

MeSH terms

Bioreactors
Denitrification
Metagenomics
Microbiota*
Nitrogen*
Oxidation-Reduction

Substances

Nitrogen