Soil anammox and denitrification processes connected with N cycling genes co-supporting or contrasting under different water conditions

Touqeer Abbas; Qichun Zhang; Xiang Zou; Muhammad Tahir; Dan Wu; Shuquan Jin; Hongjie Di

doi:10.1016/j.envint.2020.105757

Soil anammox and denitrification processes connected with N cycling genes co-supporting or contrasting under different water conditions

Environ Int. 2020 Jul:140:105757. doi: 10.1016/j.envint.2020.105757. Epub 2020 Apr 30.

Authors

Touqeer Abbas¹, Qichun Zhang², Xiang Zou¹, Muhammad Tahir³, Dan Wu⁴, Shuquan Jin⁵, Hongjie Di¹

Affiliations

¹ Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, Zhejiang University, Hangzhou 310058, PR China.
² Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, Zhejiang University, Hangzhou 310058, PR China. Electronic address: qczhang@zju.edu.cn.
³ Department of Soil, Water, & Climate, Univ. of Minnesota, 1991 Upper Buford Cir, Falcon Heights, MN 55108, USA.
⁴ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, PR China.
⁵ Ecology and Environment Institute, Ningbo Academy of Agricultural Science, Ningbo 315040, PR China.

PMID: 32361577
DOI: 10.1016/j.envint.2020.105757

Abstract

The anaerobic ammonium oxidizing bacteria (anammox) are the hidden culprit behind the excessive nitrogen loss under a favorable environment, since their detection and abundance get disturbed by several unknown factors. This study intends to find the gap between actual anammox working capacity under different water conditions and fertilizers in the laboratory. The ¹⁵N-isotopic tracer technique was used to measure anammox and denitrification rate, and anammox community structure was analyzed through high-throughput sequencing with cytochrome cd-1 nitrite reductase functional gene (an_nirS gene, initially found in Candidatus Scalindua). The experiment consisted of four treatments, i.e., (I) CK_ Control, (II) UR_Urea, (III) PM_Pig Manure, and (IV) SRF_ Slow release fertilizer, under two water conditions, i.e., (a) Continuous flooding_ CF, (b) Alternate wetting and drying_ AWD. Results showed that anammox under CF decreased over time by -40.24%, and denitrification increased up to 39.25%. However, anammox activity under AWD increased up to 10.62% with the availability of NO₂^-, and surprisingly accompanied by the reduction in denitrification loss (-31.97%), being the most critical factor. We found that soil nifH and AOB genes were strongly favorable for anammox activity, while we observed the presence of anammox and AOB genes co-existing at the same time in paddy soil. The high-throughput sequencing with an_nirS functional gene showed a much higher diversity of anammox genera ever reported, mostly uncultured and unidentified. We concluded that water management is more prominent than fertilizer for anammox, and the most critical factor is the duration of AWD cycle, because of short term air supply could boost anammox activity and gene abundance, and could reduce denitrifier activity as well as nirK gene abundance.

Keywords: (15)N isotopic tracer; Alternate wetting and drying; Anammox; High throughput-sequencing with anammox cd-1 nirS (an_nirS gene); Partial nitritation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Denitrification*
Fertilizers / analysis
Nitrogen
Oxidation-Reduction
Soil Microbiology
Soil*
Swine
Water

Substances

Fertilizers
Soil
Water
Nitrogen