Using adaptive and aggressive N2O-reducing bacteria to augment digestate fertilizer for mitigating N2O emissions from agricultural soils

Xinhui Wang; Baoyu Xiang; Ji Li; Menghui Zhang; Asa Frostegard; Lars Bakken; Xiaojun Zhang

doi:10.1016/j.scitotenv.2023.166284

Using adaptive and aggressive N₂O-reducing bacteria to augment digestate fertilizer for mitigating N₂O emissions from agricultural soils

Sci Total Environ. 2023 Dec 10:903:166284. doi: 10.1016/j.scitotenv.2023.166284. Epub 2023 Aug 14.

Authors

Xinhui Wang¹, Baoyu Xiang¹, Ji Li¹, Menghui Zhang¹, Asa Frostegard², Lars Bakken², Xiaojun Zhang³

Affiliations

¹ State Key Laboratory of Microbial Metabolism, and Joint International Research Laboratory of Metabolic & Developmental Sciences, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
² Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Aas, Norway.
³ State Key Laboratory of Microbial Metabolism, and Joint International Research Laboratory of Metabolic & Developmental Sciences, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: xjzhang68@sjtu.edu.cn.

PMID: 37586512
DOI: 10.1016/j.scitotenv.2023.166284

Abstract

Nitrous oxide (N₂O) emitted from agricultural soils destroys stratospheric ozone and contributes to global warming. A promising approach to reduce emissions is fertilizing the soil using organic wastes augmented by non-denitrifying N₂O-reducing bacteria (NNRB). To realize this potential, we need a suite of NNRB strains that fulfill several criteria: efficient reduction of N₂O, ability to grow in organic waste, and ability to survive in farmland soil. In this study, we enriched such organisms by sequential anaerobic batch incubations with N₂O and reciprocating inoculation between the sterilized substrates of anaerobic manure digestate and soils. 16S rDNA amplicon sequencing and metagenomics analysis showed that a cluster of bacteria containing nosZ genes encoding N₂O-reductase, was enriched during the incubation process. Strains of several dominant members were then isolated and characterized, and three of them were found to harbor the nosZ gene but none of the other denitrifying genes, thus qualifying as NNRB. The selected isolates were tested for their capacities to reduce N₂O emissions from three different typical Chinese farmland soils. The results indicated the significant mitigation effect of these isolates, even in very acidic red soil. In conclusion, this study demonstrated a strategy to engineer the soil microbiome with promising NNRB with high adaptability to livestock manure digestate as well as different agricultural soils, which would be suitable for developing novel fertilizer for farmland application to efficiently mitigate the N₂O emissions from agricultural soils.

Keywords: Digestate; Farmland soil; N(2)O reduction; Nitrous oxide emission; nosZ gene.