Diversity of nitrogen cycling genes at a Midwest long-term ecological research site with different management practices

• Published in: Applied microbiology and biotechnology 2021-05, Vol.105 (10), p.4309-4327
• Main Authors: Li, Zheng, Cupples, Alison M.
• Format: Article
• Language: English
• Subjects: Abundance; Agricultural management; Agricultural practices; Biomedical and Life Sciences; Biotechnology; Community involvement; Comparative analysis; Consumption; Cycles; Denitrification; Ecological effects; Ecological research; Emissions control; Environmental aspects; Environmental Biotechnology; Farm buildings; Genes; Genetic aspects; Greenhouse gases; Life Sciences; Metabolism; Microbial activity; Microbial Genetics and Genomics; Microbiology; Microorganisms; Nitrogen; Nitrogen cycle; Nitrogen fertilizers; Nitrogen metabolism; Nitrous oxide; NorB protein; Ozone depletion; Relative abundance; Soils; Tillage
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-021-11303-0

Nitrogen fertilizer results in the release of nitrous oxide (N 2 O), a concern because N 2 O is an ozone-depleting substance and a greenhouse gas. Although the reduction of N 2 O to nitrogen gas can control emissions, the factors impacting the enzymes involved have not been fully explored. The current study investigated the abundance and diversity of genes involved in nitrogen cycling (primarily denitrification) under four agricultural management practices (no tillage [NT], conventional tillage [CT], reduced input, biologically-based). The work involved examining soil shotgun sequencing data for nine genes ( napA , narG, nirK , nirS , norB , nosZ , nirA , nirB , nifH ). For each gene, relative abundance values, diversity and richness indices, and taxonomic classification were determined. Additionally, the genes associated with nitrogen metabolism (defined by the KEGG hierarchy) were examined. The data generated were statistically compared between the four management practices. The relative abundance of four genes ( nifH , nirK , nirS , and norB ) were significantly lower in the NT treatment compared to one or more of the other soils. The abundance values of napA , narG , nifH , nirA , and nirB were not significantly different between NT and CT. The relative abundance of nirS was significantly higher in the CT treatment compared to the others. Diversity and richness values were higher for four of the nine genes ( napA , narG , nirA , nirB ). Based on nirS/nirK ratios, CT represents the highest N 2 O consumption potential in four soils. In conclusion, the microbial communities involved in nitrogen metabolism were sensitive to different agricultural practices, which in turn, likely has implications for N 2 O emissions. Key points • Four genes were less abundant in NT compared to one or more of the others soils (nifH, nirK, nirS, norB). • The most abundant sequences for many of the genes classified within the Proteobacteria. • Higher diversity and richness indices were observed for four genes (napA, narG, nirA, nirB). • Based on nirS/nirK ratios, CT represents the highest N 2 O consumption potential.