Dissimilatory nitrate reduction to ammonium increased with rising temperature

• Published in: Biology and fertility of soils 2021-04, Vol.57 (3), p.363-372
• Main Authors: Lai, Thang V., Ryder, Maarten H., Rathjen, Judith R., Bolan, Nanthi S., Croxford, Adam E., Denton, Matthew D.
• Format: Article
• Language: English
• Subjects: Agriculture; Ammonium; Ammonium compounds; Biomedical and Life Sciences; Denitrification; Genes; High temperature; Life Sciences; Nitrate reduction; Nitrates; Nitrification; Nitrogen isotopes; Original Paper; Reduction; Soil Science & Conservation; Soil temperature; Temperature; Tracers
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-020-01529-x

Although recent studies have explored dissimilatory nitrate reduction to ammonium (DNRA), little is known about the dependence of this process on temperature. A laboratory experiment was conducted to investigate if temperature regulates nitrate (NO 3 ˉ) reduction by DNRA and denitrification. Soil samples were incubated at 10 to 40 °C for 28 days, and 15 N tracer methods were applied to estimate the reduction of 15 NO 3 ˉ to 15 NH 4 + by DNRA organisms and to 15 N 2 O or 15 N 2 by denitrifiers. Raising the temperature from 10 to 40 °C increased DNRA, which contributed to enrichment of the NH 4 + pool, particularly at 40 °C. The percentage of 15 NO 3 ˉ reduced by DNRA was from 4 to 30% of that reduced by denitrification, and decreased with increasing temperature. DNRA and denitrification were positively correlated with the abundance of nrfA and nosZ genes, respectively. The accumulation of 15 NH 4 + slowed in the final 12 h of sampling times, which may be due to a re-conversion of 15 NH 4 + to 15 NO 3 ˉ by nitrification. High temperatures (30 to 40 °C) enhanced 15 N 2 production, which suggests that temperature plays an important role in regulating complete denitrification from NO 3 ˉ to N 2 .