Response of activity, abundance, and composition of anammox bacterial community to different fertilization in a paddy soil

Abstract

The anaerobic oxidation of ammonium (anammox) process plays a critical role in the loss of nitrogen (N) in paddy soils, yet the response of anammox to different fertilization is not well documented. In this study, three different fertilized (control, CK; soil treated with inorganic fertilizers, NPK; soil treated with inorganic fertilizer and involving the incorporation of straw, NPKS) paddy soils were selected to investigate the activity, functional gene abundance, diversity, and composition of anammox bacterial community using isotope-tracing technique, quantitative PCR assays, and Illumina sequencing. The anammox rate in the NPKS treatment was 2.4 nmol N g−1 soil h−1, significantly higher than that in CK and NPK treatments (1.7 and 1.8 nmol N g−1 soil h−1, respectively). Potential anammox contributed 6.2–7.8% to total N loss with the remainder being due to denitrification. Significant differences in the number of hydrazine synthase β-subunit (hzsB) gene were observed in three treatments with the highest value being observed in the NPK treatment. The anammox rate of per functional gene in the NPKS treatment (11.4 fmol day−1) was higher than that in CK and NPK treatments (8.3 and 7.0 fmol day−1, respectively). Three genera of anammox bacteria were identified: Candidatus Brocadia, Candidatus Anammoxoglobus, and Candidatus Scalindua, with Candidatus Brocadia being the dominant. Anammox bacteria diversity was significantly lower in the NPK than in CK and NPKS treatments as shown by Shannon, Simpson, Chao 1, and ACE indices (p < 0.05). The results showed that activity, abundance, and composition of anammox bacterial community depended on the type of fertilization.