Activity, abundance and community composition of nitrite-dependent methanotrophs in response to fertilization in paddy soils

Nitrite-dependent anaerobic oxidation of methane (AOM), which is mediated by Candidatus Methylomirabilis oxyfera (M. oxyfera)-like bacteria, has the great potential to reduce methane emissions from paddy ecosystems. Fertilization, a necessary practice for increasing crop yields, could greatly affect nitrite-dependent AOM process. Here, we investigated the abundance, community composition and activity of M. oxyfera-like bacteria at different layers (0-10, 20-30 and 40-50 cm) of paddy soils under three fertilization treatments, including unfertilized control (CK), chemical fertilization (CF) and organic fertilization (OF). The 16S rRNA gene abundance of M. oxyfera-like bacteria in soils under CF (6.1 x 106-2.2 x 107 copies g-1 dry soil) and OF (8.9 x 106-1.8 x 107 copies g-1 dry soil) treatments was higher than that under CK treatment (5.0 x 106-1.5 x 107 copies g-1 dry soil). An obvious separation of M. oxyfera-like bacterial communities was observed between different fertilization treatments, and a higher diversity of these bacteria was detected in CF and OF soils. The nitrite-dependent AOM activity was increased in soils under CF (3.6-11.5 nmol CO2 g- 1 (dry soil) d-1) and OF (3.4-7.2 nmol CO2 g- 1 (dry soil) d-1) treatments as compared to CK (1.6-4.4 nmol CO2 g- 1 (dry soil) d-1) treatment, particularly at the layer of 20-30 cm. Overall, our results demonstrated that the communities and activity of M. oxyfera-like bacteria responded positively to both chemical and organic fertilization, which expanded our knowledge of the role of nitrite-dependent AOM in regulating methane emissions from paddy ecosystems.

Automated summary

The use of chemical and organic fertilizers can enhance the abundance and activity of nitrite-dependent anaerobic oxidation of methane (AOM) bacteria, leading to a reduction in methane emissions from paddy ecosystems.