Responses of anaerobic ammonia-oxidizing bacteria and methane-oxidizing archaea communities from different tillage modes in paddy fields

摘要

PurposeThe process of anaerobic ammonium (anammox) and methane oxidation reactions with nitrite as an electron acceptor is of great significance for the global carbon and nitrogen cycle. This study aims to explore the effects of different tillage modes on the abundance and community structure of anammox bacteria and anaerobic methane-oxidizing archaea (ANME-2d), and anaerobic methane-oxidation rate in paddy fields to manage the paddy fields sustainably and reduce the greenhouse gas emissions.MethodsThe abundance and community structure of anammox bacteria and ANME-2d, and anaerobic methane-oxidation rate were investigated in a 0-100 cm depth of paddy soil under three tillage modes: conventional paddy-upland rotation tillage (CT), combing ridge with no-tillage (RNT), and flooded paddy fields (FPF).ResultThe highest abundance of anammox bacteria was recorded under RNT (2.35 x 10(5) - 6.01 x 10(6) gene copies g(-1) dry soil). The 16S rRNA gene copy numbers of ANME-2d archaea under CT, RNT and FPF were 3.68 x 10(5) - 2.20 x 10(6), 4.92 x 10(5) - 3.54 x 10(6) and 5.79 x 10(5) - 5.19 x 10(6) gene copies g(-1) dry soil, respectively. The community compositions of anammox bacteria varied with tillage modes. In the CT mode, three species namely: Candidatus (Ca). Brocadia fulgida, Ca. Brocadia anammoxidans, and Ca. Kuenenia were detected, while Ca. Brocadia fulgida, Ca. Brocadia I and Ca. Brocadia II species were detected in the RNT. Two species of Ca. Brocadia fulgida and Ca. Jettenia were detected in the FPF. The species Ca. Brocadia was dominant and found in all tillage modes. All of the sequences in the three tillage modes were ANME-2d. The net methane-oxidation rate in RNT was two times higher than the other two tillage modes.ConclusionOur findings demonstrated that RNT mode increased the abundance of anammox bacteria and ANME-2d, improved soil fertility and increased the net methane-oxidation rate of the soil. This study thus provides a reliable practice for expanding RNT to rice cultivation for mitigation of greenhouse gas emissions.