Effects of different long-term fertilizations on community properties and functions of methanotrophs in dark brown soil
长期不同施肥对暗棕壤甲烷氧化菌群落特征与功能的影响

The microbial mechanisms of how different long-term fertilizations change methane oxidation of Chinese upland arable soil is unclear so far. In the present study, we attempted to investigate the "soil properties-community properties of methanotrophs-methane oxidation" relation of dark brown soil in Northeastern China under different long-term fertilization regimes. Community structure and abundance were monitored with PCR-DGGE and real time PCR, respectively. Methane oxidizing rate and soil properties were measured as well. The results show that combined use of mineral fertilizer and compost (MNP) reduce soil methane oxidation by 61.2%, whereas either mineral fertilizer (NP) or compost (M) shows no effect. Comparing with no fertilizer (CK), M and MNP increase the Shannon index of methanotrophs by 91.9% and 102.5%, respectively, whereas NP has no effect. Similarly, M ( M or MNP) significantly increases pmoA gene abundance by up to 12.7 folds compared with no M addition (CK or NP). Methane oxidizing rates are significantly correlated with community structure and specific activity of methanotrophs, with correlation coefficients of 0.363 and 0.684, respectively. However, methane oxidizing rates do not correlate with abundance and diversity of methanotrophs. In addition, community structures and specific activity of methanotrophs are significantly correlated with soil pH and content of total nitrogen and organic matter. Our results suggest that long-term different fertilizations may change soil properties (such as pH and content of total nitrogen and organic matter) and thereafter the community structure and specific activity of soil methanotrophs, by which long-term different fertilizations influence soil methane oxidizing rate. The opposite change of methane oxidation to methanotrophs diversity and abundance in MNP suggests that only parts of the methanotrophs are active, which needs further research.