Heterogeneity of CH4-derived carbon induced by the O2:CH4 mediates bacterial community assembly processes

Although the ratio of O2:CH4 has already been proved to play a critical role in the process of aerobic methane oxidation coupled to denitrification (AME-D), the mechanism by which the O2:CH4 controls the microbial community assembly is still unclear. In this study, we characterized the changes in the bacterial community in the fed-batch serum bottle reactors under the different O2:CH4. The results showed that the selection patterns under the high and low O2:CH4 were totally different. The coherence process dominated the selection at the high O2:CH4, while the diversification process played a role when the O2:CH4 was low. The heterogeneity of the CH4-derived carbon induced by the O2:CH4 might lead to the differences in the selection patterns. Our findings bridged the gaps between the observations of the bacterial community perturbations and ecological community assembly theories, and highlighted the totally different patterns of the microbial community assembly induced by the O2:CH4.