Functional and phylogenetic response of soil prokaryotic community under an artificial moisture gradient

Moisture is recognized as a key factor shaping the structure of soil microbial community and its function in soil ecosystem. However, the temporal response patterns of soil microbes under various moisture regimes remain poorly understood. Therefore, the main objective of our study was to reveal how moisture regulates prokaryotic community structure, diversity, phylogenetic structure and finally how moisture regulates greenhouse gas emissions, as an indicator of microbial community function. We monitored prokaryotic community in soil incubated under an artificial moisture gradient for three months. We observed robust effects of both moisture gradient and incubation time on increased greenhouse gas emissions (methane, carbon dioxide and nitrous oxide). Furthermore, the moisture gradient as well as the incubation time exerted significant effects on species turnover of the soil prokaryotic community. In contrast, the artificial moisture gradient did not show any significant effects on prokaryotic alpha diversity. Alpha diversity of the soil prokaryotic community decreased significantly with incubation time. Different community assembly patterns were observed (based on both the mean nearest relatedness index (NRI) and nearest taxon index (NTI)). The mean NRI exhibited the dominance of stochastic factors, while the NTI indicated the dominance of deterministic factors. The prokaryotic communities in soils with less moisture tended to be controlled by stochastic factors, while prokaryotes in soils with higher moisture (60%) were controlled by deterministic factors. Relative abundances of oligotrophs and copiotrophs did not change significantly along the artificial moisture gradient, while the relative abundances of some prokaryotic taxa did vary significantly along the artificial moisture gradient.