Temporal variations of soil prokaryotic community and activity under different pH

Soil pH plays important role in shaping microbial community structure and diversity. Altered pH regimes may change microbial community composition by selecting species/groups with ecological strategies to optimize their fitness. However, it remains unresolved whether bacterial community exhibits phylogenetically conserved or stochastic responses to pH. In this study, we investigated the responses of greenhouse gas emission and prokarotic community structure to the artificial pH gradient using three-month incubation experiments by adjusting soil pH from 4.5 to 8.5. We found the decreasing of OTUs richness with incubation time under laboratory conditions. Phylogenetic clustering of prokaryotic community was shown at earlier incubation times, while higher phylogenetic distance of prokaryotic community was found at later incubation time. Our results showed different responses of soil bacterial taxa to pH within various incubation times. Relative abundances of oligotrophs increased significantly along artificial pH gradient from 2 to 30 days of incubation. Furthermore, relative abundances of oligotrophs didn’t change from 60 to 90 days under various pH´s, but strongly decreased after 90 days. In contrast, relative abundance of copiotrophs decreased significantly along elevated pH gradient from 2 and 30 days of incubation, and increased after 90 days. Methane emission increased with pH increase as well as with incubation time, while carbon dioxide and nitrous oxide only increased with incubation time. Methane emission correlated with relative abundance of bacterial community at phylum level.