Shifts in microbial community function and structure along the successional gradient of coastal wetlands in Yellow River Estuary

This study was designed to explore the responses of soil microbial communities to vegetation succession of wetlands and to investigate whether microorganism parameters can be used as an indicator in this evolution process. The investigation was carried out in coastal wetlands along the successional gradients in Yellow River Estuary of East China. Environmental variables were monitored and the metabolic capabilities of the microbial community were studied using Biolog EcoPlates®. The pyrosequencing was applied to the bacterial community structure studies. 57,684 quality sequences from 66,849 reads were classified as Bacteria with a read length of ≥200 bp. The dominant phyla across all samples were Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Acidobacteria, Chloroflexi, and Verrucomicrobia, representing 40.45%, 23.54%, 9.01%, 8.31%, 1.74%, 1.60%, and 0.21%, respectively. Salinity may be the major factor that caused the reduced number of halophilic microbes, such as genera Halobacillus and Bacillus. Meanwhile, the microbial communities were significantly correlated with vegetation and soil organic matter. In particular, the relative abundances of aprophytic microbes were increased with succession. Although the vegetation and soil parameters explain a large proportion of the changes in carbon utilization, single parameter of microbial community alone should not be used to monitor the overall changes in wetlands succession.