Partial function prediction of sulfate-reducing bacterial community from the rhizospheres of two typical coastal wetland plants in China

Sulfate-reducing bacteria (SRB) are ubiquitous anaerobic microorganisms that play significant roles in the global biogeochemical cycle. Coastal wetlands, one of the major habitats of SRB, exhibit high sulfate-reducing activity and thus play significant roles in organic carbon remineralization, benthic geochemical action, and plant-microbe interactions. Recent studies have provided credible evidence that the functional rather than the taxonomic composition of microbes responds more closely to environmental factors. Therefore, in this study, functional gene prediction based on PacBio single molecular real-time sequencing of 16S rDNA was applied to determine the sulfate-reducing and organic substrate-decomposing activities of SRB in the rhizospheres of two typical coastal wetland plants in North and South China: Zostera japonica and Scirpus mariqueter . To this end, some physicochemical characteristics of the sediments as well as the phylogenetic structure, community composition, diversity, and proportions of several functional genes of the SRB in the two plant rhizospheres were analyzed. The Z. japonica meadow had a higher dissimilatory sulfate reduction capability than the S. mariqueter -comprising saltmarsh, owing to its larger proportion of SRB in the microbial community, larger proportions of functional genes involved in dissimilatory sulfate reduction, and the stronger ability of the SRB to degrade organic substrates completely. This study confirmed the feasibility of applying microbial community function prediction in research on the metabolic features of SRB, which will be helpful for gaining new knowledge of the biogeochemical and ecological roles of these bacteria in coastal wetlands.