Discovering the Characteristics of Community Structures and Functional Properties of Epiphytic Bacteria on Spartina alterniflora in the Coastal Salt Marsh Area

The invasive submerged Spartina alterniflora is dominant in the coastal Yellow River Delta wetland. Although sediment microorganisms have been found to mediate the nutrient cycle in wetlands, the role of epiphytic bacteria on submerged S. alterniflora has rarely drawn attention. In the present study, we analyzed the characteristics of epiphytic microbial community diversity and functional properties related to S. alterniflora in summer and winter by Illumina MiSeq sequencing and functional prediction. Marked high abundances of Proteobacteria, Actinobacteriota, Planctomycetota, Cyanobacteria and Desulfobacterota were found in S. alterniflora epiphytic microbiome. Beta diversity based on NMDS and LDA analysis revealed that the distribution of these epiphytic microbial communities clustered according to the leaf locations and variation in seasons. Environmental factors, including temperature, salinity, DO and total organic matter, exert important roles in impacting the microbial community. Significantly higher abundances of chemoheterotrophy, aerobic_chemoheterotrophy, hydrocarbon degradation, fermentation, nitrate reduction and nitrate respiration were correlated with the submerged S. alterniflora epiphytic microbiome. Collectively, the results indicated that S. alterniflora epiphytic bacterial community diversity and functional guilds varied greatly with variations in leaf locations and seasons. These results will also provide guidance for the isolation of functional bacteria in controlling plant spread.