Characterization of bacterial community in biofilm and sediments of wetlands dominated by aquatic macrophytes

• Floating and submersed macrophytes provide special niches for microbes.
• Bacteria composition appears to be diverse and somewhat host-specific.
• Aquatic plant potentially alter the bacterial community structure of sediment.

Though aquatic macrophytes play an important role in wetlands, their effects on bacteria community structures in biofilms and sediments are far from clear. In the present study, bacterial communities were investigated in biofilm attached to leaves, stems and roots of aquatic macrophytes (Myriophyllum verticillatum, Nymphoides peltatum and Trapa japonica) and in vertical sediment cores from vegetated and unvegetated areas in a wetland located in Lake Hongze. The densities of microbes and epiphytic algae in biofilms were higher on leaves of M. verticillatum than those of two floating macrophytes. Phyla Proteobacteria, Bacteroidetes, Chloroflexi, Firmicutes and Verrucomicrobia were detected in both biofilms and sediments. As revealed by cluster analysis and principal component analysis, differences in structures of microbial communities were detected between biofilms and sediments and between vegetated and unvegetated sediments. The potential roles of nitrifying- and denitrifying- bacteria in sediments with respect to those in biofilms were discussed. These results highlight that the restoration of aquatic macrophytes can increase bacteria diversity and the surface and quantity of biofilms and therefore bacteria diversity. These data provide useful information for further understanding the role of aquatic macrophyte-biofilm system in wetlands in future.