Resumo

The Atlantic Forest is one of the main biodiversity hotspots in the world. However, the microbial diversity associated with plant surfaces, such as dermosphere (bark surface) and phyllosphere (leaf surface) is mostly unknown. The aim of this study was to characterize the bacterial communities associated with the dermosphere of Guapira opposite and Euterpe edullis, in different ecosystems of the Brazilian Atlantic forest, using pyrosequencing of the 16S rRNA V4 region. The study was performed at the at Picinguaba and Santa Virginia nuclei of the Serra do Mar State Park,(São Paulo, Brazil). Samples were collected from plants in the restinga, lowland and montane forests, located at the sea level, 100 and 1000 m above sea level, respectively. The valid sequences were grouped into 19,739 Operational Taxonomic Units (OTUs), distributed into 33 phyla. Proteobacteria was the most abundant phyla (37.6% of the valid sequences). Acidobacteria (8.9%), Actinobacteria (4.8%), Bacteroidetes (7.7%), Firmicutes (5.6%), Planctomycetes (9.3%) and Verrucomicrobia (7.2%) phyla were less represented. It is possible that Actinobacteria, Bacteroidetes, Firmicutes and Acidobacteria are associated to lichens and bryophytes, on the bark surfaces. Cyanobacteria showed to be present at low abundances, but may have a potential role in N₂ fixation. Rhodopila, Sphingomonas, Methylobacterium (Alphaproteobacteria) and Pseudomonas (Gammaproteobacteria) were the most abundant genera on the dermosphere. Diversity indices (Shannon and reciprocal of Simpson’s) and species richness estimations were significantly different among the studied areas, showing a geographical effect on the bacterial communities associated with the dermosphere of a plant species. The tree species also affected the structure of the bacterial community, suggesting that so far unknown plant traits also contribute to the selection of specific bacterial species on the dermosphere.