Soil bacterial community composition across different topographic sites characterized by 16S rRNA gene clones in the Fushan Forest of Taiwan

Bacterial communities present in soils from the valley, middle-slope, and ridge sites of the Fushan forest in Taiwan were characterized using 16S rDNA analysis of genomic DNA after polymerase chain reaction amplification, cloning, and denaturing gradient gel electrophoresis analysis. Phylogenetic analysis revealed that the clones from nine clone libraries included members of the phyla Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes, candidate division TM7, and Verrucomicrobia. Members of Proteobacteria, Acidobacteria, and Actinobacteria constituted 49.1%, 32.3%, and 6.3% of the clone libraries, respectively, while the remaining bacterial divisions each comprised less than 6%. The ridge site exhibited the most bacterial species number, indicating the influence of topography. Bacterial composition was more diverse in the organic layer than in the deeper horizons. In addition, bacterial species numbers varied across the gradient horizons.