Abstract
To determine the spatial and seasonal variations in bacterial community structure and abundance in the small and steep rivers typically present in Japan, bacterial populations in two rivers, the Yodo River and Kita River, were investigated using a DNA microarray technique. A total of 24 river water samples seasonally collected from four stations in the Yodo River and two stations in the Kita River were analyzed by an oligonucleotide DNA microarray targeting the conserved region of 16S rDNA in 1016 bacterial species. The phyla Proteobacteria, Firmicutes, Actinobacteria, Cyanobacteria, and Bacteroidetes were the dominant bacterial groups in the river water samples investigated, and alpha-Proteobacteria appeared to be the most dominant among the Proteobacteria. Overall diversity, composition and shifts in the bacterial communities depended mainly on the season. Pollution level (as indicated by nutrient concentration) and specific bacterial sources, such as effluent from wastewater treatment plants and backflow of seawater, also appeared to influence bacterial community structure in these small, fast-flowing rivers.
