Abstract
The microbial community detected in the biofilm of two types of riverbed stone, mudstone and sandstone, were compared for bacterial community composition and LV-SEM observation. The surface microbial community of each type of stone was divided into three fractions by ultrasonic treatment, and we obtained bacterial strains from each fraction. Those strains were examined and compared for their physiological characteristics. The bacterial community composition of each fraction differed in both kinds of substrate stones. Especially, the bacterial community in the crack of sandstone had similar bacterial strains that were seemed to flourish in that crack. It was suggested that the pioneer of the microbial community on the river bed stones was determined by the crack size of the surface structure of the substrate stones.
