Abstract
The numbers of bacteria in river water and the epilithon of the river bed were enumerated using color image-analyzed epifluorescence microscopy. Bacteria stained by acridine orange (AO) are known to show fluorescent green or red-orange colors. The two colors of stained particles were separated and counted independently by an image analyzer (nexusQube), and the area of each stained particle displayed on the microscope field was measured. Bacterial communities in the river water and river epilithon were composed of two subcommunities which were stained red-orange or green. The bacterial particles stained fluorescent green were small in area, but the red-orange ones were composed of various sizes of stained particles. Judging from the particle area and color, no differences were observed in the composition of bacterial communities between the river water and the epilithon at the Koremasa site of the Tamagawa River.
