Isolation and Distribution of Obligate Anaerobic Bacteria from the Intestines of Freshwater Fish

Abstract

Enumeration and isolation of obligate anaerobes from the intestines of freshwater fish were undertaken using various media and anaerobic culture methods. NBGT modified (NBGT-1/3S) was found to be the most useful medium in selection of obligate anaerobes from freshwater fish. Obligate anaerobes were commonly present in the intestines of various freshwater fish and showed a range of viable counts on NBGT-1/3S agar from 10⁶ to 10⁹ per gram of intestinal contents. Obligate anaerobes were predominant over facultative anaerobes especially in the intestines of Tilapia fish and ayu among the fish samples tested. Using EG and NBGT-1/3S agar, two types of bacteria which belong to the family Bacteroidaceae were isolated from various freshwater fish.