Study on the Intestinal Microflora of Salmonids

Abstract

A study on the actual condition and changes of normal bacterial flora in the intestines of salmonids was carried out to determine the actual status of bacterial flora in the digestive tract, particularly in the intestines, in the course of their life cycle, i.e. migration from fresh water to the sea and back to the original river. From the results of this study, it would be concluded as follows. The intestinal microflora of healthy salmonids are mainly composed of the genus Aeromonas and the family Enterobacteriaceae of a so called terrestrial type, if they are living in fresh water. Contrarily, the flora are mainly composed of the genus Vibrio of marine or halophilic type when they are living in sea water. If fish move to the sea or upstream a river in their life cycle, the flora in their intestines would undergo changes in order to adequaely adapt the fish themselves for their living environments. A study on the actual condition and changes of normal bacterial flora in the intestines of salmonids was carried out to determine the actual status of bacterial flora in the digestive tract, particularly in the intestines, in the course of their life cycle, i. e. migration from fresh water to the sea and back to the original river. From the results of this study, it would be concluded as follows. The intestinal microflora of healthy salmonids are mainly composed of the genus Aeromonas and the family Enterobacteriaceae of a so called terrestrial type, if they are living in fresh water. Contrarily, the flora are mainly composed of the genus Vibrio of marine or halophilic type when they are living in sea water. If fish move to the sea or upstream a river in their life cycle, the flora in their intestines would undergo changes in order to adequaely adapt the fish themselves for their living environments. © 1976, The Japanese Society of Fish Pathology. All rights reserved.