Microflora in the Alimentary Tract of Gray Mullet—IV Estimation of Enzymic Activities of the Intestinal Bacteria

Abstract

Polyacrylamide gel electrophoresis was used to compare the enzymic activities of the bacteria in the intestine of gray mullet, Mugil cephalus, an amphidromous fish with an undeveloped stomach. These bacteria may help the digestion of high molecular weight compounds in the intestine. It was found that most of the isolates possessed strong proteolytic activity, in which the gelatinolytic activity was stronger than the caseinolytic activity. Almost all Vibrio and Enterobacter isolated from the intestine possessed strong protease and amylase isozymal electrophoretic bands. Clear differences between the protease and amylase isozyme zymograms were noticed with Vibrio, Enterobacter, and the other isolates. Some of the isolates possessed chitinase and lecithinase activities, but none of the isolates tested showed these activity bands by polyacrylamide gel electrophoresis. All the active patterns obtained from Vibrio and Enterobacter showed more and stronger bands than those from the other isolates. On the other hand, the mullet intestine possessed a detectable level of proteolytic activity, but it did not show any chitinase or amylase activity. The enzymic activities in the digestion of high molecular weight compounds were discussed. © 1979, The Japanese Society of Fisheries Science. All rights reserved.