Intestinal Enzyme Activity and Enzyme Producing Microbial Flora in Relation to Feeding Behaviour in Some Brackishwater Teleosts

Abstract

Estimation of digestive enzyme activity, isolation and enumeration of aerobic microbial flora from the gastrointestinal tract of five brackishwater fish species (Mugil cephalus, Liza macrolepis, Mugil Lade, Chanos chanos, Lates calcarifer and Oreochromis mossambicus) of different feeding habits were carried out. The herbivorous (M. cephalus, C. chanos, M. Lade and L. macrolepis) and omnivorous (0. mossambicus) showed marked protease activity, whereas moderate protease activity was recorded in carnivorous L. calcarifer. In the herbivorous and omnivorous fish species the concentration of amylase was moderate to high. A very weak amylase activity was recorded in L. calcarifer. Cellulase activity has been found to be more pronounced in C. chanos, whereas, 0. mossambicus, M. cephalus, M. fade and L. macrolepis showed only moderate cellulase activity. Cellulase activity was weak in L. calcarzfer. Proteolytic, amylolytic, lipolytic and cellulolytic microflora were identified from the culture plates using selective media. The isolates were qualitatively screened on the basis of their extracellular enzyme producing ability. The selected isolates were further quantitatively assayed for protease, amylase and cellulase activities. Proteolytic activity was high in 0. mossambicus, whereas the activity of amylase and cellulase was high in the gastrointestinal tract of C. chanos. Protease activity was exhibited by almost all the bacterial isolates. Maximum activity of protease was exhibited by an isolate from L. macrolepis, followed by an isolate from L. calcartfer. Isolates isolated from 0. mossambicus and C. chanos exhibited high cellulase and amylase activity. Study indicated a distinct microbial source of the digestive enzymes (protease, amylase and cellulase) apart from endogenous sources in fish gut.