Production of extracellular enzymes by the gut and gill microflora of Tilapia fish (Oreochromis niloticus)

Mala Sasmal, Rina Rani Ray


Tilapia (Oreochromis niloticus), is one of the most widely consumed and cultured fish in West Bengal, India.  Being a fish with high range of ecological adaptivity, deserves extensive research to study the correlation between the food habit of the fish and the contribution of the associated microflora. This is further required for the preparation of high quality functional feeds from inexpensive precursor materials.

 An attempt was made to investigate the gill and gut micro flora associated with fresh Tilapia fish, to study their competence to produce various enzymes that would help the fish to digest its food.The prominent isolates from bacterial inhabitants of gill and gut of Tilapia were found to produce extracellular amylase, cellulase, pectinase and xylanase. Major colony forming bacterial strains were Gram positive, catalase positive, non-motile rods. The strains, after 48 hours showed remarkable growth and production of huge amount of extracellular pectinase and xylanase  and moderate amount of cellulase and amylase which indicated the abundance of hemicellulosic and pectin rich food in the gut of Tilapia fish. The change in pH profile showed a drastic fall in pH concomitant with sugar uptake. The bacterial isolates from gills showed a relatively lower enzymatic activities than their intestinal counterparts.


amylase, cellulase, pectinase, xylanase, Oreochromis niloticus, fish microflora.

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