Studies on the intestinal bacterial flora of tilapia Oreochromis mossambicus (Peters, 1852) and optimization of alkaline protease by Virgibacillus pantothenticus

Abstract

The intestinal bacterial flora of the fish Oreochromis mossambicus and optimization of alkaline protease production was carried out in this study. The fish, tilapia were collected from the Buckingham canal and were segregated into four size groups namely, 5 to 8, 9 to 12, 13 to 16 and 17 to 20 cm. The maximum number of gut bacteria (2.5×10 6 Cfu/g ml -1) was enumerated in 5-8 cm group of fish and minimum (4.9×10 5 Cfu/g ml -1) in 17 to 20 cm. The isolated strains were identified as Virgibacillus pantothenticus, Bacillus cereus, Bacillus licheniformis, Enterococcus faecalis and Virgibacillus alginolyticus. Among the isolated bacteria, V. pantothenticus gave the maximum yield of alkaline protease at pH of 9.5 and 40°C temperature. It is also inferred from the study that the seaweed, Sargassum tenerrimum and oil sardine, Sardinella longiceps fish waste were found as good carbon and nitrogen sources respectively for the production of alkaline protease. The studies on fish gut microflora are very much needed for the management both in aquaculture and public health. The result of alkaline protease production by V. pantothenticus is encouraging and it can be applied for bioconversion of fish waste and sea weed from aquafeed formulation and subsequent reduction in feed related waste outputs.