INCIDENCE OF GRAM-NEGATIVE BACTERIA ASSOCIATED WITH GUTS OF FISH FED HERBAL MIXTURES OF TREATMENT

This study examined the incidence and diversity of Gram-negative bacteria associated with gut of Clarias gariepinus (African catfish) fed herbal mixed feeds in Okitipupa local government Olusegun Agagu University of Science and Technology, Ondo state, Nigeria. Gut samples were collected from fish subjected to herbal treatments, and microbial isolates were identified based on colonial morphology, Gram staining, and standard biochemical tests. Serial dilutions were carried out on the samples collected and cultured on the plate with Nutrient Agar and the sample was incubated for 24hours, subculturing were carried out to obtain pure colonies. colonial counts ranged from 680 to 204 for isolations done at 10-1 to 10-5 on the samples. Gram staining revealed only one of the isolates to be gram negative with cocci shaped pinkish colour , Biochemical reactions revealed positive results for catalase and oxidase test while coagulase test is negative. Sugar fermentation tests showed acid and gas production for glucose, lactose, mannitol and xylose . Based on biochemical tests, the organism was confirmed to be Psychrobacter immobilis. These microbes exhibited characteristic acid and gas production from carbohydrate fermentation, suggesting their probiotic potential. It is then concluded that the results of this study demonstrate that incorporating herbal mixtures into the diet of Clarias gariepinus significantly affects the composition of gut microflora. Psychrobacter immobilis was isolated, suggesting a shift in microbial balance toward more probiotic and non-pathogenic species. The ability of this bacteria to ferment various sugars and produce acid or gas indicates their functional role in nutrient metabolism and gut health.