Inhibition potential of gut-derived bacterial from Nile Tilapia against Aeromonas Hydrophila

Abstract

Bacterial diseases, particularly caused by Aeromonas hydrophila, remain a major constraint to Nile tilapia (Oreochromis niloticus) aquaculture. Management of infections relies on application of antibiotics, resulting in accelerated development and spread of antimicrobial resistance. The present study assessed the diversity and probiotic potential against A. hydrophila of gut-derived bacteria from Nile tilapia, using and the cell-free supernatant and satellitism assays. Mature Nile tilapia individuals from three aquaculture farms were dissected, and gut bacteria isolated and identified using culture conventional culture techniques and the VITEK 2 Compact system respectively. Nine bacterial species, namely Staphylococcus gallinarum, S. sciuri, Micrococcus luteus, Kocuria kristinae, Bacillus subtilis, Aeromonas veronii, A. sobria, Rhizobium radiobacter, and Plesiomonas shigelloides, were recorded. None of the five selected gram-positive isolates — S. gallinarum, M. luteus, K. kristinae, B. subtilis, and S. sciuri — showed inhibitory activity against A. hydrophila probably due to inhibitions associated with culture media and conditions. The study recommends improvement in culture techniques that have the potential of maintaining the antagonist activities.