Genetic diversity studies of bacteria isolated from Clarias gariepinus along Yewa river in Nigeria using Random Amplified Polymorphic DNA (RAPD) techniques and their antibiotic resistance profile

Abstract

Pathogenic bacteria are responsible for heavy mortality in both wild and cultured fish. Molecular characterization was carried out using Random Amplified Polymorphic DNAPolymerase Chain Reaction technique (RAPD-PCR), sensitivity to antibiotics of bacteria in Clarias gariepinus post juveniles sampled. Bacteria were isolated from the gut, gills and skin of the fish. Identification was done using the conventional culture-based method. Thirty bacteria isolates were selected and the DNAs were extracted using CTAB method, PCR amplification of the isolates was carried out using RAPD primer and five primers were used. Data collected were subjected to descriptive (mean and standard deviation) statistics. There were 63 polymorphic and 14 monomorphic markers generated from the five RAPD markers. The primers generated 77 alleles altogether. Out of the 10 antibiotics used, Cephalexin recorded the highest inhibition zone (33 mm) on one sample, Gentamicin on second sample had (30 mm). The least inhibition zone was recorded in Cotrimoxazole on the second sample with (8 mm), 70.5 % bacteria strains were susceptible to Gentamicin while two samples displayed 100 % resistance to all the antibiotics. This study concluded that there are pathogenic and opportunistic bacteria species in C. gariepinus which could be zoonotic.

Keywords: bacteria isolates, genetic diversity, RAPD-PCR, DNA extraction, sensitivity, Clarias gariepinus Polymorphism, Antiboitic