Abstract

Introduction: The identification of bacterial species from catfish is an important tool useful on the gene bank on fish bacteria. Aim: This study assessed the use of ultra-violet (UV) light in the treatment of fish pathogens isolated from the eggs of catfish (clarias gariepinus). Materials and Methods: Nine broodstocks of Clarias gariepinus were used. Their eggs were stripped, collected and taken to the laboratory of International Institute of Tropical Agriculture (IITA) Nigeria for culturing, microbial analysis of the eggs and DNA extraction of bacteria from nutrient broth and amplicon taken for molecular characterization. Bio-edit software was used for importing and mining nucleotide sequences into gene bank. Results: The molecular examination of the Clarias gariepinus eggs showed the presence of five bacterial species namely Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, Pseudomonas putida, and Staphylococcus succinus. Prior to UV treatment, on the basis of percentage of similarity, Bacillus species was the most predominant bacterial species isolated from the eggs of the fish sample with 92.95% similarity. Escherichia coli with 91.83% closely followed while the least was recorded in Pseudomonas putida with 84.89%. After exposure to UV treatment, only Bacillus species and Klebsiella pneumonia were detected with % similarity of 96.87% and 90.33% respectively. Pseudomonas putida had the highest nucleic acid (5707.3 ng/µl), followed by Klebsiella pneumonia (4770.1 ng/µl) while the least nucleic acid was recorded in Bacillus subtilis (1299.5 ng/µl). Conclusion: The ultra-violet (UV) light contributed immensely towards the reduction of microbes and its nucleic acid contents in the fish eggs, however in order to preclude adverse effects on egg and survival, UV irradiation, of (200–280 nm) is advised.

Keywords: Broodstock eggs, Ultraviolet light, Bacteria, and Molecular method