Molecular Characterization of Bacteria Isolates from Farm-Raised Catfish Clarias gariepinus (Burchell, 1822)

Selected bacterial isolates from skin, gut and gills of Clarias gariepinus were collected from five fish farms at Ijebu Ode. The isolates were assessed using 16S rRNA gene sequencing method to identify them and to construct the phylogenetic relationship. A total of 10 isolates were selected, their colonial morphology determined, thereafter the DNA of the isolates were prepared using CTAB method, PCR amplification of 16S ribosomal RNA gene of isolates was carried out using universal primer for bacteria, purification of the PCR product using ethanol precipitation, thereafter sequenced using an automated DNA sequencer. These sequence data were compared with other gene sequences in GenBank database (NCBI) using a BLAST search to find closely related sequences. 80% of the isolates belonged to different species of Pseudomonas, sharing 92% to 96% 16S ribosomal RNA identity with the respective type-strain, whereas the remaining 2 isolates belonged to Pediococcus acidilactici and Lysinibacillus fusiformis with 96% 16S ribosomal RNA homology.