Gene Sequencing and Haemolysis of Bacteria in Clarias gariepinus From Ajilete Location on Yewa River

Abstract

Gene sequencing and haemolysis of bacteria in Clarias gariepinus post juveniles sampled from Ajilete location on Yewa River, Ogun state, Nigeria was carried out. Bacteria were isolated from the gut, gills and skin of the fish. Thirty bacteria isolates were selected and the DNAs were extracted using hexadecyltrimethylammonium bromide (CTAB) method and Polymerase Chain Reaction (PCR) amplification of the isolates was carried out using universal primer for bacteria. The purification of PCR product was done using ethanol precipitation and thereafter the DNAs were sequenced using automated DNA sequencer. The sequence data were analyzed on the GenBank database (NCBI) using Basic Local Alignment Search Tool (BLAST) to find the nearest related sequence, and to construct the phylogenetic relationship. The haemolysis of the selected isolates were also carried out. Data collected were subjected to descriptive statistics. Nine genera of bacteria isolated were Escherichia, Staphylococcus, Enterobacter, Proteus, Pseudomonas, Klebsiella, Citrobacter, Streptococcus and Bacillus. The 16S rRNA gene sequencing method identified the isolates as strains of Brevibacillus agri, Bacillus cereus, Ignatzschineria indica, Comamonas kerstersii, Proteus vulgaris, Lysinibacillus sphaericus, Proteus hauseri, Clostridium bifermentans, Proteus mirabilis, Pseudomonas putida, Escherichia coli, Comamonas jiangduensis, Enterobacter cloacae, Serratia marcescens, Alcaligenes faecalis, Lysinibacillus fusiformis, Myroides odoratimimus. Haemolysis showed that M. odoratimimus, B. cereus, C. kerstersii, P. vulgaris, C. bifermentans, E. coli and E. cloacae all had β-haemolysis. A. faecalis displayed α-haemolysis while, B. agri, I. indica, L. sphaericus, P. hauseri, L. fusiformis, S. marcescens were non-haemolytic. This study confirms the reliability of the 16S rRNA gene sequencing method. This study also concludes that there are different pathogenic bacteria species that are associated with C. gariepinus.