ISOLATION AND CHARACTERIZATION OF PATHOGENIC YEAST STRAINS IN SMOKED CATFISH

Smoked catfish is a common protein source in Nigeria, but its handling and post-processing conditions can introduce pathogenic microorganisms, including yeasts. This study aimed to isolate and characterize yeast strains present in smoked and live catfish samples obtained from the same vendor at Odore Market, Ilorin. Samples were plated on Potato Dextrose Agar (PDA), and after incubation, a single, viable yeast isolate was subcultured and preserved on Yeast Extract Agar (YEA) slants and broth. Molecular identification was conducted through PCR amplification of the ITS region, followed by sequencing and BLAST analysis, which identified the isolate as Saccharomycodesludwigii. Pathogenicity assessment involved two assays. In the first, an antagonistic assay was carried out using circular filter paper discs soaked in yeast broth was placed on nutrient agar plates pre-inoculated with bacterial lawns. Zones of inhibition ranging from 6 mm to 10 mm were observed around the discs, suggesting antibacterial activity. In the second assay, haemolytic activity was tested on blood agar prepared using human blood. The yeast did not produce clear (β) or greenish (α) zones of haemolysis, although slight darkening of the surrounding agar was noted after incubation. The results indicate that Saccharomycodes ludwigii isolated from smoked catfish may exhibit antibacterial properties but lacks evidence of haemolytic ability.