Isolation and Identification of Bacteria Associated with Commercially Hawked Ready-To-Eat Fried Fish Sold in Jos Metropolis

Aims: This study aimed to isolate and identify bacteria associated with commercially hawked ready-to-eat fried fish sold in Jos metropolis in Plateau State, Nigeria.

Methodology: A total of 20 fried fish Samples were obtained through random sampling of fish from vendors and collected in a sterile polyethylene bag and packaged in a sterile foil paper and then it was transported to the laboratory. The media used such as Nutrient agar (NA), Blood agar and MacConkey agar were prepared following the manufacturer’s specification. For microbial isolation, 5mL of each sample was dissolved into 50mL sterile water inside different beakers. Then, 1mL of the dissolved sample was aseptically transferred into 9mL sterile distilled water and serially diluted up to the appropriate dilutions (i.e., 10-1 to 10-6 dilutions). From the dilutions 10-3, 0.1mL was aseptically transferred into sterile Petri dishes and their spread plated with already sterilized molten media. The Petri plates were incubated at 37oC for 24hrs for bacteria. After incubation, the cultural characteristics, colonial morphology were observed on the plates. Pure colonies were obtained by sub-culturing on a fresh growth media and stored at a refrigeration temperature of 0-4oC. Microbial isolates were identified by biochemical and phenotypic characterization.

Results: A total of 35 bacteria species were isolated from 20 commercially hawked ready-to-eat fried fish samples sold within Jos metropolis of Plateau State, Nigeria. The laboratory analysis revealed a significant microbial contamination. Pathogenic bacteria Isolated includes: Staphylococcus aureus, Klebsiella aerogenes, Escherichia coli, Salmonella spp., Pseudomonas aeruginosa and streptococcus spp., while non-pathogenic or opportunistic isolates includes: Bacillus coagulans, Bacillus circulans, Citrobacter spp., Coagulase-negative staphylococci and Rahnella inusitata. Total bacterial counts (TBC) reached alarming levels, such as 3.6 x 10^6 CFU/g in sample ABTe. Notably, Klebsiella aerogenes was the most frequently isolated organism, accounting for 28.57% of all isolates, indicating widespread contamination in the local aquatic environment.

Conclusion: The presence of pathogenic bacteria underscores the need for improved food safety measures among vendors. Comparative analysis with prior studies shows consistent contamination levels, reinforcing the necessity for stringent hygiene practices.