Evaluation of microorganisms associated with vended frozen fish in Ado Ekiti locality

Abstract

Fishes are world widely consumed by all categories of works of life because of their richness in protein, readily available and affordable by all. The basic nutrient of protein in fish that is so important in man’s diet also attracted microorganisms for their growth and multiplication. Meanwhile, the association of microorganisms in fishes depend on the environment of culture and their proliferation due to inadequate storage facilities. The aim of this study was focused on the isolation and identification of microorganisms from four frozen fish species sold in the Ado Ekiti metropolis. Frozen fish samples of Scomber scombrus (Atlantic Mackerel), Clupea harengus (Atlantic herring), Urophycis tenuis (White hake or mud hake) and Trachurus trachurus (Atlantic horse mackerel) from two markets in Ado Ekiti were microbiologically analyzed for possible microbial contamination. On the fish samples, the total heterotrophic count (THC) was 3.5×104 – 5.6×104 CFU/g, total coliform count (TCC) was 2.4×104 – 5.1×104 CFU/g, total Salmonella/Shigella count (TSSC) was 1.3×104 – 3.5×104 CFU/g, total Vibrio count (TVC) was 1.1×104 – 2.3×104 CFU/g and total fungal count (TFC) was 1.3×103 – 2.3×103 Spore/g were analyzed by cultural methods. There were variations in microbial loads among the fish species in the surveyed markets. The microorganisms identified with their percentage occurrence were Bacillus cereus (11.54%), Streptococcus faecium (13.46%), Alcaligenes faecalis (5.77%), Salmonella enterica serovar Typhi (5.77%), Micrococcus luteus (9.62%), Vibrio cholerae (7.69%), Aerococcus viridans (3.85%), Pseudomonas aeruginosa (7.69%), Xanthomonas fragariae (7.69%), Staphylococcus aureus (11.54%), Clostridium butyricum (7.68%), Escherichia coli (7.69%), Aspergillus fumigatus (11.11%), Aspergillus flavus (24.44%), Aspergillus clavatus (8.89%), Aspergillus fishcheri (6.69%), Aspergillus terreus (8.89%), Mucor mucedo (17.78%), Penicillium digitatum (13.33%) and Aspergillus parasiticus (8.89%). The results emphasized the microbial contamination of the fishes. The results obtained could serve as an awareness to consumers that microbial infection is possible from frozen fishes and as data for future reference in epidemiology or outbreak of disease from eating frozen fish.