Occurrence of Bacterial Contaminants in Fin-fishes (Clarias gariepinus and Coptodon guineensis) from Humic Freshwater Ecosystem of Eniong River, Itu, Akwa Ibom State, Nigeria

Abstract

The occurrence of bacterial isolates in fin-fishes (Clarias gariepinus and Coptodon guineensis) from the humic ecosystem of Eniong River, Akwa Ibom State was investigated. The results obtained from pour plate analysis showed that the fin-fishes contained bacterial contaminants. The bacterial   loads varied with the type of fin-fish and were much higher in fish intestines, when compared with the skin and gills. The heterotrophic bacterial loads obtained exceeded the 1.2 x 105 cfu/g limit recommended for fresh fishes. High and unsafe fecal coliform (1.1 ± 0.57 x 103 cfu/g -2. ± 0.26 x 103 cfu/g) loads were also obtained. The culture-able bacteria species associated with the fin-fish samples include Staphylococcus sp, Klebsiella sp, Bacillus sp, Enterobacter, Streptococcus sp, Micrococcus sp, Lactobacillus, Serratia sp, Proteus sp, Salmonella sp, Shigella sp, and Escherichia coli. The percentage of occurrence of the isolates in the various fish samples was also found to vary with the fish species. Staphylococcus sp had the highest rate of occurrence of 63% and 44.4% in C. gariepinus and C. guineensis respectively while the least prevalent organism was Micrococcus sp with 7.41%, and Serratia and Shigella sp with 11.1% for C. gariepinus and C. guineensis respectively. Twelve bacterial species with variable virulent potentials were isolated. The analysis revealed that each of the isolates exhibited varying degree of virulence. Of the 12 bacterial isolates obtained from the various fish samples, ten (Bacillus cereus, Micrococcus sp, Streptococcus sp., Proteus sp, Serratia sp, Salmonella sp., Shigella sp., E. coli, Enterobacter sp and Lactobacillus sp had the potentials to produce lipases enzyme. This enzyme is responsible for breaking down lipids.  Among the isolates Stahylococcus aureus was the most virulent. The results indicate poor microbiological quality. These call for proper processing of aquatic foods as well as routine monitoring.