Abstract

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Roadside foods are often contaminated by various pathogenic bacteria, which can cause food borne diseases. This study was aimed at using molecular methods to identify bacterial contaminants in pounded yam sold along major roads in Makurdi metropolis, Benue State, Nigeria. Isolation and biochemical characterization of the bacterial contaminants in pounded yam samples was done on Nutrient agar, Eosine methylene blue and Mannitol salt agar. The ZR DNA Miniprep was utilized in DNA extraction. BigDye Terminator kit was used for sequencing on a 3510 ABI sequencer. BLAST analysis was performed on the sequences. Results of isolation and biochemical characterization revealed six bacterial genera: Pseudomonas spp, Bacillus spp, Staphylococcus spp, Escherichia coli, Klebsiella spp and Proteus spp. Lowest bacterial occurrence of 11.98 % was recorded in pounded yam samples from Gboko, Wadata samples accounted for the highest percentage occurrence of 17.19 %. Escherichia coli and Staphylococcus spp were implicated as the most contaminating bacteria accounting for 20.84 and 19.27% respectively. Bacillus spp was the least contaminating bacteria accounting for 8.33 %. The 16SrRNA gene amplification of the isolated bacterial DNA was at 1500 bp. Result of BLAST analysis revealed the bacterial contaminants in the pounded yam samples as Staphylococcus aureus strain B3A22 (93.80 % pairwise identity), Staphylococcus sciuri strain LZH-22 (93.10 % pairwise identity) and Escherichia coli strain G1F12 (76.70 % pairwise identity). The bacterial contaminants in the pounded yam contain some species involved in food-borne illnesses. Therefore, hygienic way of food preparation is of utmost importance.

Keywords: Molecular characterization, Bacteria, Pounded yam; Food contamination.