BACTERIOLOGICAL ASSESMENT OF FRESHLY VENDED Cyperus esculentus (L.) IN SOME MARKETS IN BENIN CITY

ABSTRACT

Two (2) samples of fresh tiger nuts were bought from each of four (4) tiger nut hawkers. A surplus quantity of the tiger nuts were obtained at each sampling point, labelled and transported to the laboratory, in sterile ziploc bags, within 2 hrs for further analysis. A 5 g of the fresh tiger nuts sample obtained from each sampling point was washed in 5 ml sterile distilled water in a sterile glass container to form stock. Each sample was shaken vigorously during washing to ensure adequate disengagement of microorganisms. One (1) ml of the stock was serially diluted with nine (9) ml of sterile distilled water up to five (5) fold, and then one (1) ml aliquot was plated on nutrient agar and macconkey agar and incubated at 30 ^oC for 24 hr. The mean total heterotrophic bacterial count ranged from 0.20 x 10⁴ cfu/mlto 8.53 x 10⁴ cfu/ml while the mean coliform count ranged from 0.20 x 10⁴ cfu/ml to 2.13 x 10⁴ cfu/ml. The bacteria species associated with the tiger nut samples included Escherichia coli, Serratia sp., Bacillus sp., Micrococcus luteus, Citrobacter sp., Enterobacter sp., Klebsiella sp and Pseudomonas aeruginosa. The percentage susceptibility of the isolates to the ten commercial antibiotics used ranged from 30% (in Citrobacter sp. and Pseudomonas aeruginosa) to 100% (in Serratia sp.). Micrococcus sp. had the highest distribution, being isolated from six of the eight samples while Bacillus sp., Escherichia coli and Pseudomonas aeruginosa were isolated from only one sample each. The isolation of total bacterial count and coliform count up to 10⁴ indicated a heavy contamination of these fresh tiger nut samples. The satisfactory limit for non-prepackaged beverages and fruits is 10⁴ cfu/ml, count as high as 10² for organisms such as Escherichia coli is considered too high and constitute the infectious dose of this organism. The quality of tiger nut needs to be maintained for the safety of its consumers. This can be actualized by improving the procedures involved in the harvesting, handling, washing, storage and exposure of this fruit.