ISOLATION AND IDENTIFICATION OF BACTERIA FROM ENVIRONMENTALLY EXPOSED TIGERNUT TUBERS (Cyperus esculentus)

ABSTRACT

Tiger nuts (Cyperus esculentus) are annual crops that are consumed as snack, for their medicinal and nutritional values. Thus, if exposed to microbial contamination, can result public health threat. This present study was aimed at analyzing the bacteria load in environmentally exposed tiger nuts tubers (Cyperus esculentus) sold by street vendors in different markets in Benin City, Nigeria. Tigernut samples were obtained from three (3) different markets. The samples were taken to the laboratory and assessed using microbiological techniques. Serial dilutions were made and required volumes (0.1ml) of test samples were dispensed separately into sterile Petri dishes and spread plated with Nutrient Agar for enumeration of colonies. The bacteria coliform counts (CFU) for each market ranged from 1.5±2.42x104 cfu/ml to 9.0±2.62x103 cfu/ml (Ekosodin Market), 1.4±1.19x104 cfu/ml to 7.7±1.17x103 cfu/ml (New Benin market) and 2.42±1.8x103 cfu/ml to 5.7±2.68x103 cfu/ml (Oba market) in that order. The frequency of occurrence for the bacterial isolated were 18 for Bacillus subtilis, 5.7 for Staphylococcus aureus , and 4 for Micrococcus sp in Ekosodin market ; 13.7 for Bacillus subtilis, 7.5 for Staphylococcus aureus , 2 for Serretia marcescens and 3 for Micrococcus sp in New Benin market; 14.7 for Bacillus subtilis, 9 for Staphylococcus aureus , 5 for Serretia marcescens and 7 for Micrococcus sp in Oba market, Ring road. The high microbial count reported in this work which are above acceptable thresholds are indications of serious health concerns since the tubers are usually consumed without further washing. Therefore, tigernut tubers purchased from vendors/hawkers should be decontaminated by proper washing and surface sterilization before processing it into tigernut drink in order to drastically reduce microbial contamination of the finished product.