Isolation And Characterization Of The Bacterial Flora Of Soy Milk Sold In Nsukka Market

Abstract

A total of five bacterial isolates designated A1, A2, A3, A4 and A5 were obtained from twelve locally produced soy milk samples purchased from different locations in Nsukka town. The soy milk samples comprised seven unrefrigerated and five refrigerated samples. All samples were 24h-old according to information gathered from the sellers. Using conventional microbiological and biochemical procedures, the isolates were presumptively identified as Aeromonas spp, Bacillus cereus, Klebsiella spp, Pseudomonas spp and Staphylococcus aureus. The total viable bacterial counts in the beverage ranged from 3.4 x 108—7.5 x 108 cfu/ml. The highest number of viable cells was recorded with Staphylococcus aureus, which also had the highest percentage frequency (100%), as it occurred in all the soy milk samples studied. Aeromonas spp had the lowest percentage frequency, occurring in only two samples. Generally, there were relatively higher bacterial numbers in the unrefrigerated than in the refrigerated soy milk samples. Results of the study highlight the laxity in hygiene on the part of the producers of the beverage since majority of the isolates are members of the human body flora.

Keywords: Aeromonas spp, Bacillus cereus, Klebsiella spp, Pseudomonas spp and Staphylococcus aureus

Plant Product Research Journal Vol. 12 2008: pp. 23-26