Isolation and identification of spoilage microorganisms from different varieties of tomatoes

Abstract

Tomatoes is one of the perishable fruits grown in large quantity in Nigeria and the world over. Six different varieties that are mostly grown in Nigeria was studied for the microorganisms responsible for their spoilage using standard microbiological methods. Different media was used to help identify the bacteria and fungi and determine their load. The results showed that cherry tomatoes have the highest bacterial load of 6.9×104 cfu/g, while the grape and beske tomatoes both have the least bacterial loads of 2.6×104 cfu/g respectively. Beef tomato had the second highest bacterial load of 5.5×104 cfu/g, while this is closely followed by plum tomato. In all, a total of six (6) bacteria were isolated from the different species of tomatoes used for this assay. They are Enterobacter aerogenes, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli and Proteus mirabilis. A total of nine (9) fungi were isolated from the tomato samples and they are Aspergillus Niger, Rhizopus stolonifer, Mucor mucedo, Aspergillus flavus, Fusarium oxysporium, Penicillium oxalicum, Pithomyces sp, Penicillium notatum and Rhizopus oligosporus. The results obtained has shown that spoilt tomatoes habour pathogenic bacteria and fungi which can produce different types of mycotoxins that are toxic to man’s health. Therefore, tomatoes should be preserved properly and spoilt tomatoes should never be consumed. Also, spoilt tomatoes should be disposed properly in order not to endanger the public. Tomatoes to be eaten raw should be washed properly with clean water to avoid consumption of these bacteria and fungi as well as their toxins.