Microbial infections of yam could be at any stage in its growth, from the seedling stage through to postharvest. Thus, this research study has been designed to investigate, compare and evaluate various microbes (bacteria and fungi) that may be present on and associated with selected commercial dry white and water yam at two popular Ibadan markets. Yam chips were purposively obtained from two markets (Oja Oba and Bodija) and were milled in the laboratory using a sterile milling machine. The microbial result of the first, second, and third analysis of white yam flour showed that Oja Oba samples had total viable microbial count ranging from 2.9 × 104 to 1.7 × 104, 2.9 × 104 to 1.4 × 104 and 8.1 × 104 to 1.5 × 104 respectively compared to Bodija samples which range from 1.3 × 104 to 7 × 103, 1.8 × 104 to 7 × 103 and 3.6 × 104 to 9 × 103 respectively. For water yam flour samples analysis, Bodija samples showed the result counts of 4.2 × 104, 4.4 × 104 and 1.02 × 105 respectively while Oja Oba samples showed counts of 5.4 × 104, 6.3 × 104, and 1.62 × 105 respectively. Different bacteria and fungi were isolated namely Bacillus cereus, Bacillus subtilis, Pseudomonas sp, Enterobacter sp, Flavobacterium sp, Rhizopus stolonifer, Aspergillus niger, Penicillum oxalicum, Monillia, Mucor, Aspergillus flavus, Pythium. Thus, the result of this study has shown that dried yam flour samples from Oja Oba had a higher total viable microbial count compared to the samples from Bodija while the prepared control samples had a low micro-organism population compared with all the collected market samples. The bacteria and fungi isolated from white yam and water yam samples irrespective of the market, were similar. Bacillus spp, Rhizopus stolonifer, Aspergillus niger, Penicillum oxalicum, Aspergillus flavus were found to commonly present in both water yam and white yam of the two markets and in addition, Monillia and Pythium were found only on water yam and white yam sample respectively in Bodija market. The microorganisms commonly isolated from all the yam flour samples irrespective of variety and location were Rhizopus stolonifer, Aspergillus flavus, Penicillium oxalicum and Aspergillus niger.
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