D.Tech. (Biomedical Technology) / To determine the quality of human food commodities commonly consumed in Cameroon, various districts in the western highland (Bamenda and Kumbo) and tropical rain forest (Douala and Yaounde) regions were sampled. Two mycological investigations were conducted to evaluate the incidences of mycotoxigenic fungi (95 samples) and mycotoxins (82 samples). Serial dilution of ground samples was employed to isolate fungi, subculture on various culture media and fungal species were identified morphologically followed by molecular phylogenetic approach. In general, data obtained indicate samples from various geographical regions showed no consistent variation with regard to the type of fungal species. The mycobiota of food materials were characterized by a diversity of fungal species with the predominance of Aspergillus (125 isolates) followed by Penicillium (94 isolates) and Fusarium (52 isolates). The less predominant genera include Rhizopus (14 isolates) and the Alternaria (9 isolates). Aspergillus flavus and A. parasiticus occurred in 53 and 44% of the samples, respectively, with higher frequencies in maize than peanuts or beans and absent in rice, pumpkin seed and cassava products. Aspergillus fumigatus was detected in 20% of samples and A. niger in 18% of the samples. Aspergillus isolated less frequently included A. carbonarius A. awamori, A. oryzae and A. tamarii, A. pseudotamarii, A. ochraceus, A. ostianus, A. avenaceum, A. oryzae and A. variabile. Consistent results were observed for A. tamarii, A. pseudotamarii, A. ochraceus and A. ostianus with respect to substrate specificity. While A. tamarii, A. pseudotamarii and A. ochraceus were isolated only from peanuts, A. ostianus strains occurred only in bean samples. Penicillium contamination was dominated by P. polonicum and P. crustosum with incidence rates of 43 and 41%, respectively, with highest contamination levels registered in samples from Yaounde. Penicillium citrinum, P. purpurogenum, P. islandicum, P. aurantiogriseum, P. expansum were also inconsistently isolated from food samples. There was a relatively low incidence of Penicillium spp. in pumpkin seed and fermented cassava product samples.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:7738 |
| Date | 17 September 2013 |
| Creators | Berka, Njobeh Patrick |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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