Microbial Load of Some Medicinal Plants Sold in Some Local Markets in Abeokuta, Nigeria

Purpose: To evaluate the microbial load on 17 randomly selected plant samples from 60 ethnobotanically collected medicinal plants from five local markets in Abeokuta, Ogun State, Nigeria. Method: The pour plate method was used to cultivate serially diluted portions of the medicinal plant samples investigated. Enumeration of bacteria was carried out on nutrient agar (NA) while that of fungi was effected on Sabouraud agar (SA). Results: The identified microbial isolates include 12 bacterial and 6 fungal genera. The mean heterotrophic bacteria counts of the different herbal samples ranged from 1.3 × 10^5 cfu/g (Cnestis ferruginea) to 6.7 × 10^6 cfu/g (Daniellia oliveri), while total fungal propagule counts ranged from 0.0 × 10^1 cfu/g (Terminalia superba, Cola gigantea, Rauwolfia vomitoria, Zingiber officinale and Argemone mexicana) to 7.1 × 10^6 cfu/g (Nesogordonia papaverifera). The synopsis and frequency (prevalence rate) of microbial species isolation showed that Bacillus spp. (82.4 %) and Mucor spp. (47.1 %) had the highest prevalence rates among bacteria and fungi, respectively. Conclusion: The findings from this study emphasized the need for constant quality assessment of herbal drugs on sale in order to ensure the production of therapeutic products suitable for human consumption.