Antifungal effects of Ocimum Kilimandscharicum oil on Aspergillus flavus Infecting Maize after Harvest

Abstract

Maize is consumed throughout the year in Kenya. Storage facilities of Maize vary with the economic status of the producers. Poor resource producers are likely to have unsuitable storage facilities whose conditions may predispose stored maize to post-harvest fungal infections. The most frequently encountered fungus in stored maize is Aspergillus flavus which produces aflatoxins that causes teratogenic, carcinogenic, mutagenic and hepatotoxic problems. Fungicides are used to control post-harvest fungi, but these have health implications. Hence an alternative safe method is the use of plant-based products which have anti-fungal compounds. This study was therefore designed to evaluate growth inhibitory effects of Ocimum kilimandscharicum oil on Aspergillus flavus. The leaves were collected from the plants growing naturally in Ruiru in Kiambu County, and the leaves were air dried in a shed, and oil was extracted through hydro-distillation. A total of 80 kg of threshed stored maize collected from randomly selected farms in Murang'a County were used to isolate Aspergillus flavus. Fungal growth experiments were done on PDA amended with different concentrations of the oil. Significant (p ˂ 0.001) inhibition of fungal radial growth occurred at oil concentration of 3.33 ul/ml. However, concentrations above 6.67ul/ml totally inhibited the growth of the fungus. Similarly, significantly (p ˂ 0.001) large zones of inhibition were observed in the highest concentration of 400 ul/ml. From the results, it can be concluded that O. kilimandscharicum oil acts against Aspergillus flavus and is a potential source for developing an antifungal agent. It is recommended that the efficacy of this oil needs to be tested on other post-harvest fungi.