Fungi Associated with Contaminated Stored Grains and their Biological Control using Zanthoxylum rhetsa Essential Oil

Abstract

In the present investigation antifungal activity of essential oil obtained from Zanthoxylum rhetsa was studied against some fungi contaminating stored grains. A total of 83 fungal isolates were obtained from contaminated samples collected from West Guwahati markets, India. The frequently isolated fungal species were Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus and fungi belonging to genera Penicillium and Mucor. Essential oil of Zanthoxylum rhetsa was obtained by hydro-distillation using Clevenger apparatus. Antifungal efficacy of the essential oil against the isolated fungi was carried out by Agar Cup Diffusion assay. The result indicated that all the fungal species showed varying degree of antifungal activity. Amongst the fungi, Aspergillus niger showed high susceptibility toward the oil followed by Aspergillus fumigatus and Penicillium italicum while least antifungal activity was observed in Aspergillus flavus. The essential oil of Zanthoxylum rhetsa was characterized by GCMS analysis. The result indicated one strong peak and two minor peaks indicating the presence of bioactive metabolites. Since most of the isolated fungal genera produced aflatoxin which causes toxicity to living organisms including humans, the inhibition of these fungi genera by the essential oil of Zanthoxylum rhetsa is promising eco-friendly approach to control such contamination.