Antifungal Effect of Thymus vulgaris Methanolic Extract on Growth of Aflatoxins Producing Aspergillus parasiticus

Abstract

THIS STUDY illustrates a simple method for the detection of the ability of Aspergillus parasiticus, isolated from peanut seeds, for the production of aflatoxins. The indicator of aflatoxins production ability is the appearance of colony reverse yellow color of the fungus on the agar media and the natural fluorescence of aflatoxin around the colony when observed under UV (black light 350BL) after three days of incubation at 28oC. The morphological identification of A. parasiticus was confirmed by molecular identification rDNA sequencing. The addition of β-Cyclodextrin to media enhanced the natural fluorescence of aflatoxin around the colony under UV. The extract of Thymus vulgaris had an inhibitory effect on the growth of A. parasiticus. The minimum inhibitory concentration (MIC) of Thymus extract against A. parasiticus was 80μL of Thymus extract /10 ml of YSA medium. The effective concentration of Thymus extract causing a 50% inhibition of mycelial growth (EC50) was 20μL of Thymus extract /10mL of YSA medium. The chemical analysis of Thymus extract by Gas Chromatography-Mass Spectroscopy (GC-MS) illustrated that the thymol has a retention time (RT) (min) of 37.538 at the highest percent area (13.8717 Area %).