The inhibitory effect of oregano extract on the growth of Aspergillus spp. and on sterigmatocystin biosynthesis

Abstract

The aim of this study was to investigate the effect of oregano extract on the growth of Aspergillus species (Aspergillus niger, Aspergillus carbonarius, and Aspergillus wentii) isolated from food and biosynthesis of sterigmatocystin (SIC) by Aspergillus versicolor. Antifungal determinations were conducted using the agar plate method. The effect of oregano extract on the biosynthesis of STC was determined in a Yeast Extract Sucrose (YES) broth. The SIC content and mycelial growth of A. versicolor were determined on the 7th, 14th, and 21st day with all applied concentrations of oregano extract and control sample. The composition of oregano extract was determined by gas chromatography-mass spectrometry (GC-MS) and 21 different components were identified. The major components were carvacrol (34.20%) and carvone (18.05%). At 2.5 mL/100 mL concentration, the oregano extract completely inhibited the growth of A. wentii, while the growth of A. carbonarius and A. niger was reduced by 95.6% and 45.6%, respectively. Significant reductions in SIC biosynthesis during 21 days of incubation were observed for extract concentrations higher than 0.06 mL/100 mL. The obtained results showed that the tested oregano extract could be used as a food preservative to prevent food-borne fungal infections and mycotoxin production.