Antifungal activities of volatile substances generated by yeast isolated from Iranian commercial cheese

A yeast isolate, Candida maltosa NP9, was obtained from a fermented food, Iranian commercial cheese. The strain grown on YPD agar inhibited spore germination of Aspergillus brasiliensis by vapor-agar contact method. Seven volatile compounds generated from the strain were detected by SPME–GC/MS analysis, and three of them were identified as isoamyl alcohol, isoamyl acetate, and phenethyl alcohol by GC/MS analysis. Although phenethyl alcohol did not inhibit the germination at 160 μl/dish by 48 h exposure, isoamyl alcohol fungicidally inhibited at 80 μl/dish and isoamyl acetate fungiostatically inhibited at 160 μl/dish. In antifungal spectra with 15 kinds of filamentous fungi, isoamyl alcohol inhibited the germination of all strains at 20 μl/dish, while isoamyl acetate did not inhibit the germination of three strains even at 160 μl/dish. We demonstrated that C. maltosa NP9 from the fermented food generated volatile isoamyl acetate and isoamyl alcohol to inhibit the germination of those fungi.