Biological control of aflatoxin-producing Aspergillus flavus by volatile organic compound-producing antagonistic yeasts

Abstract

Aspergillus spp. are the most common phytopathogenic fungi able to produce various types of aflatoxins. Yeasts can produce volatile organic compounds (VOCs) that may be used as biocontrol agents against mycotoxigenic fungi. In this study, we aimed to evaluate antagonistic yeasts that are potentially capable of producing active VOCs against the aflatoxin-producing fungus, Aspergillus flavus A39. In total, 366 epiphytic and endophytic yeast strains isolated from leaves of rice, sugarcane, and corn in Thailand were screened for their potential. Only 49 yeast strains were able to produce antifungal volatile organic compounds (VOCs). Candida nivariensis DMKU-CE18 was the most effective yeast strain to inhibit the mycelium growth (64.9 ± 7.0% inhibition) and conidial germination (49.3 ± 3.3% inhibition) of A. flavus A39, and to reduce aflatoxin production (74.8 ± 6.5% reduction) in corn grains. The analysis results of headspace gas chromatography/mass spectrometry (GC/MS) revealed that the major VOC produced by this yeast strain was closest to 1-pentanol.