Volatile organic metabolites associated with some toxic fungi and their mycotoxins
A toxigenic strain of Fusarium sporotrichioides Sherbakoff was cultivated on straw, wheat and oat grains at a relative humidity of air (RH) of 84–100% for 17 days. Likewise, toxigenic and non-toxigenic strains of Penicillium verrucosum Dierckx were cultured on oat grain, aspen wood and wallpaper at RH 78–98% for 26 days. During the incubation, air samples were collected from the incubation chambers into Tenax TA adsorbent tubes every second day, and 12 microbial volatile organic compounds (MVOC) were identified from the air samples by thermal desorption–gas chromatography. The main MVOC included oct-1-en-3-ol, 3-methylbutan-2-ol, octan-1-ol, octan-3-ol, octan-3-one, hexan-2-one, heptan-2-one, α-pinene, and limonene. Especially ketones were formed in the grain cultures, possibly because of the high lipid content of grain. A relationship between the synthesis of mycotoxins and the relative proportion of different MVOC groups was detected, probably resulting from similar metabolic pathways. The production of volatile terpenes seemed to be linked to the formation of trichothecenes in the F. sporotrichioides cultures, and the P. verrucosum strain that is capable of synthesizing ochratoxin showed an accelerated production of volatile ketones compared with the ketone production of the non-toxigenic strain.