Cultures of the basidiomycete Fistulina hepatica have been studied to determine the times of appearance of acetylenic natural products. A triacetylenic alcohol has been isolated from the ethereal extract of mycelial cultures of F. hepatica. On the basis of spectroscopic data, its structure was determined to be cis-3-tridecene-5,7,9-triyne-1,11- diol. The structure has also been determined for an unsaturated fatty acid, which accumulates when a parsley desaturase is expressed in soybeans. The compound, identified as (14Z)-dehydrocrepenynic acid by NMR and mass spectral data, is believed to be a widely used intermediate in the crepenynate pathway to polyacetylene production in plants and, presumably, fungi. A yeast expression system capable of overexpressing FAD2-type desaturases that may be involved in the biosynthesis of acetylenic natural products was optimized with respect to growth conditions and host cell strain. This system may be suitable for the expression of fungal acetylenases from F. hepatica.