Abstract The fatty acid desaturation and elongation reactions catalyzed by Trichoderma sp. 1- OH-2-3 were investigated. This strain converted palmitic acid (16: 0) mainly to stearic acid (18: 0), and further to oleic acid (c 9-18: 1), linoleic acid (c 9, c 12-18: 2), and α-linolenic acid (c 9, c 12, c 15-18: 3) through elongation, and Δ9, Δ12, and Δ15 desaturation reactions, respectively. Palmitoleic acid (c 9-16: 1) and cis-9, cis-12-hexadecadienoic acid were also ...