Identification and characterization of Δ12 and Δ12/Δ15 bifunctional fatty acid desaturases in the oleaginous yeast Lipomyces starkeyi.

Fatty acid desaturases play vital roles in the synthesis of unsaturated fatty acids. In this study， Δ12 and Δ12/Δ15 fatty acid desaturases of the oleaginous yeast Lipomyces starkeyi， termed LsFad2 and LsFad3， respectively， were identified and characterized. Saccharomyces cerevisiae expressing LsFAD2 converted oleic acid (C18:1) to linoleic acid (C18:2)， while a strain of LsFAD3-expressing S. cerevisiae converted oleic acid to linoleic acid， and linoleic acid to α-linolenic acid (C18:3)， indicating that LsFad2 and LsFad3 were Δ12 and bifunctional Δ12/Δ15 fatty acid desaturases， respectively. The overexpression of LsFAD2 in L. starkeyi caused an accumulation of linoleic acid and a reduction in oleic acid levels. In contrast， overexpression of LsFAD3 induced the production of α-linolenic acid. Deletion of LsFAD2 and LsFAD3 induced the accumulation of oleic acid and linoleic acid， respectively. Our findings are significant for the commercial production of polyunsaturated fatty acids， such as ω-3 polyunsaturated fatty acids， in L. starkeyi.