Double-bond requirement in a fatty acid desaturase mutant of Saccharomyces cerevisiae.

A fatty acid Delta(9)-desaturase mutant of yeast was analyzed to establish the specificity of the fatty acid structural requirement. Several double-bond-containing and substituted fatty acids were tested. It was concluded that the presence of a Delta(9)cis double bond is necessary for growth. The need for a specific chain length or a specific number of double bonds, or for both, is more flexible. Tracer-containing 16:1Delta(9)cis, 18:1Delta(9)cis, 18:2Delta(9,12)cis,cis and 18:3Delta(9,12,15) all cis revealed that each of these growth-supporting components, once taken up, was not converted into other fatty acids. Concentration effects on doubling time were also considered.