Formation of a 5 hydroxy sterol by Saccharomyces cerevisiae

The incorporation of 28 ¹⁴C] ergosta-7,24(28)-dien-3β-ol into ergosta-7,22-dien-3β,5α-diol by aerobically growing $\text{S.}\text{cerevisiae}$ has established its presence in this organism. This, coupled with previous work, is considered to be substantive evidence for the operation of a hydroxylation-dehydration mechanism in the introduction of Δ⁵ unsaturation in ergosterol biosynthesis in yeast.