Patent ID: 7670829

Claim:
A Saccharomyces cerevisiae yeast strain genetically modified to autonomously produce, from a simple carbon source, a steroid or steroid derivative derived from cholesterol metabolism, wherein said steroid or steroid derivative is selected from the group consisting of pregnenolone, 17α-hydroxypregnenolone, cortisol, cortexolone, progesterone, 17α-hydroxyprogesterone, and derivatives thereof; wherein the genetic modification comprises: a) the inactivation of ATF2, GCY1 and YPR1, and b) at least one heterologous gene or cDNA in an expression cassette, wherein the gene or cDNA is selected from the group consisting of the gene or cDNA encoding A. thaliana sterol Δ7-reductase, bovine cytochrome P450 SCC , bovine adrenodoxin, bovine adrenodoxin reductase, bovine 3β-hydroxysteroid dehydrogenase/isomerase, human 3β-hydroxysteroid dehydrogenase/isomerase, bovine cytochrome P450 C17, human cytochrome P450 C21, human cytochrome P450 C11, bovine cytochrome P450 C11 and human-bovine hybrid cytochrome P450 C11.