Rewiring yeast for drug synthesis

You can’t teach an old dog new tricks (so the adage goes). But it appears that baker’s yeast is more accommodating. In one of the most comprehensive metabolic engineering feats ever accomplished, a report in this issue1 describes a yeast strain with altered sterol pathway that can use a simple carbon source to synthesize hydrocortisone,an anti-inflammatory steroid hormone commonly used to treat ailments such as arthritis, skin disorders, and adrenal insufficiency.