An adjuvant made in yeast could lower vaccine cost and boost availability

Adjuvants make vaccines more effective, though one of the best is an expensive extract from the soap bark tree. To lower the cost and avoid the laborious extraction process from bark, synthetic biologists introduced 38 separate genes into yeast to recreate the synthesis of the active molecule, a complex chemical, QS-21, that has a terpene core and numerous sugars. This may be the longest biosynthetic pathway ever inserted into yeast.