Engineering of Saccharomyces cerevisiae for the production of dihydroxyacetone (DHA) from sugars: a proof of concept.

Dihydroxyacetone (DHA) has numerous industrial applications. In this work, we pursue the idea to produce DHA from sugars in the yeast Saccharomyces cerevisiae, via glycerol as an intermediate. Firstly, three glycerol dehydrogenase (GDH) genes from different microbial sources were expressed in yeast. Among them, the NAD(+)-dependent GDH of Hansenula polymorpha showed the highest glycerol-oxidizing activity. DHA concentration in shake-flask experiments was roughly 100mg/lDHA from 20g/l glucose, i.e. five times the wild-type level. This level was achieved only when cultures were subjected to osmotic stress, known to enhance glycerol production and accumulation in S. cerevisiae. Secondly, DHA kinase activity was abolished to prevent conversion of DHA to dihydroxyacetone phosphate (DHAP). The dak1Deltadak2Delta double-deletion mutant overexpressing H. polymorpha gdh produced 700mg/l DHA under the same conditions. Although current DHA yield and titer still need to be optimized, our approach provides the proof of concept for producing DHA from sugars in yeast.