Genetic Modification of Pichia Pastoris for Production of Propylene Glycol from Glycerol

Biodiesel is emerging as a major renewable energy resource. Glycerol is byproduct of biodiesel production, which cannot be directly used as fuel. Using Pichia pastoris as aerobic yeast cell factory, we engineered pathway to convert glycerol to propylene glycol (PG; 1,2-propanediol, 1,2-dihydroxypropane), a fuel additive and commodity compound. PG biosynthetic pathway was designed with unique combination of 3 enzymes: Escherichia coli methylglyoxal synthase and alcohol dehydrogenase; and Pichia ofunaensis glycerol dehydrogenase. Engineered genes were successfully integrated in yeast genome and actively expressed. Analysis, by HPLC of shake flask and fermenter broths of glycerol-grown cells, demonstrated engineered yeast produced PG. In fermenter, highest PG concentration was 0.11 g/L. When engineered P. pastoris was grown on biodiesel crude glycerol as sole carbon source, PG was detected. Basically, this is a proof of concept to demonstrate that Pichia was engineered to produce PG from glycerol.