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Saccharomyces cerevisiae is one of the industrially important microorganisms. In our laboratory, S. cerevisiae sake K6 was developed to overproduce S‐adenosyl‐L‐methionine (SAM). S. cerevisiae K6 has not been engineered with DNA recombinant technology due to the lack of a proper genetic marker. An UV mutagenesis was conducted with S. cerevisiae sake K6 and a mutant with leucine auxotroph, K6‐1, was selected. The mutant showed similar growth rate and SAM productivity to its wild type. Using the auxotroph as a genetic marker, a SAM synthase (SAM2) and a ethionine resistant (ERC1) genes were overexpressed. The recombinant DNA successfully enhanced SAM productivity in sake yeast.
We also metabolically engineered S. cerevisae to produce 1,2‐propanediol using glycerol as a main carbon source. The introduction of two genes, mgs (methylglyoxal synthase) and gldA (glycerol dehydrogenase) from Escherichia coli, not only made S. cerevisiae produce 1,2‐propanediol, but also increased the growth rate in glycerol and glycerol utilization rate of S.
cerevisiae. Further increase of 1,2‐propnaediol production and glycerol utilization rate were achieved by overexpression of endogenous GUT1(glycerol kinase) and GUT2 (glycerol 3‐phosphate dehydrogenase) as well as GUP1 gene which involved in glycerol transport in S. cerevisiae.
Lastly, additional glycerol dissimilation pathway was introduced by expressing a glycerol dehydrogenase gene from Pichia angusta in S. cereviaise. By engineering, 0.98 g/l of 1,2‐propanediol concentration was achieved in flask culture with 1% (v/v) glycerol as a main carbon source.