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Saccharomyces cerevisiae M3G3를 이용한 1,2-Propanediol의 생산 최적화
구자룡(Ja-Ryong Koo),Nancy A. DaSilva,윤현식(Hyun Shik Yun) 한국생물공학회 2011 KSBB Journal Vol.26 No.5
1,2-propanediol (1,2-PD) is a commodity chemical that is currently produced from petrochemical derivatives. Saccharomyces cerevisiae is well characterized and a successful industrial microorganism to enable the improvement of the 1,2-propanediol production by metabolic engineering. A recombinant S. cerevisiae M3G3 was used to produce 1,2-propanediol. S. cerevisiae M3G3 is the diploid strain that contains 3 copies of mgs (methylglyoxal synthase) and gldA (glycerol dehydrogenase). S. cerevisiae M3G3 was cultivated at various culture conditions by changing culture temperature, glucose concentration, and inducer concentration. Also the effect of induction time was studied to optimize the production of 1,2-propanediol. Batch and fed-batch cultivation of S. cerevisiae M3G3 was performed by using a 5 L jar fermenter. The highest concentration of 1,2-propanediol in batch cultivation was 0.86 g/L and it was further improved to 1.33 g/L in fed-batch cultivation.
Effects of Expression of lcb1/lcb2 and lac1/lag1 Genes on the Biosynthesis of Ceramides
김세경,Yong Ho Noh,Ja-Ryong Koo,윤현식,Nancy A. DaSilva 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.1
Ceramides are important signal messenger molecules due to their role in regulating diverse responses such as cell cycle arrest, apoptosis, and senescence. Yeasts are more suitable for ceramides production than any other microorganisms since they grow fast and are non-pathogenic. However, regulations of the expression of genes involved in sphingolipid synthesis pathway are required to enhance ceramides production. In this study, we investigated the effects of co-expression of two pairs of genes that encode for serine palmitoyltransferase and ceramide synthase,respectively. Effect of other genes of the enzymes associated with the sphingolipid synthesis pathway, 3-ketosphinganine reductase and sphinganine C-4 hydroxylase were also studied and compared. The genes were cloned in to pESC-URA vector. Saccharomyces cerevisiae was cultivated aerobically in YPDG medium at 30oC. Ceramides were seperated from cell extracts by solvent extraction and quantified by HPLC with ELSD. The highest ceramides production (10.52 mg ceramides/g cell) was obtained when 3-ketosphinganine reductase, which is encoded by tsc10gene, was overexpressed. Also, S. cerevisiae SCEL2,1 overexpressing serine palmitoyltransferase encoded by lcb2 and lcb1 genes, and S. cerevisiae SCEG1C1 overexpressing ceramide synthase encode by lag1 and lac1 genes, showed a high level of ceramides production (10.08 mg ceramides/g cell and 9.88 mg ceramides/g cell, respectively).