재조합 대장균에서 수크로즈로부터의 젖산을 모노머로 함유한 폴리하이드록시알칸산 생산 연구

Abstract

Biosynthesis of lactate-containing polyhydroxyalkanoates(PHAs) was examined in recombinant Escherichiacoli W strain from sucrose. The Pseudomonas sp. MBEL 6-19 phaC1437 gene and the Clostridium propionicum pct540gene, which encode engineered Pseudomonas sp. MBEL 6-19 PHA synthase 1 (PhaC1Ps6-19) and engineered C. propionicumpropionyl-CoA transferase (PctCp), respectively, wereexpressed in E. coli W to construct key metabolic pathway toproduce poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)]. The recombinant E. coli W expressing the phaC1437 geneand the pct540 gene could synthesize P(3HB-co-13mol%LA)up to the polymer content of 31.3 wt% when it was culturedin chemically defined MR medium containing 20 g/L of sucroseand 2 g/L of sodium 3-hydroxybutyrate. When Ralstoniaeutropha phaAB genes were additionally expressed toprovide 3-hydroxybutyrate-CoA (3HB-CoA) from sucrose,P(3HB-co-16mol%LA) could be synthesized from sucrose asa sole carbon source without supplement of sodium 3-hydroxybutyratein culture medium, but the PHA content was decreasedto 12.2 wt%. The molecular weight of P(3HB-co-16mol%LA) synthesized in E. coli W using sucrose as carbonsource were 1.53×104 (Mn) and 2.78×104 (Mw), respectively,which are not different from those that have previously beenreported by other recombinant E. coli strains. Engineered E. coli strains developed in this study should be useful for theproduction of lactate-containing PHAs from sucrose, one ofthe most abundant and least expensive carbon sources.