Biosynthesis of Lactate-containing Polyhydroxyalkanoates in Recombinant Escherichia coli from Sucrose

Abstract

Biosynthesis of lactate-containing polyhydroxyalkanoates (PHAs) was examined in recombinant Escherichia coli W strain from sucrose. The Pseudomonas sp. MBEL 6-19 phaC1437 gene and the Clostridium propionicum pct540 gene, which encode engineered Pseudomonas sp. MBEL 6-19 PHA synthase 1 (PhaC1 ) and engineered C. propionicum propionyl-CoA transferase (Pct Cp ), respectively, were expressed in E. coli W to construct key metabolic pathway to produce poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)].The recombinant E. coli W expressing the phaC1437 gene and the pct540 gene could synthesize P(3HB-co-13mol%LA) up to the polymer content of 31.3 wt% when it was cultured in chemically defined MR medium containing 20 g/L of sucrose and 2 g/L of sodium 3-hydroxybutyrate. When Ralstonia eutropha phaAB genes were additionally expressed to provide 3-hydroxybutyrate-CoA (3HB-CoA) from sucrose, P(3HB-co-16mol%LA) could be synthesized from sucrose as a sole carbon source without supplement of sodium 3-hydroxybutyrate in culture medium, but the PHA content was decreased to 12.2 wt%. The molecular weight of P(3HB-co-16 mol%LA) synthesized in E. coli W using sucrose as carbon source were 1.53×10 4 (M n ) and 2.78×10 4 (M w ), respectively, which are not different from those that have previously been reported by other recombinant E. coli strains. Engineered E. coli strains developed in this study should be useful for the production of lactate-containing PHAs from sucrose, one of the most abundant and least expensive carbon sources.

Recent advances in the microbial synthesis of lactate-based copolymer

“…Sucrose is undoubtedly one of the most abundant and the least expensive carbon sources. Engineered E. coli W can break down 20 g/L sucrose into fructose and glucose, and further to synthesize 12.2 wt% P(16 mol% LA-co-3HB) in vivo (Oh et al 2014).…”

“…Sucrose is undoubtedly one of the most abundant and the least expensive carbon sources. Engineered E. coli W can break down 20 g/L sucrose into fructose and glucose, and further to synthesize 12.2 wt% P(16 mol% LA- co -3HB) in vivo (Oh et al 2014 ). To establish an efficient sucrose utilization pathway, the β-fructofuranosidase gene ( sacC ) of Mannheimia succiniciproducens MBEL55E is introduced into different genetically modified E. coli strains.…”