Engineering of pha operon on Cupriavidus necator chromosome for efficient biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from vegetable oil

摘要

Cupriavidus necator H16C_(Ac), previously constructed for production of poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) [P(3HB-co-3HHx)] from soybean oil, was further engineered aiming to increase 3HHx composition in the copolyester. PHA synthase gene derived from Aeromonas caviae on the H16C_(Ac) chromosome was replaced by a gene encoding the N149S/D171G mutant and this recombination enhanced PHA productivity as well as slightly increased 3HHx composition. Manipulation of phaA_(Cn) locus partially reduced the amount of 3HB unit concomitantly with relative increase of 3HHx composition, whereas deletion of phaB1_(Cn) resulted in drastic decline of 3HB unit in P(3HB-co-3HHx). Insertion of phaJ_(Ac) encoding (R)-specific enoyl-CoA hydratase from A caviae into pha operon significantly enlarged 3HHx fraction without negative effects on the cell growth and polyester accumulation. Consequently, efficient production of P(3HB-co-3HHx) with 3HHx composition of 5.7-9.9 mol% was successfully achieved from soybean oil by the engineered strains.