Biosynthesis of biodegradable plastic, poly(3HB-co-3HP), using methane as sole carbon source in metabolically...

We report a biosynthetic method for producing poly(3-hydroxybutyrate-co-3-hydroxypropionate) [P(3HB-co-3HP)] copolymer from methane alone; we developed a 3-hydroxypropionate (3HP) biosynthetic pathway starting from methane in Methylosinus trichosporium OB3b and overexpressed 3HP-CoA transferase to optimize 3HP incorporation into P(3HB-co-3HP) copolymers. Upon comparing the β-alanine and malonyl-CoA pathways, we discovered that the latter showed greater potential for the formation of 3HP monomers. In addition, we examined the activities of 3HP-CoA synthetases from three distinct sources and found that the enzyme from Metallosphaera sedula was the most effective for 3HP incorporation. Using methane as the sole carbon source in a shake-flask culture, we developed recombinant strains and found that the best strain was OB3b-MCRM-3S, which formed a P(3HB-co-3HP) copolymer, up to 25.62 % of the biomass, with a maximum 3HP level of 9.02 mol%. Our research demonstrates the successful production of a biopolymer, the P(3HB-co-3HP) copolymer, via methane bioconversion using methanotrophs.