Poly-3-hydroxybutyrate production from acetate by recombinant with blocked L-leucine catabolism and enhanced growth in acetate.

Acetate is a low-cost feedstock for the production of different bio-chemicals. Electrochemical reduction of CO into acetate and subsequent acetate fermentation is a promising method for transforming CO into value-added chemicals. However, the significant inhibitory effect of acetate on microbial growth remains a barrier for acetate-based biorefinery. In this study, the deletion of genes involved in L-leucine degradation was found to be beneficial for the growth of A1501 in acetate. (Δ), in which the hydroxymethylglutaryl-CoA lyase catalyzing -hydroxy--methylglutaryl-CoA into acetyl-CoA and acetoacetate was deleted, grew faster than other mutants and exhibited increased tolerance to acetate. Then, the genes from H16 for poly-3-hydroxybutyrate (PHB) biosynthesis were overexpressed in (∆) and the recombinant strain (∆-) can accumulate 0.11 g L PHB from commercial acetate. Importantly, (∆-) can also use CO-derived acetate to produce PHB and the accumulated PHB accounted for 5.42% (w/w) of dried cell weight of (∆-).