Further engineering of R. toruloides for the production of terpenes from lignocellulosic biomass

Abstract Background Mitigation of climate change requires that new routes for the production fuels and chemicals be as oil-independent possible. The microbial conversion lignocellulosic feedstocks into terpene-based biofuels bioproducts represents one such route. This work builds upon previous demonstrations single-celled carotenogenic basidiomycete, Rhodosporidium toruloides , is a promising host terpenes from hydrolysates. Results study focuses on optimization monoterpene 1,8-cineole sesquiterpene ?-bisabolene in R. . titer attained was found to proportional copy number bisabolene synthase (BIS) expression cassette, which turn influenced level several native mevalonate pathway genes. addition more copies BIS under stronger promoter resulted at 2.2 g/L hydrolysate 2-L fermenter. Production limited by availability precursor geranylgeranyl pyrophosphate (GPP) an appropriate GPP increased fourfold 143 mg/L bench scale. Targeted metabolite analysis suggested 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGR), kinase (MK) phosphomevalonate (PMK) may bottlenecks are were therefore selected targets overexpression. Expression HMGR, MK, PMK orthologs growth optimized medium additional tenfold 1.4 g/L. same genes did not have large impact production, although final higher 2.6 Furthermore, intermediates accumulated mevalonate-engineered strains, suggesting room further improvement. Conclusions brings closer being able make industrially relevant quantities terpene biomass.