glycerine and levulinic acid: renewable co-substrates for the fermentative synthesis of short-chain poly(hydroxyalkanoate) biopolymers

glycerine (a biodiesel co-product) and levulinic acid (a pulp and paper co-product) were used as co-substrates for the fermentative synthesis of short-chain polyhydroxyalkanoate (sc-pha) biopolymers with tunable monomer and molecular weight characteristics. pseudomonas oleovorans nrrl b-14682 utilized glycerine alone to produce poly(3-hydroxybutyrate) (phb). when levulinic acid was added to the media at shake-flask scale in concentrations ⩽0.6 wt.%, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (phb/v) copolymers were produced with 3-hv contents ranging from 37 to 97 mol%; a glycerine:levulinic acid ratio of 0.2%:0.8% (w/v) resulted in poly(3-hydroxyvalerate) (phv). ten-liter batch fermentations using glycerine:levulinic acid ratios of 1%:0, 0.75%:0.25%, 0.5%:0.5% and 0.25%:0.75% (w/v) resulted in phb, p(73%-3hb-co-27%-3hv), p(30%-3hb-co-70%-3hv) and phv with increasing number average molecular weights (×10³ g/mol) of 328, 511, 728 and 1330, respectively, owing to glycerine-based chain termination. these results provide a novel means by which glycerine and levulinic acid can be used collectively to produce an array of distinct sc-pha biopolymers.