1 1 Biosynthesis and properties of P ( 3 HB / 3 HV / 3 H 4 MV ) produced by using 2 Cupriavidus eutrophus B-10646 3 4

20 Synthesis of poly(3-hydroxybutyrate/3-hydroxyvalerate/3-hydroxy-4-methylvalerate) 21 [P(3HB/3HV/3H4MV)] has been studied in batch culture of Cupriavidus eutrophus B-10646 under 22 nitrogen deficiency and varied conditions of carbon nutrition. A study has been conducted to determine 23 the effect of the carbon substrate (sugars, butyric acid) and concentration of methylvalerate as a precursor 24 substrate necessary for synthesis of 3H4MV monomer units on cell concentration, total polymer yield, 25 and 3H4MV content of the copolymer. The results suggest that methylvalerate concentration in the 26 culture medium must not be higher than 1 g L -1 , and that methylvalerate must be carefully dosed, with at 27 least 10-12 h intervals between supplementations. Bacterial cells were cultivated in the modes that 28 enabled production of a series of copolymers with molar fractions of 3H4MV of between 2.7 and 11.3 29 mol.%. Degrees of crystallinity, molecular weight characteristics, and thermal properties of the 30 copolymers have been investigated as dependent on proportions of monomers. Results suggest that the 31 molar fraction of 3H4MV has the strongest effect on the crystalline to amorphous region ratio. 32 P(3HB/3HV/3H4MV) specimens synthesized in this study had a degree of crystallinity of below 50%, 33 which remained unchanged for 2.5 years. 34