ACCUMULATION OF BIODEGRADABLE COPOLYESTERS OF 3-HYDROXY-BUTYRATE AND 3-HYDROXYVALERATE IN ALCALIGENES-EUTROPHUS

Biodegradable copolyesters of 3-hydroxybutyrate-co-3-hydroxyvalerate ( 3HB-3HV) were produced by Alcaligenes eutrophus in a two-staged proces s, namely growth stage and nitrogen-deficient polyester-accumulation s tage. When C-5 was used as the sole carbon source, the copolyester con tained 43 mol % of 3HV. A range of copolyesters with 0-43 mol % of 3HV could be produced by using a medium containing different concentratio n ratios of butyric acid C-4 and C-5. Tm of PHB homopolymer was 177.6 degrees C and that of copolyester with highest 3HV mol fraction of 43% was 99.0 degrees C. C-5 concentration in the medium could be an effec tive means to control the polymeric composition and mechanical propert ies of the copolyesters accumulated in A. eutrophus.