MICROBIAL SYNTHESIS AND CHARACTERIZATION OF POLY(3-HYDROXYBUTYRATE-CO-4-HYDROXYBUTYRATE)

Copolyesters of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB) with a wide range of compositions from 0 to 100 mol % 4HB were microbially synthesized at 30-degrees-C by Alcaligenes eutrophus from 4-hydroxybutyric acid in the presence of some additives. When 4-hydroxybutyric acid, citrate, and ammonium sulfate were fed as mixed substrates in the aqueous culture of A. eutrophus, P(3HB-co-4HB) copolymers with compositions of 70-100 mol % 4HB were produced. The structure and physical properties of P(3HB-co-4HB) copolymers were characterized by H-1 and C-13 NMR spectroscopy, X-ray diffraction, gel-permeation chromatography, differential scanning calorimetry, tensile test, and dynamic mechanical spectroscopy. In addition, the effects of 4HB units on the rate of enzymatic degradation of P(3HB-co-4HB) films were studied in the aqueous solution of an extracellular P(3HB) depolymerase from A. faecalis.