Biosynthesis and characterization of biodegradable Poly(3-hydroxybutyrate) from renewable sources

Poly(3-hydroxybutyrate) was produced in fed-batch cultures of Ralstonia eutropha DSM 428 and Alcaligenes latus ATCC 29712 on a mineral medium with different carbon sources such as sucrose, sodium lactate, lactic acid, soybean oil and fatty acid. The bacteria converted the different carbon sources supplied into P3HB. The best results were obtained when lactate or soybean oil were supplied as the sole carbon source. The range of number average molar mass (Mn) for the polymers, analyzed by Gel Permeation Chromatography was 1.65 to 0.79 x 10(5) g mol(-1). FTIR spectroscopy revealed a characteristic absorbance associated with polyester structures. The crystallinity degree, determinate from X-ray diffractograms, was about 69% in all synthesized polymers. The thermal properties associated to semicrystalline polymers indicated a glass transition at 0.1 degrees C and a melting point at about 175 degrees C and enthalpy of 63-89 J g(-1). The (1)H-NMR and (13)C-NMR spectra of the polymers were in agreement with the calculated chemical shifts associated with P3HB structures.