Pyrolysis of bacterial polyalkanoates

Abstract

Pyrolysis products from bacterial polyesters, poly-.beta.-hydroxybutyrate (PHB) and from a heteropolyester (.beta.-hydroxyvalerate and .beta.-hydroxybutyrate) were identified. Different physical forms of PHB were studied: PHB purified by dissolution in chloroform, native granules of PHB and PHB in bacterial cells. The products were characterized by GC, MS, [gas chromatography, mass spectrometry] and NMR analysis. The yield of crotonic acid obtained by the pyrolysis of purified PHB was 60-65%. Pyrolysis of PHB native granules yielded crotonic acid and oligomers of PHB with a terminal crotonate. Upon direct pyrolysis of dry bacterial cells, the yield of crotonic acid was 20-25% of the PHB in the cells. From the heteropolymer, 2-pentenoic acid and terminally unsaturated oligomers of polyhydroxyvalerate were obtained. The usefulness of the pyrolysis method for obtaining vinyl compounds from bacterial cultures containing polyalkanoates is discussed.