BIOSYNTHESIS OF POLY(3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE) BY NEWLY ISOLATED AGROBACTERIUM SP SH-1 AND GW-014 FROM STRUCTURALLY UNRELATED SINGLE CARBON SUBSTRATES

Various isolates from activated sludge and soil samples were investigated for their ability to synthesize poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), from structurally unrelated single carbon substrates. Isolated Gram-negative bacteria, Agrobacterium sp. SH-1 and GW-014, could synthesize P(3HB-co-3HV) with 3HV monomer mole percent in the range from 1.3 to 11.4 from single carbon substrate, such as glucose, xylose or sucrose. Terpolyesters of 3HB, 3HV and 4-hydroxybutyrate (4HB) were also accumulated by Agrobacterium sp. SH-1 and GW-014 in a nitrogen-free production stage with various hydroxyalkanoate substrates. The structure of P(3HB-co-3HV) synthesized from glucose was confirmed by gas chromatographic-mass spectrometric (GC-MS) analysis, and its molecular weight, polydispersity index and melting temperature were determined to be 620000, 1.2 and 178 degrees C, respectively. Total polymer content up to 78% (w/w) of dry cell weight and 3HV mole percent up to 50% could be achieved by fed-batch production from glucose and propionate.