Characterization of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Biosynthesized by Mixed Microbial Consortia Fed Fermented Dairy Manure

摘要

The bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), was isolated from a bioreactor using mixed microbial consortia fed volatile fatty acids (VFA), from fermented dairy manure, as the carbon source. The molar fraction of 3- hydroxyvalerate (3HV) amounted to 0.33 mol mol~(-1) for two isolated PHBV samples as determined by GC-MS and ~1H-NMR spectroscopy. The chemical, thermal, and mechanical properties were determined. The PHBVs had relatively high M_w (~790,000 g mol~(-1)). Only a single glass transition temperature (T_g) and melting point (T_m) were observed. Isolated PHBVs exhibited good flexibility and elongation to break as compared with commercial PHBVs with lower HV. The diad and triad sequence distributions of the monomeric units were determined by ~(13)C-NMR spectroscopy and followed Bernoullian statistics suggesting that the PHBVs were random. The PHBV sequence distribution was also characterized by electrospray ionization-mass spectrometry (ESI-MSn) after partial alkaline hydrolysis to oligomers showing a random 3HV distribution.