Production and characterization of bacterial polyhydroxyalkanoate copolymers and evaluation of their blends by fourier transform infrared spectroscopy and scanning electron microscopy

Rhizobium meliloti produced a copolymer of
short chain length polyhydroxyalkanoate (scl-PHA) on
sucrose and rice bran oil as carbon substrates. Recombinant
Escherichia coli (JC7623ABC1J4), bearing PHA synthesis
genes, was used to synthesize short chain length-co-medium
chain length PHA (scl-co-mcl-PHA) on glucose and
decanoic acid. Fourier transform infrared spectroscopy
(FTIR) spectra of the PHAs indicated strong characteristic
bands at 1282, 1723, and 2934 cm–1 for scl-PHA and at
2933 and 2976 cm–1 for scl-co-mcl-PHA polymer. Differentiation
of polyhydroxybutyrate (PHB) and polyhydroxybutyrate-
co-hydroxyvalerate-P(HB-co-HV) copolymer was
obseverd using FTIR, with absorption bands at 1723 and
1281 for PHB, and at 1738, 1134, 1215 cm–1 for HV-copolymer.
The copolymers were analyzed by GC and 1H NMR
spectroscopy. Films of polymer blends of PHA produced
by R. meliloti and recombinant E. coli were prepared using
glycerol, polyethylene glycol, polyvinyl acetate, individually
(1:1 ratio), to modify the mechanical properties of the
fi lms and these fi lms were evaluated by FTIR and scanning
electron microscopy.