Biosynthesis and accumulation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-polyethylene glycol, a hybrid co-polymer by endophytic Bacillus cereus RCL 02
Co-polymerization of microbial polyesters, polyhydroxyalkanoates (PHAs), with synthetic polymers has become an established and promising tool in the recent past for improving the material and biological properties of the biopolyesters. Bacillus cereus RCL 02, a leaf endophytic bacterium of the oleaginous plant Ricinus communis L., has been reported to produce a significant amount of poly(3-hydroxybutyrate) [P(3HB)] and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] under batch cultivation. The present study demonstrates the synthesis and accumulation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-polyethylene glycol [P(3HB-co-3HV)–PEG] co-polymer by the isolate RCL 02 in glucose, valeric acid, and PEG-200 supplemented mineral salts medium following dual-step cultivation. The identity of P(3HB-co-3HV)–PEG co-polymer so produced has been confirmed by X-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR), and proton nuclear magnetic resonance (1H NMR) spectroscopic studies, and the purified co-polymer was found to be composed of 3.2 mol% ethylene glycol (EG) and 8.4 mol% 3HV along with 3HB. While the thermogravimetric analysis (TGA) revealed that P(3HB-co-3HV)–PEG films degraded at 269.32 °C, differential scanning calorimetry (DSC) recorded the melting peak of the co-polymer at 163.8 °C. This study emphasized to explore the endophytic Bacillus spp. for production of P(3HB-co-3HV)–PEG co-polymers with improved material properties which may find possible application for biomedical purposes.
KeywordsPolyhydroxyalkanoates Polyethylene glycol Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)- polyethylene glycol co-polymer Bacillus cereus Endophytic bacteria Oleaginous plant
Research support to Rituparna Das from the Department of Science and Technology, New Delhi, India (Grant No. DST/INSPIRE Fellowship/REL5/2013/C1) is duly acknowledged.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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