Bioconversion of sugarcane molasses to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by endophytic Bacillus cereus RCL 02

Abstract

Sugarcane molasses, the by-product of sugar industry are rich in nutrients, growth factors and minerals and are efficiently utilized by the microorganisms for growth and production of primary as well as secondary metabolites of commercial importance. In this communication, we report the utilization of sugarcane molasses as the sole source of carbon for the production of copolymers of polyhydroxyalkanoates (PHAs) with improved material properties. The endophytic bacterium Bacillus cereus RCL 02 (MCC 3436) produced 7.8 g/L of PHA when grown in MS medium with 4% (w/v) sugarcane molasses under batch cultivation. Proton nuclear magnetic resonance (1H NMR) analysis revealed that the copolymer so produced contain 12.4 mol% 3-hydroxyvalerate (3HV) along with 87.6 mol% 3-hydroxybutyrate (3HB). The copolyester, P(3HB-co-12.4 mol%-3HV) has been isolated and purified following standard solvent extraction method and partially characterized by Fourier-transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric (TG) and differential scanning calorimetric (DSC) analysis. The material and thermal properties of the copolyester so produced indicated its potential for industrial application.