Effective production of low crystallinity Poly(3-hydroxybutyrate) by recombinant E. coli strain JM109 using crude glycerol as sole carbon source

Abstract

Utilization of bio-diesel by-products (glycerol) for microbial polymer production has created a novel biorefinery concept. In the present study, recombinant Escherichia coli JM109 was used for the production of P(3HB) from glycerol as carbon source. Batch fermentation in a 7.5L bioreactor with the statistically optimized culture condition (pre-treated glycerol: 27.5g/L and casein hydrolysate: 5.25g/L) scaled up the P3HB production to 65% (∼8g/L). FTIR, 1H and 13C NMR analysis proved the polymer produced to be P(3HB). Gel permeation chromatography, Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) demonstrated the produced P(3HB) to have high molecular weight (2.84×106) and lowered crystallinity (∼30%) compared to commercial polymer. Integrating the production efficiency and the thermal characteristics of the polymer produced by recombinant E. coli, the viability and sustainability of biofuels and biopolymers for economic human need could be enhanced.