Process design for the microbial synthesis of poly-β-hydroxybutyrate (PHB) from natural gas

A process design for a two-stage procedure for the production of PHB from natural gas based on the results, obtained on a laboratory and small technical scale, was developed. For this purpose, four bioreactors were dimensioned and interconnected so as to achieve a quasi-continuous PHB production. A price of 6.35 Euro/kg PHB was pre-calculated for the biosynthesis in a plant producing 500 t PHB/year. An extrapolation, which included the incorporation of various downstream procedures to achieve purities dependent on applications, resulted in prices between 11.50 and 14.00 Euro/kg for the purified final product. Estimations indicate that an expansion of the plant capacity to 5,000 t/year could enable a price reduction of approx. 30-35%.