Synthesis of Polyhydroxyalkanoates by Hydrogen-Oxidizing Bacteria in a Pilot Production Process

Abstract

Synthesis of polyhydroxyalkanoates (PHA) was scaled up to pilot production in a 150-L fermenter on sugars (fructose and glucose) and purified and crude glycerol in a culture of the wild-type strain Cupriavidus eutrophus B-10646. Over 60 h of cultivation, cell concentration of 150-160 g/L was obtained on purified glycerol and glucose; cultivation on fructose and crude glycerol resulted in cell concentration of 130±10 g/L. Polymer content and yield coefficients for the biomass, kg biomass/kg carbon substrate, were similar on all substrates (80-85% and 0.29-0.33 kg biomass/kg carbon substrate, respectively). Bipolymers poly(3-hydroxybutyrate/3-hydroxyvalerate) and poly(3-hydroxybutyrate/4-hydroxybutyrate) and terpolymers poly(3-hydroxybutyrate/3-hydroxyvalerate/4-hydroxybutyrate) having a decreased degree of crystallinity (36-46%) were first synthesized in the scaled-up process using C. eutrophus B-10646 cultivated on glycerol. These results will provide the basis for scaling-up PHA synthesis in organotrophic C. eutrophus B-10646 culture.