Medium chain length polyhydroxyalkanoate produced from ethanol by Pseudomonas putida grown in liquid obtained from acidogenic digestion of organic municipal solid waste.

ABSTRACT

Production of medium chain length polyhydroxyalkanoate (mcl-PHA) up to about 6 g.L-1 was obtained by feeding ethanol to Pseudomonas putida growing in liquid obtained from acidogenic digestion of organic municipal solid waste. Washing the wet, heat-inactivated Pseudomonas cells at the end of the fermentation with ethanol obviated the need of drying the biomass and enabled the removal of contaminating lipids before solvent-mediated extraction of PHA. Using 'green' solvents, 90 to near 100% of the mcl-PHA was extracted and purities of 71-78% mcl-PHA were reached already by centrifugation and decantation without further filtration for biomass removal. The mcl-PHA produced in this way consists of 10-18% C8, 72-78% C10 and 8-12% C12 chains (entirely medium chain length), has a crystallinity and melting temperature of ∼13% and ∼49 °C, respectively, and is a stiff rubberlike, colourless material at room temperature.