A selected soil bacterium is used as production strain for Biomer formulations. The bacteria are grown in an aqueous medium at 35°C in a steam of air. Sugar is used as feed stock. At the end of the fermentation process PHB makes up some 80% of the bacterial dry mass. About 100 kg of PHB are produced per m³ of fermentation medium.
After the fermentation the bacteria are collected and washed. PHB is extracted with a solvent and separated from the remaining biomass. By injecting the solvent into water, PHB precipitates as white powder of a purity of over 98%. The solvent is recycled in a closed system.
The powder obtained in the extraction process is transformed into pellets in an extruder. At the same time nucleating agents and plastisizers are added to improve processability and mechanical properties. The additives used are toxically safe and do not harm the composting process.
White area in microorganism is PHB