Production of PHAs from agricultural waste material

Polyhydroxyalkanoates (PHAs) are biodegradable substitutes to fossil fuel p lastics that can be produced from renewable raw materials such as saccharid es, alcohols and low-molecular-weight fatty acids. They are completely degr adable to carbon dioxide and water through natural microbiological minerali zation. Consequently, neither their production nor their use or degradation have a negative ecological impact. By keeping closed the cycle of producti on and re-use, PHAs can enable at least part of the polymer producing indus try to switch from ecologically harmful end-of-the-pipe production methods towards sounder technologies. Up to now such polyesters have been produced biotechnologically from refined raw materials (e.g. glucose and sodium prop ionate), but they can as well be produced much cheaper from agricultural wa ste materials (e.g. molasses, maltose, glycerol phase from biodiesel produc tion, whey); as long as these materials have a known composition and are av ailable in appropriate quantities. Yield factors and specific rates for gro wth and PHA accumulation are shown for 3 strains of Alcaligenes latus for d ifferent agricultural waste carbon sources.