EFFICIENT PRODUCTION OF MEDIUM-CHAIN-LENGTH POLY(3-HYDROXYALKANOATES)FROM OCTANE BY PSEUDOMONAS-OLEOVORANS - ECONOMIC-CONSIDERATIONS

Poly(3-hydroxyalkanoates) (PHA) have the to become a biodegradable alt ernative for conventional plastics. In order to produce PHA at competi tive costs in comparison with commonly used plastics, efficient PHA pr oduction systems will have to be developed. Poly(3-hydroxybutyrate) fe rmentations are well developed and in actual use on an industrial scal e: medium-chain-length PHA (mcl-PHA) production is less well described , although the vast majority of all PHA known today are mcl-PHA. This paper compares and describes mcl-PHA production systems with respect t o the volumetric productivity, the cellular PHA content and the polyme r yield on carbon substrates. Nitrogen was shown to be the most effect ive limitation to trigger PHA formation in P. oleovorans after differe nt nutrient limitations had been compared. By using an economic model for the calculation of PHA production costs, we show that it should be possible to produce octane-based mcl-PHA on a large scale (more than 1000 tonnes/year) at costs below U.S. $ 10 kg(-1).