Y. Doi

Department of Innovative and Engineered Materials, Tokyo Institute of Technology,

4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan, and Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan

Since polyhydroxyalkanoates (PHAs) were identified as environmental-friendly biodegradable polyesters, the PHA production from renewable carbon sources in microbes or plants has been an interesting commercial prospect due to lower carbon feedstock costs and capital investments. To date, we have demonstrated that random copolymers of (R)-3-hydroxybutyrate (3HB) with longer chain (R)-3-hydroxyalkanoates (3HA) exhibit preferable mechanical properties. For biosynthesis of polyesters with desired properties, it is important how to control copolymer compositions and molecular weights of polyesters.

       Large-scale fermentative production of poly(3-hydroxybutyrate-co-5mol% 3-hydroxy- hexanoate) [P(3HB-co-5mol% 3HHx)] from soybean oil as sole carbon source was simulated using a recombinant strain of Ralstonia eutropha harboring a PHA synthase gene from Aeromonas caviae. Its production costs, life cycle inventories (LCI) of energy consumption and carbon dioxide emissions from the cradle-to-factory gate were calculated and compared with the counterparts for microbial production of ultra-high molecular weight P(3HB) from glucose as sole carbon source. Annual production of 5000 tones of P(3HB-co-5mol% 3HHx) was estimated to cost from 3.5 to 4.5 US$/kg, depending on presumed production performances. Similar scale production of ultra-high molecular weight P(3HB) from glucose was estimated to cost 3.8-4.2 US$/kg. The life cycle inventories of energy consumption and carbon dioxide emissions of bio-based polymers were markedly lower than those of typical petrochemical polymers.
       The physical properties and biodegradabilities of PHA homopolymers and copolymers will be presented.

         论文来源：International Symposium on Biological Polyesters