Industrial Production of PHA

A subsidiary of ICI Ltd. in Great Britain produces Biopol from Alcaligenes eutrophus (H16). Either PHB homopolymer or copolymers of PHB and B-hydroxyvalerate can be produced by these cells depending on the substrate or substrate mixture used for growth and production. For industrial applications it is desirable to control the incorporation of different repeating units i nto the polymer in order to produce polyesters with specific material characteristics because their physical and chemical properties depend strongly on copolymer composition. Tailor-made copolymers can be made for this purpose by the use of controlled conditions. If a defined mixture of nutrients for certain type of microorganisms is supplied for growth, a defined and reproducible copolymer is formed. Biochemically there are 2 different ways of achieving polymer formation in microbes 

Parallel process has been demonstrated in R.rubrum and P.oleovorans. During cell growth, however part of the polymer forming potential is lost because of its utilization of substrate to maintain the cell's metabolism. In serial process of industrial polymer production micro-organisms are first grown on C source to obtain large biomass, then the medium is depleted of a n essential nutrient and polymer forming substrate is added. This is converted directly to polymers and essentially only little growth occurs. This approach is used for large scale PHA production by A. eutrophus.