Formation of blends of various poly(3-hydroxyalkanoic acids) by a recombinant strain ofPseudomonas oleovorans
✍ Scribed by Arnulf Timm; David Byrom; Alexander Steinbüchel
- Book ID
- 104650877
- Publisher
- Springer
- Year
- 1990
- Tongue
- English
- Weight
- 642 KB
- Volume
- 33
- Category
- Article
- ISSN
- 1432-0614
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✦ Synopsis
Recombinant strains of Pseudomonas oleovorans, which harbour the poly(3-hydroxybutyrate)-bio- synthetic genes of Alcaligenes eutrophus, accumulated poly(hydroxyalkanoates), composed of 3-hydroxybutyrate(3HB), 3-hydroxyhexanoate (3HHx) and 3-hydroxyoctanoate (3HO), up to 70% of the cell dry weight if the cells were cultivated with sodium octanoate as the carbon source. Physiological and chemical analysis revealed multiple evidence that this polymer is a blend of the homopolyester poly(3HB) and of the copolyester poly(3HHx-co-3HO) rather than a random or a block copolyester of 3HB, 3HHx and 3HO. The molar ratio between poly(3HHx-co-3HO) and poly(3HB) varied drastically during the process of fermentation. Whereas synthesis of poly(3HHx-co-3HO) started immediately after ammonium was exhausted in the medium, synthesis of poly(3HB) occurred only after a lag-phase. From freeze-dried cells poly(3HHx-co-3HO) was much more readily extracted with chloroform than was poly(3HB). The blend was fractionated into petrol-ether-insoluble poly(3HB) and petrol-ether-soluble poly(3HHx-co-3HO). The molecular weight values of these polyesters measured by gel permeation chromatography were 2.96 × 10 6 and 0.35 × 10 6 and were similar of those polymers accumulated by A. eutrophus or by wild-type P. oleovorans, respectively.