PRODUCTION OF POLY-BETA-HYDROXYBUTYRATE BY ALCALIGENES-EUTROPHUS ON DIFFERENT CARBON-SOURCES

Poly-beta-hydroxybutyrate was produced in shake cultures by Alcaligenes eutrophus H16 on fructose, xylose, and fumaric, itaconic, lactic and propionic acids in a three-stage process. The maximum polymer concentration of 6.9 g l-1 (69% of cell dry matter) was obtained with 20 g l-1 of fructose with a volumetric productivity of about 0.22 g l-1 h-1 at 24 h. Up to about 3 g l-1 (about 50% of cell dry matter) of polymer was also produced on lactic and propionic acids as the sole carbon source during the production phase. In multivariate optimization employing an orthogonal 2(3)-factorial central composite experimental design with fructose as the substrate in a single-stage process, the optimal initial fructose concentration decreased from 35 g l-1 to 24 g l-1 when the incubation time was increased from about 35 h to 96 h. The optimal shaking speed range was 90-113 rpm.