Production of polyhydroxyalkanoic acids by Ralstonia eutropha and Pseudomonas oleovorans from an oil remaining from biotechnological rhamnose production.

Screening experiments identified several bacteria which were able to use residual oil from biotechnological rhamnose production as a carbon source for growth. Ralstonia eutropha H16 and Pseudomonas oleovorans were able to use this waste material as the sole carbon source for growth and for the accumulation of polyhydroxyalkanoic acids (PHA). R. eutropha and P. oleovorans accumulated PHA amounting to 41.3% and 38.9%, respectively, of the cell dry mass, when these strains were cultivated in mineral salt medium with the oil from the rhamnose production as the sole carbon source. The accumulated PHA isolated from R. eutropha consisted of only 3-hydroxybutyric acid, whereas the PHA isolated from P. oleovorans consisted of 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxydecanoic acid, and 3-hydroxydodecanoic acid. The composition was confirmed by gas chromatography of the isolated polyesters. Batch and fed-batch cultivations in stirred-tank reactors were done.