Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) Produced by Delftia acidovorans in Different Cell-Concentration and Fed-Batch Cultures

Delftia acidovorans (IFO13582) was grown in fed-batch and chemostat cultures with n-butyric acid and 1,4-butanediol as mixed carbon substrates. In fed-batch cultures, the synthesis rate of the polymer was considerably increased with the increment of the cell growth. The polymer content increased and reached to a maximum of 27 wt% with increasing the cell dry-weight of ca. 4.4-5.2 g/l at 26 °C for 72 h and the maximum 4HB unit composition of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] was slightly low value of ca. 66 mol%. Whereas the maximum 4HB unit composition of P(3HB-co-4HB) obtained by the fed-batch culture with lower cell concentration of ca. 2.5 g/l reached to 94 mol% though the content of P(3HB-co-4HB) was always low, at ca. 13 wt%.