Production of poly(3-hydroxybutyric-co-3-hydroxyvaleric acid) having a high hydroxyvalerate content with valeric acid feeding.

The capability of different organic acids to produce a derivative of PHB [poly(3-hydroxybutyric-co-3-hydroxyvaleric acid), P(3HB-co-3HV)] was examined in shake flask cultivations. Propionic and valeric acids demonstrated the potential to produce P(3HB-co-3HV) under nitrogen limiting conditions at 30 degrees C. The addition time and the initial concentration of valeric acid needed for a high cellular HV content were identified by extensive experimentation. Fed-batch cultivation in 7-l bioreactor with valeric acid feeding resulted in the production of PHA containing 54% HV units.