PRODUCTION OF POLY(3-HYDROXYBUTYRATE) BY HIGH CELL-DENSITY FED-BATCH CULTURE OF ALCALIGENES-EUTROPHUS WITH PHOSPHATE LIMITATION

High cell density fed-batch fermentation of Alcaligenes eutrophus was carried out for the production of poly(3-hydroxybutyrate) (PHB) in a 6 0-L fermenter. During the fermentation, pH was controlled with NH,OH s olution and PHB accumulation was induced by phosphate limitation inste ad of nitrogen limitation. The glucose feeding was controlled by monit oring dissolved oxygen (DO) concentration and glucose concentration in the culture broth. The glucose concentration fluctuated within the ra nge of 0-20 g/L. We have investigated the effect of initial phosphate concentration on the PHB production when the initial volume was fixed. Using an initial phosphate concentration of 5.5 g/L, the fed-batch fe rmentation resulted in a final cell concentration of 281 g/L, a PHB co ncentration of 232 g/L, and a PHB productivity of 3.14 g/L.h, which ar e the highest values ever report:ed to date. In this case, PHB content , cell yield from glucose, and PHB yield from glucose were 80, 0.46, a nd 0.38% (w/w), respectively. (C) 1997 John Wiley & Sons, Inc.