Kd. Rane et Ka. Sims, OXYGEN-UPTAKE AND CITRIC-ACID PRODUCTION BY CANDIDA LIPOLYTICA-Y 1095, Biotechnology and bioengineering, 43(2), 1994, pp. 131-137
The rates of oxygen uptake and oxygen transfer during cell growth and
citric acid production by Candida lipolytica Y 1095 were determined. T
he maximum cell growth rate, 1.43 g cell/L . h, and volumetric oxygen
uptake rate, 343 Mg 02/L . h, occurred approximately 21 to 22 h after
inoculation. At the time of maximum oxygen uptake, the biomass concent
ration was 1.3% w/v and the specific oxygen uptake rate was slightly g
reater than 26 Mg 02/g cell . h. The specific oxygen uptake rate decre
ased to approximately 3 mg 02/g Cell . h by the end of the growth phas
e. During citric acid production, as the concentration of dissolved ox
ygen was increased from 20% to 80% saturation, the specific oxygen upt
ake and specific citric acid productivity (mg citric acid/g cell . h)
increased by 160% and 71%, respectively, at a biomass concentration of
3% w/v. At a biomass concentration of 5% w/v, the specific oxygen upt
ake and specific citric acid productivity increased by 230% and 82%, r
espectively, over the same range of dissolved oxygen concentrations. T
he effect of dissolved oxygen on citric acid yields and productivities
was also determined. Citric acid yields appeared to be independent of
dissolved oxygen concentration during the initial production phase; h
owever, volumetric productivity (g citric acid/L.h) increased sharply
with an increase in dissolved oxygen. During the second or subsequent
production phase, citric acid yields increased by approximately 50%, b
ut productivities decreased by roughly the same percentage due to a lo
ss of cell viability under prolonged nitrogen-deficient conditions. (C
) 1994 John Wiley & Sons, Inc.