M. Taniguchi et al., ETHANOL-PRODUCTION FROM A MIXTURE OF GLUCOSE AND XYLOSE BY COCULTURE OF PICHIA-STIPITIS AND A RESPIRATORY-DEFICIENT MUTANT OF SACCHAROMYCES-CEREVISIAE, Journal of fermentation and bioengineering, 83(4), 1997, pp. 364-370
The effect of oxygenation on ethanol production from xylose or glucose
by Pichia stipitis in batch culture was investigated, The fermentatio
n parameters with respect to ethanol production by P. stipitis were st
rongly dependent on the oxygen transfer rate (OTR). On the basis of OT
R values, the relationship between the optimum specific oxygen uptake
rate (qO(2)) and maximum specific ethanol production rate ((q(p))(max)
was evaluated. The optimum qO(2) for ethanol production was 14.3 or 6
6.7 mg.(g cell)(-1).h(-1) when xylose or glucose was used as a carbon
source, respectively. When a mixture of glucose and xylose was used as
the carbon source in a culture of P. stipitis alone, the yield and pr
oductivity of ethanol were significantly enhanced when qO(2) was adjus
ted to an optimum level dependent upon the type of sugar consumed. In
a co-culture of Saccharomyces cerevisiae and P. stipitis, it was impos
sible to control qO(2) at an optimum value for xylose fermentation by
P. stipitis because oxygen was consumed by the S. cerevisiae. In a co-
culture of P. stipitis and a respiratory-deficient mutant of S. cerevi
siae, the optimum qO(2) for xylose fermentation by P. stipitis was suc
cessfully maintained due to the low oxygen consumption of the mutant y
east strain. Co-culture of these two strains resulted in the maximum y
ield and the highest productivity of ethanol from a mixture of glucose
and xylose.