The D-xylose fermenting capacities of immobilizedPichia stipitis andPachysolen tannophilus

Summary The yeastsP. stipitis NRRL Y-7124 andP. tannophilus NRRL Y-2460 were entrapped in -carrageenan beads and used for repeated batch fermentation of D-xylose, in a series of four reactors. The operating conditions finally chosen gave an oxygen coefficient (K_La) of 0.83 min^–1, as measured by the sulphite method. Ethanol yields were 0.40 g/g forP. stipitis and 0.36 g/g forP. tannophilus (respectively 78.4% and 70.5% of the theoretical yields). In spite of its lower retention by the gel,P. stipitis exhibited greater fermenting capacities thanP. tannophilus.