K. marxianus IMB4 produced more ethanol at a greater yield
than K. marxianusIMB2 and IMB5. Ethanol yields were greater
at 40 C than at 45 C and they were greater at pH 5.5 than at pH
4.5 and 5.0. K. marxianus IMB2 and IMB5 produced more
xylitol than IMB4. Xylitol yield was greater at 45 C than at
40 8C for IMB2, while the opposite was true for IMB4. The
strains were observed to produce lower ethanol yields and
productivities from xylose than other wild-type xylose fermenters
or microorganisms genetically modified to ferment xylose to
produce ethanol [14–17]. IMB4 produced xylitol yields similar
to other proposed xylitol producing strains, but with lower
volumetric productivity [19]. Overall, anaerobic xylose fermentation
by these strains was not promising, and other strategies,
such as using microaerobic conditions, should be explored.