Although the type strain (CBS 712) of K. marxianus var. marxianus produced up to 6% (wt/vol)
ethanol at 43°C, cell viability was low, 30 to 50%, and the fermentation time was 24 to 30 h. On the basis of
currently available strains, we suggest that it may be possible by genetic engineering to construct yeasts capable
of fermenting carbohydrates at temperatures close to 50°C to produce 10 to 15% (wt/vol) ethanol in 12 to 18
h with retention of cell viability.