Yeast strains for concentrated substrates

Summary The screening of twenty yeast strains for ethanol productivity at high osmotic pressure at temperatures ranging from 32°C to 45°C is described. Shake flask fermentations of 30°, 40°, and 50° Bx cane molasses were performed. The effect of temperature on productivity at a non-inhibitory ethanol level is weakly pronounced. Most strains fermented poorly at 50° Bx molasses but two Schizosaccharomyces pombe and one commercial baker's yeast, Saccharomyces cerevisiae performed well at all concentrations of molasses. In an extended study with Schizosaccharomyces pombe (CBS 352) and Saccharomyces cerevisiae (SJAB, fresh yeast), simulating a continuous run it was shown that Schizosaccharomyces pombe was less sensitive to high DS than Saccharomyces cerevisiae. At 25% DS the productivity of Schizosaccharomyces pombe is almost twice that of Saccharomyces cerevisiae.