Table 2 Yields of biomass and ethanol on glucose, sorbitol consumption, biomass-specific sorbitol uptake rates and stoichiometric relationships between glycerol production and biomass formation in anaerobic bioreactor chemostat cultures of S. cerevisiae strains IME324 (reference strain), IME611 (overexpression cassettes for HXT15 and SOR2), IMX1489 (optimized PRK-RuBisCO bypass and gpd2∆ mutation, [26]) and IMX2506 (optimized PRK-RuBisCO bypass and gpd2∆ mutation, overexpression cassettes for HXT15 and SOR2). ‘Substrates’ refers to the combination of glucose and sorbitol. Cultures were grown at a dilution rate of 0.025 h−1 on 10 g L−1 of glucose and 10 g L−1 of sorbitol (pH 5)
Strain | IME324 | IME611 | IMX1489 | IMX2506 |
|---|---|---|---|---|
HXT15 and SOR2 cassettes | no | yes | no | yes |
PRK-RuBisCO bypass and gpd2∆ | no | no | yes | yes |
Biomass yield on substrates (gx mol−1) | 14.2 ± 0.1 | 14.3 ± 0.7 | 12.0 ± 0.9 | 13.3 ± 0.4 |
Yield of ethanol on glucose (mol mol−1)a | 1.62 ± 0.03 | 1.66 ± 0.07 | 2.96 ± 0.00 | 2.86 ± 0.02 |
Ethanol yield on substrates (mol mol−1) | 1.63 ± 0.04 | 1.61 ± 0.06 | 1.76 ± 0.01 | 1.83 ± 0.04 |
Glycerol/biomass (mmol gx−1) | 8.1 ± 0.2 | 10.8 ± 0.5 | 0.6 ± 0.2 | 1.0 ± 0.0 |
Sorbitol consumed (mmol gx−1) |  < 0.5 | 2.2 ± 1.1 | 33.9 ± 3.0 | 27.0 ± 0.1 |
Biomass-specific sorbitol uptake rate (mmol gx−1 h−1) |  < 0.02 | 0.06 ± 0.03 | 0.89 ± 0.08 | 0.67 ± 0.00 |
Degree of reduction recovery (%) | 99–100 | 98–102 | 98–99 | 100–101 |