Quantification and mitigation of byproduct formation by low-glycerol-producing Saccharomyces cerevisiae strains containing Calvin-cycle enzymes

Table 1 Yields of biomass, acetaldehyde, acetate and ethanol on glucose and ratio of glycerol production and biomass (x) formation in anaerobic chemostat cultures of S. cerevisiae strains IME324 (reference strain lacking PRK/RuBisCO bypass) and IMX1489 (Δgpd2, non-ox PPP↑, pDAN1-prk, 15 × cbbm, GroES/GroEL) at 0.05 h⁻¹, 0.1 h⁻¹ and at 0.25 h⁻¹

Strain	IME324			IMX1489
Relevant genotype	GPD2			Δgpd2 pDAN1-prk 15 × cbbm
Dilution rate (h⁻¹)	0.05	0.1	0.25	0.05	0.1	0.25
Biomass/glucose (g_x/g)	0.084 ± 0.002	0.096 ± 0.004	0.093 ± 0.001	0.078 ± 0.001	0.090 ± 0.001	0.093 ± 0.001
Ethanol/glucose (mol/mol)	1.539 ± 0.010	1.590 ± 0.039	1.487 ± 0.001	1.585 ± 0.010	1.574 ± 0.018	1.630 ± 0.007
Acetaldehyde/glucose (mol/mol)	0.001 ± 0.000	0.001 ± 0.000	0.000 ± 0.000	0.056 ± 0.002	0.071 ± 0.003	0.020 ± 0.000
Acetate/glucose (mol/mol)	0.002 ± 0.000	0.003 ± 0.001	0.011 ± 0.000	0.045 ± 0.001	0.024 ± 0.000	0.022 ± 0.001
Glycerol/glucose (mol/mol)	0.108 ± 0.001	0.118 ± 0.003	0.161 ± 0.000	0.004 ± 0.000	0.011 ± 0.002	0.016 ± 0.001
Glycerol/biomass (mmol/g_x)	7.10 ± 0.10	6.85 ± 0.10	9.65 ± 0.06	0.25 ± 0.00	0.70 ± 0.12	0.96 ± 0.04
Electron recovery (%)	95–95	98–102	98–98	95–95	96–97	97–98

Values represent average ± mean deviation of measurements on independent steady-state duplicate cultures. Electron recoveries were calculated as balances of degree of reduction of substrates and products [21]

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