Physiological effects of over-expressing compartment-specific components of the protein folding machinery in xylose-fermenting Saccharomyces cerevisiae

Table 3 Maximum specific growth rates and product yields in anaerobic batch fermentation of 20 g/L glucose and 50 g/L xylose in complex medium (10 g/L yeast extract) using strains TMB3455, TMB3457 and TMB3459

	Glucose phase			Xylose phase
	TMB3455 (control)	TMB3457 (OSM1)	TMB3459 (OSM1 ERO1)	TMB3455 (control)	TMB3457 (OSM1)	TMB3459 (OSM1 ERO1)
μ_max (1/h)	0.37 ± 0.003	0.38 ± 0.001	0.38 ± 0.003	0.033 ± 0.004	0.024 ± 0.000	0.016 ± 0.008
Yields per substrate (mol/mol sugar)
Y _xylt/s	–	–	–	0.14 ± 0.01	0.16 ± 0.01	0.13 ± 0.01
Y _glyc/s	0.13 ± 0.01	0.11 ± 0.01	0.11 ± 0.01	0.013 ± 0.001	0.009 ± 0.001	0.009 ± 0.002
Y _ac/s	0.030 ± 0.006	0.022 ± 0.000	0.025 ± 0.003	0.022 ± 0.003	0.037 ± 0.005	0.037 ± 0.001
Y _etoh/s	2.7 ± 0.6	2.6 ± 0.2	2.6 ± 0.2	1.4 ± 0.1	1.4 ± 0.0	1.1 ± 0.0
Y _succ/s	0.005 ± 0.004	0.003 ± 0.001	0.003 ± 0.001	0.003 ± 0.001	0.006 ± 0.000	0.005 ± 0.001
Y_x/s (g/mol)	17.5 ± 1.4	18.4 ± 0.9	19.5 ± 0.6	6.4 ± 0.8	6.3 ± 0.7	4.2 ± 0.8
Yields per biomass (mmol/g CDW)
Y _xylt/x	–	–	–	22.3 ± 0.8	25.5 ± 1.2	31.0 ± 8.7
Y _glyc/x	7.3 ± 0.5	6.4 ± 0.2	6.4 ± 0.0	2.1 ± 0.0	1.5 ± 0.4	2.3 ± 0.9
Y _ac/x	1.3 ± 0.4	1.3 ± 0.1	1.5 ± 0.1	3.4 ± 0.0	5.9 ± 0.2	8.8 ± 1.4
Y _etoh/x	94.2 ± 5.0	91.3 ± 5.9	93.0 ± 3.5	222 ± 11	228 ± 21	272 ± 62
Y _succcxxx	0.12 ± 0.07	0.17 ± 0.08	0.21 ± 0.02	0.54 ± 0.03	0.91 ± 0.03	1.2 ± 0.5

Values are given as mean ± standard deviation of two independent experiments. Data for strains TMB3456 and TMB3458 is reported in Additional file 2: Table S4.

ISSN: 1472-6750