Enhanced xylose fermentation and ethanol production by engineered Saccharomyces cerevisiae strain

AMB Express

Table 1 Specific glucose and xylose consumption rates

Growth medium containing YNB	Specific Consumption (g/L/h) in the fermentation medium (D2%X2%)
Growth medium containing YNB	D4%		D3%X1%		D2%X2%		D1%X3%		X4%
Strains	Glucose	Xylose	Glucose	Xylose	Glucose	Xylose	Glucose	Xylose	Glucose	Xylose
Non-adapted	0.48 ± 0.07	0.08 ± 0.04	0.47 ± 0.02	0.08 ± 0.02	0.47 ± 0.02	0.06 ± 0.04	0.45 ± 0.02	0.06 ± 0.03	0.41 ± 0.01	0.05 ± 0.02
Adapted	0.73 ± 0.03	0.60 ± 0.02	0.73 ± 0.07	0.59 ± 0.09	0.73 ± 0.05	0.55 ± 0.03	0.73 ± 0.06	0.55 ± 0.02	0.70 ± 0.09	0.49 ± 0.02

Initially, both original (un-evolved) and evolved on xylose strains were grown in YNB medium containing different proportions of glucose-xylose until mid-log phase of growth and, then, shifted to the fermentation medium containing 2% glucose and 2% xylose. The aliquots were harvested in time of 24 hours, centrifuged and the supernatants were used to determine the concentration of glucose and xylose, which were used to calculate the rate of sugar consumption. The results represent the mean ± standard deviation of at least three independent experiments.