Simultaneously improving xylose fermentation and tolerance to lignocellulosic inhibitors through evolutionary engineering of recombinant Saccharomyces cerevisiaeharbouring xylose isomerase

Table 3 Growth parameters with xylose as carbon source

Yield coefficients and specific rates of growth, substrate consumption and ethanol production for strains D5A⁺, D5A^+H and TMB3400 with 20 g xylose/L as primary carbon source in batch culture with and without with 50% (v/v) hydrolysate liquor from steam-pretreated triticale. Standard deviations from duplicate fermentations are shown.
N/D None detected.
^†Biomass and product concentrations at the end of the exponential growth phase.
^‡Y_x/s, biomass yield on xylose, calculated from the slope of the biomass concentration plotted as a function of the residual xylose concentration.
^§Y_p/s, ethanol yield on xylose, calculated from the slope of the ethanol concentration plotted as a function of the residual xylose concentration.
^¶Y_p/x, ethanol yield on biomass, calculated from the slope of the ethanol concentration plotted as a function of the biomass concentration.
^*q_s, specific rate of substrate utilisation in g xylose/g biomass per hour during the mid-exponential phase.
^††q_p, specific rate of product formation in g ethanol/g biomass per hour during the mid-exponential phase.

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