Decrease of cell viability during multifeed SSCF and limited effects of nutrient supplementation. Cell viability (% of CFU/total cell counts) and concentrations of glucose and ethanol during a laboratory-scale SSCF of material M1 with all the yeast added initially; and b demonstration-scale SSCF with feeding of yeast and substrate material M2. Ethanol concentration and cell viability during c 7% WIS and d 20% WIS (with 2-h pre-hydrolysis) shake flask SSCF of material M1 with additions of indicated nutrients. S. cerevisiae KE6-12.A was used, and the temperature was 35 °C in all cases. Arrows in (a–b) indicate the loading of yeast cells. TM trace metals. Error bars show the results of duplicate experiments. Error bars for ethanol concentration in (c–d) are smaller than the symbols. The measured cell viability in (d) was 0 at 48 h for all cases.