Optimization of ethanol production by Saccharomyces cerevisiae (ATCC 60868) and Pichia stipitis Y-7124: A response surface model for simultaneous hydrolysis and fermentation of wheat straw

Optimization models are useful in ascertaining optimum parameters as they r elate to a particular response. Ethanol production with different cellulase -systems and substrate concentrations were subjected to this model and the results revealed that crude unextracted cellulase-systems ave more efficien t than crude extracted cellulase-systems in producing hydrolysates for etha nol production with Pichia stipitis (Y-7124), Saccharomyces cerevisiae (AT 60868) and their mixture. Response surface plots showed that for 80-90% of high concentrations of delignified wheat straw up to 11% could be converted into ethanol by simultaneous hydrolysis with enzyme loading of 16 IU/mL an d fermentation with P. stipitis. P. stipitis was found to be the most suita ble yeast for the fermentation of mixed hexose and pentose sugars in the wh eat straw hydrolysate.