To evaluate the influence of remaining ionic liquid in fermentable sugars from lignocellulosic materials on subsequent ethanol fermentation

the toxicity of ionic liquid 1-ethyl-3-methylimidazolium acetate([Emim]Ac)to Saccharomyces cerevisiae AY93161 and its influence on ethanol fermentation process were investigated.After methylene blue staining

the morphological structure

budding and metabolic activity of Saccharomyces cerevisiae AY93161 at log growth phase in the presence of different concentrations of[Emim]Ac were observed under microscope-OLYMPUS CX41.The result showed that its single cell morphology changed when[Emim]Ac concentration was greater than 5 g·L-1

and its reproduction rate by budding and its metabolic activity decreased with increasing[Emim]Ac concentration when[Emim]Ac concentration was greater than 0.1 g·L-1.The half effective concentration(EC50)and the half inhibition concentration(IC50)of[Emim]Ac to Saccharomyces cerevisiae AY93161 were then measured by using solid and liquid suspension culture and their values were 4.45 and 7.70 g·L-1 respectively.According to the parameters measured during the ethanol fermentation process at different[Emim]Ac concentrations

when[Emim]Ac in the medium was below 0.1 g·L-1

there was almost no effect on the ethanol fermentation process

but when[Emim]Ac in the medium was greater than 0.1 g·L-1

the ethanol fermentation was inhibited

resulting from its inhibitory effect on growth of the yeast Saccharomyces cerevisiae AY93161.