Influence of 1-butyl-3-methylimidazolium Chloride on the Ethanol Fermentation Process of Pichia pastoris GS115

Abstract

To evaluate the influence of 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) on the ethanol fermentation process of Pichia pastoris GS115, this paper investigated the yeast growth, ethanol formation and the fermentable sugars consumption during the ethanol fermentation process of Pichia pastoris GS115 at different [Bmim]Cl concentrations in the medium. The results indicated that the [Bmim]Cl had no influence on the ethanol fermentation process at its concentration less than 0.0001 g.L^-1. The [Bmim]Cl inhibited the yeast growth and had a negative effect on ethanol formation at its concentration higher than 0.0001 g.L^-1. The final biomass and ethanol concentration, and the overall ethanol yield from the fermentable sugars all decreased with its concentration increasing. The yeast growth was very slow and nearly no ethanol formed when its concentration reached 5 g.L^-1. Compared to Saccharomyces cerevisiae, the growth of Pichia pastoris GS115 was more sensitive to the [Bmim]Cl, and its ethanol fermentation had lower final ethanol concentration and overall ethanol yield from fermentable sugars at the same [Bmim]Cl concentration. This work provides useful information on selecting suitable strains for ethanol fermentation containing the [Bmim]Cl in the medium.