Background: Ionic liquids (ILs) are claimed as green solvents and have demonstrated ability
in the dissolution of several biomaterials and polymers, thus promoting their applications in wide
scope. The aim of this study was to evaluate the yeast cells in the ionic liquid (IL), choline acetate
[Cho]OAc as an eco-friendlier IL for their growth and ability of fermentation of the empty fruit bunch
(EFB) biomass for ethanol production via monitoring the cell growth curve and kinetics.
Methods: The Saccharomyces cerevisiae was cultured for five days on yeast extract-peptone-dextrose
(YPD) agar and the sub-culturing was carried out every two weeks to evaluate the growth of yeast in
[Cho]OAc at different concentrations; 5%, 10%, and 20%, where it was pre-cultivated for 24 h at
30 °C and 150 rpm in a shaking incubator as a control culture. Yeast cell number was determined by
counting using a hemocytometer. Also, the kinetic growth of yeast during the fermentation of EFB
Result: Cell concentration increased, ethanol production increased along with the optical density with
the peak reached at 72 h, then declined. Enzymatic hydrolysis process followed by fermentation of
EFB using [Cho][OAc] improved the yield of sugar, saccharification and ethanol around 1.938, 2.879,
and 2.165 times in comparison with untreated EFB with IL. Furthermore, values of specific growth
rates obtained in IL-medium and non-IL-medium are applicable for ethanol production to take place.
The results showed the ability of yeast cells for fermentation even in the presence of IL.
Conclusion: The results showed that the presence of the IL did not suppress the growth of the yeast
cells and did not impair the fermentation productivity.