Publication: Short-term adaptation as a tool to improve bioethanol production using grass press-juice as fermentation medium

Our newest publication "Short-term adaptation as a tool to improve bioethanol production using grass press-juice as fermentation medium" is accepted in the journal "Applied Microbiology and Biotechnology".

Grass raw materials collected from grasslands cover more than 30% of Europe’s agricultural area. They are considered very attractive for the production of different biochemicals and biofuels due to the high availability and renewability. In this study, a perennial ryegrass (Lolium perenne) was exploited for second-generation bioethanol production. Grass press-cake and grass press-juice were separated using mechanical pretreatment, and the obtained juice was used as a fermentation medium. In this work, Saccharomyces cerevisiae was utilized for bioethanol production using the grass press-juice as the sole fermentation medium. The yeast was able to release about 11 g/L of ethanol in 72 h, with a total production yield of 0.38 ± 0.2 g_Ethanol/g_sugars. It was assessed to improve the fermentation ability of Saccharomyces cerevisiae by using the short-term adaptation. For this purpose, the yeast was initially propagated in increasing concentration of press-juice. Then, the yeast cells were re-cultivated in 100 %(v/v) fresh juice to verify if it had improved the fermentation efficiency. The fructose conversion increased from 79% to 90%, the ethanol titers reached 18 g/L resulting in a final yield of 0.50 ± 0.06 g_Ethanol/g_sugars with a volumetric productivity of 0.44 ± 0.00 g/Lh. The overall results proved that short-term adaptation was successfully used to improve bioethanol production with S. cerevisiae using grass press-juice as fermentation medium.

L. Varriale, D. Geib, R. Ulber; Short-term adaptation as a tool to improve bioethanol production using grass press-juice as fermentation medium; Applied Microbiology and Biotechnology (2024) accepted paper