Towards a practical industrial 2G ethanol production process based on immobilized recombinant S. cerevisiae: Medium and strain selection for robust integrated fixed-bed reactor operation

The development of a robust and scalable process for 2G ethanol production from renewable feedstock requires high ethanol titers and long-term stability. A strategy based on strain evaluation and integration with 1G ethanol production was used to overcome these challenges. Three engineered superior S. cerevisiae strains were evaluated in industrial media, using either pure sugarcane bagasse hydrolysates or mixed with molasses from sugarcane processing. Cell recycling was limited to 4 batches and decreasing productivity was observed in fermentation media based on concentrated bagasse hydrolysate, even after detoxification. When crude bagasse hydrolysate was mixed with molasses (MBH medium), fermentations with up to 10 cell recycles and final ethanol concentrations over 50 g/L were achieved with all strains. In a fixed-bed reactor operated with the selected MDS130 strain and MBH medium, remarkable ethanol productivities up to 22.8 g/L/h were reached and up to 20 cell recycles were possible.(c) 2021 Elsevier Ltd. All rights reserved.