Efficient ethanol production from corncob residues by repeated fermentation of an adapted yeast

For economically feasible lignocellulosic ethanol production, it is crucial to obtain a robust strain and develop an efficient fermentation process. An earlier-screened yeast strain Pichia guilliermondii was adapted to corncob residues (CCR) hydrolysate and used for high titer ethanol production without any detoxification or external nutrient supplementation. With an optimized fed-batch strategy, the maximum ethanol titer and productivity reached 56.3 g/l and 0.47 g l(-1) h(-1), respectively. To further increase the ethanol productivity, the fed-batch process was repeated three times with cell reuse, and the maximum ethanol titer and productivity reached 51.2 g/l and 1.11 g l(-1) h(-1), respectively. The results demonstrated that the combination of fed-batch with repeated fermentation was effective in improving the fermentation efficiency and achieving high ethanol productivity from CCR. The reported system is considered promising for commercial production of bioethanol from biomass hydrolysate in the future.