Quantitative understanding of the impact of stress factors on xylose fermentation at different high solid biomass loads

Abstract

During lignocellulosic fermentation, cells are challenged by multiple stresses, leading to decreased performances, especially xylose conversion. Quantitatively understanding stress factors in alcoholic fermentation on xylose fermentation is prerequisite for designing and/or modifying lignocellulosic ethanol fermentation. Nonetheless, most studies only focus on just one type of stress, even only one target chemical compound, making it difficult to comprehensively understand the whole stress factors on xylose fermentation. In this study, stress factors in alcoholic fermentation of lignocellulosic hydrolysate were divided into five categories: inhibitors, fermentation metabolites, solid biomass residues, metal ions, and ethanol. Especially, extracted inhibitors, instead of target known inhibitors, were used for studying their effects on fermentation. The effects of each stress on xylose utilization were detailed investigated and compared. Principal component analysis was then performed for comprehensively analyzing effects of the above-mentioned five stresses on xylose fermentation. Results showed that high dose of ethanol is the most significant inhibition factor for xylose fermentation, followed by inhibitors and fermentation metabolites. Metal ions and solid biomass residues in hydrolysate have small effects on xylose fermentation. This study will provide fundamental theoretical support for designing efficient xylose conversion processes and constructing robust xylose-utilizing S. cerevisiae.