Evaluating the Impact of Byproducts Generated by an Industrially Relevant Crop Pretreatment on Lignocellulosic Ethanol Yields

Abstract

Lignocellulosic ethanol is an emerging biofuel industry close to implementation in the market; however refinements are still needed to make the technology profitable. Shell has developed a system by which high yields of ethanol can be obtained from lignocellulose, however reaching profitability is limited by inhibition of enzymatic saccharification of the lignocellulose and subsequent fermentation. A better understanding of inhibitors of cellulase enzymes and the GM-strain of S. cerevisiae is needed to troubleshoot the technology and the biological systems involved. In this work Central Composite design demonstrated that ethanol, lactic acid and acetic acid act to synergistically inhibit fermentation, allowing a model of their effect to be produced, but only ethanol inhibited saccharification. Solid Phase Extraction was used to discriminate molecules, showing that non-polar components of the biomass strongly inhibit saccharification final yield, but worked alongside polar acids to achieve inhibition in fermentation. Propagation strategies were also tested to determine how conditioning impacted the results.