Efficient ethanol production from beetle-killed lodgepole pine using SPORL technology and Saccharomyces cerevisiae without detoxification

This study applied Sulfite Pretreatment to Overcome Recalcitrance of Lignocelluloses (SPORL) to evaluate the potential of mountain pine beetle-killed lodgepole pine for ethanol production using conventional Saccharomyces cerevisiae without hydrolysate detoxification. The results indicate that the beetle-killed trees are more susceptible to SPORL pretreatment than live trees in addition to having enriched glucan and mannan content as reported in the literature. Ethanol yields of 200 and 250 L/metric ton wood were achieved from a live tree and a dead tree (four years after infestation) without process optimization. Ethanol yield of 220 L/metric ton of wood was obtained from a downed tree with more advanced decomposition, which is approximately 10% more than that from a corresponding live tree. Process mass and energy balance analyses suggest that net ethanol energy output (before distillation, lignin energy excluded) from the decomposing tree was approximately 3.2 GJ/metric ton wood, which is 23% more than that from a corresponding live tree. The study demonstrated the robustness of the SPORL process and the utility of beetle-killed trees for cellulosic ethanol production even after many years post mortality.