Recent advancements in various steps of ethanol, butanol, and isobutanol productions from woody materials.

In this review, the recent advancements and technical challenges associated with the production of ethanol, butanol, and isobutanol via bioconversion routes from celluloses of woody materials are reviewed. Physicochemical processes, e.g. steam explosion, seem to be the most viable process for pretreating woody materials. Although enzymatic hydrolysis is selective, it is rather a slow process. Acid hydrolysis is a relatively fast process with a high yield, but it produces inhibitory compounds of fermentation, which necessitates a detoxification process before the fermentation. Presently, the major challenges in the production of ethanol, butanol, and isobutanol via biological conversions are the rather low production yield and the sensitivity of microorganisms to the presence of inhibitors and products in fermentation media. In this study, the recent advancements in the applications of Saccharomyces cerevisiae, Clostridium acetobutylicum, and Corynebacterium glutamicum, the most promising microorganisms, for ethanol, butanol, and isobutanol production are also discussed.