Engineering bacterial processes for cellulosic ethanol production

Abstract

Over the past decade, ethanol has emerged as the single most-important alternative fuel to gasoline. In many countries, a blend of gasoline and alcohol (gasohol) is being supplied as a liquid fuel for transportation. Bioethanol produced from agricultural feed stocks is renewable in nature and reduces the problem of ghg emissions associated with petroleum-derived gasoline. While most current processes for production of bioethanol are dependent on microbial fermentation of food feedstocks (e.g., corn and sugarcane), second-generation technology based on the fermentation of nonfood feedstocks (e.g., corn stover and switch grass) is under development. Successful commercialization of bioethanol production requires an efficient microbe, rapid hydrolysis of feedstock into fermentable sugars and an optimized fermentation process. This article consolidates the current state of the art in upstream processing of cellulose for bioethanol production with bacteria. Recent advances in microbial cocultures involving one or more bacteria for efficient production of bioethanol are also discussed. The importance of engineering bacterial processes for efficient cellulosic bioethanol production is emphasized.