Advances in Consolidated Bioprocessing Using Clostridium thermocellum and Thermoanaerobacter saccharolyticum

Biological conversion of lignocellulose to fuels and chemicals has been a major research focus since the 1970s. This chapters draws upon recently published and unpublished works, to provide an aggregated perspective on the status for consolidated bioprocessing (CBP) using thermophilic bacteria. It focuses on two microbes that have received particular attention in this context: the cellulose-fermenting Clostridium thermocellum and the hemicellulose-fermenting Thermoanaerobacterium saccharolyticum. The chapter focuses on ethanol because it has received the most attention in the context of organism development for CBP, and because cellulosic ethanol production is the logical point of entry and proving ground for CBP. It comments on CBP organism development strategies and addresses plant cell wall solubilization by C. thermocellum, with an emphasis on comparison to industry-standard fungal cellulase. The chapter addresses bioenergetics of C. thermocellum cellulose fermentation and metabolic engineering including development of genetic tools, the high-functioning ethanol pathway in T. saccharolyticum, and the current state of strain development.