7-03: Development and Deployment of Consolidated Bioprocessing for Production of Ethanol

Consolidated Bioprocessing (“CBP”) employs  single microorganism that simultaneously generates sugars and produces ethanol from wood and other forms of pretreated lignocellulosic biomass.  Pretreatment opens up the structure of wood by disrupting the lignin seal and exposing cellulosic plant cell wall components.  This enables CBP microorganisms to access the cellulosic constituents, hydrolyze them, and produce ethanol.  The microorganisms not only ferment sugars to ethanol, but also generate the biocatalysts – enzymes – that are needed to break down cellulose into fermentable sugars.  Mascoma’s research is combining naturally occurring metabolic activities into a single microorganism by modifying the fermentative pathways of nature’s most efficient processors of cellulose, including the thermophilic anaerobic bacterium, Cl. thermocellum, to produce high yields of ethanol from hardwoods and biomass feedstocks. In addition, the ability to modify the fermentative pathways of a thermophilic anaerobe to achieve high ethanol yield from sugars was previously demonstrated through metabolic engineering of T. saccharolyticum. The practical application of Consolidated Bioprocessing is based on combining new biotechnology and unique but established process engineering.  We discuss the four basic steps convert wood to ethanol;  (1) feedstock preparation (chipping); (2) simple pretreatment of  wood to make it accessible to microbial action; (3) fermentation to ethanol; and (4) product separations for recovery of fuel-grade ethanol and lignin.  The design of a commercial facility is being informed by pilot and demonstration scale validation of fermentation parameters and designs that have evolved from work of NREL, DOE and USDA sponsored programs in both the public and private sectors.