Tuesday, April 20, 2010
11-53

Consolidated bioelectrochemical processing of cellulosic biomass to ethanol and hydrogen

Tsutomu Shimotori1, Milenka Arispe-Angulo2, Brian Corbett1, Randhir Makkar1, Michael J.K. Nelson1, and Harold May2. (1) Microbial Fuel Cell Technologies, LLC, P.O. Box 1981, Mount Pleasant, SC 29464, (2) Microbiology & Immunology, Medical University of South Carolina, Charleston, SC

Consolidated bioprocessing of cellulosic biomass leverages the catalytic activity of cellulolytic and ethanologenic bacteria to produce ethanol.  Thermophilic bacteria such as Clostridium thermocellum and Thermoanaerobacter thermosaccharolyticum are typically used in this process due to their rapid and effective ability to metabolize cellulose and hemicellulose.  However, the by-product formation, especially fatty acids such as acetate, is common. This not only reduces the ethanol yield but also inhibits the overall fermentation.  In order to overcome this problem, MFC Technologies developed an innovative consolidated bio-electrochemical process to convert cellulosic biomass into ethanol and/or hydrogen. The approach is a unique combination of cellulolytic, ethanologenic and electricigenic bacteria in a single system.  The yields of ethanol versus fatty acids were increased when the anaerobic fermentation of cellulose took place in a microbial electrolysis cell (MEC) inoculated with a coculture of C. thermocellum, T. thermosaccharolyticum and the electricigenic bacterium Thermincola ferriacetica.  To our knowledge, this is the first successful combination of this type for enhancing production of ethanol and hydrogen. Thus far, this process has increased the ratio of acetate to ethanol 3-fold. We also demonstrated hydrogen production in a similar system using other cellulolytic, fermentative bacteria.  Higher hydrogen yields than those by fermentation alone were achieved due to the more effective conversion of fatty acids to hydrogen and water hydrolysis. This process requires only a limited amount of external electrical input and it has the potential to enhance biofuels production from cellulosic biomass in the future.


Web Page: www.mfctech.net

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