Carboxylic acids to biofuels via syngas fermentation CCTEC sixth annual Cornell Technology Venture Forum™ (CTVF) on October 25, 2012 in the East Hill Office Building Training Room and Atrium (395 Pine Tree Road, Ithaca, NY) Carboxylic acids to biofuels via syngas fermentation Hanno Richter, Michael E. Martin, and Largus T. Angenent Cornell University, Biological & Environmental Engineering, Ithaca, NY 14853 http://angenent.bee.cornell.edu/ http://www.css.cornell.edu/faculty/lehmann/village_pyrolysis/index.html Carboxylic acid conversion in batch syngas reactors Continuous syngas fermentation with gas- and cell recycling for increased productivity ABSTRACT Short chain carboxylic acids such as n-butyric acid have been suggested as potential precursors for production of biofuels, e.g. n-butanol (Dwidar et al., 2012. The Scientic World Journal doi:10.1100/2012/471417). Our lab has developed the carboxylate platform, a fermentation technology with open cultures of microbial consortia that generates short-chain carboxylic acids, such as n-butyric acid (Agler et al., 2012. Environ. Sci. Technol. 46(18): 10229-38), or n-caproic acid (Agler et al., 2012. Energy Environ. Sci. 5: 8189-8192) as end-products. Also this year, we have published a manuscript on the conversion of n-butyric acid into n-butanol using glucose as a source of electrons and energy (Richter et al., 2012. Biotechnol Bioeng. 109(4): 913-921). In August 2012, we have submitted another manuscript to Biotechnology & Bioengineering, and filed a patent for the invention of a technology that uses carbon monoxide and hydrogen (potentially derived from biomass pyrolysis), as a source of electrons and energy for microbial conversion of short-chain carboxylic acids, such as n-butyric acid and n-caproic acid, into their corresponding alcohols (n-butanol and n-hexanol, respectively). Results of that latest innovation and on improvement of syngas fermentation efficiency are presented here. * OD600 + pH ● butyrate □ acetate ● butanol ▪ ethanol Clostridium ljungdahlii in anaerobic batch reactors, continuously sparged with syngas Formation of products in syngas- reactors with 15 mM n-butyric acid Table: range of substrates tested (15 mM); results for 2 different microbial species effluent Pumps Growth medium Microbubbles, required for efficient mass transfer pH control Stage II Stage I Parameters for 2nd fermentation stage Overview Rates of mMol/(L*min) g/(L*h) CO in 0.808 1.357 CO out 0.110 0.185 CO consumption 0.698 1.172 H2 in 0.471 0.057 H2 out 0.085 0.010 H2 consumption 0.386 0.046 CO2 in 0.067 0.177 CO2 out 0.371 0.979 CO2 production 0.304 0.803 Ethanol production 0.136 0.375 Acetic acid production 0.025 0.090 Species Concentration stage 2 inlet outlet CO (g) 60 vol% 19 vol% H2 (g) 35 vol% 14 vol% CO2 (g) 5 vol% 63 vol% Ethanol (l) 428 mM (19.7 g/L) Acetic acid (l) 143 mM (8.6 g/L) Gasification Syngas (CO, H2, CO2) CO2 Lignocellulose N-butyric Acid N-butanol Carboxylate platform Solvento- genic Clostridium Efficiency (%) Stage 2 CO consumption 86 H2 consumption 82 CO recovery in etOH 28* CO recovery in acetic acid 5* FUNDING The presentation focuses on the conversion of carboxylic acids into alcohols (highlighted here). Yossie Hollander and the Foundation de Fondateurs Northeastern SunGrant Initiative Achieved: An ethanol productivity, Ca. 10% of yeast in biofuel plants. * Syngas consumption of stage 1 is considered