ABSTRACT In this research, metabolic fixation of CO2 by growing cells of C. acetobutylicum cultivated with electrochemical reducing power was tested on the basis of the metabolites production and genes expression. In cyclic voltammetry, electrochemical oxidation and reduction reaction of neutral red (NR) immobilized in intact cells of C. acetobutylicum was stationarily repeated like the soluble one in the condition without CO2 but the electrochemical reduction reaction was selectively increased by addition of CO2. In electrochemical bioreactor, the modified graphite felt cathode with NR (NR-cathode) induced C. acetobutylicum to generate acetate, propionate, and butyrate from CO2 in defined medium. When H2 and CO2 were used as an electron donor and an electron acceptor, respectively, C. acetobutylicum also produced the same metabolites in a defined medium. C. acetobutylicum was not grown in the defined medium without substituted electron donors (H2 or electrochemical reducing power). C. acetobutylicum cultivated with electrochemical reducing power produced more butyrate than acetate in complex medium but produced more acetate than butyrate in defined medium. The genes of encoding the enzymes catalyzing acetyl-CoA in C. acetobutylicum electrochemically cultivated in defined medium than conventionally cultivated in complex medium. These results are a clue that C. acetobutylicum may metabolically convert CO2 to metabolites and produce free energy from the electrochemical reducing power.
Cite this paper
B. Young Jeon, I. Lae Jung and D. Hyun Park, "Conversion of Carbon Dioxide to Metabolites by Clostridium acetobutylicum KCTC1037 Cultivated with Electrochemical Reducing Power," Advances in Microbiology, Vol. 2 No. 3, 2012, pp. 332-339. doi: 10.4236/aim.2012.23040.
 R. Thauer, K. Jungermann and K. Decker, “Energy Conservation in Chemotrophic Anaerobic Bacteria,” Bacteriological Review, Vol. 41, No. 1, 1977, pp. 100-180.
 A. M. Blackmer, J. M. Bremner and E. L. Schmidt, “Production of Nitrous Oxide by Ammonia-Oxidizing Chemoautotrophic Microorganisms in Soil,” Applied and Environmental Microbiology, Vol. 40, No. 6, 1980, pp. 1060-1066.
 E. Siefert and N. Pfennig, “Chemoautotrophic Growth of Rhodopesudomonas Species with Hydrogen and Chemotrophic Utilization of Methanol and Formate,” Archives of Microbiology, Vol. 122, No. 2, 1979, pp. 177-182.
 C. Castelle, M. Guiral, G. Malarte, F. Ledgham, G. Leroy, M. Brugna and M.-T. Giudici-Orticon, “A New Iron-Oxidizing/O2-Reducing Supercomplex Spanning Both Inner and Outer Membranes, Isolated from the Extreme Acidophile Acidithiobacillus ferrooxidans,” Journal of Biological Chemistry, Vol. 283, No. 38, 2008, pp. 25803-25811. doi:10.1074/jbc.M802496200
 A. Elbehti, G. Brasseur and D. Lemesle-Meunier, “First Evidence for Existence of an Uphill Electron Transfer through the bc1 and NADH-Q Oxidoreductase Complexes of the Acidophilic Obligate Chemoautotrophic Ferrous Ion-Oxidizing Bacterium Thibacillus ferroxidans,” Journal of Bacteriology, Vol. 182, No. 12, 2000, pp. 3602-3606. doi:10.1128/JB.182.12.3602-3606.2000
 D. H. Park and J. G. Zeikus, “Utilization of Electrically Reduced Neutral Red by Actinobacillus succinogenes: Physiological Function of Neutral Red in Membrane-Driven Fumarate Reduction and Energy Conservation,” Journal of Bacteriology, Vol. 181, No. 8, pp. 2403-2410.
 A. A. Karyakin, O. A. Bobrova and E. E. Karyakina, “Electroreduction of NAD+ to Enzymatically Active NADH at Poly(Neutral Red) Modified Electrodes,” Journal of Electroanalytical Chemistry, Vol. 399, No. 1-2, 1995, pp. 179-184. doi:10.1016/0022-0728(95)04300-4
 M. Hügler, C. Menendez, H. Sch?gger and G. Fuchs, “Malonyl-Coenzyme A Reductase from Chloroflexus aurantiacus, a Key Enzyme of the 3-Hydroxypropionate Cycle for Autotrophic CO2 Fixation,” Journal of Bacteriology, Vol. 184, No. 9, 2002, pp. 2404-2410.
 H. Buschhhorn, P. Dürre and G. Gottschalk, “Production and Utilization of Ethanol by the HomoacetogenAcetobacterium woodii,” Applied and Environmental Microbiology, Vol. 55, No. 7, 1989, pp. 1835-1840.
 H. Zhang, M. A. Bruns and B. E. Logan, “Biological Hydrogen Production by Clostridium acetobutylicum in an Unsaturated Flow Reactor,” Water Research, Vol. 40, No. 4, 2006, pp. 728-734.
 J. Zhang, J. Sun, X. Zhang, Y. Zhao and S. Zhang, “The Recent Development of CO2 Fixation and Conversion by Ionic Liquid,” Greenhouse Gases: Science and Technology, Vol. 1, No. 2, 2011, pp. 142-159.
 B. Wang, Y. Li, N. Wu and C. Q. Lan, “CO2 Bio-Mitigation Using Microalgae,” Applied Microbiology and Biotechnology, Vol. 79, No. 5, 2008, pp. 707-718.
 J. E. Funk, “Thermochemical Hydrogen Production: Past and Present,” International Journal of Hydrogen Energy, Vol. 26, No. 3, 2001, pp. 185-190.
 A. Steinfeld, “Solar Hydrogen Production via a Two-Step Water-Splitting Thermochemical Cycle Based on Zn/ZnO Redox Reactions,” International Journal of Hydrogen Energy, Vol. 27, 2002, pp. 611-619.
 B. Y. Jeon, I. L. Jung and D. H. Park, “Enrichment and Isolation of CO2-Fixing Bacteria with Electrochemical Reducing Power as a Sole Energy Source,” Journal of Environmental Protection, Vol. 3, 2012, pp. 55-60.
 B. Y. Jeon, I. L. Jung and D. H. Park, “Enrichment of CO2-Fixing Bacteria in Cylinder-Type Electrochemical Bioreactor with Built-In Anode Compartment,” Journal of Microbiology and Biotechnology, Vol. 21, No. 6, 2011, pp. 590-598.
 C. J. Kay, L. P. Solomonson and M. J. Barber, “Electrochemical and Kinetic Analysis of Electron-Transfer Reactions of Chlorella Nitrate Reductase,” Biochemistry, Vol. 30, No. 48, 1991, pp. 11445-11450.
 X. Zhong, J. Chen, B. Liu, Y. Xu and Y. Kuang, “Neutral Red as Electron Transfer Mediator Enhanced Electrocatalytic Activity of Platinum Catalyst for Methanol Electro-Oxidation,” Journal of Solid State Electrochemistry, Vol. 11, No. 4, 2007, pp. 463-468.
 L. Huang, J. M. Regan and X. Quan, “Electron Transfer Mechanisms, New Applications, and performance of Biocathode Microbial Fuel Cells,” Bioresource Technology, Vol. 102, 2011, pp. 316-323.
 G. Reguera, K. D. McCarthy, T. Mehta, J. S. Nicoll, M. T. Tuominen and D. R. Lovley, “Extracellular Electron Transfer via Microbial Nanowires,” Nature, Vol. 435, 2005, pp. 1098-1101. doi:10.1038/nature03661
 J. Song, Y. Kim, M. Lim, H, Lee, J. I. Lee and W. Shin, “Microbes as Electrochemical CO2 Conversion Catalysts,” ChemSusChem, Vol. 4, No. 5, 2011, pp. 587-590.