Ethanol and acetate production by Clostridium ljungdahlii and Clostridium autoethanogenum using resting cells
- 1.5k Downloads
Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification generates synthesis gas consisting primarily of CO, CO2, H2, N2, with smaller amounts of CH4, NOx, O2, C2 compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas constituents. However, there are challenges to maintaining culture viability of synthesis gas exposed cells. This study was designed to enhance culture stability and improve ethanol-to-acetate ratios using resting (non-growing) cells in synthesis gas fermentation. Resting cell states were induced in autotrophic Clostridium ljungdahlii cultures with minimal ethanol and acetate production due to low metabolic activity compared to growing cell production levels of 5.2 and 40.1 mM of ethanol and acetate. Clostridium autoethanogenum cultures were not induced into true resting states but did show improvement in total ethanol production (from 5.1 mM in growing cultures to 9.4 in one nitrogen-limited medium) as well as increased shifts in ethanol-to-acetate production ratios.
KeywordsClostridium ljungdahlii Clostridium autoethanaogenum Ethanol Acetate Resting cells Non-growing cells
The authors acknowledge the financial support of the North Carolina State University Faculty Research and Professional Development Grant.
- 4.Bryant MP (1972) Am J Clin Nutr 25:1324–1328Google Scholar
- 9.Fordyce AM, Crow VL, Thomas TD (1984) Appl Environ Microbiol 48(2):332–337Google Scholar
- 10.Gaddy JL, Clausen EC (1992) US Pataent 612:221Google Scholar
- 12.Kini KA, Lahiri A (1975) J Sci Ind Res 34(2):97–99Google Scholar
- 14.Larsson C, Stockar U, Marison I, Gustafsson L (1993) J Bacteriol 175(15):4809–4816Google Scholar
- 15.Lebloas P, Guilbert N, Loubiere P, Lindley ND (1993) J Gen Microbiol 139:1861–1868Google Scholar
- 19.Padan E, Zilberstein D, Schuldiner S (1981) Biochim Biophys Acta 650:151–166Google Scholar
- 21.Rao G, Mutharasan R (1987) Appl Environ Microbiol 53(6):1232–1235Google Scholar
- 23.Saha SK, Sivasanker S (1992) Indian J Technol 30(2):71–76Google Scholar
- 26.Terracciano JS, Kashket ER (1986) Appl Environ Microbiol 52(1):86–91Google Scholar
- 28.Vasconcelos I, Girbal L, Soucaille P (1994) J Bacteriol 176(3):1443–1450Google Scholar