BIOLOGICAL PRODUCTION OF ETHANOL FROM COAL SYNTHESIS GAS - MEDIUM DEVELOPMENT STUDIES

The anaerobic bacteria Clostridium ljungdahlii produces ethanol and ac etate from CO, CO2, and H-2 in synthesis gas. Early studies with the b acterium showed that relatively high concentrations of ethanol could b e produced by lowering the fermentation pH and eliminating yeast extra ct from the medium in favor of a defined medium. This article presents the results from a medium development study based on the aerobic bact erium Escherichia coli. The results of continuous-reactor studies in a continuously stirred tank reactor (CSTR) with and without cell recycl e are shown to demonstrate the utility of this improved medium.