High concentration ethanol production based on CO gas-utilizing clostridium autoethanogenum

다국어 초록 (Multilingual Abstract)

Anaerobic acetogens like Clostridium autoethanogenum, Clostridium ljungdahlii, and Clostridium ragsdalei are known to be capable of production of ethanol from carbon monoxide (CO). C. autoethanogenum is extremely anaerobic and known to produce acetate and ethanol through Wood-Ljungdahl pathway with CO as sole carbon source. First we choose growth-related factors like yeast extract, fructose, phosphate, Na2S from defined minimal media and changed concentration of those factors to improve cell growth. After that, we controlled some production-related media components, synthetic gas composition of H2 to CO ratio and existence of CO2 which affect ethanol production. Synthetic gas we used as control has almost same components with Blas Furnace Gas (BFG) ; 20% CO, 20% CO2, 10% H2, N2 balance. All factors above were tested on 100 ml serum flask. Also, fed-batch culture was performed in 2.5 L Stirred-Tank Reactor (STR) at 37 ℃, 400 rpm, pH 7.0. Synthetic gas in the reactor was replaced by flow rate of 300 ml/min. After 15 days of fermentation, acetate and 2,3-BDO was observed with ethanol. Final ethanol concentration was 7.0 g/L