초기 pH 조건이 C. ljungdahlii를 이용한 합성가스 발효공정에 미치는 영향 = Influence of initial pH and buffering agent on growth of C. ljungdahlii on synthesis gas

다국어 초록 (Multilingual Abstract)

Clostridium ljungdahlii, a microorganism which has an ability to ferment hydrogen and carbon monoxide to ethanol and acetic acid, was cultured in a nutrient medium under anaerobic conditions and synthesis gas. The optimal pH for synthesis gas fermenting is known to be between 5.8 and 6.0. The initial pH of growth medium was about 6.0. In this study phosphate buffer solution was used to adjust pH value of growth medium, but production of ethanol was slow. It is found that C. ljungdahlii can grow fast in this medium and the production of ethanol concentration reached to 0.117g/L and acetic acid concentration 0.753g/L at 117 hours. The most ethanol concentrations reached to 0.22g/L and acetic acid concentration reached to 2.67g/L at 120 days. Groups of experiment of medium change showed C. ljungdahlii can grow well either in medium with or without phosphate buffer solution. The experiments showed the ethanol production needed longer time in the medium with phosphate buffer solution. C. ljungdahlii can grow well in another medium which removed NaHCO₃ and added NaOH to adjust pH value and initial pH was 7.40. The production of ethanol concentration reached to 0.51g/L and acetic acid reached to 0.43g/L just for 4 days. The second growth medium promoted the ethanol production and restrained acetic acid production.