초록
<P><B>Abstract</B></P> <P>The effect of pH and butyric acid supplementation on the production of butanol by a new local isolate of <I>Clostridium acetobutylicum</I> YM1 during batch culture fermentation was investigated. The results showed that pH had a significant effect on bacterial growth and butanol yield and productivity. The optimal initial pH that maximized butanol production was pH 6.0±0.2. Controlled pH was found to be unsuitable for butanol production in strain YM1, while the uncontrolled pH condition with an initial pH of 6.0±0.2 was suitable for bacterial growth, butanol yield and productivity. The maximum butanol concentration of 13.5±1.42g/L was obtained from cultures grown under the uncontrolled pH condition, resulting in a butanol yield (<I>Y<SUB>P</SUB> </I> <SUB>/</SUB> <I> <SUB>S</SUB> </I>) and productivity of 0.27g/g and 0.188g/Lh, respectively. Supplementation of the pH-controlled cultures with 4.0g/L butyric acid did not improve butanol production; however, supplementation of the uncontrolled pH cultures resulted in high butanol concentrations, yield and productivity (16.50±0.8g/L, 0.345g/g and 0.163g/Lh, respectively). pH influenced the activity of NADH-dependent butanol dehydrogenase, with the highest activity obtained under the uncontrolled pH condition. This study revealed that pH is a very important factor in butanol fermentation by <I>C. acetobutylicum</I> YM1.</P>