(580a) Influences of Process Parameters On Cell Growth and Product Distribution of Clostridium Autoethanogenum

Ethanol production from syngas or CO-rich waste gas fermentation is a promising technique and has received much attention due to its advantages. Up to date several acetogens have been isolated and demonstrated to have the ability of converting syngas to ethanol. Compared to other acetogens, Clostridium autoethanogenum is less studied, and the ethanol it produced appears to be little. In this study, influences of several process parameters on cell growth and products distribution of Clostridium autoethanogenum were investigated. Clostridium autoethanogenum was grown in serum bottles, aluminum bags and a 3L-fermentor with modified medium, respectively. Results show that pH and Oxidation-Reduction Potential(ORP) play an important role in the process of ethanol production. pH and ORP decreased rapidly accompanying with cell growth and acetic acid production, and then increased while ethanol concentration started to increase. The maximum ethanol concentration obtained in the 3L-fermentor was 2.86g/L with continuous CO supply, while in an aluminum bag it reached the level of 3.46 g/L after feeding the bag with 1L CO twice, which is 340% or 430% greater than the maximum ethanol concentration achieved in other studies. In addition, Clostridium autoethanogenum can grow on xylose, but produce little ethanol with it. Since hydrolysate of bagasse treated with liquid hot water contains xylose, it was used to prepare the growth medium for Clostridium autoethanogenum. After growing in the hydrolysate medium for 2 days, Clostridium autoethanogenum was transferred to an aluminum bag filled with 1L CO. 3.13g/L ethanol was detected in the medium when CO was exhausted, indicating that the medium made of bagasse hydrolysate didn't inhibit Clostridium autoethanogenum from growing and converting CO to ethanol. A new technique combining CO fermentation with lignocellulose hydrolysis was suggested in the end.