| 초록 |
Syngas fermentation is an attractive process. Several anaerobic bacteria species can be used in the process, converting syngas into bioethanol. However, there are challenges to maintaining high cell density of the anaerobes. In this study, the time-separated two-stage operation was introduced in a stirred tank reactor for high-density culture of Clostridium autoethanogenum and ethanol production. In the early growth stage, fructose was supplied as a carbon source for accelerating bacterial growth and the cell-recycle system was used to increase the maximum cell density. In the following production stage, the pH was adjusted from 6.0 to 5.5 for efficient ethanol production. And for the accumulation of ethanol, the cell recycle was stopped and the reactor was operated in batch mode. During 115 hours of growth stage, cell density reaches 21.68 of OD600. The reactor was eventually operated for 352 hours, and the total amount of ethanol produced was 23.0 g/L. |
