Ethanol production from syngas by Clostridium strain P11 using corn steep liquor as a nutrient replacement to yeast extract

摘要

The feasibility of replacing yeast extract (YE) by corn steep liquor (CSL), a low cost nutrient source, for syngas fermentation to produce ethanol using Clostridium strain P11 was investigated. About 32% more ethanol (1.7gL~(-1)) was produced with 20gL~(-1) CSL media in 250-mL bottle fermentations compared to media with 1gL~(-1) YE after 360h. Maximum ethanol concentrations after 360h of fermentation in a 7.5-L fermentor with 10 and 20gL~(-1) CSL media were 8.6 and 9.6gL~(-1), respectively, which represent 57% and 60% of the theoretical ethanol yields from CO. Only about 6.1gL~(-1) of ethanol was obtained in the medium with 1gL~(-1) YE after 360h, which represents 53% of the theoretical ethanol yield from CO. The use of CSL also enhanced butanol production by sevenfold compared to YE in bottle fermentations. These results demonstrate that CSL can replace YE as the primary medium component and significantly enhance ethanol production by Clostridium strain P11.