Monday, July 27, 2009
P46

Effects of nutrient limitation on ethanol and acetic acid production by Clostridium strain P11

Mark R. Wilkins, Dimple Kundiyana, and Raymond L. Huhnke. Biosystems and Agricultural Engineering, Oklahoma State University, 224 Ag Hall, Stillwater, OK 74078

Clostridium strain P11 is a novel bacterium that can utilize CO, CO2, and H2 to produce ethanol and acetic acid. Other bacteria, such as Clostridium carboxidivorans and Clostridium ljungdahlii, have also been shown to have this capability. In previous work on C. ljungdahlii, researchers varied the concentrations of calcium pantothenate and cobalt in the media in order to promote the production of reducing equivalents in the media and the formation of ethanol. In this study, a factorial study was done to investigate the effect of cobalt chloride, calcium pantothenate, and Vitamin B12 concentration on ethanol and acetic acid production by Clostridium strain P11. Fermentations were done in 250 ml bottles with a bottled gas mix containing 40% CO, 30% CO2 and 30% H2. Ethanol production ceased after 9 days and acetic acid ceased after 7 days. The calcium pantothenate concentration in our current media increased ethanol and acetic acid production as opposed to the media from the C. ljungdahlii study (p<0.05). Also, there was a significant two-way interaction between cobalt chloride and Vitamin B12 for ethanol production (p<0.05). When both nutrients were either at the current levels or the C. ljungdahlii study’s levels, ethanol production was increased with respect to when one nutrient was at the current level and the other was at the C. ljungdahlii study’s level.