Heat Shocking of Clostridium Strain Pll to Promote Sporulation and Ethanol Production

摘要

Producer gas fermentation is a developing technology that uses aceto-genic bacteria for the conversion of CO and H_2 into biofuels and commodity chemicals. While different methods have been employed to enhance product concentrations, heat shocking isa physical parameter that is less investigated. This study employs Clostridium strain Pll for the conversion of CO and H_2 into ethanol and acetic acid. The strategy for this study was to expose Pll cells to two different temperatures, 75deg C and 92degC, for a short duration (3 min), to induce spore formation and enhance ethanol production. Inocula from these cultures were then transferred into fresh culture media and were compared to cells that were not heat shocked. Spores were observed when a 24 hsample was withdrawn from bottles containing cells that were heated at 75deg C and 92deg C. Product concentrations were similar among all treatments (p > 0.05), but cells heat shocked at 92deg C had a greater yield of ethanol and a lower yield of aceticacid from CO than did the other treatments (p < 0.05). It was observed that heat shocking at 92 deg C also resulted in an increase in gas utilization over the control (p < 0.05). Thus, heat shocking of Pll cells prior to using them for producer gas fermentation enhanced ethanol production. This strategy could be applied to other sporulating acetogenic Clostridial bacteria that have ability to produce solvents autotrophically.