Exploring Starch Sources for the Refreshment Process of Acetone-Butanol-Ethanol Fermentation with Clostridium Saccharoperbutylacetonicum N1-4

Abstract

Biobutanol is a renewable fuel that can be used as a gasoline substitute and a chemical feedstock. Its production using the Clostridial bacterial strain involves three steps: refreshment from a stock, a preculture for bacterial propagation, and primary fermentation for butanol production. Refreshment is an important process to activate the bacteria and multiply the stock. This process uses potato glucose media for C. saccharoperbutylacetonicum N1-4, while the use of starch from other sources has not been studied. This study aimed to understand various carbon sources’ effects on this refreshment process as part of ABE (acetone-butanol-ethanol) fermentation. Starch was substituted in refreshment media with several types of potato, rice, sweet corn, and sweet potato at 15% w/v. After 24 hours of refreshment at an ambient temperature, fermentation was run for 48 hours in TYA (tryptone-yeast-acetate) glucose media. All the starch sources could be used in the refreshment process, resulting in butanol and total solvent concentration ranging from 7.58 to 8.76 g/L and 12.5 to 14.6 g/L, respectively. Among the samples, sweet corn provided the highest fermentation performance, with butanol of 8.76 g/L, total solvents of 14.6 g/L, average butanol productivity of 0.182 g/L/h, and a butanol yield per substrate of 0.481 C-mol/C-mol. All the starchy materials used in this experiment offered potential for ABE fermentation, while sweet corn performed remarkably—producing the highest final butanol concentration, productivity, and yield.

Keywords

• biobutanol
• potato
• rice
• refreshment
• sweet corn
• sweet potato