The production of butanol and isopropanol from energycane syrup using Clostridium beijerinckii optinoii.

Clostridium beijerinckii optinoii produces butanol, isopropanol, and very little ethanol/acetone in a 6.0: 3.8: 0.2 weight ratio, unlike other ABE organisms where the ratio is 6:3:1 (butanol:acetone:ethanol, weight ratio). Acetone is not considered to be favorable for downstream process due to its corrosiveness and volatility. The butanol/isopropanol mix produced by Clostridium beijerinckii optinoii is expected to be more practical for butanol production than the butanol/acetone mix from the ABE fermentations. The sugar feeds from sugarcane molasses and energycane were tested in batch fermentations (10 L scale) to maximize the production of butanol and isopropanol using Clostridium beijerinckii optinoii. Using 3% glucose as a carbon source, the solvent concentrations (butanol and isopropanol) and solvent yields were 10.03 g/L and 0.43 g/g, respectively, with a sugar utilization of 81.7%. However, on 2.5% glucose medium supplemented with an additional 0.5% sugar supplied as sugarcane molasses, sugar consumption was 100% and the solvent concentrations (13.37 g/L) and solvent yields (0.45 g/g) were both higher. Energycane syrup (2.5%) with sugarcane molasses (0.5%) with invertase produced a solvent concentration of 10.61 g/L and solvent yield of. 0.36 g/g with sugar consumption of 100%. This work showed that the production of butanol and isopropanol from glucose or energycane using Clostridium beijerinckii optinoii can be increased by adding sugarcane molasses as a cheap supplementary nutrient. Due to the low productivity for butanol production in batch fermentation, an immobilized cell production system for the energycane syrup with sugarcane molasses is being tested to improve the butanol productivity.