As scientists and researchers earnestly delve for the most environmentally sound source of energy, that is, renewable, efficiently reduces greenhouse gases emissions, and in no competition with food production, a high-yield (87% of theoretical maximum) biobutanol production using metabolically engineered bacterium comes into the scene.
Biobutanol, a liquid biofuel that has properties superior to ethanol and similar to gasoline and thus, may potentially replace gasoline, can be naturally produced from fermentation of biomass using an anaerobic bacterium, Clostridium acetobutylicum, as a catalyst.
However, due to its toxicity to the host organisms and the production of its byproducts, its production efficiency is not sufficient enough to match that ethanol and to meet industrial needs.
In a recent research entitled, “Enhanced butanol production obtained by reinforcing the direct butanol-forming route in Clostridium acetobutilycum,” by Korea Advanced Institute of Science and Technology (KAIST), the efficiency of the anaerobic bacterium in biobutanol production was enhanced and optimized through a technique called systems metabolic engineering, a practice of designing and optimizing cellular metabolic and regulatory networks.
The researchers found two metabolic pathways they called hot channel and cold channel. In hot channel, butanol is directly produced from carbon source. In the cold channel, acids produced earlier in fermentation are converted to butanol.
The former pathway was shown in the study using modeling and simulation tools to produce more butanol than the latter. Hence, they systematically engineered the bacterium’s metabolic network such that the metabolic flux will be reinforced toward the more efficient direct butanol-forming pathway.
The said reinforcement in biobutanol production indulged a yield that is 160% and 245% higher than those obtained with the conventional clostridium strains. The overall process development resulted to production of 585 g of butanol from 1.8 kg of glucose, which is 87% of the theoretical maximum yield.