Ten years ago, who would have thought that in 2016 scientists would be using bacteria to transform switchgrass biomass into D-limonene, a precursor for bio-jet fuel?
Regardless of doubts in biofuel uses, the global commercial airline industry is behind such methods. Scientists at Lawrence Berkeley National Laboratory recently engineered a [C2C1Im]-tolerant E. coli strain to express a D-limonene production pathway.
Escherichia coli, or E.coli is a characterized bacterium that comes in different forms, or strains, that serve a particular function. The E.coli bacteria, applied to switchgrass, have one main job: produce biofuel by eating sugars. Before the bacteria can “eat” the sugars, the plant is broken down, accomplished in the past by expensive measures.
The new one-pot method is more efficient: a salty liquid, 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]), is used to pretreat switchgrass and deconstruct the plant. The E.coli digests the plant and by using sugars, produces D-limonene. This success overcame past barriers that used multi-step methods.
Older methods performed the procedure in separate pots. The plant organic compounds cellulose, hemicellulose, and lignin are first broken apart. The addition of enzymes allows the production of sugars that serve as food for the bacteria, which in turn produces the biofuel.
The liquid pretreatment was the main problem, because in later steps it needed to be washed away, being that it leaves behind residues that harm relevant enzymes as well as the host. The washing process is expensive and time-consuming.
This problem was overcome by the [C2C1Im]-tolerant E. coli strain that not only tolerates the pretreatment liquid, eliminating the need to wash away the salty liquid, but produces ionic-liquid-tolerant enzymes that digest the biomass and produce sugars. The utilization of a cheaper and more efficient method that can directly produce biofuel, while reducing the carbon footprint, is a predictable accomplishment in the near-future.