Tuesday, 22 May 2012

Genetically Engineered Bacteria May Be the Future of Energy

Humanity’s pursuit for clean energy has, up until the present, been like a childish attempt at trapping water with one’s hands; semi-progressive but ultimately fruitless. Recent biofuel research conducted by the United States Department of Energy’s Join BioEnergy Institute (JBEI) however may have provided mankind with the proverbial bucket it needs (Bokinsky et al. 2011).


The use of biofuels has been limited so far for several reasons, a major one being that the corn and sugarcane grown for biofuel production occupy agricultural land critical to food crops. (Service 2011). The logical solution then was to find a non-food crop plant suitable for fuel production which researchers at JBEI found in Panicum virgatum, a commonly occurring grass more widely known as switchgrass.

Another shortcoming of the biofuel production process which needed addressing was production cost. The cellulose and hemicellulose present within the plant mass must first be broken down into simple sugars before in order to make them suitable for fuel synthesis. The enzymes required to do this are expensive to manufacture and makes mass production impractical.

The answer to this issue came in two parts. Firstly, researchers treated the switchgrass with an ionic liquid, in this case molten salt, dissolving it and isolating the cellulose and hemicellulose embedded in the cell wall present within switchgrass cells (Korosec 2011). Specially engineered bacteria were then introduced into the resulting biomass. These bacterium were modified to possess enzyme secretion pathways, allowing them to naturally produce the enzymes necessary to break down the cellulose and hemicellulose present. The bacteria chosen to act as the base for the new strain was Escherichia coli (E. coli), a bacterium that accepts new genes relatively easily (Service 2011). These enzyme secretion genes also allowed the E. coli to digest the cellulose and hemicellulose and grow on switchgrass, something E. coli is incapable of doing. (Yarris 2011).

The bacteria were then further modified with biofuel production pathways, allowing them to produce fuels viable as substitutes for gasoline, diesel and jet engines (Bokinsky et al. 2011). These engineered E. coli strains utilize their enzyme secretion pathways to break down the complex cellulose and hemicellulose molecules present down into simple sugars which the bacterium can then synthesize into ethanol using the biofuel production pathways.
The combination of the enzyme secretion and ethanol synthesis functions into one organism would reduce the production costs of biofuel significantly and makes their use as a replacement for fossil fuels a viable possibility. With enough research and time, the entirety of humanity’s fuel requirements could be fulfilled by naturally grown ‘fuel fields’ and the help of these special bacteria.


Bibliography

Bokinsky, G, Peralta-Yahyaa, P, Georgea, A, Holmesa, BM, Steena, EJ, Dietricha, J, Leea, TS, Tullman-Erceka, D, Voigt, C, Simmons, B & Keasling, J 2011, 'Synthesis of three advanced biofuels from ionic liquid-pretreated switchgrass using engineered Escherichia coli', Proceedings of the National Academy of Sciences of the United States of America, 2 May 2011.

DOE/Lawrence Berkeley National Laboratory 2011, 'E. Coli Bacteria Engineered to Eat Switchgrass and Make Transportation Fuels', Science Daily, 29 November 2011.

Korosec, K 2011, 'E.coli bacteria that eats switchgrass to make fuel', Smart Planet, 13 December 2011.
Service, RF 2011, 'Fuel From Waste?', Science NOW, 5 December 2011.

Yarris, L 2011, 'E. Coli Bacteria Engineered to Eat Switchgrass and Make Transportation Fuels', Lawrence Berkely National Laboratory.




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