Research is currently being conducted into the use of the Bacteria Escherichia coli (E. coli) for biofuel. E. coli naturally convert sugars into low energy, short chained alcohol molecules. A recent study has shown that it is possible to force the bacteria’s metabolism beyond its natural levels, in order to create long-chained alcohols (each containing more than six carbon atoms), which are more energy dense, and thus cheap and effective sources of biofuel. They are also easier to isolate, as they are less soluble in water.
The researchers redesigned E. coli’s metabolism through the use of various enzymes. One enzyme was used to force a keto acid into an elongation cycle, which involves an increase in carbon content. Then a further two enzymes were borrowed from other bacteria, and used to form a six carbon alcohol (3-methyl-1-pentanol). In seeing that this worked, the researchers engineered E. coli to express these enzymes.
Unfortunately, the production yield was low, so the team had to introduce two new enzymes, which produced 59 times more yield. Further research is being conducted to maximise productivity, so as to enable the use this method.
Barras, Coiln 2008, 'Super Biofuel cooked up by bacterial brewers', New Scientist,
