Super-biofuel cooked up by bacterial brewers

Bacteria have been genetically rewired to produce "non-natural" alcohols that would make ideal biofuel.In a new study, researchers show that it is possible to push bacterial metabolism beyond its natural limits in the search for cheap ways to produce useful chemicals. It is another example of how synthetic biology is helping to redefine life.Living cells have already been engineered to metabolise unusual sugars, andJames Liao's team at the University of California, Los Angeles, has now engineered bacteria to convert standard sugars into unusually long-chained alcohols.'Promiscuous' enzymesBacteria such as Escherichia coli - a bug commonly linked to food poisoning outbreaks - naturally convert sugar into alcohol, but those alcohols tend to be short-chain molecules.Long-chain alcohols, each containing more than six carbon atoms, are more energy dense - packing more power into a smaller space - and hence make better fuels. They are also easier to isolate than short-chain alcohols because they are less soluble in water.So Liao's team looked closely at the metabolism of E. coli to see if it could be redesigned to produce these longer chains.Enzymes in the bacterium encourage one particular keto acid - a precursor to an amino acid - to undergo an "elongation cycle", increasing its carbon content. The researchers reasoned that those enzymes might be "promiscuous" enough to elongate a different keto acid.The product could then be converted to a six-carbon alcohol using two more enzymes - one borrowed from another bacterium and another from the yeastSaccharomyces cerevisiae, which is commonly used in baking and brewing.

http://www.newscientist.com/article/dn16129-superbiofuel-cooked-up-by-bacterial-brewers.html?DCMP=OTC-rss&nsref=life

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