April 24, 2013, by Tim Radford
Filling the tank could become cleaner and cheaper thanks to E. coli
Image: Andre Engels
FOR IMMEDIATE RELEASE Environmentally-friendly biofuel may have come a step closer with the news that scientists in the UK think they have found how a genetically-modified bacterium can produce diesel oil – on a very small scale so far. LONDON, 24 April – British scientists may have found a new way to pump high quality diesel into the tractors, trucks and taxis of tomorrow. They have demonstrated that, with a little help from one of humanity’s oldest acquaintances, they can produce fuel-quality diesel without benefit of oil well or refinery. A team from the University of Exeter and from the Shell Technology Centre in Chester report in the Proceedings of the National Academy of Sciences that, with a little help from the genetic engineers, and a bit of patience in the laboratory, Escherichia coli delivered a customised biofuel almost identical to the stuff now hosed in from the petrol pump. Biodiesel from renewable sources is not new – but nor is it of sufficient quality to go straight into modern, mass-produced engines: biodiesel from plants normally has to be mixed with diesel distilled from petroleum to deliver propulsive power of the right quality. There is a saving on fossil fuels, and therefore on carbon dioxide emissions, but only of between 10 and 20%. But John Love of Exeter and colleagues turned to a bacterium that has been biology’s good friend – it is in standard use in the laboratory – and industry’s too. For 6,000 years, microbes of one kind or another have been employed to ferment wine, leaven bread, make cheese and cure bacon; for the last 60 years or so microbes have been routinely making medicines, leaching metals from spoil heaps and delivering complex chemicals for big business.
“…a fuel that is independent of both global oil price fluctuations and political instability is an increasingly attractive prospect”
E. coli has been the experimenter’s favourite for many years. It lives in the human intestine, and some strains have become notorious as infectious diseases, but most are harmless to humans. Professor Love’s team took genes from several other kinds of bacteria, and pieced them together in E coli to create a particular molecular pathway normally necessary to forge the fats and oils that microbes need for their own tissue. It worked. The researchers claim that the genetically-engineered E coli produced molecules that are structurally and chemically identical to 10 retail diesel fuel hydrocarbons commonly used in temperate climates. The quantities produced were tiny. The next challenge is to see if production can be scaled up, and costs kept down, to make microbial manufacture a commercial proposition. “Replacing conventional diesel with a carbon-neutral biofuel in commercial volumes would be a tremendous step towards meeting our target of an 80% reduction in greenhouse gas emissions by 2050”, said Professor Love. “Global demand for energy is rising and a fuel that is independent of both global oil price fluctuations and political instability is an increasingly attractive prospect.” – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.