Jewel Lake, Tilden Park, East Bay Regional Park District, California

Sediment from Jewel Lake in Berkeley, California, contains bacteria that produce the hydrocarbon toluene. Credit: Chickmarkley via Wikimedia Commons/CC-BY-SA-3.0

Organic chemistry

Sewage microbes make a fuel booster

Bacterial enzyme makes the petrol additive toluene.

Researchers sifting through microbes from sewage sludge and lake sediments have identified the first enzyme that produces toluene — a hydrocarbon that is added to petrol to improve engine power.

Scientists reported in the 1980s that bacteria could synthesize toluene, but did not pinpoint the enzyme that does the work. To fill that gap, Harry Beller at the Lawrence Berkeley National Laboratory in Berkeley, California, and his colleagues grew toluene-producing microbes from sewage, then screened thousands of proteins from these microbes to identify the enzymes most likely to synthesize toluene.

Next, the authors identified genes common to toluene-producing bacteria from both the lake and sewage cultures. Finally, they manufactured the proteins encoded by those genes and tested the proteins to single out those that synthesized toluene.

The enzymes might one day be used to convert plant-based sugars into toluene to replace some of the 26 million tonnes produced from petroleum each year.

Correction: An earlier version of this article referred incorrectly to toluene as a petrol-oxygenating agent.