Biotechnologists have genetically engineered brewer's yeast to glow green in response to an ingredient found in landmines, a new study shows.

The study, published today online in the journal Nature Chemical Biology, shows the yeast can detect, or smell, airborne particles from explosives.

The scientists engineered the yeast Saccharomyces cerevisiae to sense molecules of the chemical DNT, or dinitrotoluene.

DNT is left over after making the explosive TNT, or trinitroluene. And dogs trained to sniff for explosives are believed in fact to be trained to detect DNT.

The scientists spliced a gene found in rats into the yeast's genome so that the surface of its cells reacted in response to DNT.

To get a visual cue as to whether this 'nose' had detected DNT, the scientists also added a gene to turn the yeast a fluorescent green when contact was made.

The authors, led by Associate Professor Danny Dhanasekaran of Temple University School of Medicine in Philadelphia, believe they have found a useful, if so far experimental, type of biosensor.

These gadgets use organisms to detect environmental chemicals, including biological or chemical weapons.

In the past, scientists have shown that organisms such as moths and bees can detect explosives.