‘Living biosensor’ lights up to detect wine spoilage in real time

Genetically-modified Escherichia coli bacteria that light up in the presence of acetic acid may offer wineries a way to detect wine spoilage in real-time, without the need for specialist equipment.

Unwanted microorganisms found in wine barrels often produce acetic acid as a byproduct of fermentation. A build up of acetic acid stops the conversion of sugars into ethanol and gives wine an unpleasant vinegar-like taste.

Researchers in Israel have now developed a ‘living biosensor’ that luminesces in the presence of acetic acid. The team genetically modified a strain of E. coli with DNA from Bacillus subtilis. When acetic acid levels rise in the fermenting grape juice this activates a pathway in the bacterium that turns on a light producing enzyme known as luciferase.

The team were then able to use the light signal to quantify acetic acid concentrations up to 1g/l, which is above the threshold for spoilage, as well as to detect acetic acid in the headspace above wine samples. The biosensor also remains stable in ethanol up to 14.5% – comparable to most wines.

This technology may allow wineries to detect acetic acid in real time without opening any wine bottles or barrels, helping to preserve volatile flavour molecules. It may also reduce the need for traditional monitoring methods – such as gas chromatography and high-performance liquid chromatography – which are often costly, require specialised equipment and extensive sample preparation.