Hebrew University Scientists Engineer Bacteria to Signal Wine Spoilage Before Flavor Is Affected

A team of researchers at Hebrew University has developed a new biological sensor that could help wineries detect wine spoilage before it affects flavor and quality. The innovation, described in a recent study published in Microbial Biotechnology, uses engineered bacteria that emit light when they sense acetic acid, the main chemical responsible for turning wine sour.

The project was led by PhD student Yulia Melnik-Kesler under the supervision of Professor Yael Helman, with collaboration from Professor Oded Shoseyov. Their work addresses a longstanding challenge in winemaking: catching spoilage early enough to prevent costly losses. Acetic acid buildup is a common cause of wine spoilage, leading to vinegar-like smells and sour flavors. Once levels rise above about 0.7 grams per liter, the fermentation process can stall and the wine may become undrinkable.

Traditional methods for detecting acetic acid rely on laboratory techniques such as gas chromatography or liquid chromatography. These methods are expensive, time-consuming, and require taking liquid samples from the wine. As a result, many wineries struggle to monitor fermentation in real time and often only discover problems after the damage is done.

The new biosensor offers a different approach. The team engineered bacteria to include a natural regulator called YwbIR, originally found in Bacillus subtilis. When these bacteria encounter acetic acid, YwbIR activates a gene that produces light. The intensity of the light increases as acetic acid levels rise, providing a clear and measurable signal.

In laboratory tests, the biosensor responded strongly and consistently to acetic acid concentrations between 0 and 1 gram per liter—a range that covers the critical threshold for spoilage. At levels where spoilage typically begins, the light signal increased by five to eight times compared to baseline readings. This allows winemakers to receive an early warning before the wine becomes undrinkable.

One notable feature of the biosensor is its ability to detect acetic acid not just in liquid samples but also in the air above the wine—the so-called headspace of a bottle or fermentation tank. This means wineries can monitor for spoilage without opening containers or disturbing the fermentation process. In tests with commercial red and white wines, the biosensor distinguished between normal and artificially spoiled samples within two hours.

Another advantage is its resilience in high-alcohol environments. Many electronic or optical sensors struggle to function accurately when alcohol content is high, but the new biosensor worked reliably in wines containing up to 14.5% alcohol.

The researchers believe their technology could have applications beyond winemaking. Acetic acid is an important marker in other fermentation-based industries such as food production and biofuels. It is also being studied as a potential biomarker for certain diseases, raising the possibility that future versions of the biosensor could be used for noninvasive medical diagnostics like breath analysis.

Professor Helman said that this system allows detection of acetic acid in real time without complicated equipment or sample processing. She noted that it could make on-site monitoring more affordable for producers and might eventually support medical diagnostics based on volatile biomarkers.

The development of this living biosensor represents a step forward in quality control for winemakers and other industries that rely on fermentation. By providing early warnings of spoilage, it could help reduce waste and improve product consistency while lowering costs associated with traditional laboratory testing.