Résumé
Ultra-high irradiance (UHI) blue light treatment is effective in minutes for inactivating not only the planktonic forms but also the sporicidal forms of several microorganisms, including yeasts, filamentous fungi, and bacteria. This treatment could represent a new, cost-effective, and rapid candidate for microbial inactivation in a wide range of applications, such as food or surface treatment. Our study characterized the effects of UHI blue light treatments on Brettanomyces bruxellensis planktonic or biofilm forms that can be formed on the most representative surfaces of the wine industry (wood and stainless steel). B. bruxellensis is the main spoilage microorganism of red wines and constitutes a growing problem for winemakers. Treatments of 1 to 5 min (22.2 J.cm–² to 111 J.cm–²) were performed on planktonic cells and 1 to 10 min (22.2 J.cm–² to 222 J.cm–²) on biofilms. Cultivability on yeast peptone dextrose agar medium and viability (esterase activity) of the yeasts were analyzed after treatment for each of the treatment modalities using flow cytometry after labeling with 5-carboxyfluorescein diacetate, acetoxymethyl ester. The findings of this study showed the possibility of inactivating both the planktonic forms of B. bruxellensis in phosphate-buffered saline or wine and the forms of biofilm developed on wood or stainless steel in wine or yeast peptone dextrose using UHI blue light treatments. Treatments lasting less than 10 min resulted in a loss of cultivability but a lesser loss of viability. However, a 10-min treatment resulted in a complete loss of viability for all types of biofilms studied. Therefore, this treatment process appears particularly promising for eliminating biofilms that can develop on surfaces in contact with food products, as is the case for Brettanomyces on surfaces representative of the wine industry.