Microbial contaminants of foodstuffs represent one of the main causes of food spoilage and are a potential source of health risk for consumers. Although widely used in food industry, heat treatments are not suitable on dry or fresh food raw materials. A widely used solution for the sanitation of these products is the use of antifungal and bactericide chemicals. Due to health and environmental problems, the development of non-chemical alternatives has become a priority. Among the physical parameters that potentially affect the survival of microorganisms, visible light can generate an oxidative stress in the presence of oxygen that subsequently kills microorganisms. Nevertheless, light-based decontamination processes are generally long, which limits their use in high throughput processes. Research on illumination conditions that induce rapid microbial death are therefore of great interest. Blue light (≈405 nm), which is generally used for the photooxidation (PO) of microorganisms, is known to enhance the production of singlet oxygen via the photosensitization of porphyrins. In this work, the yeast S. cerevisiae was submitted to a high density light flux treatment targeting porphyrins with a confocal laser source. Dynamics of PO in cellular structures were studied using real-time visualization under microscope. Our results show that excitation in the plasma membrane led to fast oxidation and membrane permeabilization (less than 60 s) leading to cell necrosis. Our study shows also that the higher the power of light used, the lower the energy required to permeabilize the membrane. We conclude that a rapid fungal destruction could be generated using a high density light flux. An in-depth knowledge of the conditions to induce necrosis will facilitate the development of decontamination processes based on blue light PO.

Keywords: photooxidation, decontamination process, high power light, blue light

FR3084262A1 PROCEDE D’ELIMINATION DE MICROORGANISMES PRESENTS DANS ET/OU A LA SURFACE D’UN MATERIAU A DECONTAMINER