Inactivation of Antibiotic-Resistant Listeria monocytogenes Isolated from Vegetables Using 405nm Ultraviolet Laser Light

The photo-inactivation property of light is an area of increasing interest. The invisible C region of the ultra-violet band (UVC) has been employed extensively in decontamination and sterilization processes, but the A and B (UVA, UVB) have not received such considerations. This study investigates the susceptibility of food-borne pathogen Listeria monocytogenes to selected dosages of 405nm UVA irradiation. Listeriosis ranks third in mortalities caused by food-borne bacterial pathogens. This research study focused on the inactivation of L. monocytogenes previously isolated from vegetables sold within Sokoto metropolis, Sokoto State, Nigeria. L. monocytogenes was exposed to different irradiations of doses of 90uWcm-2, 120uWcm-2, 150uWcm-2, 180uWcm-2, and 210uWcm-2, at durations of 10, 20, 30, 40, and 50 minutes. The results showed that 210uWcm-2 irradiation for 30 minutes was effective in completely inactivating the bacteria. Partial inactivation was observed at 150uWcm-2 and 180uWcm-2. The research study lends support to the potentials of photo-inactivation mechanisms as viable alternatives to established processes utilized in food industries, hospital, medical environments, etc., for disinfection and sterilization.