Investigation of the antimicrobial effect of blue light emitting diodes on several bacteria and fungus species

Alternative methods are needed to prevent bacterial problems that may occur in food and health sector. In recent years, the interest in blue light technology has been increasing in order to provide disinfection of bacteria causing food contamination and infection in hospitals day by day. In the previous studies, when disinfection effect between 400 nm and 470 nm wavelength is examined, it is seen that the best effect is at 405 nm wavelength light. In order to increase the effectiveness and the efficiency of 405 nm blue light, the light is operated at certain frequencies and at different on/off pulse durations, which is called as pulse lighting. In this study, an electronic circuit is designed on which the pulse duration of the 405 nm light is controlled via a microcontroller. With this circuit, a low cost and energy saving prototype of a lighting unit has been developed. This developed lighting unit is placed in a special cabinet and the effects of disinfection on Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Bacillus subtilis, Salmonella enteritidis, Listeria monocytogenes, Staphylococcus aureus, Enterobacter aurogenes bacteria and on Candida albicans and Candida utilis ferments were investigated. For this purpose, tests were performed at different frequencies, different duty cycles, and different time intervals. As a result, different pulse shapes and time dependent colony quantities were compared. Improvements in inactivation and lower energy consumption were achieved under pulsed conditions. In this way, to ensure food safety and to prevent the spread of infection in the health sector, an infrastructure of a practical lighting unit was created to prevent the contamination of food-borne bacteria.