Inactivation effect and damage of multi-irradiance by UVCLED on Acinetobacter baumannii

It is acknowledged that the inactivation of ultraviolet has been widely used in various fields. Much literature has been reported that ultraviolet C caused DNA damage to achieve inactivation of microorganisms. There is a lack of unified dose calibration and related parameters in this field. In this study, we used a device consisted of the LED of 272 nm to conduct sterilization experiments against A. baumanii. We confirmed the effectiveness of ultraviolet C sterilization for both sensitive and drug resistance strains and explored the relationship between bactericidal rate and ultraviolet doses under various irradiance. Dose requirements of various irradiance were clarified. High irradiance improved sterilization efficiency greatly. The overall damage to the total genome was observed though gel electrophoresis. Ultrastructure of damaged bacteria were investigated by transmission electron microscope in detail. The study revealed that damage to DNA and to the cytoplasm matrix and ribosomes. The study has yielded the possible effects of ultraviolet light on cells by amplifying the energy. The radiation significantly promoted the production of cell wall and cellular membrane. Significance StatementThe statistical results of bactericidal efficiency are influenced by the quantity of bacteria on the medium. Irradiance on the target surface affects the sterilization efficiency directly. And doses required in low irradiance are much more than high. A high irradiance reduced dosage efficiently to achieve the sterilization which improves the sterilization efficiency. There is a difference between low and high UVC dosage damage to the structure of bacteria. Less energy can make DNA coagulation solidified or be dispersed to the edge. Meanwhile the cytoplasm matrix is ruined. When the energy was enough, there is a boost of cell wall and cellular membrane production. The invisible light causes comprehensive damage to bacteria.