Some plant pathogenic bacteria species are environmentally high-risk organisms that have a negative impact on agricultural production. Experiments with these pathogens in a biosafety laboratory require safety protocols to prevent contamination from these pathogens. In this work, we investigated the efficacy of using UV-C irradiation for the purpose of sterilizing an important plant pathogenic bacterium, Erwinia pyrifoliae, in a laboratory setting. For the test, the pathogen (1.71 × 108 CFU/ml) was inoculated on the surface of Potato Dextrose Agar (PDA) and the inoculated media were placed on a work surface in a biosafety cabinet (Class 2 Type A1) as well as on three different surfaces located within the laboratory: a laboratory bench, a laboratory bench shelf, and the floor. All the surfaces where the media were placed were in range of the UV-C beam projected by the UV lamp installed in the ceiling of the BSL 2 Class biosafety laboratory. Measurements of the reduction rate of bacteria under UV-C irradiation were conducted at different time intervals: after 10 minutes, 30 minutes, 1 hour, 2 hours, and 3 hours, respectively. The reduction rate of bacteria ranged from 90% to 99% after 10min irradiation, from 97.8% to 100% after 30 minutes of irradiation, from 99.1% to 100% after 1 hour of irradiation, and from 99.99% to 100% after 2 hours of irradiation. After 3 hours of irradiation, the pathogen was completely killed in all the test conditions. In the cases of the laboratory bench and the shelf of the laboratory bench, the effectiveness of UV-C irradiation differed slightly between the site where the bacteria located vertically under the lamp and the site where the bacteria were located 1 meter away horizontally from the site under of the lamp.

High-risk microbial pathogens are handled in a biosafety laboratory. After experiments, the pathogens may remain as contaminants. To safely manage a biosafety laboratory, disinfection of microbial contaminants is necessary. This study was carried out to evaluate the effect of UV-C irradiation for the disinfection of a high-risk plant pathogenic bacterium Erwinia amylovora in a laboratory setting. For the test, the bacterium (8.7 × 106 CFU/ml) was embedded on the surface of PDA and placed on the work surface in a biosafety cabinet (Class 2 Type A1), and on the three different surfaces of the laboratory bench, laboratory bench shelf, and the floor which were positioned in a straight line from the UV lamp installed in the ceiling of the biosafety laboratory (BSL 2 class). UV-C irradiation was administered for 10min, 30min, 1 hr, 2hr, 3 hr, and 4hr, respectively. The reduction rate of bacteria ranged from 95% to 99% in regard to 10 min irradiation, from 97% to 99% in regard to 30 min irradiation, from 99.8% to 99.9% in regard to 1 hr irradiation, and higher than 99.99% in regard to 2 hr irradiation. The bacterium was completely inactivated after 3 hr irradiation. A similar UV-C irradiation effect was obtained when the bacterium was placed at a distance of 1 m from the three different surface points. Bacterial reduction by UV-C irradiation was not significantly different among the three different surface points.