Inactivation influences on Escherichia coli DS5α by irradiation with 405 nm violet-light

Young-Sun Kim1,†, Mun-Jin Choi1,†, Dae-Young Lee2, Sang-Ook Kang3,*, Geung-Joo Lee4,*

1Department of Horticultural Science, Daegu University, Gyeongsan 38453, Korea
2Kingstar Lighting LTD Co., Kimpo 10048, Korea
3Department of Advanced Material Chemistry, Korea University Sejong Campus, Sejong 30019, Korea
4Department of Horticultural Science and Department of Smart Agriculture System, Chungnam National University, Daejeon 34134, Korea

†These authors contributed equally to this work.

*Corresponding author:,


Because an irradiation of 405 nm violet light could have a strong energy, it was used to be sterilized against various microbes in the indoor air condition or fresh food. Escherichia coli is a representative bio-pollutant in the indoor air-borne bacteria, and a hygienic microbe in the horticultural food. This study evaluated the inactivation influences on E. coli DS5α after exposure to 405 nm violet-light (VL) by investigating irradiating time, and the vertical and horizonal distance from light source. The illumination of 405 nm VL was inversely proportional to the distance from the VL source. E. coli DS5α on nutrient agar (NA) was inactivated approximately 50% more than the control when irradiated at 65 cm from 405 nm VL for 3 hours. When compared to the control, E. coli DS5α was inactivated approximately 50% within 70 cm from 405 nm VL for 3 hours. As it was irradiated for 3 hours 70 cm away from 405 nm VL, the horizonal distance from the point was negatively correlated to the inactivation of E. coli DS5α. These results indicated that the inactivation of E. coli DS5α grown on NA medium needs to be irradiated with 405 nm within 70 cm from the light source for 3 hours.


405 nm violet-light, Escherichia coli DS5α, inactivation of E. coli, irradiation distance, irradiation time

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