A Study of the Bactericidal Action of Ultra Violet Light

Abstract

In this study of the bactericidal action of ultra violet light the first paper (1) described the reaction of an 18 hour culture of Staphylococcus aureus to monochromatic radiations. It was shown that the course of the reaction among large numbers of organisms was approximately the same at each wave length studied but that widely different incident energies were required at different wave lengths to produce these similar effects.The second paper (2) discussed the limits of the bactericidal zone, showed that the reaction had a low temperature coefficient, (approximately 1.1), gave evidence that within the variations of the methods used no significant errors were introduced by differences in the measured intensity of the source or in the hydrogen ion concentration of the medium, and indicated that plane polarization of the incident light had no effect upon the reaction.The present paper deals with the absorption of ultra violet light by intact bacteria. A final paper in this series will discuss structural and chemical units of bacterial protoplasm that may prove to be involved in the reaction which results in the organism's death. Incident Energy Relationships at Various Wave LengthsText- fig. 1, reproduced from the first paper of this series, shows that although the course of the bactericidal reaction was approximately the same at each wave length studied, these similar curves were found at very different incident energy levels at different points in the ultra violet spectrum.

Blue 470-nm Light Kills Methicillin-Resistant Staphylococcus aureus (MRSA) in Vitro

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Evidence that Initial Ultraviolet Lethal Damage in Escherichia coli Strain 15 T-A-U- is Independent of Growth Phase

“…photons that kill Escherichia coli (Gates, 1930) and a variety of evidence strongly suggests that the initial lethal damage occurs predominantly and directly in deoxyribonucleic acid (DNA; see, for example, Wacker, 1963). Furthermore, selective inhibition, by U.V.…”

Cell killing and mutation induction on Chinese hamster cells by photoradiations

“…The first series of action spectra of bacterial cell killing by far-UV were reported in the 1920's by Gates (1928Gates ( , 1929Gates ( and 1930. The maximum killing effectiveness was found to be at about 260 nm, which was soon confirmed by others with the same or different bacterial strains (Wykoff, 1932;Hollaender and Dugger, 1936).…”