Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 1, 2003 | public
Journal Article

Soluble Sunscreens Fully Protect E. coli from Disinfection by Electrohydraulic Discharges


We show that the ultraviolet radiation emitted, rather than the thermal/pressure shocks or the chemical species that are generated in these events, is the lethal agent that inactivates Escherichia coli colonies exposed to electrohydraulic discharges, EHD. Disinfection is completely suppressed in the presence of <100 mg L^(-1) of 2,2'-dihydroxy-4,4'-dimethoxybenzophenone-5,5'-disulfonic acid, BP9, a commercial water-soluble sunscreen. Viable bacteria decay by logit kinetics with the number of EHD. The fact that the slopes of the logit plots depend inversely on BP9 concentration, and vanish above ∼ 30 mg BP9 L^(-1), is direct evidence that E. coli is exclusively sterilized by UV radiation in these experiments. Present LD_(50) photon doses are about 10^3 times larger than those required from low-power germicidal lamps, indicating that high-intensity radiation is able to further promote into inactive channels the lower excited state(s) of nucleic acids responsible for DNA damage. The present study confirms the existence of a significant trade-off between photon efficiency and radiative power in bacterial disinfection by UV light.

Additional Information

© 2003 American Chemical Society. Received for review February 27, 2003. Revised manuscript received August 7, 2003. Accepted August 11, 2003.

Additional details

August 19, 2023
October 23, 2023