Efficiency of pyrimidine dimer formation in Escherichia coli across UV wavelengths.
OBJECTIVE
Inactivation of Escherichia coli as a function of ultraviolet (UV) wavelength was investigated by using the endonuclease-sensitive site (ESS) assay to quantify pyrimidine dimer formation.


RESULTS
Ultraviolet dose-response curves were determined based on both log reduction in colony-forming units (CFU) and endonuclease-sensitive sites per kb DNA (ESS/kb) for monochromatic 254-nm low-pressure (LP) UV, polychromatic medium-pressure (MP) UV, 228 and 289-nm UV irradiation. UV irradiation from LP and MP UV sources were approx. equal in both CFU reduction and pyrimidine dimer formation at all UV doses studied; 228-nm irradiation was less effective than LP or MP, and 289-nm irradiation was the least effective in both CFU reduction and pyrimidine dimer formation. These results are in qualitative agreement with the absorption spectrum of pyrimidine bases in DNA. Results indicated an approx. linear relationship between ESS/kb and log CFU reduction.


CONCLUSIONS
Formation of pyrimidine dimers in genomic DNA is primarily responsible for UV inactivation of E. coli.


CONCLUSIONS
This work contributed to fundamental understanding of UV disinfection and aids in UV reactor design.
Eischeid
A C
AC
Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708-0287, USA.
Linden
K G
KG
D015169:Colony Count, Microbial; D004307:Dose-Response Relationship, Radiation; D004720:Endonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D016680:Genome, Bacterial / Q000528:radiation effects; D011740:Pyrimidine Dimers / Q000378:metabolism*; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
D011740:Pyrimidine Dimers; D004720:Endonucleases