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Applied and Environmental Microbiology, October 2001, p. 4630-4637, Vol. 67, No. 10
0099-2240/01/$04.00+0   DOI: 10.1128/AEM.67.10.4630-4637.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.

Determination of Pyrimidine Dimers in Escherichia coli and Cryptosporidium parvum during UV Light Inactivation, Photoreactivation, and Dark Repair

Kumiko Oguma,1,* Hiroyuki Katayama,1 Hiroshi Mitani,2 Shigemitsu Morita,3 Tsuyoshi Hirata,3 and Shinichiro Ohgaki1

Department of Urban Engineering,1 and Department of Integrated Biosciences,2 University of Tokyo, Bunkyo-ku, Tokyo, and College of Environmental Health, Azabu University, Sagamihara, Kanagawa,3 Japan

Received 2 April 2001/Accepted 20 July 2001

UV inactivation, photoreactivation, and dark repair of Escherichia coli and Cryptosporidium parvum were investigated with the endonuclease sensitive site (ESS) assay, which can determine UV-induced pyrimidine dimers in the genomic DNA of microorganisms. In a 99.9% inactivation of E. coli, high correlation was observed between the dose of UV irradiation and the number of pyrimidine dimers induced in the DNA of E. coli. The colony-forming ability of E. coli also correlated highly with the number of pyrimidine dimers in the DNA, indicating that the ESS assay is comparable to the method conventionally used to measure colony-forming ability. When E. coli were exposed to fluorescent light after a 99.9% inactivation by UV irradiation, UV-induced pyrimidine dimers in the DNA were continuously repaired and the colony-forming ability recovered gradually. When kept in darkness after the UV inactivation, however, E. coli showed neither repair of pyrimidine dimers nor recovery of colony-forming ability. When C. parvum were exposed to fluorescent light after UV inactivation, UV-induced pyrimidine dimers in the DNA were continuously repaired, while no recovery of animal infectivity was observed. When kept in darkness after UV inactivation, C. parvum also showed no recovery of infectivity in spite of the repair of pyrimidine dimers. It was suggested, therefore, that the infectivity of C. parvum would not recover either by photoreactivation or by dark repair even after the repair of pyrimidine dimers in the genomic DNA.

* Corresponding author. Mailing address: Department of Urban Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. Phone: (81)3-5841-6242. Fax: (81)3-5841-8533. E-mail: oguma{at}env.t.u-tokyo.ac.jp.

Applied and Environmental Microbiology, October 2001, p. 4630-4637, Vol. 67, No. 10
0099-2240/01/$04.00+0   DOI: 10.1128/AEM.67.10.4630-4637.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:

  • Hu, J., Quek, P. H. (2008). Effects of UV Radiation on Photolyase and Implications with Regards to Photoreactivation following Low- and Medium-Pressure UV Disinfection. Appl. Environ. Microbiol. 74: 327-328 [Abstract] [Full Text]  
  • Al-Adhami, B. H., Nichols, R. A. B., Kusel, J. R., O'Grady, J., Smith, H. V. (2007). Detection of UV-Induced Thymine Dimers in Individual Cryptosporidium parvum and Cryptosporidium hominis Oocysts by Immunofluorescence Microscopy. Appl. Environ. Microbiol. 73: 947-955 [Abstract] [Full Text]  
  • Oguma, K., Katayama, H., Ohgaki, S. (2002). Photoreactivation of Escherichia coli after Low- or Medium-Pressure UV Disinfection Determined by an Endonuclease Sensitive Site Assay. Appl. Environ. Microbiol. 68: 6029-6035 [Abstract] [Full Text]  
  • Morita, S., Namikoshi, A., Hirata, T., Oguma, K., Katayama, H., Ohgaki, S., Motoyama, N., Fujiwara, M. (2002). Efficacy of UV Irradiation in Inactivating Cryptosporidiumparvum Oocysts. Appl. Environ. Microbiol. 68: 5387-5393 [Abstract] [Full Text]  


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