Potential Repair of Escherichia coli DNA following Exposure to UV Radiation from Both Medium- and Low-Pressure UV Sources Used in Drinking Water Treatment

Abstract

The increased use of UV radiation as a drinking water treatment technology has instigated studies of the repair potential of microorganisms following treatment. This study challenged the repair potential of an optimally grown nonpathogenic laboratory strain of Escherichia coli after UV radiation from low-and mediumpressure lamps. Samples were irradiated with doses of 5, 8, and 10 mJ/cm 2 from a low-pressure lamp and 3, 5, 8, and 10 mJ/cm 2 from a medium-pressure UV lamp housed in a bench-scale collimated beam apparatus. Following irradiation, samples were incubated at 37°C under photoreactivating light or in the dark. Sample aliquots were analyzed for up to 4 h following incubation using a standard plate count. Results of this study showed that E. coli underwent photorepair following exposure to the low-pressure UV source, but no repair was detectable following exposure to the medium-pressure UV source at the initial doses examined. Minimal repair was eventually observed upon medium-pressure UV lamp exposure when doses were lowered to 3 mJ/cm 2 . This study clearly indicates differences in repair potential under laboratory conditions between irradiation from low-pressure and medium-pressure UV sources of the type used in water treatment.

DETEKSI BAKTERI Escherichia coli DALAM AIR MINUM ISI ULANG YANG DISTERILISASI ULTRAVIOLET DI WILAYAH KECAMATAN JAGAKARSA

“…Menurut Zimmer (2002), dalam sistem distribusi air minum, air yang diolah dapat mengalami waktu penahanan yang panjang sebelum mencapai konsumen. Selama itu, mikroorganisme yang diiradiasi UV dapat memiliki kesempatan untuk melakukan perbaikan dan berpotensi tumbuh kembali dalam sistem.…”

Effectiveness of UV Disinfection for Contaminated Surface Water

“…However, higher exposure means higher power consumption and lower lamp-life, and therefore it is important to estimate the optimum exposure time for a particular condition of UV irradiation and water quality [16], [17]. Table III and Table IV show that exposure time has a clear effect on disinfection efficiency; higher the exposure time, the better is the disinfection efficiency (Figs.…”

Removal of Methylene Blue Using UV-C Pretreated Citrobacter freundii JH 11-2 and Bacillus pseudomycoides JH 2-2 Biomass

“…UV-C generally used for inactivating pathogenic microorganisms in sewage and drinking water (Zimmer and Slawson, 2002;Song et al, 2009). Since UV-C has a short wavelength of 245 nm it generates oxygen radical and induces RNA/DNA damage (Widmann et al, 1998).…”