Inactivation of Bacteriophage Infecting Bacteroides Strain GB124 Using UV-B Radiation

• Published in: Photochemistry and photobiology Vol. 90; no. 3; pp. 622 - 627
• Main Authors: Diston, David, Ebdon, James E., Taylor, Huw D.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.05.2014
• Subjects: Bacteria; Bacteriophages - radiation effects; Bacteroides fragilis; Bacteroides fragilis - virology; Contamination; Effluents; Fecal coliforms; Inactivation; Indicator species; Microorganisms; Municipal wastewater; Natural environment; Solar radiation; Ultraviolet radiation; Ultraviolet Rays
• ISSN: 0031-8655; 1751-1097; 1751-1097
• DOI: 10.1111/php.12223

Ultraviolet‐B radiation (280–320 nm) has long been associated with the inactivation of microorganisms in the natural environment. Determination of the environmental inactivation kinetics of specific indicator organisms [used as tools in the field of microbial source tracking (MST)] is fundamental to their successful deployment, particularly in geographic regions subject to high levels of solar radiation. Phage infecting Bacteroides fragilis host strain GB124 (B124 phage) have been demonstrated to be highly specific indicators of human fecal contamination, but to date, little is known about their susceptibility to UV‐B radiation. Therefore, B124 phage (n = 7) isolated from municipal wastewater effluent, were irradiated in a controlled laboratory environment using UV‐B collimated beam experiments. All B124 phage suspensions possessed highly similar first order log‐linear inactivation profiles and the mean fluence required to inactivate phage by 4 − log10 was 320 mJ cm−2. These findings suggest that phage infecting GB124 are likely to be inactivated when exposed to the levels of UV‐B solar radiation experienced in a variety of environmental settings. As such, this may limit the utility of such methods for determining more remote inputs of fecal contamination in areas subject to high levels of solar radiation. Bacteriophage infecting Bacteroides fragilis strain GB‐124 are a useful tool in determining the source of fecal pollution within aquatic environments. Here we present insights into the UV‐B inactivation ecology of this important phage group by conducting controlled laboratory collimated‐beam UV‐B irradiation experiments. Results indicate that B124 phage may be inactivated at levels of UV‐B commonly recorded in the environment, and inactivation potential should be considered when interpreting environmental B124 phage data.