ABSTRACT

This paper presents the results of a new method for the determination of rates of inactivation and of adsorption to colloidal clay particles (CCP) by bacteriophages. These rates are used to determine the suitability of bacteriophages as biological tracers. Inactivation rates were determined by agitating a vessel containing the phages in a standard liquid medium. Adsorption rates were obtained by adding a small concentration (0.030mg/ml) of Attapulgite CCP to the medium. In the presence of this small amount of CCP, the behaviors of six phages (T7, f1, MS2, Psf2, H6/1 and H40/1) change radically from the one in water only. Each bacteriophage reacts differently to the presence of CCP. For three phages (T7, H40/1 and H6/1) the presence of CCP offers an effective protection from the physical inactivation due to agitation of the liquid medium. However, reactions to presence of CCP range from a rapid inactivation by a massive adsorption (f1) to a dramatic enhancement of the virulence (MS2). These data are in good correspondence with the breakthrough results of tracing experiments performed in two karstic aquifers in the Swiss Jura. They show that it is possible to predict the breakthrough of a phage according to its absorption rates. But these experiments also demonstrate that it is difficult to generalize the behavior of a particular phage. Consequently, it may not be valid to use randomly selected bacteriophages to model the migration of vertebrate pathogenic viruses.