Optimal preparation and purification of PRD1-like bacteriophages for use in environmental fate and transport studies

Bacteriophages are bacterial viruses with unique characteristics that make them excellent surrogates for mammalian pathogenic viruses in environmental studies. Simple and reliable methodologies for isolation, detection, characterization and enumeration of somatic and F-specific bacteriophage are available in the literature. Limited information or methods are available for producing high-titer purified phage suspensions for studying microbial transport and survival in natural and engineered environments. This deficiency arises because most research on the production of high-titer phage suspensions was completed over half a century ago and more recent advances on these methods have not been compiled in a single publication. We present a review of the available methods and new data on the propagation, concentration and purification of two bacteriophage host systems (somatic PRD1/Salmonella thyphimurium and F-specific PR772/Escherichia coli) that are commonly utilized in laboratory and field-scale assessments of subsurface microbial transport and survival. The focus of the present study is to recommend the approach(es) that will ensure maximum bacteriophage yields while optimizing suspension purification (i.e. avoiding modification of surface charge of the phage capsids and/or inadvertent introduction of dissolved organic matter to the study system).