Beyond Indicators: Alternative Methods for Phage Detection in Activated Sludge

Numerous phages have been identified in wastewater treatment plants, with many studies focusing on phages associated with coliform bacteria as indicators of fecal contamination. Additional research into the role of other phages is limited in part because traditional methods of study require uniform growth of the host bacterium on semi-solid media, a characteristic not shown by many wastewater bacteria. This study evaluates three methods to detect phage infection in broth cultures of a host bacterium. Cell density estimates by absorbance, ATP analysis by a bioluminescent assay, and membrane integrity measured by fluorimetry all showed clear evidence of phage infection compared to control samples of bacterial cultures with no phage. The cost of luminescent or fluorescent reagents may be offset by the time and labor savings.