DETECTION OF FRNA COLIPHAGES IN GROUNDWATER - INTERFERENCE WITH THE ASSAY BY SOMATIC SALMONELLA BACTERIOPHAGES

Groundwater samples from two sites in Alabama, USA were plaque assayed for F-specific RNA (FRNA) coliphages using Salmonella typhimurium WG49 as the host bacterium. While numerous plaques were detected with WG49 (a strain possessing Escherichia coli F pill), plaques were also observed with an F- control strain of Salm. typhimurium. Five isolates were plaque purified and examined by electron microscopy. All of the isolate particles were observed to be tailed, with five distinct particle types being differentiated. None of the isolate particles were consistent in morphology with the cubic FRNA coliphages. Host range evaluation supported classification of the isolates as salmonella phages. Somatic salmonella phages have previously been found to interfere with the assay of surface waters for FRNA coliphages. Their detection here demonstrates that such interference is also encountered in the assay of groundwaters.