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 WG4 9 as the host bacterium. While numerous plaques were detected with WG4 9 (a strain possessing Escherichia coli F pill), plaques were also obs erved with an F- control strain of Salm. typhimurium. Five isolates we re plaque purified and examined by electron microscopy. All of the iso late particles were observed to be tailed, with five distinct particle types being differentiated. None of the isolate particles were consis tent in morphology with the cubic FRNA coliphages. Host range evaluati on supported classification of the isolates as salmonella phages. Soma tic salmonella phages have previously been found to interfere with the assay of surface waters for FRNA coliphages. Their detection here dem onstrates that such interference is also encountered in the assay of g roundwaters.