Detection of FRNA coliphages in groundwater: interference with the assay by somatic salmonella bacteriophages

Abstract

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 pili), 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.

Pretreatment to reduce somatic salmonella phage interference with FRNA coliphage assays: successful use in a one-year survey of vulnerable groundwaters

“…Since strain WG49 is naturally susceptible to SS phages, such assay interference is a potential problem in waters where SS phages outnumber FRNA coliphages. We found that to be the case during the examination of groundwater at two sites in Alabama, USA (Williams and Stetler 1994). That finding and the findings of Handzel et al and Rhodes and Kator suggest it is not uncommon for SS phages to occur in greater numbers than FRNA coliphages in environmental waters.…”

“…The initial FRNA coliphage assays (without pretreatment) of groundwater samples from two sites in Alabama detected SS phages and not FRNA coliphages (Williams and Stetler 1994), and it was concluded that SS phages in survey samples could significantly hinder detection of FRNA coliphages. Pretreatment with WG45 cells was then implemented to remove SS phages prior to FRNA coliphage assay, and in subsequent groundwater analyses both SS phages and FRNA coliphages were assayed.…”

“…Only the CT average recovery was lower than the corresponding FRNA coliphage recovery. " Classified according to plaque characteristics described by Williams and Stetler (1994). CT, Contractile tailed phage ; LNT, long non-contractile tailed phage ; SNT1-3, short noncontractile tailed phage variants 1-3.…”

“…Analysis of the SS phages isolated from initial groundwater samples revealed that this group of phages was composed of different phage types. Five distinct types were differentiated by plaque morphology, host range and particle characteristics as imaged by electron microscopy (Williams and Stetler 1994). The five types that were identified included a contractile-tailed phage (CT), a long non-contractile-tailed phage (LNT) and three short non-contractile-tailed phages (SNT-1, SNT-2, .…”

Study of the potential relationship between the morphology of infectious somatic coliphages and their persistence in the environment

“…Our results indicate that Siphoviridae with flexible tails, and among these those with curled tails, are the most persistent in freshwater environments under adverse conditions. Data reported elsewhere on survival of B. fragilis bacteriophages (Jofre et al 1986;Tartera et al 1988;Gironés et al 1989;Chung and Sobsey 1993), coliphages (Dee and Fogleman 1992;Yanko et al 1999) or phages infecting Salmonella typhimurium (Rhodes and Kator 1991;Williams and Stetler 1994) support this hypothesis.…”