J Water Health 02 (2003) 15-22

A comparison of the survival of F+RNA and F+DNA coliphages in lake water microcosms

Sharon C. Long and Mark D. Sobsey

Civil and Environmental Engineering, 18 Marston Hall, University of Massachusetts, Amherst, MA 01003, USA Tel: +1 (413) 545-5390 Fax: +1 (413) 545-2202 Email: long@ecs.umass.edu

Environmental Sciences and Engineering, McGavran-Greenberg Hall, CB#7400, University of North Carolina, Chapel Hill, NC 27599-7400, USA Tel: +1 (919) 966-7303 Fax: +1 (919) 966-4711 Email: mark_sobsey@unc.edu

The survival of seven F+RNA phages (MS2 Group I ATCC type strain, two Group I environmental isolates, a Group II environmental isolate, a Group III environmental isolate, and two Group IV environmental isolates) and six F+DNA phages (M13, fd, f1, and ZJ/2 ATCC type strains, and two environmental isolates) were examined in microcosms using a surface drinking water source. Phages were spiked into replicate aliquots of a source water at about 20,000 pfu/ml. Replicate spikes were incubated at 4 and 20^oC and monitored for 110 days. At 4^oC, Groups I and II F+ RNA phages were detectable through 110 days, with reductions of about 1 and 3 log₁₀, respectively. The Group III F+RNA phage demonstrated 5 log₁₀ reduction after 3 weeks, and the Group IV F+RNA phages were reduced to detection limits (5 log₁₀ reduction) within 10 days. Of the F+DNA phages, all four type strains were detectable with about 2.5 log₁₀ reduction after 110 days at 4^oC. The F+DNA environmental isolates were detectable with about a 4 log₁₀ reduction after 110 days at 4^oC. All phages demonstrated faster decay at 20^oC. These results suggest that differences in F+ phage survival may influence their prevalence in environmental waters and the ability to attribute their prevalence to specific human and animal sources of faecal contamination.

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