Persistence of MS-2 and PRD-1 bacteriophages in an ultrapure water system

Abstract

The persistence of bacteriophages MS-2 and PRD-1 was evaluated in tap water, in reverse osmosis (RO) permeate, and in three locations within an ultrapure water system; ultrapure samples included pre- and post-UV sterilization and post-mixed bed ion exchange tank. The inactivation rates for MS-2 were calculated as log10 reduction per hour and per day: k = -(log 10 Ct/C0)/t. PRD-1 was found to persist with no significant loss of infectivity in all water purity environments evaluated. Inactivation of MS-2 was dependent on water quality and pH. Short-term inactivation rates for chlorinated tap water, post-RO, pre-UV, post-UV and post-ion exchange sample locations were 0.028, 0.455, 0.231, 0.191 and 0.168 log10 h-1, respectively. Long-term inactivation rates for chlorinated tap water, post-RO, pre-UV, post-UV and post-ion exchange sample locations were 0.485, 0.911, 0.605, 0.632 and 0.684 log10 day-1, respectively. Since phages were found to remain intact as well as to lyse in the ultrapure water environment, the phages have the potential to contaminate the ultrapure water environments of the microelectronics, pharmaceutical and power generation industries in both colloidal and dissolved form. Further work is proceeding to generate standardized and cost-effective methods to detect viruses in water environments.

Effects of pH and temperature on the survival of coliphages MS2 and Q?

“…1. The relationship between the log of MS2 concentration and time was approximately linear over the pH (3)(4)(5)(6)(7)(8)(9)(10)(11) and temperature (5-35°C) values studied, while this was not always the case for Qb. Although a linear relationship between the log of Qb concentration and time existed for most of the pH and temperature values studied (pH range 5-10 in the temperature range of 5-35°C, and for pH 11 under the temperature range of 5-15°C), a linear relationship did not hold for pH 3-4 under the temperature range 5-35°C and for pH 11 under the temperature range 25-35°C.…”

“…At extreme pH values, the high concentrations of hydrogen ion and hydroxyl ion present in water are considered to be far greater than the concentration of free reactive radicals and therefore dominate viral inactivation mechanisms. Previous work [8] has shown that highly reactive radicals in a water environment (including hydroxyl and superoxyl ions) have relatively long lifetimes. These reactive radicals can oxidise materials in the water environment.…”

Microencapsulation of Clostridium difficile specific bacteriophages using microfluidic glass capillary devices for colon delivery using pH triggered release

“…Osmotic damage to phage during phage processing and storage is an important consideration [76]. Governal and Gerba [77] reported activity of an E . coli phage dropped by 2 log upon exposure to ultrapure water.…”

Application of Pesticide Sprays to Fresh Produce: A Risk Assessment for Hepatitis A and Salmonella

“…The same was true for the selection of E. coli as a model for Salmonella (Stine et al 2005a). PRD1 coliphage was obtained from the University of Arizona Department of Soil, Water, and Environmental Science and propagated using Salmonella typhimurium ATCC 19585 (Governal and Gerba 1997). Escherichia coli ATCC 25922 (American Type Culture Collection, ATCC, Rockville, MD) was grown for 18-24 h in tryptic soy broth (Difco Company, Detroit, MI) at 37°C.…”

“…Escherichia coli ATCC 25922 (American Type Culture Collection, ATCC, Rockville, MD) was grown for 18-24 h in tryptic soy broth (Difco Company, Detroit, MI) at 37°C. E. coli ATCC 25922 was assayed using the Colilert quanti-tray system (IDEXX, Westbrook, MA); while PRD1 was assayed in duplicate using the plaque-forming unit method (Governal and Gerba 1997).…”