ARS | Publication request: Salmonella Phages from Swine Manure Lagoons

Submitted to: American Society For Microbiology Conference
Publication Acceptance Date: June 11, 2004
Publication Date: August 1, 2004
Citation: Mclaughlin, M.R., El Balaa, M.F., Sims, J., Andersland, J., King, R. 2004. Salmonella Phages From Swine Manure Lagoons [abstract]. Proceedings American Society For Microbiology Conference New Phage Biology Conference. P. 21.

Technical Abstract: Phages isolated from manure have potential as typing reagents, indicators and biocontrol agents of bacterial pathogens. A study of phages in swine manure was begun by making a collection of Salmonella phages from nine lagoons. Phages were isolated by either an enrichment protocol or directly from clarified filtered effluent. In the enrichment protocol, samples were treated with chloroform and passed through 0.22 micron filters. Lytic phages were selectively enriched by mixing filtered effluent with double strength trypticase soy broth inoculated with a mixture of Salmonella strains. After overnight incubation at 35 C, chloroform was added and samples were stored at 5 C. Enriched samples were tested by double agar layer (DAL) plaque assay against individual Salmonella isolates. Phage titers of 2.9 x 10 8 to 2.1 x 10 9 plaque forming units (pfu) per ml were produced, but estimation of phage titers in lagoons was not possible. In the direct protocol, effluent was clarified by centrifugation, passed through 0.22 micron filters and used in DAL plaque assays against Salmonella isolates. Single-plaque phage isolates were recovered, but plaque formation varied among host isolates and lagoons. The most sensitive host for direct recovery of phages was ATCC 13311 followed by BAA-712. Phage titers among the lagoons were estimated by the direct isolation protocol with ATCC 13311 and ranged from 12-148 pfu per ml. Limited host range tests of 66 isolates recovered by the enrichment protocol, showed all to be specific for serotypes Enteritidis and Typhimurium and none produced plaques on lagoon isolates of species of Citrobacter, Escherichia, Proteus, Providencia or Serratia. Electron microscopy of purified phages from 12 enrichment protocol isolates showed icosahedral heads about 50 nm across with tail spikes lacking a shaft. Swine manure lagoons were a good source of Salmonella phages and both isolation protocols were effective, but only the direct protocol could be used to estimate lagoon phage titers.