title: UV light inactivation of Mycobacterium avium subsp. paratuberculosis in milk as assessed by FASTPlaqueTB phage assay and culture.
abstract: UV light inactivation of Mycobacterium avium subsp. paratuberculosis in Middlebrook 7H9 broth and whole and semiskim milk was investigated using a laboratory-scale UV machine that incorporated static mixers within UV-penetrable pipes. UV treatment proved to be less effective in killing M. avium subsp. paratuberculosis suspended in milk (0.5- to 1.0-log(10) reduction per 1,000 mJ/ml) than that suspended in Middlebrook 7H9 broth (2.5- to 3.3-log(10) reduction per 1,000 mJ/ml). The FASTPlaqueTB phage assay provided more rapid enumeration of surviving M. avium subsp. paratuberculosis (within 24 h) than culture on Herrold's egg yolk medium (6 to 8 weeks). Despite the fact that plaque counts were consistently 1 to 2 log(10) lower than colony counts throughout the study, UV inactivation rates for M. avium subsp. paratuberculosis derived using the phage assay and culture results were not significantly different (P = 0.077).
authors: Institute of Agri-Food and Land Use, School of Biological Sciences, Queen's University Belfast, UK.
authors: Leslie C
authors: LC
authors: Altic
authors: Michael T
authors: MT
authors: Rowe
authors: Irene R
authors: IR
authors: Grant
mesh_terms: D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial / Q000379:methods*; D004203:Disinfection / Q000379:methods*; D005514:Food Irradiation; D050296:Microbial Viability; D008892:Milk / Q000382:microbiology*; D009160:Mycobacteriophages / Q000254:growth & development; D016927:Mycobacterium avium subsp. paratuberculosis / Q000528:radiation effects* / Q000821:virology; D014466:Ultraviolet Rays; D010948:Viral Plaque Assay / Q000379:methods*