An optimised milk testing protocol to ensure accurate enumeration of viable Mycobacterium avium subsp. paratuberculosis by the PMS-phage assay

Antonio C. G. Foddai, Irene R. Grant

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
285 Downloads (Pure)

Abstract

There is interest in determining levels of Mycobacterium avium subsp. paratuberculosis (MAP) contamination in milk. The optimal sample preparation for raw cows' milk to ensure accurate enumeration of viable MAP by the peptide-mediated magnetic separation (PMS)-phage assay was determined. Results indicated that milk samples should be refrigerated at 4 C after collection and MAP testing should commence within 24 h, or samples can be frozen at 70 C for up to one month without loss of MAP viability. Use of Bronopol is not advised as MAP viability is affected. The vast majority (>95%) of MAP in raw milk sedimented to the pellet upon centrifugation at 2500 g for 15 min, so this milk fraction should be tested. De-clumping of MAP cells was most effectively achieved by ultrasonication of the resuspended milk pellet on ice in a sonicator bath at 37 kHz for 4 min in ‘Pulse’ mode.

Original languageEnglish
Pages (from-to)16-23
Number of pages8
JournalInternational Dairy Journal
Volume51
Early online date18 Jul 2015
DOIs
Publication statusPublished - Dec 2015

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