Comparing effects of freezing at -196 °C and -20 °C on the viability of mastitis pathogens

Show simple item record Petzer, Inge-Marie Karzis, Joanne Van der Schans, Theodorus J. Watermeyer, Johanna C. Mitchell-Innes, Norman Eloff, Stephanie Fosgate, Geoffrey T. 2012-03-05T13:13:35Z 2012-03-05T13:13:35Z 2012-02-10
dc.description I.M.P. (University of Pretoria) was the project leader. I.M.P. (University of Pretoria), J.C.W. (University of Pretoria) and T.J.v.d.S. (University of Pretoria) were responsible for experimental and project design. N.M.I. (Herd Husbandry Help CC) assisted with the storage of samples in liquid nitrogen (-196 ºC) by making facilities available. S.E. (University of Pretoria) assisted with data capturing. J.K. (University of Pretoria) and I.M.P. (University of Pretoria) were responsible for the literature review, the writing-up of the article, and G.T.F. (University of Pretoria) assisted with data utilisation and statistical analysis. en
dc.description.abstract The aim of this study was to compare the effects of cryopreservation at approximately -196 °C in liquid nitrogen (N) and freezing at approximately -20 °C in a freezer, on the viability and survival of eight different mastitogenic bacteria inoculated in milk. Bacteria were frozen at approximately -20 °C in a freezer and cryopreserved at approximately -196 °C in liquid nitrogen. An effective preservation method was needed for follow-up samples from cows identified in the South African National Milk Recording Scheme (NMRS) with somatic cell counts above 250 000 cells/mL milk. The organisation responsible for sample collection of the NMRS milk samples also provides producers with liquid nitrogen for their semen flasks at the collection sites. This existing mode of storage and transport could therefore be utilised. Ten samples of each organism were thawed and cultured bi-weekly until week 18 for both temperature treatments. An additional sampling was performed at week 30 for samples frozen at approximately -20 °C. Freezing and cryopreservation did not impair subsequent isolation of Streptococcus dysgalactiae, Streptococcus uberis, Enterococcus faecalis, Staphylococcus aureus (STH) (phage type lytic group III) or Sta. aureus (STA) (phage typed, other than lytic group III). Survival was indicated by the isolation of bacteria from samples, and viability by the strength of growth of the bacteria isolated. The survival of Streptococcus agalactiae decreased after week 12 and Escherichia coli after week 16 of freezing, but both organisms survived under cryogenic preservation until week 18. Coagulase-negative staphylococci survived until week 18 for both freezing and cryogenic preservation. Both storage methods could thus contribute to the improvement of a pro-active approach towards udder health management in South African dairy herds. en
dc.description.librarian ab2012 en
dc.description.uri en
dc.identifier.citation Petzer, I.M., Karzis, J., Van der Schans, T.J., Watermeyer, J.C., Mitchell-Innes, N., Eloff, S. & Fosgate, G.T., 2012, ‘Comparing effects of freezing at -196 °C and -20 °C on the viability of mastitis pathogens’, Onderstepoort Journal of Veterinary Research 79(1), Art. #343, 6 pages. 10.4102/ojvr.v79i1.343 en
dc.identifier.issn 0030-2465
dc.identifier.other 10.4102/ojvr.v79i1.343
dc.identifier.other 6603440077
dc.language.iso en en
dc.publisher Agricultural Research Council, ARC-OVI and the University of Pretoria en
dc.relation.requires Adobe Acrobat Reader en
dc.rights © 2012. The Authors. Licensee: AOSIS OpenJournals. This work is licensed under the Creative Commons Attribution License. en
dc.subject Mastitis pathogens en
dc.subject Cryopreservation en
dc.subject Freezing en
dc.subject Liquid nitrogen (N) en
dc.subject.lcsh Mastitis en
dc.subject.lcsh Udder -- Diseases en
dc.subject.lcsh Cryopreservation of organs, tissues, etc. en
dc.title Comparing effects of freezing at -196 °C and -20 °C on the viability of mastitis pathogens en
dc.type Article en

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