Effect of Different Heat Treatments and Disinfectants on the Survival of <Emphasis Type="Italic">Prototheca zopfii</Emphasis> |
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Authors: | Henryka Lassa Tomasz Jagielski Edward Malinowski |
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Institution: | 1.Department of Pathophysiology of Reproduction and Mammary Gland,National Veterinary Research Institute,Bydgoszcz,Poland;2.Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology,University of Warsaw,Warsaw,Poland |
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Abstract: | Bovine mastitis caused by the yeast-like alga Prototheca zopfii represents a serious veterinary problem and may result in heavy economic losses to particular dairy farms. The purpose of
this study was to evaluate the survival of 50 isolates of P. zopfii in milk subjected to different heat treatments and the survival of further 106 P. zopfii isolates after exposure to three classes of teat disinfectants: iodine (Dipal), quaternary ammonium compounds (Teat), and
dodecylbenzenesulphonic acid (Blu-gard). Of the 50 isolates tested for thermal tolerance, 29 (58%) survived heat treatment
at 62°C for 30 s and 13 (26% of all isolates) of those survived after heat treatment at 72°C for 15 s. None of the 106 isolates
were able to withstand the in-use concentrations of the three disinfectants tested. The highest disinfectant concentrations
that permitted survival of at least one isolate were dilutions: 1:1,000 for Dipal (survival rate of 52.8–57.5%), 1:100 for
Teat (88.7–90.6%), and 1:10 for Blu-gard (100%). No differences in the survival rates of P. zopfii were observed with respect to the duration of exposure to disinfectant. The results of this study support the previous findings
that P. zopfii may resist high-temperature treatments, including that applied in the high-temperature, short-time (HTST) pasteurization
process. The obtained data also demonstrate the efficacy of the three classes of teat disinfectants against P. zopfii, with the efficacy of iodine being most pronounced. The study emphasizes the necessity of using higher temperatures in the
pasteurization of raw milk to kill the Prototheca algae, as well as the particular suitability of the iodine for the control procedures of protothecal mastitis. |
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