The Survival of Mycoplasma bovis at Different Temperatures

The survival of Mycoplasma bovis in milk samples was investigated at three storage temperatures (5°C, -30°C and -80°C) during 5 weeks. For the storage temperatures -30°C and -80°C, the respective samples were prepared weekly and those for culture by repeated defrosting. At 5°C the total number of M. bovis CFU/ml decreased from the initial of 1.13 x 107 CFU/ml to the final of 3.92 x 106 CFU/ml. The development in the frozen samples prepared for each week was as follow: (1) at -30°C - from the initial of 1.13 x 107 CFU/ml to 5.69 x 106 CFU/ml; (2) at -80°C - from the initial of 1.13 x 107 CFU/ml to 9.75 x 106 CFU/ml. The decrease in M. bovis colony count was more evident in the samples that were repeatedly defrosted: (1) at -30°C - the initial of 1.13 x 107 CFU/ml to the final of 2.18 x 106 CFU/ml; (2) at -80°C - the initial and final values were 1.13 x 107 CFU/ml and 7.89 x 106 CFU/ml, respectively.