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 10 7 CFU/ml to the final of 3.92 x 10 6 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 10 7 CFU/ml to 5.69 x 10 6 CFU/ml; (2) at ―80°C ― from the initial of 1.13 x 10 7 CFU/ml to 9.75 x 10 6 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 10 7 CFU/ml to the final of 2.18 × 10 6 CFU/ml; (2) at ―80°C ― the initial and final values were 1.13 x 10 7 CFU/ml and 7.89 x 10 6 CFU/ml, respectively.