Isolation, identification and biological characteristics of Mycoplasma bovis in yaks.

Mycoplasma bovis (M. bovis) is one of the important pathogens which may cause bovine respiratory disease syndrome (BRDS), and results in huge economic losses for yaks (Bos gaurus) breeding industry. However, there is limited information about M. bovis in yaks. In our study, 145 nasal mucus samples from yaks with pneumonia were collected to clarify. Bacteriological determination was carried out through biochemical identification and Polymerase Chain Reaction (PCR) detection. And ten strains of Mycoplasma bovis (M. bovis) were found from collected samples. Then, the growth curve of isolated strains was determined by the change of optical density (OD630), pH value and Color Change Cnit (CCU). K-B disk method was also used for antimicrobial susceptibility testing. Results of colony morphology and biochemical testing were consistent with the biological characters of M. bovis. The nucleotide sequences of uvrC specific gene and 16S rRNA gene among the 10 strains were highly homologous. The growth curve assay showed that the isolates cultured in PPLO medium were in lag phase for 24 h, entered stable period in 42 h, and entered decline phase after 78 h. The isolates were found resistant to macrolides, aminoglycosides and lincomycin at various degrees, but they were sensitive or moderately sensitive to doxycycline and kanamycin under antimicrobial susceptibility analysis. In conclusion, the results provided certain reference for the follow-up research and guiding for the treatment of M. bovis in yaks.