Genes regarded as essential in previous studies found to be dispensable in this study.

1Essential genes in M. pulmonis, with percentage amino acid sequence identity with M. bovis strain PG45 in parentheses (French et al., 2008). #M. pulmonis genes found disruptable in later study (Dybvig et al., 2010). 2Gene essentiality in transposon mutagenesis studies in M. genitalium (Glass et al., 2006). Y indicates gene essentiality; N indicates gene dispensability; NA indicates orthologous gene not found. 3Database of predicted essential genes http://tubic.tju.edu.cn/pdeg/ (Lin & Zhang, 2011). 4Number of mycoplasma species (out of 20) in which gene is conserved (Liu et al., 2012). 5Essentiality in Bacillus subtilis (Bs) and E. coli (Ec). N indicates dispensability. 6Gene persistence in Bacillus subtilis (Bs) and E. coli (Ec) (Fang et al., 2005). *0323 paralogue in M. bovis shares 43% identity with 0153. **0526 paralogue in M. bovis shares 48% identity with 0527.