Non-Essential Adhesion- and Virulence-Related Genes of Mycoplasma bovis

Mycoplasma bovis is an emerging pathogen causing bovine mycoplasmosis. While clinical manifestations are vast, pneumonia, mastitis and arthritis cases are mainly reported. At the molecular level, there is limited understanding of disease development and mechanisms of pathogenicity. Random transposon mutagenesis is a widely used method in Mycoplasma species to identify potential functions of proteins and to screen genes essential for survival. We generated a random transposon mutant library of M. bovis strain JF4278 containing approximately 4,000 independent insertion sites. Using a high-throughput analysis approach, 352 genes of M. bovis were assigned as essential for growth on rich medium. The non-essential genes set of M. bovis, represents a concise list of genes that can be individually disrupted to further characterize their function. Putative non-essential virulence-related factors were identified. Moreover, several non-essential genes of M. bovis had essential orthologues in M. pulmonis. The complete mutant library was subsequently screened for adhesion using primary bovine mammary gland epithelial cells. An expanded list of conditional-essential genes containing putative adhesion-related factors was obtained. By individually assessing the adhesion capacity of six mutants, two previously unknown factors and the adhesin TrmFO showed a reduced adhesion phenotype. This study extends the list of M. bovis genes tolerating disruption and provides an expanded list of putative adhesion-related factors. This data might be useful for future studies aiming to obtain M. bovis mutants of specific genes for subsequent functional characterization.