Pathogenic avian mycoplasmas show phenotypic differences in their biofilm forming ability compared to non-pathogenic species in vitro

Mycoplasmas are known as the minimalist microorganisms in the microbes’ world. Their minimalist nature makes them highly sensitive to the environmental conditions and limits their ability to survive for extended periods outside their animal host. Nevertheless, there are documented instances of mycoplasma transmission over significant distances and this phenomenon may be linked to relatively unexplored abilities of mycoplasmas, such as their capacity to synthesize biofilm—the predominant mode of bacterial growth in nature. The authors decided to establish a method aimed at inducing the clustering of mycoplasma planktonic cells within a biofilm in vitro and subsequently assess the capacity of certain avian mycoplasmas to synthesize a biofilm. A total of 299 avian mycoplasma isolates were included in the study, encompassing both pathogenic (Mycoplasma gallisepticum, M. synoviae, M. meleagridis, M. iowae) and non-pathogenic species (M. gallinaceum, M. gallinarum, M. iners and M. pullorum). The authors successfully demonstrated the feasibility of inducing avian mycoplasmas to synthetize in vitro a biofilm, which can be visually quantified. The only species that did not produce any biofilm was M. iowae. In general, the pathogenic mycoplasmas produced greater quantities of biofilm compared to the non-pathogenic ones. Furthermore, it was observed that the ability to produce biofilm appeared to vary, both qualitatively and quantitatively, not only among different species but also among isolates of a single species. Future studies will be necessary to determine whether biofilm production plays a pivotal epidemiological role for the pathogenic avian mycoplasmas.