Natural Transformation of Riemerella columbina and Its Determinants

In a previous study, it was shown that , a member of , is naturally competent. However, whether natural competence is universal in remains unknown. In this study, it was shown for the first time that was naturally competent in the laboratory condition; however, was not naturally competent under the same conditions. The competence of was maintained throughout the growth phases, and the transformation frequency was highest during the logarithmic phase. A competition assay revealed that preferentially took up its own genomic DNA over heterologous DNA. The natural transformation frequency of was significantly increased in GCB medium without peptone or phosphate. Furthermore, natural transformation of was inhibited by 0.5 mM EDTA, but could be restored by the addition of CaCl , MgCl , ZnCl , and MnCl , suggesting that these divalent cations promote the natural transformation of . Overall, this study revealed that natural competence is not universal in members and triggering of competence differs from species to species.