AUTHOR=Zhang Li , Huang Li , Huang Mi , Wang Mengying , Zhu Dekang , Wang Mingshu , Jia Renyong , Chen Shun , Zhao Xinxin , Yang Qiao , Wu Ying , Zhang Shaqiu , Huang Juan , Ou Xumin , Mao Sai , Gao Qun , Tian Bin , Cheng Anchun , Liu Mafeng 

TITLE=Effect of Nutritional Determinants and TonB on the Natural Transformation of Riemerella anatipestifer

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.644868

DOI=10.3389/fmicb.2021.644868

ISSN=1664-302X

ABSTRACT=<p><italic>Riemerella anatipestifer</italic> is a gram-negative bacterium that is the first naturally competent bacterium identified in the family <italic>Flavobacteriaceae</italic>. However, the determinants that influence the natural transformation and the underlying mechanism remain unknown. In this study, we evaluated the effects of various nutritional factors of the GCB medium [glucose, L-glutamine, vitamin B1, Fe (NO<sub>3</sub>)<sub>3</sub>, NaCl, phosphate, and peptone], on the natural transformation of <italic>R. anatipestifer</italic> ATCC 11845. Among the assayed nutrients, peptone and phosphate affected the natural transformation of <italic>R. anatipestifer</italic> ATCC 11845, and the transformation frequency was significantly decreased when phosphate or peptone was removed from the GCB medium. When the iron chelator 2,2′-dipyridyl (Dip) was added, the transformation frequency was decreased by approximately 100-fold and restored gradually when Fe (NO<sub>3</sub>)<sub>3</sub> was added, suggesting that the natural transformation of <italic>R. anatipestifer</italic> ATCC 11845 requires iron. Given the importance of TonB in nutrient transportation, we further identified whether TonB is involved in the natural transformation of <italic>R. anatipestifer</italic> ATCC 11845. Mutation of <italic>tonBA</italic> or <italic>tonBB</italic>, but not <italic>tbfA</italic>, was shown to inhibit the natural transformation of <italic>R. anatipestifer</italic> ATCC 11845 in the GCB medium. In parallel, it was shown that the <italic>tonBB</italic> mutant, but not the <italic>tonBA</italic> mutant, decreased iron acquisition in the GCB medium. This result suggested that the <italic>tonBB</italic> mutant affects the natural transformation frequency due to the deficiency of iron utilization.</p>