The novel function of RND efflux pump was characterized in Gram-negative bacterium Riemerella anatipestifer by the College of Veterinary Medicine of Sichuan Agricultural University. It was shown that the RND (resistance-nodulation-cell division) family efflux pump of Riemerella anatipestifer was able to efflux manganese. The paper was published in the journal of Applied and Environmental Microbiology.

   The RND efflux pumps play an important role in multidrug resistance in Gram-negative bacteria. The RND efflux pump is also recognized as one of the most effective host defiance systems that can actively efflux harmful substances. However, the types of natural substrates for RND efflux pumps have not been fully identified.

   In this study, 12 efflux pumps deletion strains were constructed and their sensitivity to manganese were measured. The results showed that the two RND efflux pumps (B739_RS08835 and B739_RS04280) mutant strains were more sensitive to manganese and the intracellular manganese was accumulated. The accumulation of intracellular manganese leads to inhibition of bacterial division and disruption of iron homeostasis.

   This study extends the range of natural substrates transported by the RND efflux pump of Gram-negative bacteria, which is of great importance for further understanding the mechanism of bacterial metal homeostasis.

   This work was supported by the National Natural Science Foundation of China(Grant No., 32172851; http://www.nsfc.gov.cn/), the Sichuan Science and Technology Program (2020YJ0344), the earmarked fund for China Agriculture Research System (CARS-42-17), and the Sichuan Veterinary Medicine and Drug Innovation Group of the China Agricultural Research System (SCCXTD-2020-18).

    The link: https://doi.org/10.1128/aem.01835-22