Identification of Antimicrobial Peptides from Nibribacter radioresistens, a UV and Gamma Radiation Tolerant Bacterium.

Abstract

Background: Nibribacter radioresistens, a UV and gamma radiation-tolerant bacterium, was reported to have superior antibacterial activities against a variety of pathogenic bacteria through the production of antimicrobial peptides (AMPs), but nothing is known about its AMPs.

Methods/results: In this study, our genomic and transcriptomic data showed that the N. radioresistens genome contains 11 AMP gene candidates, designated as NB_AMP1 to NB_AMP11, which are expressed differently in logarithmic growth and stationary phase. Moreover, the cell-free supernatant of all Escherichia coli DH5α strains containing cloned AMPs except for NB_AMP5 and NB_AMP7 exhibited antibacterial activities against both Gram-negative and Gram-positive bacteria such as E. coli and Staphylococcus aureus. Synthetic AMPs supported the antibacterial activities of cloned AMPs, and, in particular, the synthetic NB_AMP2 showed superior antibacterial activities against both E. coli and S. aureus.

Conclusions: Altogether, these results suggest that the AMP candidates from N. radioresistens may function as antimicrobial peptides, effectively causing cellular lysis through pore formation in the bacterial membrane.