Alzhraa Ali Mohamed

Conference 2022 Live Talk


Talk title

Nano-tail and antibiotic resistance: characterization of R-pyocin activity against Gram-positive pathogens


Authors and Affiliations

Alzhraa Ali Mohamed1, Ashraf M. El-shawadfy1; Gehan Amin1 and Ahmed Askora1

1. Department of Microbiology and Botany, Faculty of Science, Zagazig University, 44519, Egypt.




Antibiotic and antimicrobial resistance (AMR) is a growing threat that faces the world since several years and still increasing every year. Moreover, according to the World Health Organization (WHO), AMR by 2050 will kill up to 10 million per year worldwide. This requires intensive research for finding new antimicrobials. R-pyocins are kind of peptide nano-tails that possess antibacterial activity and could serve as future antibiotic alternatives.
This study is aimed at characterization of both antimicrobial and anti-biofilm activity of R-pyocin from clinical Pseudomonas aeruginosa against Gram-positive pathogens including Staphylococcus aureus.


Pyocinogenic P. aeruginosa was detected using reverse side method, and pyocinogeny typing was confirmed using revised-spotting method. Transmission electron microscopy (TEM) was used for morphological characterization of R-pyocin and for detection of changes in membrane of R-pyocin-treated S. aureus. SDS-PAGE analysis was used for detection of the molecular weight of R-pyocin protein-subunits and Poisson-killing-distribution assay for burst-size calculation. Lipotechoic-acid (LTA) adsorption-assay was used to confirm whether LTA in Gram-positive bacteria served as R-pyocin receptor. Moreover, R-pyocin production at 10–60°C was assessed. Host-range of activity of R-pyocin was tested against antimicrobial resistant (AMR) pathogens. The anti-biofilm activity of R-pyocin was detected against sensitive bacterial strains. Chemical, enzymatic, pH and thermo-stability of R-pyocin were evaluated.


TEM micrographs revealed a typical morphology of myotailocins indicating the production of R-pyocin designated as RPU15. TEM revealed pores formation in S. aureus membrane, and bacteriophage-like plaques were obvious on plates of R-pyocin-treated S. aureus. R-pyocin activity was neutralized by LTA of S. aureus and Listeria monocytogenes. P. aeruginosa PU15 produced ~428 non-inducible R-pyocin particles. RPU15 sheath and tube protein-subunits exhibited a molecular weight of 38 and 23 kDa, respectively. RPU15 possessed activity against S. aureus, L. monocytogenes, Bacillus cereus and Candida albicans and reduced biofilm biomasses of tested AMR strains.


Our results show the potential therapeutic use of R-pyocin due to its effectiveness on tested bacterial biofilms.
Significance and Impact of the Study:
This is the first study that investigates antimicrobial and anti-biofilm activity of R-pyocin activity against S. aureus. R-pyocin shows new phenomenon of bacteriophage-like plaques. Our findings represent a future therapeutic agent targeting both methicillin-resistant and vancomycin-resistant S. aureus