🔬 Tailocin

An apparently defective prophage that can serve as an antibacterial agent, where head and DNA are absent from an otherwise adsorption-competent phage particle.

by Stephen T. Abedon Ph.D. Steve Abedon, Ph.D., has taught well over 100 individual classes and ~10 individual courses (including introductory biology, microbiology, physiology, biochemistry, etc.) over his 30+ years as a college professor. He has over 150 publications, including multiple monographs, and is ranked in the top 1 or 2 percent among researchers of all disciplines worldwide. His research focuses on bacteriophage biology and phage therapy. (abedon.1@osu.edu)

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About this entry: Tailocin is one of a growing set of phage biology and phage therapy terms defined here. For more phage terms, see Abedon, S.T. (2025). Phage Therapy Annotated Glossary. Preprints.org. 10.20944/preprints202508.0347.v1
To share a particular section, use the 🔗 link beside its heading, which copies a web address that opens the page right there. To cite this page: Abedon, S.T. (2026). Phage Terms. terms.phage.org.  ·  DOI: 10.5281/zenodo.20173633

phage.org/terms/tailocin.html  ·  Abedon’s Books  ·  DOI: 10.5281/zenodo.20173633

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Tailocin: An apparently defective prophage that can serve as an antibacterial agent, where head and DNA are absent from an otherwise adsorption-competent phage particle.
Also in the Phage Therapy Annotated Glossary: see the entries “Phage Tail-like Bacteriocin” (p. 43) and “Tailocin” (p. 54). Read the Glossary · Abedon, S.T. (2025). Preprints.org. doi:10.20944/preprints202508.0347.v1

Discussion

The term tailocin has been proposed as an alternative to high-molecular weight pyocin or bacteriocin. They basically consist of tailed phage tails but without the rest of the phage.

From Gill and Young (2011), p. 377: "Many bacteria have taken advantage of the cellular leakage associated with the phage DNA ejection process by evolving 'tailocins', a term we propose here for what were originally called 'high-molecular weight pyocins' when they were first identified in Pseudomonas strains... Basically, these are the apparent products of degenerate prophage elements which lack head genes; when the tailocin determinants are expressed, headless phage particles are produced that appear to kill the target cells by the same hole-forming process used for phage DNA ejection, except that no DNA ever goes through to cause re-sealing of the hole. The new term tailocin is justified because the same entities have now been found in many other bacterial species, and the continued use of the pyocin term would be misleading."

References

  • Gill, J.J. & Young, R. (2011). Therapeutic applications of phage biology: history, practice and recommendations. In: Miller, A.A. & Miller, P.F. (eds.) Emerging Trends in Antibacterial Discovery: Answering the Call to Arms. Caister Academic Press, Norfolk, UK, pp. 367–410.
  • Abedon, S.T. (2025). Phage therapy annotated glossary. Preprints.org. 10.20944/preprints202508.0347.v1

How to cite this page

Abedon, S.T. (2026). Phage Terms. https://terms.phage.org  ·  10.5281/zenodo.20173633

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