🔬 Confluent Lysis

Clearance of a bacterial lawn or, especially, failure of a bacterial lawn to substantially develop as a consequence of substantial phage-induced bacterial lysis.

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

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Confluent Lysis: Clearance of a bacterial lawn or, especially, failure of a bacterial lawn to substantially develop as a consequence of substantial phage-induced bacterial lysis.
Also in the Phage Therapy Annotated Glossary: see the entry “Confluent Lysis” (p. 20). Read the Glossary · Abedon, S.T. (2025). Preprints.org. doi:10.20944/preprints202508.0347.v1

Discussion

Confluent lysis occurs when too many phage particles are plated (or, more precisely, too many plaque-forming units). The result is formation of sufficient numbers of plaques that there is no delineation between their borders. Another perspective on confluent lysis is that it is a degree of clearing that is equivalent to that seen with spotting, though up to the entire plate can be involved due to mixture of phages with bacteria prior to bacteria application to a plate.

Note that one means by which phage stocks may be prepared in fact involves phage-bacterial interaction as it occurs on a plate, a so-called plate lysate, and successful phage propagation in this case generally will result in confluent lysis. Alternatively, dripping of condensation onto a bacterial lawn can result in sufficiently rapid phage diffusion within the droplet, prior to its drying, that again confluent lysis can occur, though generally not across the entire plate.

Stent (1963), p. 182, states: "The multiplication of the phages on this plate produces 105 plaques, so that after incubation the entire surface of this plate will consist of nothing but plaques, or show confluent lysis. However, on such a confluent lysis plate there will generally remain a few bacterial colonies, which can be picked and restreaked through several passages on fresh nutrient agar to free the cells from any contaminating [phages] carried over from the original confluent lysis plate.” (Emphasis in original)

References

  • Stent, G.S. (1963). Molecular Biology of Bacterial Viruses. W.H. Freeman, San Francisco.
  • 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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