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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phage.org/terms/plaque_halo.html · Abedon’s Books · DOI: 10.5281/zenodo.20173633
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Plaque halos particularly tend to lack either phage particles or phage infections. Instead, halos are formed via the diffusion and subsequent enzymatic action especially of soluble (not virion associated), phage-produced EPS depolymerases. Because these enzymes are substantially smaller than phage particles they are able to diffuse substantially further into bacterial lawns.
Halos often form following plaque formation, and indeed can form during plate refrigeration. This occurs because halos, as noted, are not a direct consequence of phage population growth but instead of extra-virion diffusion along with virion-free enzymatic degradation of bacteria. Furthermore, that degradation is not of the bacterium as a whole but instead of just exterior layers that are bacterium produced and associated.
Abedon, S.T. (2026). Phage Terms. https://terms.phage.org · 10.5281/zenodo.20173633
Every term in the Glossary of Bacteriophage Terms. The current page is highlighted purple.