The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique

BACKGROUND: The Double-Layer Agar (DLA) technique is extensively used in phage research to enumerate and identify phages and to isolate mutants and new phages. Many phages form large and well-defined plaques that are easily observed so that they can be enumerated when plated by the DLA technique. Ho...

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Autores principales: Santos, Sílvio B, Carvalho, Carla M, Sillankorva, Sanna, Nicolau, Ana, Ferreira, Eugénio C, Azeredo, Joana
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2009
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2728735/
https://www.ncbi.nlm.nih.gov/pubmed/19627589
http://dx.doi.org/10.1186/1471-2180-9-148
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author Santos, Sílvio B
Carvalho, Carla M
Sillankorva, Sanna
Nicolau, Ana
Ferreira, Eugénio C
Azeredo, Joana
author_facet Santos, Sílvio B
Carvalho, Carla M
Sillankorva, Sanna
Nicolau, Ana
Ferreira, Eugénio C
Azeredo, Joana
author_sort Santos, Sílvio B
collection PubMed
description BACKGROUND: The Double-Layer Agar (DLA) technique is extensively used in phage research to enumerate and identify phages and to isolate mutants and new phages. Many phages form large and well-defined plaques that are easily observed so that they can be enumerated when plated by the DLA technique. However, some give rise to small and turbid plaques that are very difficult to detect and count. To overcome these problems, some authors have suggested the use of dyes to improve the contrast between the plaques and the turbid host lawns. It has been reported that some antibiotics stimulate bacteria to produce phages, resulting in an increase in final titer. Thus, antibiotics might contribute to increasing plaque size in solid media. RESULTS: Antibiotics with different mechanisms of action were tested for their ability to enhance plaque morphology without suppressing phage development. Some antibiotics increased the phage plaque surface by up to 50-fold. CONCLUSION: This work presents a modification of the DLA technique that can be used routinely in the laboratory, leading to a more accurate enumeration of phages that would be difficult or even impossible otherwise.
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spelling pubmed-27287352009-08-19 The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique Santos, Sílvio B Carvalho, Carla M Sillankorva, Sanna Nicolau, Ana Ferreira, Eugénio C Azeredo, Joana BMC Microbiol Methodology article BACKGROUND: The Double-Layer Agar (DLA) technique is extensively used in phage research to enumerate and identify phages and to isolate mutants and new phages. Many phages form large and well-defined plaques that are easily observed so that they can be enumerated when plated by the DLA technique. However, some give rise to small and turbid plaques that are very difficult to detect and count. To overcome these problems, some authors have suggested the use of dyes to improve the contrast between the plaques and the turbid host lawns. It has been reported that some antibiotics stimulate bacteria to produce phages, resulting in an increase in final titer. Thus, antibiotics might contribute to increasing plaque size in solid media. RESULTS: Antibiotics with different mechanisms of action were tested for their ability to enhance plaque morphology without suppressing phage development. Some antibiotics increased the phage plaque surface by up to 50-fold. CONCLUSION: This work presents a modification of the DLA technique that can be used routinely in the laboratory, leading to a more accurate enumeration of phages that would be difficult or even impossible otherwise. BioMed Central 2009-07-23 /pmc/articles/PMC2728735/ /pubmed/19627589 http://dx.doi.org/10.1186/1471-2180-9-148 Text en Copyright ©2009 Santos et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Methodology article
Santos, Sílvio B
Carvalho, Carla M
Sillankorva, Sanna
Nicolau, Ana
Ferreira, Eugénio C
Azeredo, Joana
The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique
title The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique
title_full The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique
title_fullStr The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique
title_full_unstemmed The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique
title_short The use of antibiotics to improve phage detection and enumeration by the double-layer agar technique
title_sort use of antibiotics to improve phage detection and enumeration by the double-layer agar technique
topic Methodology article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2728735/
https://www.ncbi.nlm.nih.gov/pubmed/19627589
http://dx.doi.org/10.1186/1471-2180-9-148
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