Phage Enumeration
Phage Enumeration - Related Videos
04:30
Phage Purification from Borrelia burgdorferi
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2026
Source: Eggers, C. H. Phage-Mediated Genetic Manipulation of the Lyme Disease Spirochete Borrelia burgdorferi. J. Vis. Exp. (2022).This video demonstrates the isolation of borrelial phage particles from a Borrelia burgdorferi suspension using polyethylene glycol-mediated phase separation. The sample is centrifuged, treated with a salt solution, and a molecular crowding agent to precipitate phages. Chloroform extraction is done to remove debris and concentrate phage particles. The purified phage...
03:25
Quantitative Polymerase Chain Reaction to Enumerate Bacteriophages
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2025
In this video, we discuss the quantitative polymerase chain reaction, qPCR, to enumerate T7 bacteriophages through DNA quantification. The fluorescent dye in the PCR mixture binds with the newly synthesized DNA strands and emits fluorescence, which is measured.
09:29
Algae Enumeration via Culturable Methodology
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2023
Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona Demonstrating Author: Bradley Schmitz Algae are a highly heterogeneous group of microorganisms that have one common trait, namely the possession of photosynthetic pigments. In the environment, algae can cause problems for swimming pool owners by growing in the water. Algae can also cause problems in surface waters, such as lakes and reservoirs, due to algal blooms that release toxins. More recently, algae...
03:17
Measuring Spontaneous Phage Induction in Lysogenic Bacteria Over Time
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2026
Source: Krishnamurthi, R., et al. Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics. J. Vis. Exp. (2024).This video demonstrates the temporal enumeration of spontaneous phage induction in lysogenic Pseudomonas aeruginosa by quantifying viable bacterial cells (CFUs) and infective phage particles (PFUs) over time. By sampling at defined intervals during growth and analyzing both colony and plaque formation, the method reveals when spontaneous induction...
10:53
Serial Dilutions and Plating: Microbial Enumeration
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2023
Source: Jonathan F. Blaize1, Elizabeth Suter1, and Christopher P. Corbo1 1 Department of Biological Sciences, Wagner College, 1 Campus Road, Staten Island NY, 10301 Quantitative assessment of prokaryotes can be onerous given their abundance, propensity for exponential proliferation, species diversity within a population, and specific physiological needs. Compounding this challenge, is the four-phase nature in which bacteria replicate (lag, log, stationary and death). The ability to accurately...
FAQs
Each visible plaque represents a localized zone where phage infection, replication, and host-cell lysis have occurred in the bacterial culture. Counting these cleared areas connects the observed result to phages capable of infecting the selected host under the test conditions. This makes plaque formation the key observable outcome for estimating infective concentration in an environmental sample.
The host provides the cells required for phage infection and replication, while the culture medium supports the bacterial population in which plaques become visible. Because plaque formation depends on this phage-host interaction, the measured concentration reflects activity against the chosen susceptible bacterium rather than an unrestricted count of every viral particle present in the sample.
A plaque-forming unit, or PFU, expresses the amount of infective phage activity represented by plaque production in the assay. The value links the number of observed plaques with the sample's infective concentration under the selected host and culture conditions. PFU reporting therefore provides a consistent basis for describing phage levels across environmental samples.
Phages regulate microbial populations through infection and lysis of bacterial hosts, so changes in their measured concentration can provide context for changing phage-bacterium interactions. In environmental sciences, these measurements help examine how viral activity relates to microbial ecology and environmental change in settings such as soil, freshwater, wastewater, and marine systems.
A basic assay combines the environmental sample with susceptible bacterial host cells and culture medium, then provides conditions in which infection, phage replication, and host-cell lysis can produce visible plaques. The plaques are counted and converted into plaque-forming units. This workflow turns an environmental sample into a quantitative measure of infective phage concentration.
Phage enumeration can be applied to samples from soil, freshwater, wastewater, and marine environments. Researchers use the resulting measurements to characterize phage-bacterium interactions, investigate microbial ecology, track environmental change, and assess water quality. The same general measurement also supports evaluation of phage-based approaches intended to manage bacterial populations.
Reporting results as plaque-forming units allows phage abundance or infective concentration to be expressed quantitatively rather than described only by visible effects. Comparing these measurements across soil, freshwater, wastewater, or marine samples can reveal differences in phage activity and provide evidence for shifts in microbial or environmental conditions.
Environmental systems contain interacting microbial populations whose abundance and activity can be influenced by bacteriophages. Measuring infective phage levels supplies evidence about these interactions and their ecological significance. The approach therefore connects a culture-based laboratory observation with broader questions involving microbial population regulation, environmental monitoring, water quality, and bacterial management.