Streptomyces Bacteriophage plaque assay
From ActinoBase
Streptomyces bacteriophage plaque assay
This protocol has been confirmed to work for the following organisms:
- Streptomyces coelicolor with ΦC31
- Streptomyces venezuelae with ΦSV1
Bacteriophage plaque assay
Protocol
Strains needed:
- Streptomyces strain sensitive to the bacteriophage
Materials needed:
- Pour agar plates with Difco Nutrient agar (DNA) and allow to set and dry.
- For ΦC31, the DNA plates should contain 10 mM MgSO4 and 8 mM CaCl2 (to 100 mL of medium, add (1ml of 1M MgSO4 and 1ml of 0.8M CaCl2)
- Melt Difco soft nutrient agar (SNA; 8 gL-1 Difco nutrient broth powder, 5 gL-1 BactoAgar) and store in 50oC water bath.
- Dilute phage suspension (10-fold serial dilution) using Difco nutrient broth (DNB; 100-108 should cover most preparations of phage from high-titre lysates through to enriched environmental samples).
- Pipette 0.1 ml of each phage sample on to the centre of the agar plates.
- Add spores to the SNA to give a slightly turbid suspension – it is often useful to do this in universal bottles as it makes pouring on to plates easier.
- Add 2-3ml of soft nutrient agar (containing the indicator strain) to the surface of the plate and swirl immediately to cover the whole plate. Leave to set for 10-15 minutes.
- Incubate the plates overnight at the required temperature (usually 30oC).
- The following morning inspect the plates for plaques – plaques can be visible within 10-12 hours, be careful not to allow the plates to overgrow as some lytic phage plaques may appear turbid and temperate phage (turbid plauques) ma be lost to overgrowth. Proceed to the high-titre phage stock preparation or single plaque isolation.
Notes
- Each phage with have an optimal divalent cation requirement for propagation – this is generally in the range of 0-10 mM MgSO4 and 8-25 mM CaCl2 but will need to be optimised for each phage – for isolation of novel phages the standard C31 parameters are suitable for isolation.
Protocol adapted for ActinoBase by Paul Hoskisson from the University of Strathclyde.