Phage Spot Lysis Test

Procedure 

1. Prepare bacterial lawns of target bacterial isolates or reference bacterial strains by adding 500 µl of LB 18 h cultures on LA plates, allowing the liquid bacterial culture to soak into the LA, with a half lid cover on the plate, at room temperature or incubator at 37 °C for 20 min (Culture cells are healthy and grow rapidly, therefore, to prevent bacterial growth and too much thickening of the bacterial lawn, the plate should be used within 1 h at room temperature).
2. Transfer 10 µl of the possible phage solution (this is the actual spotting) to the bacterial lawns and then incubate at 37 °C.
3. Check for plaques or lysis spots that are observed after 6–18 h. The detection of phage presence is based on the visual appearance of a lysis zone at the site where the 10 µl solution was added onto the surface of the target bacterial lawn.

Results of the test

Positive results are expressed by either clear or semi-clear (turbid) lysis zones, while negative results are expressed by the absence of such lysis zones