Phage on a petri-dish can be isolated for further study. 

If you are considering this method, congratulations are probably in accord!  You have most likely isolated a unique phage.  To study your phage further, this method allows for the selection of a plaque that began from a unique virus, and allows for the expansion of the plaque for further purification and study.

1) Using a pipette tip, plastic bacterial loop, sterilized toothpicks, or anything else that is sterile such as a bacterial inoculation loop, carefully scoop up only the plaque area from a single plaque.  You will be capturing M. smegmatis and a portion of the agar beneath the plaque, this is expected. 

2) Transfer the phage plaque into 1 mL sterile MP buffer, within a micro-centrifuge tube. Mix the plaque with the MP buffer by pipetting up-and-down a bit.  Incubate at room temperature for 2 hours, preferably on a platform shaker. 

3) Phage Dilution Plating.  Dilute the plaque to 10⁰, 10^-1 and 10^-2 for plating.  The objective is to make lacy plates that can be extracted from the plate.