You can extract spores of Glomus sp. from their substrate using a mixture of wet-sieving and sucrose gradient techniques (Brundrett et al., 1996). Stereoscopic microscope is useful in counting and identification of mycorrhizal spores. So, if you will extract from a single spore culture of Glomus, you don't need  the microscope.

Dear Emran,

It is difficult to isolate and purify a particular Genus and even more difficult to isolate and purify a particular species. I would suggest you to make monosporal cultural of a particular species using maize as the host plant. This is the best way to get a pure culture of a particular genus of species.

Regards

Dr. Rafiq Lone

First you can let grow host  plants in  native  soil, them you will be  isolating  from spores, which will be separated  by a sievieng procedure. You can isolate Glomus sp in "pot cultures" by growing and inoculated host plant in a sandy soil supplemented with a nutrient solution with "low" levels of phosporus .