I am trying to isolate cyanobacteria from soil and freshwater samples, but I have zero experience with them. They grow really slow on plates in colonies ranging from green to brown/black colour. The pictures I attach come from black/brown colonies in three different samples, although the green colours that can be seen in them are not represented in the colony colour. I can only differentiate diatoms in one of the pictures because they are easily distinguishable.
Could anyone with more experience tell me if they look like cyanobacteria? I am trying to obtain pure cultures but they tend to form diffuse colonies which usually overlap.
Any advice in any way will be deeply appreciated. Thank you in advance.
EDIT: Sorry if the quality of the pictures is not enough. I took them with my smartphone directly from an old microscope.