Fungi that grows in Gatorade (What is it)

Today I found some very unusual growth in an old bottle of
Gatorade. I was a little surprised because as a college student I leave
many bottles of Gatorade laying around, and I have never noticed
anything growing in the bottles before.
There were twenty or so small fuzzy black circles, that seemed to
have an unusual tendency to collect together in a certain spot at the
bottom, even though they were all free floating. It occurred to me that
there is a very significant amount of electrolytes in Gatorade. I had
always assumed that this is what prevented most things from growing in it.

Does anyone out there have any idea what this (most likely common) form
of fungi is?