. . .your enterprising and investigative spirit most sincerely.
At a guess it appears to be perhaps
Saccharomyces ?
This is a yeast (which would account for the whitish coloration.)
Here's a micrograph from the University of Edinburgh:
Saccharomyces on the left; cryptococcus on the right.
What do you think, close? Yeast spores are fairly ubiquitous environmentally so it's a good guess at least.
Jack