Originally Posted by 40watt
Isolating only the yeast would be difficult if not impossible without a microscope.
I have yet to attempt it, but have plans to try it at some point.
Actually, it is quite easy. One would expose a plate to a yeast source, like fruit or beard, allow it to grow, then select the yeast from the plate based on the look of the culture (morphology), and streak another plate. A scope would be useful to confirm, although it is certainly possible without one.
A google search of yeast morphology on a plate would provide enough information to select the right culture.
I second the question about "natural yeast technique," what is that?