Asklemmy

Closest I've come to Mad Scientist was probably yeast ranching to control costs in homebrewing.

• sterilize agar media and plates/tubes in poor man's autoclave (pressure coooker) and hood (open oven door and vent fan) - infection rates were surprisingly low with this low-tech approach. I lost maybe 5% of cultures to spurious growth.
• streak yeast from $$$ pure liquid cultures, grow, store if successful.
• also experimented with yeast suspensions in sterile distilled water based on a 1930s science journal article from a dude in Africa. The suspensions did better in the heat where agar would just remelt....
• a few days before needed scrape the streak into a small amount of sterile wort (20ml? on a homemade stirplate (PC fan and HD magnets under an unpended tupperware bowl!), stepping up to pitchable volume coinciding with the batch cooling to pitch temperature....

It was a lot of fun and instead of one 5gal batch of beer from an exotic $20 yeast sample you could get as many as you wanted. In practice I usually did 5-10 cultures from each pure sample. Could do more than that but there was a limit to how much stuff I could sterilize in my "autoclave" at one time.

Edited to add: I successfully cultured yeast from hefeweizen, but since what's in the bottle is typically for secondary/priming rather than primary it was only for fun. I had 100% failure trying to harvest wild yeast from the air or sampled from fruit skins. I couldn't isolate the yeast from other critters.