Wild yeast!

[Brewddah]

After numerous failures, I think I finally captured/isolated a wild yeast! I left pasteurized apple juice out on a window sill, and eventually it started to ferment. I then plated it, and got this:

I think it looks like yeast. My concern is, how do I know that I haven't accidentally cultured some kind of pathogenic yeast, like candida? Will those kinds of yeasts grow on malt/agar? I realize I'm probably being paranoid here.

 

[yourlastchance89]

Various plates and microscopic slide techniques can be used to assess the phenotype characteristics and aid in narrowing down the specific yeast. At least I assume similar techniques are used like they are in determining strains of bacteria

 

[Brewddah]

I've been trying to find something like that, but nothing is coming up. At least, nothing that would be all that helpful. Copper sulfate can be used to determine whether Brettanomyces is present, but that's about it. Saccharomyces and Candida are both inhibited by copper.

 

[yourlastchance89]

I've been trying to find something like that, but nothing is coming up. At least, nothing that would be all that helpful. Copper sulfate can be used to determine whether Brettanomyces is present, but that's about it. Saccharomyces and Candida are both inhibited by copper.

I believe you are correct. I've found some articles that discuss differentiating some strains based on determining fatty acid content (which I have no idea how to do), but everything else points to differentiating through PCR. Even if you did have access to the resources to implement PCR analysis, I have no idea where you would go to access a database to compare your results with. If you wanna try it out, I would verify it is a yeast under a microscope, and just do a small test sample to see if it is actually capable of producing adequate beer