Winemakers will tell you that Brettanomyces is either the root of all evil, or amazing yeasts with something beautiful to share with the world. Brett can also be a Jekyll and Hyde: an asset one moment, a destructive force shortly thereafter.
Confused? You’re not alone.
Brettanomyces, also known as “Brett,” is a complex, resourceful organism that scientists and winemakers have just begun to understand. First isolated in 1889 by a scientist at Kalinkin Brewery, it was identified in wine in the 1930s. Brett is both anaerobic and aerobic, which means it can thrive with or without oxygen. Typically, it enters wineries on the skins of grapes, through barrels or via fruit flies. Once it’s there, it can hang around indefinitely.
When it makes its way into a wine, Brettanomyces produces compounds that alter the aromas and flavors, primarily through volatile phenols. Most labs that test for Brett activity will measure levels of 4-ethylphenol and 4-ethylguaiacol.
https://www.winemag.com/2020/07/14/the-divisive-impact-of-brettanomyces-in-wine/I put this here for Cincy
I went all the way back to page 95 looking for his "wine thread"
couldn't find it, but came across this thread on page 74