Some time ago I got my hands on a bottle of 2007 Cantillon Iris. While the beer, in my opinion, is one of the worst ones I’ve had (dry-hopped woody vinegar hehe) the main purpose for getting it was the analysis of the dregs because it would be totally awesome to brew something with the wild yeast floating around at that brewery.
The procedure was pretty simple: Collect the dregs, shake it gently to homogenize, dilute 1:100 and plate. After waiting 3-4 weeks for something to grow, nothing did and I threw the plates out and almost gave up. As a “just in case” attempt, I decided to plate straight dregs and voila! I got colonies. For this purpose milk lactose + bromcresol green as well as brilliant green agar plates were used (sorry no pictures) resulting in three colony types: matte, rough colonies (C1), matte round colonies (C2), and smooth, round, glossy colonies (C3). I am still not sure whether the first two are the same or not as I suspect one may just be the later stage of the other one, but perhaps they are not due to some observations. The colonies were picked and used to inoculate 5mL of LB. The rough colonies formed pellicles in the tubes while the smooth one did not. Pellicle resulting from rough matte colonies fell away after a couple days, while the round matte one persists to this day. Subsequent plating didn’t give me much for some reason and I will have to replate. Meanwhile, here are some pictures from the liquid cultures.
It seems to me that cells grown in suspension culture have a different morphology than the ones grown in plates. Everyone who’s done cell culturing knows this, but I didn’t think it was true for yeast too. From what I see, though I did not show pictures, cells from plates tend to be shorter and rounder than the ones from tubes. If anyone has any ideas or knowledge, please share.
I also noticed that the rough colonies flocculate well and the medium is crystal clear with a sediment and a pellicle, while the smooth ones, while also forming sediment, remain suspended resulting in turbid medium. That is interesting because I noticed similar behavior and colony morphology from WY Berliner Weisse Blend Brettanomyces strain, but the cells look different.
They also smell different. C1 smells very slightly funky, C2 is quite funky, and C3 just smells like medium. Interesting…