#8 Agar plates (Wyeast’s Roeselare Blend)

Eureka, today the latest results from the bugs from Wyeast’s #3763 Roeselare Blend. This post is about further results from the original plates which can be found in this post. Just a brief follow-up what I did. I first streaked some beer which is fermented with the Wyeast’s Roeselare Blend on a Sabouraud plate. Then incubated it at room temperature. After three days were some colonies visible (Fig 1). I then picked a colony of each of the two different colonies (off-white and white ones) and re-streaked them on a separate plate. I had to discharge the plate from Fig 1 due to a mold contamination. I then had a look at the different strains in the first post.

The off-white, glossy, bigger colonies were determined to be a kind of “normal” yeast and the white ones were a kind of different yeast. Maybe Brettanomyces? I let the plates with the two isolated strains incubate further and had another look at them.

Fig 1: #3763 Roeselare Blend on Sabouraud agar after three days of incubation

First about the colonies that turned out to be brewer’s yeast. This would be the off-white, bigger and glossy colonies in Fig 1. And the re-streaked colonies looked very alike normal brewer’s yeast (Fig 2). The reason why some colonies on the right part of the plate seem to have a kind of a hill is due to the incubation: The plates were upside down and the bigger yeast colonies tend to form a kind of drop.

Fig 2: Off-white colonies from Roeselare Blend after 10 days of incubation on Sabouraud agar

And the microscopy showed the typical yeast cells (Fig 3). Once again, these cells are indeed a kind of typical Saccharomyces. As there are several yeast strains in the blend, these cells could be a brewer’s yeast strain or a sherry strain as well. But that’s not what I am interested in. It is enough for me to know that these cells here are “normal” yeasts. Lets move on.

Fig 3: Off-white colonies from Fig 2 under microscope

There still were the other colonies. The ones that tend to grow on top of the yeast cells (Fig 1). I re-streaked these cells as well and had to re-streak it for several times because of a mold contamination (Fig 4). And I finally discharged all these plates. I therefore lost this kind of strain… Unfortunately, the microscope showed a kind of yeast that I am interested in (Fig 5).

Fig 4: White colonies from Roeselare Blend after 10 days of incubation on Sabouraud agar

And these are really no “normal” yeast cells. I had a feeling in the first post that these cells looked very similar to Brettanomyces. And I already mentioned that I ordered pure Brettanomyces strains for a future brew. By the time I wrote this post, I already had a look at the two different strains, Brettanomyces bruxellensis and Brettanomyces lambicus. And I dare to guess that these cells here in Fig 5, are Brettanomyces. But I unfortunately lost them due to a mold infection…

Fig 5: White colonies from Fig 4 under microscope

Well, this experiment was fun and I will definitely try to repeat this and try to isolate the Bretts from the blend once again. Another thing that I found out and already repeated with other Brettanomyces is the fact, that these yeasts can grow nearly as fast as Saccharomyces. When I streaked Brettanomyces colonies directly on a new plate or plated some liquid from the Wyeast’s Brettanomyces Activator pack, the cells were visible on the Sabouraud plates within days. The growth is completely different when I streaked some dregs with Brettanomyces. Then it took nearly three weeks to get any Brettanomyces colonies on the plates.

The next post about souring bugs will be about the pure Brettanomyces strains from Wyeast’s and the fermentation tests I did with some isolated bugs from a 3 Fonteinen Geuze and Girardin Gueuze. Stay tuned.