Microscopy pictures of BFM La Torpille dregs

Besides the dregs from the Girardin Gueuze, I also had dregs from BFM’s “La Torpille” to have a look at. Since BFM is a rather small Swiss brewery, it is well known in the US for their legendary L’Abbaye de Saint Bon-Chien. I am very lucky to have full access to all of their brews and I am a big fan of their La Torpille. It is in my opinion quite unique for Switzerland because the beer culture here is quite similar to Germany. BFM stands out because they produce sour beers, beers with spices and so on. To summarize: they brew not according to the Reinheitsgebot…and thats quite rare here in Switzerland, another country where the fizzy yellow stuff dominates.

What I did with the dregs is the following: I had two times 5 liters of a Belgian style beer to do some funky stuff with. After the primary fermentation with Wyeast’s #3522 Belgian Ardennes and #3787 High Gravity Trappist I blended the two and racked it in a secondary fermenter and put two dregs from BFM’s La Torpille in there. The beer, after nearly three month after adding the dregs, is quite clear and has a little funky aroma and some cherry notes. No sourness so far. After taking a sample to see how it tastes, I took the opportunity to look at the bugs with my microscope. Lets have a look at the pictures from the dregs:
Since there are not a lot of pictures of Brettanomyces on the web, it is therefore quite difficult to determine what those bugs are. But looking at Jasons Sciencebrewer page, the cells from my last picture look like those in Jasons picture CB-2 (bottom). He concludes his cells to be wild yeasts, Brettanomyces to be exactly. In the comments below his post it is assumed that it could be Brettanomyces lambicus. I therefore assume that my wild yeasts are B. lambicus due to the morphological similarities. This seems to make sense to me as the Brettanomyces cells look like torpedos and the name of the beer, La Torpille (French), means “The torpedo”….

Beside the wild yeasts there were some Saccharomyces detectable (not shown). But I could not find any kind of bacteria.

The only thing I am interested is what the wild yeasts can contribute to the aroma and flavor of a beer. I therefore will compare this yeasts from the dregs against other known wild yeasts from Wyeast in the future. Since the wild yeasts are already in a beer, I already mentioned that the beer has a very nice cherry note. Since B. lambicus tends to produce cherry notes (see Wyeast description), I therefore assume that the wild yeasts in the dregs of La Torpille are of the specie Brettanomyces lambicus.

I will streak the bugs from the BFM La Torpille dregs on Sabouraud agar in the future to have a look at the morphology of the cells on the agar. Sabouraud is an agar used to cultivate yeasts and not specific for Brettanomyces or any other yeasts and I use it for Saccharomyces cultivations and purification purposes. I purchased some B. lambicus and B. bruxellensis from Wyeast and will streak them as well.


2 thoughts on “Microscopy pictures of BFM La Torpille dregs

  1. Hi Samuel,

    Jason here. Great pics! However, I’m not so sure you may have Brett L. I’m not even sure that I have Brett L!

    While our two strains look similar, I can tell you that there are some differences. For example, your strain has more branching at the ends of the cells than mine, and they seem to be longer in shape. Is this what you see in the whole slide? Can you see single cells? In the top image, the cells look more ovoid than CB-2.

    Ultimately, it may be hard to tell if what you have is definitely Brett L. Only PCR of divergent genes within the subspecies will determine this.

    Another thing to keep in mind is the source of the yeast. I isolated CB-2 from a lambic, so it could be anything. With La Torpille, was the beer spontaneously fermented or not? If not, the strain could be traced back to commercial variations of Brettanomyces.

    Keep us informed!



    • Hi Jason,
      Thanks for your reply. I can’t remember if there were single cells. All my other pictures show some sort of aggregated cells. I have to admit that I took the sample for tasting right of the fermenter which has a spigot at the bottom. The sample represents thereby only the liquid phase meaning the beer itself. And there were very little cells at all compared to the sample from the Girardin dregs. I will have to look at the sediment directly which lies at the bottom of the fermenter to have further cells.

      I will get through the papers you posted in your comments how the wine guys used PCR to determine the Brett specie. But I guess they are more interested to
      determine whether there is some Brett or not. My stand of knowledge is that the
      phylogeny of Brettanomyces is not yet clear or consistent and there is no genomic data available of all the brewing relevant Brett species. I guess that the differences between different Brett strains are very subtle. My guess is that genetic wise B. lambicus, B. bruxellensis and B. clausenii are the same, meaning the differences between the DNA is less than 70% to be defined as a new specie (in bacteria)(Wayne et al. 1987, ijs.sgmjournals.org/content/37/4/463.full.pdf). Since this 70% is only applicable to bacteria, I would suggest that it is not different for yeasts an such.

      Another way, and easier is an MALDI-TOF analysis of the strains. Maybe a comparison would show some differences. I have to add that in my Bachelor’s thesis I worked with water bacteria which showed clear biochemical differences but were all from the same phylogeny, meaning the MALDI-TOF analysis showed three different names all meaning the same. And these bacteria looked nothing alike on agar. As already said, my guess is that we have a similar case with Brett here. Insert B. lambicus, B. bruxellensis. B. clausenii, dregs etc. and maybe getting some differences. But they differ significantly aroma wise, right? To summarize, I am not really interested in the specie but rather if I have Brett or not. And what is the flavor impact those “different” strains have in a beer.

      Concerning the beer, as far as I know is this beer no spontaneously fermented. The brewer already told me that there are no Bretts in it at all. But what could that be?

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