Culturing yeast strains from a beer that uses a blend.

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phenry

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The beer in question is Great Divide's Colette. I've done a simple culture of the yeast and am decently happy with the results, but according to the label they use a blend of four different strains, one apparently being a wild strain as per someone on this forum directly asking Great Divide. I would like to have a separate culture of each strain so I can hopefully come up with a unique blend that I like the best.

I do have a basic knowledge of microbiology and the SOPs of growing cell cultures and streak plates and such, but let me reiterate that it is very basic. I was wondering if anyone on here had any experience of doing this, I tried searching but didn't really come up with anything useful. What I was planning on doing so far based on my knowledge was:

1) Flame neck and cap of beer.
2) Open up bottle of beer, pour into glass (for later consumption of course).
3) Flame opening of bottle, swirl up sediment.
4) Dip inoculation loop into dregs, proceed to streak onto agar plate.
5) Repeat for multiple bottles and plates.

After this is where I'm kinda lost. How will I know the difference between the different strains? Don't most yeast strains look extremely similar when grown on agar? I only have experience growing E. Coli, and only the DH5-α strain at that, so I'm only used to seeing milky white colonies.
 
I've been culturing various yeast strains at home and at work for about six years and I would consider your project to be fairly advanced. I once considered doing a project such as you describe here but decided it was too much work with not enough chance of success. But don't let that discourage you -- I say go for it if you want to! Here was my plan and reasoning, and you can do with it what you will:

I opted to streak for at least two hundred single colonies in order to isolate three individual strains. In my case, one strain was used as a bottling strain and therefore it should vastly outnumber the other two strains. Add to that the facts that the fermenting strains would be less fit to grow readily on a surface medium and that different strains have inherently different abilities to grow on surface media and you see that you need lots and lots of colonies to get that one or two of the odd, less fit strain(s). I chose the 200 number based on practicality more than probability.
My next step was to see if I could distinguish the strains based on colony size, color or shape. Very flocculant strains will have a rougher edge and sometimes a crinkled appearance to their colonies, while most strains are smooth and milky. Colony size and speed of growth are to other characteristics that can be used, provided good culturing and streaking technique are used. I didn't think it was very likely that I would be able to tell them apart by their colonies.
The next step was to make a ~2-3ml culture of each colony. During fermentation I could get a rough idea of cell sizes under a microscope. You'd be surprised how much different strains' cell sizes can be. Wild yeast tend to be smaller, by the way.
Once the cultures were fermented to completion, I planned to allow them to flocculate, then evaluate them by smell to see if there were differing ester/phenol profiles.

Sounds fun, but that's not a project I really want to tackle these days. Good luck, and great success!
 
Thanks for all the advice! I do have until April for Colette to start showing up on shelves, so that should give me time to buy all the necessary supplies for this little project (I don't really want to lose my research position in the pursuit of homebrewing, but I don't think my university would mind if I took a little peek at some cultures under their microscopes from time to time).

Sounds fun, but that's not a project I really want to tackle these days. Good luck, and great success!

Well I've gotta be doing something beer related while I wait for my batches to ferment, right? I brew about 4 batches at a time, so there's a month or so in between where I'm deprived of any homebrewing activities. I figured this would be a pretty good project to fill in those gaps.
 
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