Beernik

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Unless you've put forth effort to isolate one or the other, I'd assume you have both ale and lager plus potentially other species of yeast.

The parts that are lager yeast would give you some steam beer qualities (if you have it). And funk would come from the stuff that's not ale or lager yeast.

I'm wondering if ale yeast can be isolated by skimming the top of an active fermentation.

COLObrewer

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Good call, will have to keep that in mind during testing, maybe skimming from multiple generations would isolate it completely.

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emr454

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My wild cider is still bubbling away, albeit a bit slower than before. It is only a gallon and I am wondering how long it will take to finish, these wild yeasts seem to be slower than others, but I am guessing that is normal. It is still cloudy as all get out. It will be very interesting to see the end result. I'll keep posting on its progress as it develops.

Eric

emr454

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Here is the latest news on my wild cider attempt.

http://www.homebrewtalk.com/f127/possible-brett-my-wild-cider-what-temp-ferment-187770/

I am both excited and a bit disappointed. I am excited because I've caught yeast and not mold, but it looks like Brett and may take a few months before I can taste it and see if this experiment was worth all the time involved.

I so want to take a sample, but don't want to damage the pellicle.

Eric

drummstikk

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Hi Emr,
Pellicles are formed by any aerobic microbe grown in a static liquid culture. They form when microbes cooperate to form a sticky buoyant layer in order to support themselves at the air/liquid interface. They can only grow there because they need the oxygen in the air. (Even if you're using an airlock, there's still a small amount of oxygen in the headspace.)

What you have could be any alcohol-tolerant aerobic yeast or bacteria. No reason to think it's Brett yet. If you can get your hands on some antibiotics, you can make up an antibiotic wort that will kill bacteria but spare yeast. 50 micrograms per mL of chloramphenicol is standard for isolating wild yeast from bacteria. Also, you can drop the pH of the wort to 3 or 4 using .7% 1 Molar hydrochloric acid. If you can't get your hands on either HCl or Chloramphenicol, a 5-10% lemon juice wort might get you in a bacteria-killing pH range.

Don't worry about disturbing the pellicle. You may plunge some of the pellicle into the anaerobic depths of your fermentation, but you'll open up new real estate at the air-liquid interface, and you'll probably get new growth there.

Good luck!

drummstikk

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Dear COLO and Beernik,
Lager yeast is a hybrid between two naturally-occuring yeasts, Saccharomyces cerevisiae and Saccharomyces bayanus. All lager yeasts looked at so far are highly-related to each other, while ale yeasts have much greater genetic diversity. So though we can't rule out a natural origin of lager yeast, it is probably man-made.

You probably won't isolate the same yeast hybrid from nature, but you might be able to select for some cold-fermenting yeast. You could try cold-fermenting wort inoculated from a natural source, or you could try starting warm and decreasing the temperature a few degrees each time you dilute your culture into fresh wort. Try both! You might be able to create your own lager yeast.

Keep in mind also a few other things: Fritz Maytag's steam beer yeast was created by starting with a lager yeast, then fermenting it warm until it acquired the ability to grow at ale temperatures. It was not some sort of natural lager yeast used at higher temps.

Also, it is impossible to be sure you have a pure culture unless you grow on solid media. Even if you skim from several generations of a liquid medium, you will still probably have a mixed culture. Actually, you wouldn't even know if it were mixed or not unless you grow on solid media or look in a scope. Invest in a pressure cooker, some agar, some sterile plates, and an alcohol burner. You're at the stage of yeast wrangling where this equipment is essential.

Sorry if this message is a repeat. I had a posting FAIL with my previous message...
Good luck!

ericd

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I like you

Welcome to HBT.

COLObrewer

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Very intersting stuff there drummstikk, I had suspected the juniper yeast to be a mixture of yeasties since it has yet to fail in fermenting anything I throw at it. In the future I will be testing it in a lager and also saison to see what it does, I did save some from the original starter in a tube. I will probably need to build from that for these extreme cold and hot tests.

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drummstikk

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Oh, COLO,
I don't know why I didn't think of this earlier -- there is a way to get to a pure culture without solid media if you have a lot of sterile containers. It is called limiting dilutions. The idea is to dilute a culture enough times that only single cells remain.

You will need a bunch of tubes or containers about the size of the tubes you would use to make slants. And you will need something to move your culture/fresh wort around. A pipette with sterile tips is perfect. A bunch of sanitized metal spoons will work too.

The procedure is to take a drop of the most recent mixed wild culture and dilute it into 9 drops of fresh wort. If you're using a pipette, dilute 100 micro Liters into 1 mL. Either way, you have diluted the culture 1 to 10.

Now repeat this 10-fold dilution several times, each time taking a drop of the diluted wort from the previous step and diluting it further into 9 drops of fresh wort. Use a fresh pipette tip / sanitized spoon for each dilution.

Let's say, for example, you started with 1000 cells in your tube. After one dilution, you have 100 cells per tube. After two dilutions, you have 10 per tube. After three dilutions you have just one cell per tube. After four dilutions, you'd have -- either one cell or none at all. This is the level of dilution you want to get to, where most of the tubes don't contain any cells. At this level of dilution, you know that any tube that DOES grow, started from just one cell. This will get you to a pure culture!

But how many dilutions are requried? You're starting with more than 1000 cells, so it will take more than four dilutions, but not too many more. A White Labs tube is extremely dense with yeast, and it is about a billion cells per mL. A billion is 10^9. So, if you do 9, or let's be safe and say 10 of these 10-fold dilutions in a series on your culture, you should already be in the zone.

Let's say you find that all the dilutions starting with the sixth don't grow anything. Now, go back to the undiluted culture and do the 10-fold dilution six times, but make a bunch of tubes of that sixth dilution. Make 20 or so. You already know that most of them will not grow. But a few will grow, and you will know they started with just one cell.

Cells have a tough time growing by themselves, so make sure you keep the volume small, 1 mL at the most, aerate every day, and give the cultures plenty of time to grow. It might take a few weeks of aerating every day before the most extreme dilutions show signs of growth.

This is a lot of work, and I have only read about it, not tried it. But limiting dilution it is a standard microbiology technique and it will work! You may prefer to just buy some sterile plastic plates and agar, though.

COLObrewer

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Yes, it does sound like a lot of work, Me being me, I,ll probably just use it and abuse it until it stops working then go get some more.

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