Howto: Capture Wild Yeast

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If you use solid medium (agar and malt extract) can't you also just scoop individual colonies off to get isolated strains? I tried this for the first time two days ago and I have lots of separate white spots. Aren't those each separate colonies/strains of yeast?
 
Will it be fairly obvious what is mold and what is yeast? I've got lots of white spots, and a big clump of fuzz on one corner. I'm assuming specks are yeast, fuzz is mold, but could Amy white specks be mold/bacteria? Should I just step them up and see what I get?
 
You're right. Anything that's fuzzy is mold.

Bacteria and yeast can be tough to tell apart as colonies. If you use a sterile tip (flaming a clean pin should work) to pick a colony and then re-streak it on a fresh plate, then let it grow for a few days, the differences between yeast and bacteria become apparent: yeast form dull white growths, while bacteria are shiny and tan, or any number of other colors. There are also pink and orange yeast, but saccharomyces is always a creamy white color.

One test to find good microbes for brewing is to isolate them on a plate by the restreaking method, then just open the plate and take a sniff. Most bacteria smell bad. There are all sorts of bad bacterial smells, from dirty feet to **** to spoiled food. You already know what yeast smells like, and you'll know it when you have it!

You may find that not all yeast make alcohol, but that's a different step.

In the future, you could add lemon juice to your malt extract/agar when you're pouring plates. This will lower the pH and inhibit most bacteria and mold growth. If you have pH strips, you want to shoot for pH 3-4.
 
Well it was a little too late, but I'll put them on another plate next time and restreak. For now, I took two samples out of each of my three plates, and put them each into a jar of wort.

Each of those is covered with foil, and we'll see how they come out. Hopefully I get at least one good strain out of 6 attempts. The three initial jars were placed in different areas of my yard.
 
Hey, that's a fine way to check them, too. Let me know what you find! I am planning more wild yeast wrangling myself, but for now I've just got some yeast on plates in the fridge. Still don't know if any are good for brewing, because I never grew them up. Good luck.
 
Sometimes the yeast can also appear as darker and shiny. I know that lager yeast sometimes look like that. But if you follow drummstikk his procedures you should be golden. One tip is to add some hop-tea to the water you are using to pour plates, and to keep the sugar level low. Bacteria thrive on high sugar. Also as he said if you want to do rein cultures (single strains) make sure you do a small test to see if the yeast actually metabolizes maltose. Certain strains cannot do this. You can buy maltose from your homebrew store and make some media with this, with some other stuff. But you can also just see makes the excitement bigger when it works
 
Oh, that's a good point about the hop tea. There is a recipe for Universal Beer Agar that just includes beer in the media! You could pour beer in, getting hops and alcohol. You can also add vodka until you get a certain percentage alcohol. Keep it below 10% and you'll select for alcohol-tolerant yeasts and kill bacteria and mold. If you're adding alcohol/beer, make sure to boil your wort first, then add the alcohol/beer while it's still hot, but not boiling.

Good point too about sugar levels. I have been making my media with 5% DME, which is about 1.020 wort. Another reason to keep it low is that wild yeast may not be osmotolerant, which means they may suck at growing in high-gravity worts. You can slowly acclimate them to higher gravities after you catch them.

In addition to making sure your yeast can survive on maltose, I think another good test is to make sure they're producing alcohol. It sounds obvious, but saccharomyces will always make some alcohol, even if the wort is highly-oxygenated. Other species may not.
 
In addition to making sure your yeast can survive on maltose, I think another good test is to make sure they're producing alcohol. It sounds obvious, but saccharomyces will always make some alcohol, even if the wort is highly-oxygenated. Other species may not.

I totally agree. Some yeasts produce 100% different end products, or mainly different end products besides ethanol. A sniff/swig of your fermenting/fermented media, or a pH strip will tell you whats going on, I think that would be a good test indeed.
 
OK question. I had kept a bit of extra wort from a dry stout about 2-3 months ago with the idea in mind that I would use it for this experiment. However, things happened and I forgot about said wort (which was put into a sanitized mason jar) as it sort of got lost between all my washed yeast in the same fridge. Nothing was odd about it every time I'd seen it (its in my kegerator, so I saw it rather frequently, but didn't USE it) but last night I noticed a nice little ring of bubbles. That old familiar fermenting look. I'm guessing that it couldn't have a bacteria in there, but perhaps some sort of lager strain?? Do you think this is possible or are their other bugs which ferment around 49 degrees or possibly even lower? I'm really curious to try to brew something with it, but wanted opinions if this will be a lager ferment or a "farmhouse" lambic sort of freak which ferments at LOW temps.
 
Yes, there are bacteria that thrive in cold temperatures. That's how food goes bad in the fridge (even if slower than at room temperature). Open up the mason jar and give it a whiff. If it smells like wort you're ok, but my guess is that it's been polluted by bacteria that will make it reek. In that case, I'd toss it out. It could still be ok for catching yeasts, but if the pH has gotten too low for yeast, you'll just waste your time.

I had a storage bag of wort that stayed in my fridge for about three weeks. The first couple of weeks it was ok, but by week three something had gone on and it was horrible. Probably lactobacillus, but who knows. I tossed it out.
 
After reading through Wild Brews, it has me thinking... Lowering the pH of the plates using acid should skew things in our favor here. I'm not sure what effect an acid pH would have on mold... which is my biggest problem... but if we started with a pH of ~4 rather than 5, the bacterial growth would be suppressed.

too true :tank:
 
I love this thread. It's the quintessential "homebrew" thread, I think. This encompasses the heart of so many discussions that I have with would-be and has-been homebrewers when they find out about my setup and wanna 'talk beer.' This is the heart of it all: It can be as simple or as complex as you wanna make it! Make a starter, leave it by the washing machine, then build it up and throw it into a pot of wort vs. preparing pH specific yeast-favoring agar slants and looping out specific Sacc cultures and slowly encouraging them to grow larger and larger in your fully outfitted yeast lab before pitching into your wort blends to make a variety of beers each with different subtleties.

Each method can result in success, although their success over time would certainly vary and favor those with better apparatus and methods, but even those in their hermetically sealed laboratories are at the whim of the breezes when it comes to wild yeasts!

Wonderful! (and frustrating for those mold-farmers out there)

~Mike~
 
My original test or first trial beer is still tasting like a leather glove. Its nothing like what it was out of the primary. Its 18 months old now. The bottles are well carbed though.

I am somewhat disappointed that it took a turn for the worse. I wonder if its infected? :D

Maybe I'll hold onto it for another year. The last I counted I have 28 cases so I won't miss this one for another few years. No I'm not a hoarder!!! Unless it has to do w/ HB equipment.
 
That being said, is there much risk of a yeast that makes high levels of methanol rather than ethanol?

Hi Steve,
According to this home-distilling site, it looks like methanol is produced by reducing formaldehyde, rather than the usual route of producing ethanol, which is by oxidizing sugar. Chemically, reducing and oxidizing are total opposites. So, you can't get methanol from maltose, but instead you need formaldehyde, which comes from pectin, which isn't found much in barley and hops.
I am not really sure if you could make a blanket statement to say that any microbe you catch from your backyard is going to be safe. I don't know that. But I think it's safe to say that none of them will make methanol without fermenting fruit.
 
Hi guys,

Steve's question about methanol got me thinking about another food-born toxin -- botulism. Botulism is not a concern at all in wort fermented with yeast -- the pH drops very quickly due to yeast, and nobody has ever consumed botulinum toxin from beer.

But in the techniques we're practicing, we're not exactly guaranteed to have yeast in the cultures we take from the environment. Soil in particular is known to contain spores of C. botulinum, the bacteria that produce botulism toxin. I have been using wort acidified with lemon juice to pH 3.5, which will prevent C. botulinum growth. I've also been using solid media on plates, which never becomes anaerobic. Oxygen should prevent botulinum growth. If you have a spontaneous fermentation with clear signs of yeast growth (white creamy foam, yeast-looking sediment), then I think this is also safe.

I emailed the CDC with some questions about this topic. I will report anything they say here. But in the meantime, I think it would be smart not to taste our natural fermentations unless they clearly contain yeast. Botulism toxin does not smell or taste bad, so you can't use this as an indicator.

If you've clearly got some yeast in your wild fermentation or you acidified your wort to somewhere below pH 4.0 and checked it with a pH strip, RDWHAHB and taste away.

Hope I'm not being an alarmist -- I will report back anything I learn,
Graham
 
I'm thinking about growing up a small starter this week by pitching some waxy looking grapes into some leftover ~1.030 wort this weekend, but this botulism talk is maknig me nervous. Maybe I'll add some sort of acid if I can get some pH papers from my friend.
 
Searching around here I found a "botulism thread" and a pretty informative post from Revvy -

https://www.homebrewtalk.com/f11/botulism-50389/index3.html#post773813

Now, he's quoting a biologist who is a brewer, but the information presented is in concurrence with other research I have done.

1) C. botulinum is anaerobic, so it can't get started (and produce the toxin) in wort w/ O2, so make sure its aerated (shake it well)
2) It is suppressed by alpha acids, so add some hops
3) once fermentation from a yeast or acid bacteria starts, the PH range will drop below the point where it can grow

:ban:

If this wasn't the case then I suspect lambic brewers would have become extinct at some point :D
 
Sounds good to me! I'll go ahead and grow this up to use on a pale ale.

edit: although I didn't actually use any hops in the starter... I'm wondering if that could have potentially ruined it?
 
Hi all,

This is my first posted question to HomeBrewTalk. A few months ago, I started eyeing the instructions in the first message with longing to try, and am now biting the bullet! I have a couple questions related to the yeast capture process and where / how to use it.

First, my jar of wort in the window is now just over three days old -- at the point where the lit. suggests it should have colonies of enteric bacteria and kloeckera. Today when my wife and I smelled it, it smelled like a cross between sourdough bread and yogurt. (Lactobacillus?) Is this OK at this stage? I guess I should add that part of my goal is to brew a sour beer from multiple "wild" organisms, so I'm not opposed to adding lacto per se -- only concerned if this means the capturing process will likely fail to get saccaromyces at this point.

Second, my plan to this point has been to capture some wild yeast through the open window of my appartment in Pittsburgh, PA, then add that yeast + brett from the dregs of Victory's Wild Devil (+ perhaps the dregs from other sour beers from friends, if they're willing to donate closer to brew day.) Are there any details I should pay close attention to if I do this?

Thanks for any feedback! This is the first time I'll be trying to brew a sour beer, and any feedback is much appreciated!

-- Matt
 
Hi all,

Today when my wife and I smelled it, it smelled like a cross between sourdough bread and yogurt. (Lactobacillus?) Is this OK at this stage?

That's great! Low pH favors the growth of saccharomyces by preventing competition from most bacteria and molds. When I do your technique of leaving wort out to catch wild bugs, I add lemon juice until the wort is around pH 4. You've just let acidifying bacteria do the trick for you.

Hi all,

Second, my plan to this point has been to capture some wild yeast through the open window of my appartment in Pittsburgh, PA,

-- Matt

My only advice is to put the wort in a place where insects can have access. Yeast isn't just floating around in the air -- it is carried around from one sugar source to another by flies, beetles, and any other bug that likes to eat sugar. So remove the screen from your window, or hide the wort in the shrubs outside your apt. or in a nearby park.
 
Thanks, all! An update and a couple more questions:

My only advice is to put the wort in a place where insects can have access. Yeast isn't just floating around in the air -- it is carried around from one sugar source to another by flies, beetles, and any other bug that likes to eat sugar. So remove the screen from your window, or hide the wort in the shrubs outside your apt. or in a nearby park.
As of last night, it was bubbling, although with no sacc like foam on the surface -- and I had it away from sacc carrying bugs and the time. (But, not anymore, thanks!) I wasn't aware lactobacillus made CO2, but this really smells lacto. Could that be a species of lacto, or is there something else likely in there or taking over?

Also, should I add more sugars to the fermenting mix every so often until I get sacc, as whatever is making the CO2 eats those already there? What would be a good source? It occurred to me from the comment on allowing access to sugar-loving insects that local honey might both supply food and yeasts. Would local honey be a good source, or would that likely add harmful bacteria?

Thanks again! Watching this stuff and learning about what's going on in it is fascinating!
 
In my experience, it's a little hard to predict what bugs are in an open fermentation. Every bug makes CO2 to some degree (for the same reasons we humans do), and even if you do have sac, they may not make the same krausen they would make if you isolated them and pitched a large number. Sac and lacto can grow at the same time in a wort -- they might even help each other (Sac poisons competitors with alcohol, lacto poisons competitors with lactic acid, they are both tolerant of the other's poison.)

If it has been about a week, I would take a bit of the fermentation and put it in the fridge (or mix with 15% glycerol and put in freezer). You can save some again in a week and keep on saving samples every week for as long as you'd like. It should start to get very sour after a month or so. Then pick a sample to grow up to pitching quantity and make your sour beer, or dilute them 1:100 or 1:1000 and grow a bit on a plate if you want to try to isolate yeast.

Honey usually contains more osmotolerant (can survive high sugar concentration) yeast like Zygosaccharomyces, but don't let that stop you from giving it a try. We once thought of Brettanomyces as a spoilage yeast, so I wouldn't rule Zygo out!
 
Hey folks! Thanks for the advice on how to treat the evolving yeast-capture. It's now one day over a week old, and continuing to change. I'm curious: what scents, appearences, etcetera, indicate an UNhealthy development? Yesterday, it smelt of strong cheddar; today, of cheddar in slightly rancid water. Is this autolysis of whatever was growing in it? Do I need to throw it away and start over? Take a sample from it and add that to some fresh weak wort to continue until I've captured all I want?

Thanks! -- Including for your patience with all these questions.
 
If you have something undesirable in there, transferring a sample to new wort will just produce the same results.

You will know when you have saccharomyces because it will smell, well, like fermenting beer. Otherwise, you just have a jar of bacteria. Now it's only been a week, so there might be yeasts waiting for their turn to play once the pH goes low enough. However, the bacteria might consume all of the sugars before the yeast can take their turn, causing no yeast growth. You may need to add more wort or sugar and aerate it to see if you get some yeast-like activity in the next few days.
 
Someone mentioned "evolving" the yeast. I propose the experiment below.

0. Harvest wild yeast if you don't already have a culture.
1. Pick a recipe and brewing process that you will use consistently over this experiment.
2. Brew beer with wild yeast in 5 1-gallon containers.
3. When they're ready, pick one or two that taste best to you (it will probably take several iterations for there to be a noticeable difference) and brew 5-10 more gallons with those cultures, again keeping them separate from one another. Discard or store the unused cultures.
4. Repeat step 3 until you get bored or until you've got a culture that makes something you really enjoy. Use it to brew some or all of your beers, and enjoy your home brewery's very own exclusive yeast strain!

This is essentially selective "breeding" and it's been used by agriculturists for centuries. I'm thinking this would be a very long-term experiment, on the order of years. Depending on how many strains you isolate each time through, you'd also probably wind up with tons more beer than you could ever hope to drink.

Anyone want to give this a shot??
 
Another, much easier way to capture wild yeast is to use un-pasteurized honey. I have a post detailing my first wild brew, using mostly yeast from some local honey from Newport, NY. Look for honey with some white foam growing on the surface. Best I can tell, the white foam is a miniature krausen.
 
Love this thread!

My results, using a few ounces of leftover wort from a recently brewed Old Ale. I wasn't sure what to expect using a high gravity starter, but after 3.5 days:
wild_yeast_captured_-day4.jpg


And after 6 days (and it smells great):
wild_yeast_captured_-day6.jpg
 
Sweet! Is the stuff on top just bubbles or is it a pelli of some sort?
 
Sweet! Is the stuff on top just bubbles or is it a pelli of some sort?

It's a layer just sitting there, looks sort of krausen-like, but no bubbles or 'movement' to speak of. It went from pic one to a full layer covering the glass in one day, and grew in thickness after that. Anyone had similar results?
 
I want to attempt to gather some tasty yeasties in my area. I noticed that there are a number of fruits that tend to collect yeast on there outer surface (grapes, plums, etc.) does anyone know if these are good sources of beer yeast or if I should stick to the air capture method?


Thank you!
-AjnachakrA
 
Update: Sorry it's been so long since I posted here last, but my wild yeast mead turned out excellent (I didn't step up the yeast in the sample, and it took a year and a half to grow to proper mass and ferment the test batch)

It's not as strong as the champagne yeast that I normally use (seems to be the only fermenting yeast I seem to be able to find here in Calgary, AB) but it left the mead very sweet and aromatic. It cleared beautifully (Just as good as the champagne, which surprised me)

I don't usually take gravity readings (Sorry!) but my vinometer says it's coming out at about 7 1/2% - 10% alcohol (I don't know how reliable vinometers are, but it sure doesn't taste at the normal 15% that it usually does). It oddly enough, tastes like a spring day in Calgary...

I have to say, getting weather stable enough here in Calgary for two weeks was more of a challenge then actually capturing the yeast itself. I lost a few initial attempts due to the weather suddenly getting too warm and it sprouting mold. As it was, the initial sample went to mold, but not before I extracted 10ml of yeast floating in the bottom of the capture jar with a syringe my wife stole from work for me.(I <3 my wife). Risky, I know, but the test batch (.75 gallon - a weird size I know, but I had to work with the carboys I could find) turned out fantastic.

I have since used the yeast from the test batch, swirled it around in the bottom of the little carboy, and added it to a new 3 gallon batch that I started for this purpose.

It's been four days since I started it, and I've noticed that it's forming krausen on the top of the batch. I've never seen krausen before, and it scared me because I thought it was forming mold. But research shows that it's alive and well, and it will subside as the batch ferments.

It's not producing any noticeable CO2 that I've seen (i.e. the bubbler isn't bubbling, but it's pressurized like it wants to) which, considering my inital batches were with bread yeast, and later with champagne yeast, is a little unnerving. But the fact that every morning, something new has happened in the carboy tells me that it's doing something. Good or bad, well I'll have to wait and see...

Thanks again for starting this awesome thread. It's took my mead making in an entirely new and exciting direction. :mug:
 

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