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* [http://bootlegbiology.com/diy/capturing-yeast/ Bootleg Biology] defines three methods of catching a wild yeast.
* [http://suigenerisbrewing.blogspot.ca/2014/12/two-new-videos.html Sui Generis Blog] video tutorial for catching wild yeast from fruit or from the air.
* David Thornton of [[SouthYeast Labs]] describes his favorite method of catching wild yeast/bacteria: "Most of our cultures are taken from over -ripened fruit macerated in its own juice and left to ferment 24 hours at the location in a small erlynmeyer with a perforated cap. Always grows something, and almost always get an alcohol fermenting strain, and of the alcohol fermenting strains id say 10% are worth brewing with. I like this method because I can stir my loop and do a streak on regular UBA aerobically, then pull favorable looking colonies for yeast and lacto ''Lactobacillus'' and do a quadrant streak on selective media for isolation." <ref name="Thornton">[https://www.facebook.com/groups/MilkTheFunk/permalink/1141930175835195/?comment_id=1142286619132884&reply_comment_id=1142394019122144&total_comments=4&comment_tracking=%7B%22tn%22%3A%22R6%22%7D Conversation with David Thornton on MTF. 09/06/2015.]</ref>* Monitor for mold growth. If mold begins to grow on the growth media, scrape it out and continue on with the isolation process. This should be safe since isolating the yeast will separate it from any potential mycotoxins that developed during the initial catching. Do not consume any growth media that has had mold grow on it (see [[Mold]]).* In general, summer and spring are more successful times to catch wild yeast, however any time of year can be successful. Simply choose fruits or flowers that bloom/grow during that particular season. For example, in spring, flowers and fruit blossoms are a good source. In summer, wild summer fruit can be a good source (raspberries, strawberries, cherries, etc.). In the fall, apples and grapes can be a good source. In winter, juniper berries <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1683379841690223/?comment_id=1683799054981635&comment_tracking=%7B%22tn%22%3A%22R%22%7D Milk The Funk thread on the best seasons for bioprospecting. 05/11/2017.]</ref>.* A new study showed that wild yeast actually exists more so in leaf matter on the ground than it does on bark or fruit. See the [[Wild_Yeast_Isolation#Videos|"Where (Do) the Wild Yeast Roam" video by Bryan from Sui Generis blog]] below.* [https://www.facebook.com/groups/MilkTheFunk/permalink/1034954619866085/ David Thornton's use of foam as stoppers.]
===Isolating===
* [http://suigenerisbrewing.blogspot.ca/2014/12/two-new-videos.html Sui Generis Blog] video guide on streaking plates and further isolating yeast.
* [http://basementbrewlab.com/lab/lab-media/sla/ Selecting for and isolating for ''Lactobacillus'' using Rogosa SL Agar.]
* [https://www.facebook.com/groups/MilkTheFunk/permalink/1713165188711688/ MTF thread with tips on isolating and growing from a single colony.]
===Identifying===
==Growing and Testing Without Plating==
While using agar plates to isolate yeast colonies is the most effective way to culture wild yeast, it is not the only way. Wild yeast should first be caught using DME wort as outlined in [http://bootlegbiology.com/diy/capturing-yeast/ Bootleg Biology's ''Method 1'' or ''Method 2'']. Hopping the wort will help decrease bacteria if that is desired. The wort's pH should be lowered to 4.5 or lower with lactic acid to avoid bacteria as much as possible. Molds may still grow in the yeast starter even with the lower pH, and ; wort that has grown mold should not be removed by scraping them off consumed because mycotoxins can contaminate the wort (see [[Mold]]). Keeping the foraged fruit, flowers, etc. under the surface of the surface wort will help reduce the chances of mold growth. Some brewers recommend submerging the fruit/flowers in wortfor a few minutes and then removing them to prevent them from attracting mold growth <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1659565197405021/?comment_id=1711116612249879&comment_tracking=%7B%22tn%22%3A%22R%22%7D Jeff Porn. Milk The Funk Facebook group. 06/06/2017.]</ref>. If the yeast cannot be separated from wort that mold grew on then it should be thrown out. Signs of a small krausen within 1-3 days is a good sign that viable wild yeast has been collected. After another few days, the yeast will start dropping to the bottom of the collection vessel <ref name="manoaction">[http://www.homebrewtalk.com/collecting-wild-yeast.html Collecting Wild Yeast. Manoaction. Homebrewtalk. Oct 30, 2012.]</ref>.
Once the wort has fermented out (allowing 2 weeks total is a good rule of thumb), decant the beer and pitch the collected yeast into 500ml of starter wort, again lowering the pH of the starter wort to 4.5 with lactic acid. After the starter wort has been fermented, the yeast should have enough of a population to ferment out a 1 gallon batch of wort. Keep the recipe of the wort simple, and in the 1.050 gravity range. The yeast cell count should be high enough at this point to out-compete bacteria, and lower the pH of the wort within a few days. The pH of the 1 gallon batch , therefore , does not need to be lowered, although the brewer may choose to do so anyway. For [[Wild_Yeast_Isolation#Safety|safety reasons]], test to make sure that the beer fully attenuated and has a pH of 4.5 or less. Allow for one month after fermenting the 1 gallon batch of beer before sampling. If it smells like feces or vomit, do not sample it and throw it away. If the beer smells ok, feel free to sample the beer to see if the wild yeast produced a good tasting beer. David Thornton from [[SouthYeast Labs]] estimates that only about 10% of yeast that can fully attenuate produces favorable results, so failures are to be expected (keep trying!) <ref name="Thornton"></ref>. Fermenting a few batches of beer at different temperatures is a useful method for identifying the ideal fermentation temperature range for the yeast. * See [https://www.facebook.com/groups/MilkTheFunk/permalink/1676671082361099/ advice from DeWayne Schaaf and others on bioprospecting techniques without isolating microbes on MTF]. * See [[Mold]] for identifying mold and safety issues with mold.
===Safety===
* The risk of botulism toxin is extremely low, but not zero. Generally, ''C. botulism'' is not able to grow and produce toxin in low protein (non-meats) substances at a pH lower than 4.6 <ref>[http://www.ingentaconnect.com/content/iafp/jfp/1982/00000045/00000003/art00005 Toxin Production by Clostridium Botulinum in Media at pH Lower Than 4.6. Nobumasa, Tanaka. Journal of Food Protection®, Number 3, February 1982, pp. 214-284, pp. 234-237(4)]</ref><ref>[http://edis.ifas.ufl.edu/fs104 Preventing Foodborne Illness: Clostridium botulinum. University of Florida IFAS Extension. Retrieved 7/5/2015.]</ref>. However, proteins in the wort may allow growth at a lower pH than 4.6 (studies have not been done on wort, only on meats) <ref name="BryanMTF"></ref>. The presence of more than 5% oxygen in the wort will also reduce the risk <ref>[http://www.ncbi.nlm.nih.gov/pubmed/15895734 Growth and toxin production by Clostridium botulinum in steamed rice aseptically packed under modified atmosphere. Kasai Y, Kimura B, Kawasaki S, Fukaya T, Sakuma K, Fujii T. May 2005.]</ref>.
* To our knowledge, there have been no documented cases of food poisoning from beer <ref name="Bryan"></ref>. However: "It is well established that at least a dozen human pathogens can survive in fully fermented beer; moreover, sour-brewing (and home brewing in general) offers an additional opportunity for pathogens to gain a foothold or produce toxins which persist into the final product. Reality is that the source of most food poisonings is never established. A few industries (milk, meat, canning, etc) are under close scrutiny, and as such we have firm numbers for rates of food-borne illnesses from those industries. Neither commercial nor homebrewing is subject to that monitoring, so any cases of disease arising from contaminated products from either source would likely go unidentified." - Bryan of Sui Generis Blog on MTF <ref name="BryanMTF"></ref>. For more information on the potential for pathogens surviving in beer, see this [http://suigenerisbrewing.blogspot.com/2014/02/fact-or-fiction-can-pathogens-survive.html Sui Generis Blog article.].
* In the words of Bryan from [http://suigenerisbrewing.blogspot.ca/2014/02/fact-or-fiction-can-pathogens-survive.html Sui Generis Blog]: "If you have an immunodeficiency or are immunosuppressed: Obviously, don't take medical advice off the internet. Talk to your MD medical doctor to see if you are at risk of infection - especially if you're condition/treatment increases your risk of fungal infections. If so, or if you are concerned, stick to beers that are fermented using commercial strains of Saccharomyces yeast." <ref name="Bryan"></ref>* See also [https://www.facebook.com/groups/MilkTheFunk/permalink/1283377785023766/ this thread on MTF].* See also [https://www.facebook.com/groups/MilkTheFunk/permalink/1447181778643365/?match=Ym90dWxpc20%3D this MTF thread on the mechanisms of botulism poisoning, and how it applies to different brewing processes].* [https://suigenerisbrewing.blogspot.com/2017/01/fact-of-fiction-can-pathogens-survive.html Further explanation of what makes microbes "pathogenic" by Bryan from Sui Generis Blog] and a related [https://www.facebook.com/groups/MilkTheFunk/permalink/1246624848699060 MTF discussion].* If mold grows on growth media and the yeast can be isolated cleanly, then this is not an issue. If the yeast is not being isolated on agar plates, then throw out the capture sample and do not use it. See [[Mold]] for identifying mold and safety issues with mold. ==Wild ''Brettanomyces''==* [https://www.facebook.com/groups/MilkTheFunk/permalink/1620419974652877/ MTF discussion on the rare but possible isolation of wild ''Brettanomyces''.]
==See Also==
===External Resources===
====Links====
* [https://www.facebook.com/groups/MilkTheFunk/permalink/1489822481045961/ James Howat from Black Project shares his simple setup on MTF for continuous CO2 purging in order to discourage mold in wild starters.]
* [http://www.brewingscience.com/identification_key.htm Brewing Science Bacteria on LMDA (visual identification of various bacteria species on LMDA plates).]
* [http://bootlegbiology.com Bootleg Biology provides a full toolkit and materials for yeast isolation.] They also provide a [http://bootlegbiology.com/community/ community yeast bank].
* [http://suigenerisbrewing.blogspot.ca Sui Generis Blog.]
* [http://www.dhbrewingconsulting.com/culturing-instructions/ Culturing Instructions by Double Helix Brewing Consulting.]
* [http://suigenerisbrewing.blogspot.com/2014/02/fact-or-fiction-can-pathogens-survive.html "Fact or Fiction? Can Pathogens Survive in Beer?", by Sui Generis Blog.]
* [http://www.alesoftheriverwards.com/2016/04/forest-and-main-brewing-co-exploring.html "Forest and Main Brewing Co.: Exploring their indigenous culture", By Ed Coffey on Ale of the Riverwards Blog.]
* [http://www.craftcommander.com/brewing/2016/7/14/brewing-beer-with-a-sense-of-place-foraging-yeast-for-beginners "Brewing Beer With a Sense of Place - Foraging Yeast for Beginners" by Andrew "Gus" Addkison on the Craft Commander blog.]
* [http://brouwerij-chugach.com/?p=1171 "Yeast Wrangling Adventure", Brian Hall of Brouwerij Chugach blog shares wild yeast hunting techniques in the Alaskan wilderness.]
* [https://www.youtube.com/channel/UC8_kozGERzHnjVIizhnh43g/videos "Brewing Viking" home yeast lab videos on YouTube.]
====Books====
* [http://www.amazon.com/Yeast-Practical-Fermentation-Brewing-Elements/dp/0937381969 Yeast: The Practical Guide to Beer Fermentation (Brewing Elements)], by Chris White and Jamil Zainasheff.
* [http://dunham.gs.washington.edu/DunhamLabMinistats.pdf Dunham Lab Ministat Manual.]
====Videos====
<youtube>y43x7nLTEPo</youtube>
<youtube>SwDjJKkuT74</youtube>
<youtube>viXPMtkTfk8</youtube>
<youtube>ChHcR9qaxj0</youtube>
==References==