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'''Wild yeast isolation''', sometimes known as "yeast wrangling" or more formally [https://en.wikipedia.org/wiki/Bioprospecting "bioprospecting"], refers to the process of catching wild, native yeast ([https://www.merriam-webster.com/dictionary/autochthonous autochthonous] yeast), and isolating it with agar plates as a pure culture. This article will also contain contains information on growing up a ''captured'' mixed culture in wort rather than isolating single strain yeast cultures on agar plates. Culturing wild yeast and bacteria should not be confused with [[Spontaneous Fermentation]] because many of the microbes that might make a flavor impact during spontaneous fermentation are killed off during the bioprospecting processes. For general lab techniques, see [[Laboratory Techniques]]. For more information on nonconventional microbes, see [[Nonconventional Yeasts and Bacteria]].

* [https://wwwdrive.facebookgoogle.com/groups/MilkTheFunk/permalink/1970068393021365/ open?id=17wqLEBinSVCx6zKEoXpsUI9hMPN_MAUHgZ22TD552r0 MTF thread with tips on removing bacteria from yeast colonies using selective media and antibiotics.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/3298177256877132/ Ruth Barry details her process for isolating individual strains in a mixed culture with the goal of characterizing each strain for a more controlled mixed fermentation.]* [https://www.youtube.com/watch?v=dQzbeE5_ehc Dr. Matt Winans from Imperial Yeast on "Chop n Brew" demonstrates that incubating agar plats at different temperatures can result in widely different growth success rates (~11:00 minutes in).] See also [https://www.facebook.com/groups/MilkTheFunk/posts/6025908170770680/ this MTF thread exploring this approach].

This method was developed by David Thornton of [[SouthYeast Labs]] and [https://carolinabauernhaus.com/ Carolina Bauernhaus] for collecting wild ''Saccharomyces'' yeast and lactic acid bacteria. David described his method in detail on [https://www.milkthefunk.live/podcast/2018/6/28/episode-005-bio-prospecting-with-david-thornton-and-keston-helfrich-of-southyeast-labs-and-carolina-bauernhaus the Milk The Funk "The Podcast" episode #005]. Thornton encourages people to alter this process to suit their required results and conditions; for example, developing a different approach that might allow this method to be better suited towards catching ''Brettanomyces''. The following is a summary of this process:

# Start with 75 mL of 6° Plato wort with yeast nutrient in a 250 mL flask. Add the sample (fruit, flower, bee, etc). If it's fruit, squish it up. Set the flask on a shaker or stirplate at 80-90F with a [https://www.facebook.com/groups/MilkTheFunk/permalink/1034954619866085/ foam stopper ] (the foam stoppers can be autoclaved/boiled and create an aerobicenvironment; aluminum foil should work tooas a substitute) for 12-48 hours. Look for frothing and as soon as that happens put an airlock on the flask, but keep on stirplate to assist fermentation. # After the 24-48 hours, decant and discard the liquid and leave the biomass at the bottom. Add 75 mL of new starter media to the flask (with the biomass still at the bottom of the flask) that is 8-10* Plato with yeast nutrient, and purge the flask with CO2. Put an airlock on it on a stirplate and grow until the sugars have fermented.# Again, decant and discard the liquid and leave the biomass at the bottom of the flask. Purge the flask (with the biomass still at the bottom) with CO2, and add 75 mL of 20° Plato wort with yeast nutrient and an airlock, and place on a stirplate or shaker. Look for the wort to ferment down to around 2 plato Plato or so. # After the 20° Plato wort has finished fermenting, samples from the liquid can be decanted, and (the liquid contains the more active yeast versus the biomass can be at the bottom of the flask) are streaked onto media to isolate the strains that have survived. If agar plating is not an option, a less advanced approach can be taken by [[Wild_Yeast_Isolation#Growing_and_Testing_Without_Plating|growing and testing without plating]].

* Wallenstein labs nutrient: serves as a catch -all.

* Measure pH to make sure it gets down to under 4.65; this helps monitor for fermentation activity.

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/ one of Bootleg Biology's methods] or [[Wild_Yeast_Isolation#David_Thornton.27s_.22Yeast_Bootcamp.22|David Thornton's Yeast Bootcamp method]]. 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; wort that has grown mold should not be consumed because mycotoxins can contaminate the wort (see [[Mold]]). Keeping the foraged fruit, flowers, etc. under the surface of the wort will help reduce the chances of mold growth. Some brewers recommend submerging the fruit/flowers in the wort for 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>.

* [https://www.facebook.com/groups/MilkTheFunk/permalink/1676671082361099/ advice Advice from DeWayne Schaaf and others on bioprospecting techniques without isolating microbes on MTF].

An often asked question when it comes to tasting beer fermented from a wild culture that wasn't plated and isolated is, "When is it safe to drink?" To our knowledge, no studies have shown when a wild -caught beer is scientifically ~99.9% safe to drink. However, several studies can give us some guidance on this, as well as [http://suigenerisbrewing.blogspot.com/ Dr. Bryan Heit from Sui Generis Blog].

* The addition of hops in the starter wort will inhibit or kill some gram Gram-positive bacteria pathogens (''L. monocytogenes'' and ''S. aureus'') <ref name="Menz1">[http://www.ncbi.nlm.nih.gov/pubmed/22004814 Growth and survival of foodborne pathogens in beer. Menz G., Aldred P, Vriesekoop F . Oct 2011.]</ref><ref name="BryanMTF">[https://www.facebook.com/groups/MilkTheFunk/permalink/1104757552885791/?comment_id=1105118642849682&offset=0&total_comments=15&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Bryan of Sui Generis Blog on MTF regarding when it is safe to taste wild beer. 7/6/2015.]</ref>. The use of [https://en.wikipedia.org/wiki/Lysozyme lysozyme], which kills Gram-positive bacteria, might also be a good way to limit the growth of bacteria (including lactic acid bacteria).

* 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] and this [http://suigenerisbrewing.com/index.php/2020/01/29/botulism-in-beer/ blog post on Sui Generis Brewing blog by Dr. Bryan Heit].

* If mold grows on growth media and the yeast can be isolated cleanly, then this is not an issue, however , do not consume beer or wort that has had mold growing on it. 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.

===MTF Wild Capture Swap===