How to isolate yeast strains? A primer?

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COLObrewer

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OK, simple question, How do you isolate yeast strains in a culture of wild yeasts?

I have a ton of questions regarding this, not the least of which is: Do you need a biology and chemistry degree to do this?

After I typed all the questions and click on submit, of course the stupid internet hosed me and I forgot to copy to a clipboard prior to submitting, pi$$es me off to no end every time!!!!

There are alot of references to isolating yeast strains, but I've seen no details, is this posted somewhere? F.I. Isolating Sacc from brett from peddio from lacto and within each genus?

Are the retarded ones malformed or something?

Post script: I don't have a microscope, Is this a problem?:D
 
there was a microscope on woot kids today for pretty cheap. i don't know if it was any good though and it's sold out now.
 
You can do a agar plate, let the cultures build up and then take a culture from each colony. Then make a starter from each colony and the one that doesn't sour is your good yeast. Other then this method you will need a microscope.
 
Pick up the new book, Yeast by Chris White and Jamil. It is a great source and has a whole section on starting your own yeast lab.
 
Does the book have pictures? Of the different genus of yeasts/bacterium, etc? I like pictures.
 
You can do a agar plate, let the cultures build up and then take a culture from each colony. Then make a starter from each colony and the one that doesn't sour is your good yeast. Other then this method you will need a microscope.

This.

To elaborate, use a sterile metal loop (can make one w/ a bent paper clip; heat with a flame until orange and place in plate to allow it to cool) and then touch a wild yeast liquid culture. Streak this onto an solid media plate made from malt extract and 1.5% agar (gelatin should work as well). The idea is to get less and less colonies as you streak. A google search will give you a few techniques.

Restreak individual colonies onto another plate so you have a source plate for your good yeast.

Then as said, pick individual colonies and put each one into a small (1ml or so) starter, incubate for 12-16 hrs. Dont pick fungal colonies though.

Many yeasts look very similar to the eye w/o the aid of VERY expensive microscope.
 
So how do you know which colonies are yeast, which ones are bacteria and which ones are fungal without using a microscope? Do they have different appearances on the plate? I used to do this stuff in college but it's been about 15 years...
 
Hehe, this is my kind of thread. I am interested in isolating and separating different dregs into bacteria and wild yeasts. :) I already plated and separeted different commercial dregs: (http://eurekabrewing.wordpress.com/microbiology-projects/). I therefore have the Brettanomyces from Girardin, 3 Fonteinen, Cantillon, BFM, Orval... and some others.

Having a microscope is a good help. Although, sometimes you do not gain any further information by just looking at the cells. Sure, with a microscope you should be able to tell whether you have bacteria or yeasts (due to the different sizes). There is another way to identify the things you have on a agar plate. One way is the morphology of the colonies on the agar itself. For example:

- A kind of bacteria I could not yet identify: http://eurekabrewing.wordpress.com/2012/02/03/1-agar-plates-bfm-3-fonteinen-girardin/

- Or maybe Pediococcus: http://eurekabrewing.wordpress.com/2012/02/29/6-agar-plates-3-fonteinen/

Nowadays, I just look at the colonies and I often know what I am looking at. The microscope is just to verify my observation. If you have a colony and are not sure if its Brettanomyces, do a fermentation test. The smell of it (or even the formation of a pellicle) will tell you what you have.

There is yet another way to do it. Check out the following blog: http://bkyeast.wordpress.com/experiments/. The author used different kinds of agar to isolate the different strains. Some of the yeasts can grow on it and others can't. One problem are the different growth rates of the bacteria and wild yeasts. Some wild yeasts grow very slowly. If you have bacteria cells along those wild yeasts, it is very likely that your agar plate will be covered with the bacteria colonies before the wild yeasts can build colonies. You can use plates which inhibit the growth of bacteria to isolate the wild yeasts.

Dmitri's (from BKyeast) agar media are very easy and rather inexpensive. One of his goals is to find agar media for the normal homebrewers. Sure there are other (commercial) media to do the job. However, they can be very expensive. I have to admitt, I do my platings with a commercial agar as well... :) However, I planned to give some of Dmitri's media a go to try them myself and hopefully replicate his results.

Cheers, Samuel
 
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