Isolating yeast strains - anyone doing this at home

My friend mike has done an article on HBT regarding the basics of it.
http://www.homebrewtalk.com/entries/plating-yeast-selecting-colonies.html

 

I know he has only used plating to identify the yeast cells which are circular and doesn't have a microscope to identify particular strains more accurately.

 

Yes, you can see bugs (bacteria) on agar, they grow up just like yeast do.

You can do a lot of classification without a scope, doing old school microbiology with different stains and different agar types, that can tell you a good deal about the physiology of the microbes and yeast, and help narrow down what you have on the plate.

A scope can tell you much more about cell morphology.

Its pretty easy and doesn't take much of a brain to do this shit, just decent sterile technique.

 

Do you have a good resource on how to do this type of stuff? I heard that differentiating different Bretts from each other is beyond microscopes and such. I like to get my wild yeasts for Lambics and such from local fruits (blackberry fermented Lambic 2 years ago, strawberry in last year's), but I would love to culture up the yeasts and bacterias on fruits and isolate the different yeasts, and bacterias to do single strain trials. I would love to get my own local Brett for single Brett beers and for adding to my wild stuff. No idea where to start though.

 

Let me try and pull something up for you. Somewhat overwhelmed at work today with paper review rebuttals and experiments, but should be able to pull up a nice reference at worst over the weekend.

As far as differentiating different brett strains microbiologically, I actually don't have a good answer for you other than DNA sequencing, which in itself isn't accessible to homebrewers (maybe M.Fermentationist might or Jakobson's thesis might have some better info).

Differentiating bacterial strains is fairly well worked out, although to really pinpoint exactly what subspecies you have easiest is again sequencing genomes (not usable for us at home). Many of the microbiological techniques you can do at home to classify the bacteria (response to agar types, stains, etc.) work in sort of a process of elimination type manner, where you record the responses to each test and start narrowing down the species.

 

There is a whole section on home culturing in the White/Zainasheff book "Yeast". I've been isolating and culturing from local fruit for use in brewing, but have the advantage of working in a Biology department (autoclaves, scopes, etc readily available).

 

Most of the details are on Dmitri's site/blog (BKYeast)

http://bkyeast.wordpress.com/2012/12/17/how-to-build-a-yeast-ranch/
http://bkyeast.wordpress.com/

 

I have collected several strains from Cantillon and Drei Fontenien. It is fairly easy to do.

1)I take the dregs of the beer and add it to a cup of sterilized wort and give it about 2 weeks to grow. As the sample ferments and the alcohol level climbs the bacteria will stop growing and hopefully die. This cuts down on the amount of bugs in the initial culture.
2)I then streak out a sample on a large agar plate from the sample.
3)I then wait about a week to allow for large colonies to grow.
4)I take the single colonies and streak them out on a separate plate. Looking to see if all the new colonies look uniform.
5)I then take a single colony from these new plates and allow them to grow in about 250 mL of sterilized wort.

If it is able to grow in the wort and attenuate a decent amount I then look for cultures that have a pleasant aroma.

I have used this technique to gather 9 new strains. I have access to a microscope and have viewed them through it but it is not very helpful. You can see if the yeast are normal in morphology or abnormal but it is impossible to see if they are Brett of Sach under a scope. Sometimes a normal stressed yeast will grow in off shapes and some Brett strains look like normal budding yeast under the scope.