Creating yeast strains

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crazyboy

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There are many different strains of yeast available some produce more alcohol others less, some produce esters and others do not. How can a homebrewer go about creating a strain of yeast unique from a store bought strain?

If I wanted a super yeast like the one used to brew utopias could I pitch Nottingham into a unusually high sugar wort, harvest the living yeast and repeat until I get the strongest ones?
 
It sounds like you are on the right track. You would be looking for a yeast that will withstand high alcohol levels, but you want one that give you high attenuation also.
 
In theory, yes. It's similar to selective breeding. This can take a long time though and many yeast generations. Didn't it take Sam Adams like 15 years to get the yeast for Utopias? To do it right, you'd also need some lab equipment to culture and isolate yeast strains.
 
Yeast sex. Yeast have to come across another of a different mating type to have sex. In our fermentoers, they are strictly doing it with themselves. I recall seeing a scientific paper (available online - might take some searching) on common brewing strains that had a table that gave the mating type for them. Mix two of the opposite kind together and bingo, new varieties. That is the easy part. All of the offspring produced, are going to be, just like with us, different. The trick then is to select for the ones with the characters you want.

As Mensch said, lab equipment would certainly be handy. Or if you just are into it for fun, go for it. After your yeast have sex, boil up 5 gal. batch and divide it into 5 1 gal. containers for fermentation. Bottle them up, and then taste. Keep the yeast from the one you like best. Do the same thing again, this time dividing the one you liked into 5 again. Or whatever you want, 2, 3 gal. etc batches. Keep the yeast from the batch you like best. And so on, and so on.
 
Yeast have to come across another of a different mating type to have sex. In our fermentoers, they are strictly doing it with themselves. I recall seeing a scientific paper (available online - might take some searching) on common brewing strains that had a table that gave the mating type for them. Mix two of the opposite kind together and bingo, new varieties. That is the easy part. All of the offspring produced, are going to be, just like with us, different. The trick then is to select for the ones with the characters you want.

Not that I know all that much about yeast genetics, but just from my general biology background, aren't there other contributers to selecting yeast strains? IOW, some yeast cells within a strain may have or develop better resistance to alcohol or exhibit various levels of ester production, regardless of their reproduction. Each individual brewhouse may, over time, affect a yeast strain due to wort chemistry (lauter techniques, etc.), aeration techniques, etc.

I'm just reminded of a paper I did in college on benthic invertebrates (in this case midges) and the effects of acid mine drainage on them... whether they developed resistance to various parameters of acid mine drainage pollution genetically (breeding/mutations) or if they developed certain tolerances individually.
 
There are many different strains of yeast available some produce more alcohol others less, some produce esters and others do not. How can a homebrewer go about creating a strain of yeast unique from a store bought strain?

If I wanted a super yeast like the one used to brew utopias could I pitch Nottingham into a unusually high sugar wort, harvest the living yeast and repeat until I get the strongest ones?

Or you could artificially stress your yeast. It would probably require less time and resources. Place them in a 10% ethanol solution and propagate the survivors (for example).

FLO1 is a variable green beard gene that drives bi...[Cell. 2008] - PubMed Result
 
In all honesty I'd just leave it to the pros with expensive machinery and spend you time brewing beer!
 
Or you could artificially stress your yeast. It would probably require less time and resources. Place them in a 10% ethanol solution and propagate the survivors.

This is the exact conclusion I came to earlier today! I think I could take some white labs super high gravity yeast which can take up to 25% alcohol pitch it in 15% alcohol repropagate, pitch into 20% repropagate 25% etc...

As far as lab equipment goes my other hobby is chemistry so I have beakers, flasks, a heating mantle, distillation apparatus, thermometers, graduated cylinders and a microscope (800x).
 
Not that I know all that much about yeast genetics, but just from my general biology background, aren't there other contributers to selecting yeast strains? IOW, some yeast cells within a strain may have or develop better resistance to alcohol or exhibit various levels of ester production, regardless of their reproduction. Each individual brewhouse may, over time, affect a yeast strain due to wort chemistry (lauter techniques, etc.), aeration techniques, etc.

Tis true. My point about sex is that without it you are starting with a single isolate and hoping for that one to mutate over time in the manner desired. After sex, there will be boatloads of unique individuals to go through the process - or in other words, much better odds.
 
Let’s have this discussion 50 years from now when gene technology is able to compile and synthesize DNA just like we write computer programs now. Then you put this DNA into a nucleous free yeast cell and “boot” it up. Powerful and scary, isn’t it.

I think I have created a unique strain. I do have a Weissbier yeast that stems from the WLP351 that seems to be able to ferment more types of sugars than other ale or lager yeasts. It consistently has a higher limit of attenuation in the fast ferment test. But it has a very poor head retention.

Kai
 
It would be a fairly simple thing to select for alcohol resistant mutants. As mentioned all one need do is to throw a large thriving population into a high alcohol enviroment (within limits, that phospholipid membrane is not going to survive a plunge into 50% ethanol). It will even work faster if you introduce a mutagen like radiation (for that homebrewer that would be UV - I doubt a lot of people have access to beta or gamma sources).

The problem is now you have a population of high EtOH tolerant mutants, you have to select out the ones that make tasty beer vs. unpalatable bubblegum flavoured cough medicine. That will take time.
 
Let’s have this discussion 50 years from now when gene technology is able to compile and synthesize DNA just like we write computer programs now. Then you put this DNA into a nucleous free yeast cell and “boot” it up. Powerful and scary, isn’t it.

I'll probably be pretty close to death by then. I think if we got you and Yuri together, you could make a time machine... and post the construction of it in the DIY forum.:)

I think I have created a unique strain. I do have a Weissbier yeast that stems from the WLP351 that seems to be able to ferment more types of sugars than other ale or lager yeasts. It consistently has a higher limit of attenuation in the fast ferment test. But it has a very poor head retention.

Kai

Have you tried an experiment in which you use your strain and a fresh vial of WLP351 to see if there are any differences?

I doubt a lot of people have access to beta or gamma sources.

That's easy... get a crap load of smoke detectors and take the Americium out of them... but getting mutants would probably only work in comic books.;)
 
Let’s have this discussion 50 years from now when gene technology is able to compile and synthesize DNA just like we write computer programs now. Then you put this DNA into a nucleous free yeast cell and “boot” it up. Powerful and scary, isn’t it.


Actually, in some respects, sooner than you think! The sticking point right now is knowing what genes, or multiple genes yield the desired phenotype. Once you have that, then heck, I could engineer the little buggers. I believe there has been some success in engineering multistep pathways in bacteria, maybe even yeast. There are machines know that can synthesize whole genes from scratch. Actually, now that I think of it I believe they have been able to synthesize from scratch (lab made DNA only) a funtional minimal gene set organism (microbe)
 
PJ, have you read anything about gTME (global transcription machinery engineering)? I recently did a presentation on yeast, and found a great article about S.cerevisiae and creating a mutant with a higher tolerance for EtoH AND glucose (a point I think many people forget). I can send you the link if your interested.

And, yes if only "manufacturing" DNA were cheap and accessible we'd have super-strength yeast and most likely not be in the energy crisis were in now as well! However, I did attend a microbial sciences symposium at Harvard University yesterday, and we may be closer to that than originally thought!

Also, as for the "sex" argument, they do have sex, albeit bacterial sex, which agreeably hardly constitutes as what most people define sex as...
 
Hey PJ, have you read about gTME (Global Transcription Machinery Engineering) at all? There are some great articles out there, with specific regard to S.cerevisiae, and engineering a more EtoH AND glucose tolerant yeast, I recently presented on said topic and have the link to the article if you're interested.

That being said, I think selecting for an ethanol tolerant yeast alone might not be sufficient, as yeast is just as often not tolerant to high glucose levels also. Again, this type of selective breeding is time consuming, though not NEARLY as time consuming as selective breeding in other eukaryotic organisms.

As far as the DNA manufacturing goes, I attended the Microbial Sciences Symposium at Harvard University yesterday, and it might not be as far off as one would assume!

And finally, yes yeast have "sex" albiet bacterial sex, genomic information is swapped, even if it's mechanisms aren't as exciting at those in humans!
 
Usually non-stressed yeast reproduce asexually via budding...

...however, stressful conditions (eg nutrient/nitrogen depletion) lead otherwise normal diploid yeast cells to generate haploid cells via sporulation, and the haploid spores then sexually reproduce/mate (conjugate), reforming new versions of diploid yeast cells.


I have not tried this, but if you have proper materials, here is a method for inducing Sporulation of Budding Yeast:

Starvation of diploid yeast cells for nitrogen and carbon sources induces meiosis and spore formation. The sporulation process can be induced in cells growing either on solid or in liquid medium.



1. Sporulation in liquid media:
2. Grow the diploid to be sporulated to an OD600 of 2.5 to 3.0 in YPD medium.
3. Transfer 1 ml culture to a sterile, disposable 15-ml tube and centrifuge 5min at 1200xg (3000rpm).
4. Pour off supernatant and resuspend cells in 5ml sterile water. Vortex to resuspend cells and repeat spin.
5. Pour off supernatant and resuspend cells in 1ml liquid sporulation medium supplemented with nutritional requirements of the particular diploid.
6. Shake at 30C for 3-6 days.
7. Look for sporulation microscopically.



Sporulation Medium:

10 g/l potassium acetate

1 g/l yeast extract

0.5 g/l dextrose

The yeasts - Google Book Search
 
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