Author Topic: Yeast Mutation  (Read 2006 times)

Offline TXFlyGuy

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Yeast Mutation
« on: December 02, 2020, 04:51:02 PM »
We all know that yeast, like a virus, will mutate over successive generations.

But how long does this take in the real world? How many generations will remain true to the original? Do mutations automatically mean the yeast will no longer perform?

Is there a chance that a mutant yeast would actually improve in character?

How do you know a yeast has mutated to the point of no longer being viable for beer?

My experience has been that each successive generation will actually perform better than the previous generation, up to a point. Is this the result of mutation?
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Offline denny

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Re: Yeast Mutation
« Reply #1 on: December 02, 2020, 05:09:25 PM »
How long is a piece of string?
Life begins at 60.....1.060, that is!

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Offline TXFlyGuy

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Re: Yeast Mutation
« Reply #2 on: December 02, 2020, 05:44:03 PM »
How long is a piece of string?

How long is your string, on average?
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Offline RC

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Re: Yeast Mutation
« Reply #3 on: December 02, 2020, 06:05:43 PM »
How long is a piece of string?

How long is your string, on average?

Yeah too much to unpack here regarding mutation (and genetic drift is arguably a bigger consideration anyway), but a couple of these questions can be fairly easily answered:
----------
How do you know a yeast has mutated to the point of no longer being viable for beer? Unless you want to take up yeast plating and start a microbiology lab in your house, the only way to know is via fermentation performance and flavor profile of a batch using that yeast. EDIT: But also, declining performance/flavor could instead or in addition be due to bacterial and/or wild yeast infection. This is much more likely to be the reason for declining performance/flavor at the homebrew level than mutation. Again, you'd need a lab to distinguish between the two.

My experience has been that each successive generation will actually perform better than the previous generation, up to a point. Is this the result of mutation? No. It is because the cells are fat and happy and healthy because they have been repeatedly and extremely well-fed on the food source they like the most.
« Last Edit: December 02, 2020, 06:20:58 PM by RC »

Offline denny

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Re: Yeast Mutation
« Reply #4 on: December 02, 2020, 06:21:28 PM »
How long is a piece of string?

How long is your string, on average?

About this long..... ;D
Life begins at 60.....1.060, that is!

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Offline denny

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Re: Yeast Mutation
« Reply #5 on: December 02, 2020, 06:22:20 PM »
How long is a piece of string?

How long is your string, on average?

Yeah too much to unpack here regarding mutation (and genetic drift is arguably a bigger consideration anyway), but a couple of these questions can be fairly easily answered:
----------
How do you know a yeast has mutated to the point of no longer being viable for beer? Unless you want to take up yeast plating and start a microbiology lab in your house, the only way to know is via fermentation performance and flavor profile of a batch using that yeast. EDIT: But also, declining performance/flavor could instead or in addition be due to bacterial and/or wild yeast infection. This is much more likely to be the reason for declining performance/flavor at the homebrew level than mutation. Again, you'd need a lab to distinguish between the two.

My experience has been that each successive generation will actually perform better than the previous generation, up to a point. Is this the result of mutation? No. It is because the cells are fat and happy and healthy because they have been repeatedly and extremely well-fed on the food source they like the most.

Love that last paragraph
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline BrewBama

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Yeast Mutation
« Reply #6 on: December 02, 2020, 06:34:21 PM »
How long is a piece of string? 

Tommy previously answered this question:


2*pi*r exactly. r depends on the radius of circle the string fits around.

From another post:


I recall a Dr Bamforth interview where he said he was given a lecture in England. He said something like he prefers not going into double digits repitching before a replacement pitch is grown from a master colony. A gentleman in the back stood and said they’re on something like their 4000th+ repitch at last count!



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« Last Edit: December 02, 2020, 06:54:50 PM by BrewBama »
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Offline TXFlyGuy

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Re: Yeast Mutation
« Reply #7 on: December 02, 2020, 06:36:50 PM »
Thanks for the constructive input.
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Offline tommymorris

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Re: Yeast Mutation
« Reply #8 on: December 02, 2020, 06:52:29 PM »
How long is a piece of string?
2*pi*r where r is the radius of the circle you form with the string.

Offline BrewBama

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Yeast Mutation
« Reply #9 on: December 02, 2020, 06:53:25 PM »
How long is a piece of string?
2*pi*r where r is the radius of the circle you form with the string.
Sorry Brother. I stole your thunder (#7 above).


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Offline tommymorris

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Re: Yeast Mutation
« Reply #10 on: December 02, 2020, 07:43:22 PM »
How long is a piece of string?
2*pi*r where r is the radius of the circle you form with the string.
Sorry Brother. I stole your thunder (#7 above).


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Whoops. I forgot I had already used that joke. Party fouls on my part ;)

Offline ynotbrusum

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Re: Yeast Mutation
« Reply #11 on: December 02, 2020, 08:07:34 PM »
I have experienced petite mutants arising in a single batch that was stressed in one way or another (typically underpitched, fermentation temperature issues, or similar stressor during fermentation).  Once there, I am not sure how to rid the slurry of the problem mutant presence, though plating and culturing would be one way that comes to mind.

Improvement of the beer by the existence?  I suppose it’s possible if that expression is something sought in the style (4VG, perhaps or clove character in a Hefeweizen)?

Others may have specific stressors that they seek in a style
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Offline TXFlyGuy

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Re: Yeast Mutation
« Reply #12 on: December 02, 2020, 08:40:25 PM »
I have experienced petite mutants arising in a single batch that was stressed in one way or another (typically underpitched, fermentation temperature issues, or similar stressor during fermentation).  Once there, I am not sure how to rid the slurry of the problem mutant presence, though plating and culturing would be one way that comes to mind.

Improvement of the beer by the existence?  I suppose it’s possible if that expression is something sought in the style (4VG, perhaps or clove character in a Hefeweizen)?

Others may have specific stressors that they seek in a style

Thanks. In our case with acute over pitching, might that cause mutation?
Note that my 8th generation of W-34/70 seemed just fine after rousing it with some fresh wort. It is now chugging away in another Euro-Lager.
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Offline Saccharomyces

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Re: Yeast Mutation
« Reply #13 on: December 02, 2020, 11:01:15 PM »
My experience has been that each successive generation will actually perform better than the previous generation, up to a point. Is this the result of mutation? No. It is because the cells are fat and happy and healthy because they have been repeatedly and extremely well-fed on the food source they like the most.

Your observation is absolutely correct. Yeast cultures do in fact improve in performance up to a point.  It is called adaptation. Sadly, that is selective, cropping technique, and yeast genetics dependent.  I am of the firm belief if one serially crops selectively and does not over pitch, what will happen is that yeast cells not well adapted to one's selection criteria will be winnowed out leaving those that perform well in one's brewery. 

Offline TXFlyGuy

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Re: Yeast Mutation
« Reply #14 on: December 02, 2020, 11:43:24 PM »
My experience has been that each successive generation will actually perform better than the previous generation, up to a point. Is this the result of mutation? No. It is because the cells are fat and happy and healthy because they have been repeatedly and extremely well-fed on the food source they like the most.

Your observation is absolutely correct. Yeast cultures do in fact improve in performance up to a point.  It is called adaptation. Sadly, that is selective, cropping technique, and yeast genetics dependent.  I am of the firm belief if one serially crops selectively and does not over pitch, what will happen is that yeast cells not well adapted to one's selection criteria will be winnowed out leaving those that perform well in one's brewery.

Good info. I am cutting back slightly on pitch rate.
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