Interbreeding in Yeast

[dr_bollinger]

I was recently considering why every "house strain" of yeast seems to consist of a single strain, rather than multiple co-existing strains. All of the well-known, old, European beers seem to use only a single yeast strain (e.g., Wyeast 1084 Irish Ale, which is a single strain of Saccharomyces cerevisiae and is understood to be the Guinness strain).

Contrast that with Treehouse, which apparently pitches a blend of S04, T58 and WB06.

It occurred to me today that interbreeding might be the answer. In other words, Guinness may have started with a diversity of strains of S. cerevisiae as their "house strain", which strains interbred over the centuries and became a single strain (possibly with characteristics from all of the founding strains).

Does anyone know the speed at which strains of S. cerevisiae interbreed? If Treehouse were to re-pitch the dregs from earlier batches, would S04, T58 and WB06 eventually interbreed to form a single strain unlike any of the individual founding strains? If so, how long would that take? Is the same true with strains of single species of Brettanomyces yeast and Lactobacillus bacteria?

 

[cire]

I was recently considering why every "house strain" of yeast seems to consist of a single strain, rather than multiple co-existing strains. All of the well-known, old, European beers seem to use only a single yeast strain (e.g., Wyeast 1084 Irish Ale, which is a single strain of Saccharomyces cerevisiae and is understood to be the Guinness strain).

Contrast that with Treehouse, which apparently pitches a blend of S04, T58 and WB06.

It occurred to me today that interbreeding might be the answer. In other words, Guinness may have started with a diversity of strains of S. cerevisiae as their "house strain", which strains interbred over the centuries and became a single strain (possibly with characteristics from all of the founding strains).

Does anyone know the speed at which strains of S. cerevisiae interbreed? If Treehouse were to re-pitch the dregs from earlier batches, would S04, T58 and WB06 eventually interbreed to form a single strain unlike any of the individual founding strains? If so, how long would that take? Is the same true with strains of single species of Brettanomyces yeast and Lactobacillus bacteria?

It might be that White Labs and Wyeast yeasts are single strain. British breweries rejected Hansen's pure uni-strain yeasts en masse as probably did many other Eurporean breweries.

 

[ong]

I would imagine part of this is that it would be very difficult to ensure a consistent ratio of strains in end product. And as packets get older, one strain might become more dominant.

 

[RPh_Guy]

interbreeding might be the answer.

Yeast don't "breed", so no. Reproduction is asexual.

Strains can outcompete eachother, and since the discovery of microbiology, I imagine breweries prefer single strains for clean beers because they're a lot more predictable and give more reproducible results than mixed cultures.

Cheers

 

[day_trippr]

Generally, it is true that yeast reproduction is an asexual process. However, sexual reproduction in S. cerevisiae does happen...occasionally...

Cheers!

 

[RPh_Guy]

Generally, it is true that yeast reproduction is an asexual process. However, sexual reproduction in S. cerevisiae does happen...occasionally...

Thanks

I guess this quote from the article apples to the OP:
"relatively little is known about the importance of sexual versus asexual reproduction and inbreeding versus outcrossing in shaping genome evolution in this species."

 

[S-Met]

Generally, it is true that yeast reproduction is an asexual process. However, sexual reproduction in S. cerevisiae does happen...occasionally...

Cheers!

Just like real life, crazy **** can happen when alcohol is in the mix.

 

[Northern_Brewer]

I was recently considering why every "house strain" of yeast seems to consist of a single strain, rather than multiple co-existing strains. All of the well-known, old, European beers seem to use only a single yeast strain (e.g., Wyeast 1084 Irish Ale, which is a single strain of Saccharomyces cerevisiae and is understood to be the Guinness strain).

Your starting premise is way off base. Historically multistrains were the norm in "all of the well-known, old, European beers" - as has been mentioned, Hanssen encouraged much of Europe to switch to single strains but almost all British breweries stuck with their traditional multistrains, mostly until they switched to conicals in the 1970s, but a few still have their old yeasts even to this day. Some of them are repitching yeast with 8+ strains, and have been doing so for decades. In general yeast evolves and becomes more "multi-strainy" with time.

You're seeing an artefact of yeast labs selecting just one strain out of a multistrain and selling it to homebrewers, it doesn't mean that the single strain is the only one being used by the "real" brewery.

Conversely Treehouse is relatively unusual in pitching a blend of commercial yeast - but they are constrained by a decision to only use dry yeast, which restricts their choice of strains and means that they aren't reusing yeast at all (which costs, but saves them the cost of a lab as all QC is outsourced to Fermentis).

Wild yeast is well capable of sexual reproduction, domesticated brewing strains tend to do it reluctantly if at all - must be all that time spent in monasteries!

 

[bierhaus15]

On the topic of Guinness, most breweries at the time used yeast from many different breweries; a strong belief being that you needed to mix different yeasts together to maintain "vigor." Guinness' had 7 different strains in their pitching yeast at one point and really only began using a single strain in the late 1960's. Interestingly, in 1899 a Guinness chemist identified 2 strains of Brett yeast in their primary brewing culture, but it was not know as Brett by that time. It has been suggested that their current yeast came from one of the Burton breweries, although the recent genetics on that are a bit hazy. You could argue that the whole yeast genetics thing for UK breweries is mostly moot, since virtually all the older UK breweries practiced intensive yeast mixing for most of their history.

 

[dr_bollinger]

Interesting -- thanks guys! This is really informative. I didn't realize that historical yeast cultures were so heterogeneous.

On the topic of Guinness, most breweries at the time used yeast from many different breweries; a strong belief being that you needed to mix different yeasts together to maintain "vigor." Guinness' had 7 different strains in their pitching yeast at one point and really only began using a single strain in the late 1960's. Interestingly, in 1899 a Guinness chemist identified 2 strains of Brett yeast in their primary brewing culture, but it was not know as Brett by that time. It has been suggested that their current yeast came from one of the Burton breweries, although the recent genetics on that are a bit hazy. You could argue that the whole yeast genetics thing for UK breweries is mostly moot, since virtually all the older UK breweries practiced intensive yeast mixing for most of their history.

Does this mean that Guiness was collecting krausen or dregs from multiple breweries, then pitching a mix of those yeast cultures, some from each brewery? I would love to know more about this.

Your starting premise is way off base. Historically multistrains were the norm in "all of the well-known, old, European beers" - as has been mentioned, Hanssen encouraged much of Europe to switch to single strains but almost all British breweries stuck with their traditional multistrains, mostly until they switched to conicals in the 1970s, but a few still have their old yeasts even to this day. Some of them are repitching yeast with 8+ strains, and have been doing so for decades. In general yeast evolves and becomes more "multi-strainy" with time.

Are you saying that labs have tested the house yeasts of those breweries and have determined that they contain 8+ strains? If that's the case, why don't Wyeast, etc., sell commercial cultures consisting of all of those strains?

 

[Northern_Brewer]

Does this mean that Guiness was collecting krausen or dregs from multiple breweries, then pitching a mix of those yeast cultures, some from each brewery? I would love to know more about this.

In the 19th century it was reasonably common for yeast to go "off", so it was fairly normal for breweries to buy in or otherwise acquire yeast from other breweries - the Edinburgh breweries were particularly notorious for this. It sounds like bierhaus is referring to a specific period of 41 brews in 1810-1812 where Guinness used yeast (probably each multistrains?) from 7 different breweries - but they were probably kept separate. As hygiene and inhouse labs improved, breweries became better at maintaining a house strain, so you find that most of the British regional brewers started to have a house strain after WWII or so.

Guinness had better labs than most, so made that move a bit earlier than some. By 1931 they'd identified 4 strains within their house strain, it looks like they moved to single strains (different for Dublin stout, FES and London stout) fairly soon after WWII. That's unusually early for a brewery in the British Isles - most but not all moved to a single strain (or at most a double strain) with the move to conicals in the 1960s/1970s.

Are you saying that labs have tested the house yeasts of those breweries and have determined that they contain 8+ strains? If that's the case, why don't Wyeast, etc., sell commercial cultures consisting of all of those strains?

Yes - in fact that's just from a microbiological point of view, DNA analysis turns up even more.

Because it's a monumental PITA maintaining consistency in multistrains, and the yeast labs want a simple life, and single strains are good enough for 99% of homebrewers. But you're seeing it a little bit with some of the smaller yeast labs selling multistrains of kveiks for instance.

 

[dr_bollinger]

In the 19th century it was reasonably common for yeast to go "off", so it was fairly normal for breweries to buy in or otherwise acquire yeast from other breweries - the Edinburgh breweries were particularly notorious for this. It sounds like bierhaus is referring to a specific period of 41 brews in 1810-1812 where Guinness used yeast (probably each multistrains?) from 7 different breweries - but they were probably kept separate. As hygiene and inhouse labs improved, breweries became better at maintaining a house strain, so you find that most of the British regional brewers started to have a house strain after WWII or so.

Guinness had better labs than most, so made that move a bit earlier than some. By 1931 they'd identified 4 strains within their house strain, it looks like they moved to single strains (different for Dublin stout, FES and London stout) fairly soon after WWII. That's unusually early for a brewery in the British Isles - most but not all moved to a single strain (or at most a double strain) with the move to conicals in the 1960s/1970s.



Yes - in fact that's just from a microbiological point of view, DNA analysis turns up even more.

Because it's a monumental PITA maintaining consistency in multistrains, and the yeast labs want a simple life, and single strains are good enough for 99% of homebrewers. But you're seeing it a little bit with some of the smaller yeast labs selling multistrains of kveiks for instance.

I would love to learn more about historical English brewing practices. Can you recommend any books or resources?

 

[Northern_Brewer]

Obvious places to start are :
https://barclayperkins.blogspot.com
http://zythophile.co.uk
http://beeretseq.com
abetterbeerblog427.com

But there's not really a single nice book about this stuff - and to be honest a lot of the yeast stuff tends to be couldawouldashoulda stuff until the mid-20th century or even later, I'm not entirely sure I believe some of the stories you hear from brewers in the 1970s. But if you start with the above and follow some of their links, and Google things you're specifically interested in, you'll be better-informed than most people.