There's a
new preprint out from the Dunham lab in Seattle that is mostly looking at what happens to yeast genomes as they are repitched, but they also sequenced all the Chicos they could find to get an idea of the background diversity.
View attachment 687412
The sequences were filtered against Gallone BE051 (almost certainly WLP008 East Coast) as the most divergent US strain they had.
You can see two main groups in the bottom of the chart (Fig 2 in the paper, which I've annotated in green), one based around Wyeast 1056 that includes US-05 and Imperial A07 Flagship (and "Imperial M44" - they're double checking that, it may be Mangrove Jack M44??), and one group based around White Labs WLP001 that includes the Chicos from Gigayeast, Escarpment, Craft Cultures, Omega and the old Wyeast VSS strain 1792 (Fat Tire).
If I read it right, I think they're saying that a hypothetical ancestor (at Sierra Nevada ?) of the 1056 and WLP001 groups had a A234D mutation in BAT1, a branched-chain amino acid(BCAA) aminotransferase, but the WLP001 group has a recombination on one end of chromosome VIII that restores the wild type. This seems to be a weak point in the chromosome, as the recombination seems to happen a fair bit independently. They're submitting another paper just on the BAT1 story, but "the mutation led to a number of phenotypes including a sensitivity to osmotic stress, reduced fermentation ability when grown in 20% glucose [~1.075], and a growth defect in minimal media" Per Table 3 the mutants also produce more isoamylacetate ("banana") and fusel alcohols. However the strains with the chromosome recombination don't ferment out quite as fully, and also show more diacetyl.
Both the WLP001 and 1056 groups mostly have just three copies of chromosome V, but their putative ancestor BRY-96 has four copies (green and blue squares respectively in diagram). Again this seems to be something that is rather fluid, but they observed four copies arising in a population of 1056 and spreading as it was repitched in a brewery. It could be something that gives a selective advantage in some environments but not others, or it could be just a random thing that happened at a bottleneck on the way to 1056 and WLP001.
I read "The strain BRY-96, which is used in Elysian Brewing Co." as meaning that Elysian buy in BRY-96 direct from Siebel/Lallemand, their version is certainly very close to a version sourced from Lallemand. The tree fits
previous suggestions that A30 Corporate is derived from Elysian one way or another and it's the closest strain to BRY-96 that's commercially available, but the strain sourced from Elysian is closer to BRY-96 than it is to A30. Also it looks like Bell's yeast is a BRY-96 that's spent some time evolving away from Siebel.
It's interesting the way that the "San Diego/Pacman" group are distinct from the main BRY-96 family - and how did BE082 get to Belgium?
@suregork and friends were already pretty certain that BE071 was WLP090 and this rather confirms it (also BE098 as 1056, and this tree rather suggests BE102 was US-05)
However, one surprise is that they reckon that NRRL Y-7408, isolated from Ballantine in 1972, is probably a cousin rather than an ancestor of the BRY-96 group, based on "large segments of variation" that it has lost compared to the BRY-96 group. Presumably BE065 has also lost them.
BE065/68/69 were the main uncertainties in the main run of White Labs yeasts in the original Gallone paper. Two obvious candidates are
WLP019 California IV and WLP076 Old Sonoma (New Albion) but we can't be sure - BE044-086 were pretty much all the White Lab strains in numerical order, but they may have eg had some strains from commercial customers of theirs in there somehow. Is SNPA BE007 or BE068?
There's also a ton of detail on how yeast genomes change over time, but that's another story....
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