WLP099 and maltotriose

I posted a similar post in the ‘Milk The Funk’ Facebook group recently, and thought I’d copy it over to the blog as well. This post will be about White Labs’ WLP099, which I’ve been using recently for some fermentations. What are people’s experiences with it? Reading around on various homebrew forums etc. you get the impression that this yeast is a monster that will eat through everything you throw at it. Some people are even reporting that it ferments worts down to specific gravities closer to 1.000 (just do a search for “WLP099” on Homebrewtalk). This is very much in contrast to my own experiences with. Using single cell isolates of it in test fermentations, I’ve noticed that it is unable to use maltotriose, and usually ends up with attenuations of around 70% in wort. The only other similar experience I found after googling around was (apparently with input from Mr. White himself):


This of course very much goes against the fact that this yeast could ‘super-attenuate’ plain wort (which would at least require the use of maltotriose, and possibly even longer sugars). So I guess these high attenuations can only be achieved in worts supplemented with simple sugars? Another possibility is that the yeast is actually a blend (either intentional or unintentional; more on this later below).

I did some more digging, and came across this recent study by Borneman et al.:


In it they’ve sequenced a set of mostly wine strains, but they’ve included some White Labs strains as well: one of which is WLP099. Interestingly, it was found to belong to the wine yeast clade. So the fact that it actually seems to be a wine strain, would explain the lack of maltotriose use (and would fit with it having good ethanol tolerance). This paper unfortunately doesn’t go into physiology.

Another study that probably included this strain and does go into physiology is of course the recent Gallone et al. paper:


The strain names are unfortunately encoded, but I did some more digging. Going by the fact that WLP099 is POF-, I looked at the SNPs in the sequences of its PAD1 and FDC1 genes using the reads from the Borneman et al. paper:


Cross-referencing with all the sequences from the Gallone et al. paper, I was able to find only 7 strains containing the same SNPs (Beer024, Beer033, Beer088, Spirits002, Wine001, Wine009 and Wine013); all seven of which belong to the wine clade! Of these strains one, Beer033, seems to have a familiar origin and description (from Table S1): England, Beer (Strong Ale). I think we’ve found WLP099. Anyways, looking at Figure 3 and Table S5 we see that this strain doesn’t use maltotriose! Five of the other six strains which it could be also don’t use maltotriose. Beer088 is the only strain with the same SNPs which uses maltotriose, but its origin is Germany so it’s unlikely that strain would be WLP099.

So, looking at the different independent evidence (my own ferments, the forum post with the apparent input from Chris White, and the Borneman et al. and Gallone et al. papers) it looks like WLP099 is actually a wine strain and I think we can say for sure that it doesn’t use maltotriose and thus won’t super-attenuate in wort, unless it has been supplemented with simple sugars. So regarding finishing off high-gravity ferments with this yeast, it looks like it is only useful for worts to which you add sugar. In worts made only from malt, WLP099 would likely have little to no effect when adding it as a secondary yeast (i.e. when all of the monosaccharides and most of the maltose has been consumed).

So how are peopling still getting 80+% attentuations with WLP099 as the only yeast in all-malt worts? There was some speculation in the ‘Milk The Funk’ Facebook group, that WLP099 might actually (either intentionally or unintentionally) contain two yeast strains (two independent observations were given). If the other yeast strain was a dextrin-degrading one, such as S. cerevisiae var. diastaticus, it could explain how people are seeing ‘super-attenuation’ with WLP099. These strains produce extracellular glucoamylase enzymes which break down dextrin to glucose molecules, which WLP099 could then easily ferment. But this is of course only speculation!

13 thoughts on “WLP099 and maltotriose

  1. WH

    Nice post.

    It’s funny you say this because I was reading about the belle saison incident, in which it might be S. cerevisiae var. diastaticus, and it made me browse all the other super attenuating yeasts from different labs to see which are listed as 100% attenuation. I have a few so I was planning on making some starch agar plates or broth with indicator to see if they grow. Do you think that’s would be a simple test?

  2. WH

    Also as a side note,

    I wonder if this may be the perfect yeast for Scottish Strong Ales. If you follow barclayperkins.blogspot.com you will see that a lot of the final gravities before getting casked are very high, there are tons of examples:



    I don’t want to put words into Ron’s mouth but I think he speculated that this might be to do with cooling the beer and skimming the yeast before it is finished or finishing high for bottling but perhaps this is another possibility.

  3. suregork Post author

    Starch agar plates would do the trick! Any growth on them and you could be quite sure that the yeast is capable of dextrin degradation. Remember to test your plates with a control strain as well to ensure there are no other fermentable carbohydrates present!

    I’m not that familiar with Scottish Strong Ales, but any maltotriose-negative yeast with high osmo- and ethanol tolerance (such as ‘clean’ WLP099) would be suitable if you want high ethanol and final gravity 🙂

  4. wyeastie

    I was just going to ask about these superattenuating saison yeasts (belle and 3711), but you were faster! These strains are classified as S. cerevisiae but will chew through everything. By the way, what was the incident you mentioned?

  5. WH

    I was wondering if you could solve this mystery?

    Fermentis lists w34/70 as cerevisiae, weihenstephan lists it as pastoranus, in fact all of fermentis’ products are listed as cerevisiae even though this study says it’s pastoranus?


    I tried to contact them but they ignored my email. Mangrove jacks replied to me after I asked them the same question about their yeast and they said that all of their strains are cerevisiae.

    The only dry lager strain I can find which is listed as pastoranus is danstars, diamond lager.

    I’m a bit confused.


  6. suregork Post author

    I must have missed this comment, sorry about that! You might have solved this mystery already, but Weihenstephan 34/70 is definitely S. pastorianus. One would assume that Fermentis is selling that particular strain if they are calling it W34/70, and it is just mislabeled in the product information.


  7. Anton

    Really interesting!

    I have both experienced WLP099 to be a monster (from 1.100+ down to 1.006). That was with a small starter and in the company of S-04.

    And now I have a “stuck fermentation” with it. Went from 1.140 down to 1.067 quick, and then just died..

    Donno what my options are atm. Really want it to be a monster, so my first rescue mission will be to make a new WLP099 starter and re-pitch. Don’t have much faith in that option though, so next up would be 3711 maybe?

  8. suregork Post author

    Hej Anton!
    Sorry to hear about your stuck fermentation. So now you used WLP099 as your only yeast? That might be the cause here for the low attenuation (compared to when you used it with S-04). Maybe try pitching an active starter of WLP099 and another (high attenuation) yeast. 3711 is of course an option, but you then have the risk of unwanted flavors. Maybe US-05/WLP001/WY1056 or WLP099 might be options? Good luck!


  9. qq

    So did you get anywhere with your starch plates?

    Since White Labs are now being sued over batches of WLP090 being contaminated with diastaticus leading to bottle bombs and a US$2m recall, they’re a bit sensitive about the diastaticus thing now. Allegedly they weren’t testing for it at all as of last year. So it’s interesting that the WLP099 page now warns that it has some diastaticus DNA, and attenuation is given as 80-100%, but that doesn’t mean it’s contaminated with diastaticus like the WLP090….

    The identification with Thomas Hardy’s is long-standing, but it could be complicated.

    Roger Protz gives the story of how Hanlon’s recreated it – with two yeasts. The standard Eldridge Pope yeast needed much rousing and progressive introduction of mash in order to cope – and was no good at all for the 6 month secondary fermentation in barrels, for which they used a lager yeast they’d got from Germany for their Faust lager. So if anything had been harvested from a bottle of Thomas Hardy, it would most likely be a alco-tolerant lager yeast. How that squares with Suregork identifying it as a wine yeast in the Gallone paper I don’t know.


  10. Duncan

    I know this hasn’t been active for a while. Just throwing my info into the cauldron.

    Following the thomas hardy recipe from Ron Pattinson. 6 litre starter of WLP099
    pitched into 1.107 wort at 17 degrees and it fermented down to 1.034 in 4 days, crazy krausen on it. I did oxygenate on days 1,2,3 and this obviously roused the yeast.
    I Parti gyled the brew and did a 1.037 with invert added to make up to 1.041 which I also fermented with the same yeast.
    Temperature of ferment up to 23 celsius over a week.
    I collected the yeast from the gyle brew and used that as the pitch of an imperial stout again starting 1.107, fermented again with big krausen and I’ve been feeding it about 100g of dextrose a day with a target of 2kg added in total. So far only 1200g added.
    It doesn’t look like a lager yeast fermenting, not a sulphur bomb either at the higher temperatures, in fact no smell of sulphur at all.
    The Thomas Hardy is in a secondary fermenter with some oak blocks and I’m giving it a swirl daily and seem to get activity increase so it’s probably chugging away. I’ll know in a few months when I decant for bottling.

  11. Duncan

    Gravity check in Mid December 2022 for the thomas hardy ale still at 1.034, so no further ferment.

    I’m going to add white labs bavarian ale yeast to it in secondary now and leave it a couple more months. See if that can nudge the gravity down a bit.

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