As the followers of my blog are likely aware, there has been a growing body of evidence that WLP644 (Brettanomyces trois) is, in all likelihood, a Saccharomyces (conventional brewing) species. I, and other bloggers did a series of genetic tests that pretty firmly nailed down the genus of WLP644 as Saccharomyces (although the exact species remains somewhat nebulous).
Many brewers have been directing questions at White Labs about this, and their reply to-date has been rather guarded. Today, they broke their silence (PDF), and confirmed that trois is, indeed, a Saccharomyces. Ironically, they’ve based this on a far less robust measure than the data myself and others have generated – they determined the genus simply by looking at the size of one of the regions myself, and others, sequenced to ID this yeast.
White Labs has an extensive sequencing project on-going which I expect will reveal to us some exciting (and perhaps upsetting) data on the yeast strains we know and love. While WLP644 is clearly a Saccharomyces, the exact species remains unclear – indeed, one of the sequences we have floating around suggests it may be something all together new. Indeed, white labs is rather guarded in their conclusions (they call WLP644 a “brux-like Trois”), which makes me suspect they too didn’t get a clean species ID on the yeast.
More updates to come as more information becomes available.