Add "Lachancea thermotolerans" to Your Wild Yeast Checklist

Source: UC Davis

Scientific American has a fascinating article about a new yeast strain pulled from a bumblebee with the capacity to ferment beer. (It is, parenthetically, an absolute train wreck on beer facts. If it weren't for the huge payoff, this post might have been a pedantic scolding instead.) It's an interesting strain, with the capacity to do both lactic and alcohol fermentation. Here's a bit from a presentation about the research:

Isolated and propagated at North Carolina State University, a novel strain of yeast, Lachancea thermotolerans NCSU, has been investigated for its application as a single-strain brewing yeast.... . L. thermotolerans NCSU has proven to be a viable brewing yeast in laboratory and pilot-scale fermentations, as it fermented the principal wort sugars (i.e., maltose and maltotriose) while producing CO2, ethanol, glycerol, and lactic acid. In a pilot-plant scale fermentation of lambic-style wort (malted barley and wheat, OG 1.057), L. thermotolerans NCSU was able to produce 6.8% ABV and reduce the pH to 3.60 (FG 1.005). The capability to produce beer with L. thermotolerans NCSU will provide brewers with an alternative to Saccharomyces for creating innovative beer styles and flavors using a single strain of yeast.

The principal benefit of this strain, these scientists argue, is this:

With its ability to produce lactic acid, novel sour beers can be created without the risk of bringing bacteria or other “contaminant” yeasts into the brewhouse.

Maybe. This may well not be the advantage they believe it to be. Kettle souring is pretty safe. The wort gets boiled in the kettle, killing the bacteria so it doesn't continue on in the brewhouse. Also, how virulent is the strain? Brettanomyces is a pure yeast strain, too--not a spoilage microorganism--and it's plenty dangerous in the brewhouse. But most importantly, there's little information about how much control a brewer has over the amount of acidification L. thermotolerans kicks off. So maybe some further thinking about this needs to be done.

If you Google around, you'll see some folks have already started brewing with it, with mixed results. There are a few technical papers scattered around, too, but I think we're going to have to wait until brewers really start tinkering with this little beast before we know what its potential is. In any case, fascinating stuff