New & Noteworthy
April 15, 2013
Anyone reading the SGD blog knows that the yeast Saccharomyces cerevisiae is an amazing little organism. Not only does it give us bread, wine and beer, but it also is an invaluable tool in understanding human biology. It has helped us better understand cancer, Alzheimer’s, and lots of other diseases, not to mention basic biological processes like gene regulation and cell cycle control. This little one celled beast is the rock star of biology!
And now, finally, government is starting to take notice. In a 58-0 vote, the Oregon House recently decided that yeast should be the official state microbe. If the Senate and the governor agree, then yeast will be getting the recognition it deserves. Take that, C. elegans, Drosophila, and all of you other model organisms!
Unfortunately, this recognition is not for yeast’s scientific value. Craft beer making is huge in Oregon, and designating yeast as the official state microbe is a way of celebrating this important state industry. Given all of yeast’s other important contributions to the well-being of us all, this feels a bit like celebrating Hugh Jackman for his role as Wolverine in X-Men while ignoring his roles on Broadway or his role as Jean Valjean in Les Miserables. Yes, he was great in X-Men, but that is an incomplete picture of him as an actor. Same thing with yeast.
Yeast should be celebrated for wine and bread, for medicines like anti-malarials and antifungals, for the deep biological understanding it has given us, and even for its possible future as a source for biofuels. Still, this honor is way better than nothing, and at least yeast will be the first microbe officially recognized by a state. Well, it will be if Oregon hurries.
Hawaii is voting on an official state microbe too, Flavobacterium akiainvivens. This bacterium was discovered by a high school student during a science fair project and is only found in the state of Hawaii. The Oregon senate should vote soon, or yeast will be the second officially recognized microbe.
Of course, the bill could die in the Senate. This is what happened in Wisconsin back in 2009 when their House passed a bill making Lactococcus lactis the official state microbe. This bacterium is important for making Wisconsin’s famous cheese but it wasn’t important enough for the Senate to approve it as Wisconsin’s official state microbe. Hopefully Oregon won’t make the same mistake with yeast.
November 19, 2012
A study by Blasco and coworkers confirms that beer foam is littered with corpses of dead yeast. Or at least with bits of their cell walls.
This has been known for awhile. But what these researchers did was to identify one of the key proteins in the cell wall important for maintaining a good head on beer.
The authors knew from previous studies that certain mannose binding proteins play an important role in beer foam. So they used primers that lined up with the 5’ and 3’ ends of one of the known foam-related genes from S. cerevisiae, AWA1, to look for similar genes in the brewing yeast S. pastorianus. This allowed them to PCR out the CFG1 gene.
To show that this protein was involved in the foaminess of beer, they next knocked the gene out of S. pastorianus and used this deletion strain to do some brewing. What they found was that while beer made with this strain had about the same amount of foam, it didn’t last as long. This strongly suggested that CFG1 was involved in maintaining a good head on a mug of beer, earning the gene its name: Carlsbergensis Foaming Gene.
As a final experiment, they added the gene back to a strain of S. cerevisiae, M12B, that makes beer without foam. When this strain expressed CFG1 and was used to brew up some beer, that beer was foamless no more. This suggests that CFG1 may be important for foam formation as well as stabilization.
What is probably happening is that during fermentation, yeast cells are autolysing, releasing their cell wall proteins into the beer. Since Cfg1p is hydrophilic on one end and hydrophobic on the other, it forms very stable bubbles. And foam is simply a bunch of stable bubbles.
Hopefully scientists can use this information to tweak the amount of foam a given beer yields. Then a drinker can choose lots or little foam, long lasting or short lived foam, or any combination he or she wants.
Root beer foams for a different reason
October 16, 2012
Small time craft brewers are always looking for ways to push the envelope of beer taste. They are trying to find variations in beer’s fundamental ingredients — hops, barley, and yeast — that will make their beer distinctive. Of these three, the most important is probably yeast (of course, we’re biased here at SGD!).
Something like 40-70% of beer taste comes from the yeast used to make it alcoholic. This is why brewers search high and low for new strains of yeast that will give their beer that special something which will make it stand out. They have looked on Delaware peaches, ancient twigs trapped in amber, Egyptian date palms, and in lots and lots of other places.
But brewers don’t always have to go far away because sometimes the best yeast is right under their noses. Literally.
A brewery in Oregon found the yeast they were looking for in one of their master brewers’ beards. They are now using this yeast to brew a new beer! This seems uniquely revolting but the beer supposedly is quite tasty. Perhaps if they don’t advertise the source of their yeast, this beer could become popular.
They aren’t sure where the yeast in his beard came from, but they think it may have come from some dessert he ate in the last 25 years or so (he hasn’t shaved his beard since 1978). What would be fun is if his beard wasn’t just an incubator, but a breeding ground for new yeast. Maybe yeast from a dessert from 1982 hooked up with a beer yeast blown into his beard while he was working at the brewery. The end result is a new improved hybrid yeast!
Of course we won’t have any real idea about this yeast until we get some sequence data from it. And all kidding aside, the more yeast that are found that are good for making beer, the better the chances that scientists can home in on what attributes make them beer worthy. So this beard borne yeast may help many beers in the years to come despite its troubling beginning.
Perhaps brewers also need to start searching through more beards to look for likely beer yeast candidates. Beard microbiome project anyone?