Can you genetically sequence sour dough?

06 September 2016

Question

Can you genetically sequence sour dough to find out where the yeast culture came from?

Answer

Kat Arney put this to Andrew Holding...

Andrew - So I think it's a natural fermenting so you don't need to add yeast like you do with normal bread but that's about as far as I know.

Kat - But presuming it's working on microorganisms from the environment.

Andrew - So, a lots of the alcohol you can make without adding yeast is done by the fact there's yeast on the outside of apples. So, I guess there must be yeast somewhere around the place.

Kat - Exactly. So I mean there's yeasts. Did I say there's a beer that someone's making from Roald Dahl's chair or something weird like that? There are yeasts everywhere so presumably, you could sample them and sequence them.

Andrew - You could sequence for yeast. So I mean, maybe I just know too much about alcohol but the yeasts used in different beers, they're very tightly guarded secrets because if you like took a bread yeast into a random beer, it could taste absolutely awful because they make other things at the same time. That's why marmite could be made with different brewer's yeasts. I'm not sure if it tastes any different.

Kat - Tastes disgusting. But I did go and interview someone. They're making little portable labs called the Bento Lab. I think that one of the people using it is just sampling loads of beers to look at the DNA in the yeast and doing a project on that. So I work out if any beers are related to each other and to trace the yeast's facts so that would be a cool project I reckon.

Andrew - The trouble with small organisms is they do of course evolve. They change their genome a lot quicker. So, if you tried this on bacteria, you probably would have trouble trying to pick a pattern because you find these swapping changes all over the place. They do what's called horizontal gene transfer where they don't just evolve in a linear progression. It hands a gene to its neighbour because they can.

Kat - They swap little bits of DNA, don't they? Because I did have this idea of going around all the recording studios and gig venues in London and taking samples from the microphones and to see what germs are going around.

Andrew - Don't do it.

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