Local-Global Sourdough Swap

Samantha Point

I am currently living in Toronto, Canada.

In the past, I have dehydrated a Toronto-based sourdough starter (which I believe, when dehydrated in the right way can preserve the yeast), and sent them to friends around the globe in hopes of collecting versions of thier local yeasts as well (for which I received none).

I would love to take this idea and share it with the people in this forum. If people are interested in trading a dried version of thier own local yeast, I would be happy to mail some local Toronto sourdough yeast in exchange.

Perhaps somethign like this already exists. If so, I would love to know where I can go to get involved with it!




204 users have voted.


farinam's picture
farinam 2013 January 1

Hi Samantha,

I would be happy to send you some dried starter.  However, I sort of doubt the value of the exercise because I think the yeasts and bacteria are all essentially the same the world over and even if they are not, the 'local' ones would soon come to predominate.

If I am off the track, then undoubtedly the micro-biologists out there will soon put me straight.

If you want to proceed, send me a private message with your address and I will get some to you in due course.

Keep on bakin'


shasta's picture
shasta 2013 January 2

Hi Farinam & Samantha,

I'm not sure where I stand in the debate on how a starter would evolve over time in a different location. It sounds logical to me that once a starter has been relocated to a new area that it would soon evolve and be predominated by local yeasts. I have also read that studies have shown that starters get most of the yeast from the flour it is fed. So it could be argued that if you change the flour that you feed a starter that it will evolve to the yeast that predominate in the new flour.

However, there are many bakers out there that have several starters from different locations and swear that they each maintain their distinct characteristics.

The author at the link below does a comparison of 4 different starters that she keeps. She feeds them the same amount of food at the same time and they each react differently over a period of hours.


 I myself have my own starter that I started from scratch 2 years ago here in Shasta County, California. I also acquired some Carl Griffith's 1847 Oregon Trail Sourdough Starter about a year and a half ago. The two starters do act differently but I have to admit that I don’t keep the Carl's starter active all the time. I dry it out and restore it when I want to use it. The most I have had it active has been about two months. So was that long enough for it to evolve? I don't know. I have also recently acquired some starter form Graham at Companion Bakery in Tasmania, Australia. Although I have to admit that I feed it different flour than I do my own starter, it definitely reacts slower than my own starter. I get much longer proof times with it. In one of my correspondence with Graham about the starter, he indicated that it would evolve into a unique culture.

So maybe that is it. Maybe a transplanted starter will retain some of its original characteristics but also gain new ones based on location and flour that it is fed, making a unique culture. I plan on keeping my new Australian starter going along with my original starter indefinitely to try to see for myself.  I would be willing to send samples of my original starter to anyone that would like to try it. I can eve pass along a sample of my Carl’s 1847.

oldman 2018 November 10

Hi. I'm new to the site and browsing, but the issues discussed in this post interest me.

A starter is basically a colony of bacteria in a symbiotic relationship with various species of yeast.  These colonies are stable over long periods of time is maintained properly.  By stable I mean that the balance between the various microorganism that make up the starter is maintained.

People will tell you that most of the yeast in a starter comes from flour.  This is usually true for a new starter.  Yeast eat flour.  It's the best place to find them.  But that doesn't mean they aren't introduced from the environment too. And when bacteria grows in your starter the local environment for the yeast living in your starter changes.

When you activate a new starter with a sample from a previously stabilized starter you are establishing a new colony where compatible yeasts and bacteria are present.  Rather than wait for a balance to be achieved, you start with species you know work well together, even if you don't have any idea which species they are.  Wild yeast that join the party don't usually last.  They die off before the can change the starter much because the bacteria and yeast already present are not only taking up most of the dance floor, but they also own the club.

Each start is its own club.  Sam's Toronto starter might be mild and sweet (NewAge coffeehouse?).  My Berlin starter is sour and big bubbled (punk rock rave).  If I sent Sam a sample of Otto and she started it and fed it in Toronto. Otto would still be Otto because NewAge coffeehouse yeast from the environment wouldn't thrive in Otto's rave. 

Neither would swing dance yeast or wild waltz yeast from the flour.  You might get some Toronto punk rock yeast from somewhere.  But they'd join the rave, not take over.  They couldn't join the rave if they weren't able to thrive with the established bacteria. And they can't take over unless they're better adapter to the environment that yeast that's been adapting to the local starter for thousands of generations.

This is not to say that the starter never can change.  Just that it isn't as likely as you'd think.  Even if you weren't introducing any new yeast or bacteria you'd get mutations in yeast and bacteria.  But the mutations aren't likely to have significantly different characteristics than their recent ancestors.  And even the one's that do aren't necessarily going to thrive in an environment they are optimally adapted for.  Since yeast and bacteria reproduce asexually the best adapted individuals will dominate and the starter will be stable, and have a unique set of characteristics even if it's reestablished in a new location.


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