The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Do indigenous microorganisms prevail?

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Janet Yang's picture
Janet Yang

Do indigenous microorganisms prevail?

I keep reading on the Internet that a starter will change character according to locale. For example, the culture that you created in San Francisco may start out full of Lactobacillus sanfranciscensis, but if you move it to the east coast, the starter will gradually become overrun with L. barharbor or the like and lose its SF flavor.

But why should this happen? Look at me—I'm not indigenous to New Jersey, and as an Asian I am definitely in the minority, yet I'm still here. Thriving, in fact, probably because I'm just as healthy as anyone and we're not competing over a scarce food supply.

Seems to me that as long as the starter is well fed, the various microorganisms ought to be able to hold their own. But that's just a theory. In actual practice, do imported starters become domestic?

Janet 

totels's picture
totels

But why should this happen? Look at me—I'm not indigenous to New Jersey, and as an Asian I am definitely in the minority, yet I'm still here. Thriving, in fact, probably because I'm just as healthy as anyone and we're not competing over a scarce food supply.

You're also not a eukaryotic microorganism ...

The analogy is probably more accurately something like:

100 clones of you move to Australia. They are only allowed to mate with natives. How many generations does it take before your genetic material is basically drowned out in your ancestors?

I'm not a microbiologist. So far as I understand, when you feed your starter, you are mixing in local cells. They are in the air, in your flour, on your hands, on your spoon etc. Each feeding can only add cells from the local flora (unless you import, of course). I don't believe it is a fast process. You can probably prolong the inevitable by only feeding with the most processed and whitest flour you can find, avoid Rye and WW and probably anything organic(though this might be a stretch).

Janet Yang's picture
Janet Yang

Do the Lactobacilli cross-breed? I'm not questioning it; I just don't know—also had to look up the definition of "eukaryotic" :)

Janet

Mini Oven's picture
Mini Oven

Is that you don't reproduce as fast as the bacteria and yeast in the culture.  With each generation small changes can happen.  Tell me your children are exact copies of yourself.

The bacteria and yeast go thru several generations in one feeding. This means that they can adjust quicker to a change in flour.  Feed them a different flour, water, temperature or change the maint. routine, the starter can change.  Especially the bacteria and yeast varieties on the fringes of existence could suddenly be favored or wiped out in a new environment.  It is a hotly debated topic and some starters don't change.  Most do.

There are many threads on the subject in TFL.  Using the site search machine will pull them up.  

dabrownman's picture
dabrownman

is much you can do to keep your starter LAB SF or any other strain.  None of us know what we have growing in that starter anyway.  I'm guessing there are folks that live in SF and don't have LAB SF in their culture but someone in Iowa might since it is found all over the world and not rare or restricted to SF.  What you can do is make your starter be as much as it can be based on what you want it to be, just like many of us are trying to be the best bakers we can be.  You can make it more or less sour depending on what, when, how you feed it and how you store it, make levain with it and the process you use to make your bread with it.  That is where the fun is!  Most starters can do it all regardless of what is in it,  it is the skill of the apprentice and her master that is lacking around here!  But we are working on that :-) 

Happy SD Baking

totels's picture
totels

Yeasts do not reproduce sexually(most reproduce via mitosis, or budding) , so no, they do not cross-breed. It's not a perfect analogy, but about the best I could come up with relating to human reproduction, keeping in the vein of your original.

 

What it boils down to is that merely by being in a different environment, your starter is exposed to new cells that will grow and replace the cells you use or discard. 

chris319's picture
chris319

Totels: Are we to infer that the new cells in the new environment are airborne? Would they be present in sufficient quantities to taint a sourdough starter?

I have never seen anything authoritative, outside of propaganda from a certain bakery in San Francisco, that says C. Humilis and L. SanFran are indiginous to the bay area. The wheat used by a bakery in San Francisco could have been grown and milled in Kansas for all anyone knows and shipped by rail to S.F. It would be interesting to find out.

totels's picture
totels

No inference needed, yeasts are well-known to be airborne. Indigenous probably isn't exactly the right word for L. sanfranciscensis, while true it was originally discovered in sourdough in San Francisco, it is not exclusive to the city or the region or even the country. It was named after San Francisco merely because it was discovered there. This would be like saying Lou Gehrig was the only person that could get Lou Gehrig's disease. Eponymous the city may be, exclusive it is not.

I'm not sure "taint" is the right word either, but yes, these airborne yeasts are exactly what we use to create a homemade starter. There are stories of french bakers denying schoolchildren into their bakeries because they were afraid the children would bring unfavorable spores into his kitchen. It is possible to "mix" two strains of yeast simply by setting two open jars of starter next to each other.

The truth is that most yeasts live just about everywhere, some are better able to survive in different conditions and thusly are more prevalent. By controlling the conditions of your starter you can control which yeast prevail (see: http://www.ncbi.nlm.nih.gov/pubmed/14660398).

suave's picture
suave

No, they are not airborne, there have been studies that showed that when starter composition changes with time the source of new bacteria is flour.

suave's picture
suave

There's no definitive answer to your question.  Yes, sometimes, may be.  Who knows?  At this point in time there is no real way to determine composition of the starter, so it's all conjectures, speculations, and personal opinions.  And even if genetic testing were available to home bakers and you could detect a change, how would you go about figuring the root cause?  Is it flour?  Water?  Cross-contamination?  It'd be a nice little project with some DOE involved.

DoubleMerlin's picture
DoubleMerlin

Hey y'all

I'm a food scientist student directly studying this phenomenon. My microbiologist professor believes if you inoculate a starter with certain cultures, those cultures ought to have remnants in the later starter. Every bread baker says otherwise. Thus the need for research.

All I'm trying to do is see if inoculation gives a consistent population. Jeez it's work....

totels's picture
totels

Definitely looking forward to seeing these results.

I don't think I would doubt that the original culture would/could have remnants, but would be curious to see how quickly they are replaced/lost and if there is some method that might prevent it or how to best control it (understood presently as temperature and flour used to feed).

DavidEF's picture
DavidEF

As has been mentioned, using as close to sterile ingredients as possible will tend to favor keeping your original culture. White refined flour and clean bottled water. But, that may not be enough in the long run, because local yeast are naturally everywhere. As far as changing flavor characteristics, I believe that dabrownman is right that there are more important variables than the actual strain of yeast, and many of those variables are within our control as bakers, once we understand them a little.