How does sourdough (wild yeast) starter differ from location to location?

You're right, sourdough starters are different everywhere, based on what yeasts and bacteria are prevalent in that specific location. Certainly climate and altitude affect the living things that float around, so in turn those variables affect starters. I don't know about the poles or the peaks of Denali or Everest, but you can make a perfectly good starter everywhere else, they will have their own character everywhere you go. Even a distance of a few miles can drastically change the flavor and behavior of your starter. Some places have less or slower to grow natural yeast, so starters can take longer in some places to be ready, but it will happen eventually.

Some places, San Fransisco for instance, are well known for their local starters. You can buy San Fransisco sourdough starter online, but your bread will only taste like San Fransisco Sourdough for a few days or a couple of weeks. If you keep that starter alive, it won't take long before it takes on local yeast and bacteria and creates bread that tastes like the sourdough made by everyone else in the neighborhood.

The bottom line is that without speaking to another maker of sourdough in your immediate area, you can't really predict how fast your starter will grow, how often it will need to be "fed" or what your bread will taste like. Allow for some variance due to location, but standard recipes and techniques will work just about everywhere. Once you've made a few loaves, you'll get to know your local yeast!

The different microorganisms available from location to location will affect the composition of your starter to an extent. While there are tons of different beasties that can each contribute different characteristics, they aren't as location dependent as you might think. For instance, lactobacillus sanfranciscensis, the lactic acid producing bacteria responsible for San Francisco sourdough is found all over the world. What matters most is actually the conditions that you grow your culture in. Sort of "location in your house" vs "location in the world". The differences in regional sourdough breads are more likely caused by regional differences in how the dough is handled. For instance, in many European baking traditions, a small portion of starter will be used in bread that will be proofed and baked in the same day. In San Francisco, many bakeries first make a sour sponge, then incorporate a large portion of that into the final dough which will get both a long bulk fermentation, and a long final proof, sometimes totaling over 70 hours!

Some tips to control the character of your culture are: lactobacteria prefer warmer (as in room temperature) environments, where as the organisms that produce acetic acid grow best in a cooler environment. Lactic acid is also produced more rapidly in a wet culture, and acetic acid in a dry culture. You can further manipulate these by adjusting your feeding intervals and the carbohydrates used to feed.

Tips for Manipulating Sourdough