Micro organisms - air vs grain
I've always been intrigued by the biological aspect of sourdough. There has been much debate about the validity of theories on whether the yeast and bacteria species exist on the grain or are drawn from the air around us via the provision of favourable food sources ie flour & water, etc.
Not being a micro biologist and yet having to find the perfect factual scientific paper of evidence to support either of the theories that abound, I'm yet to form a solid conclusion. I have wondered though whether I've been too simplistic in thinking that it should be one or the other or even the same yeast & bacteria speciies that exist in the air as on the grain. Is it possible that there are species that exist in the air that may be different to those that live on the grain, but still enter and contribute to our cultures during the process of sourdough activiation? There has been much valuable discussion on this site about this topic. I'd just like to revisit it and hear folk's thoughts on the matter. I had assumed that the culture of organisms that are said to exist in the air would be the same species that exist on the grain. Is it possible those found in the air could be diferent species, or different subspecies? That they all come together to make up our treasured starters?
Also, at the market the other day I noticed packets of flour from Italy for sale (I live in Australia).
If I used this to create a starter, would the new starter therefore be a culture that is a body of yeast and bacteria strains specific to the Italian locale of origin of the grain that the flour was milled from?
Just a thought.