[quietbritishjim]

Right, but that article claims that lactobacilli are critical to make the bread actually taste like sourdough at the end, whereas presumably dust isn't.

I did realise your main point is that it does include yeast, and I agree with that.

[OJFord]

Oh yeah, absolutely, I just meant that all (leavened) breads contain yeast, I suppose it's a defining feature; so it's not 'yeast vs. starter', it's 'yeast from a packet vs. yeast from the air'.