yes! i'm hoping to understand more about the beginning of this co-existence, to maybe better work out ways to make their metabolism interact with ours in more helpful ways, will start that list from 7 backwards :) ty!
The Fundamentals of Microbiome Science by Angela Douglas seems to be the definitive/authoritative work on the subject by a recognized expert (will be getting this book :-) - https://en.wikipedia.org/wiki/Angela_E._Douglas
Checkout her other books too. They all seem fascinating.
The three things i find most fascinating in Biology are 1) Neuroscience, 2) Immune Systems and 3) Microbiome on our bodies. Together; they literally define who we are (mentally and physically), how we survive and how we coexist with our environment and yet there is no one book which brings everything together.
As a kid, i had read two classic books from the Soviet-era Mir Publishers Science for Everyone series which fired my imagination and sparked a lifelong interest in the Life Sciences. You might also find these (and others from the series) interesting (though old);
https://pmc.ncbi.nlm.nih.gov/articles/PMC8061703/ is around where i started, some time after learning about https://en.wikipedia.org/wiki/Auto-brewery_syndrome