In vivo bacterial population data isn't all that accessible yet either. Faecal bacterial samples have turned out to be poor representatives of the gut microbiom

In vivo bacterial population data isn't all that accessible yet either. Faecal bacterial samples have turned out to be poor representatives of the gut microbiome, so in vivo sampling requires endoscopy. Fwiw, there are multiple biomes to sample too, with different types of bacteria lining the intestinal walls and other kinds populating the crypts, for instance. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4837114/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4837114/