host-associated 5,587 animal host 5,587 digestive tract 5,575 mammalian host 5,238 intestine 5,218 human host 2,389 adult 1,399 industrialized 1,385 rural 716 child 685 non-industrialized 658 rumen 444 infant 241 urban 194 elderly 180 traditional agriculturalist 177 hunter-gatherer 131 adolescent 109 anthropogenic 40 mouth 26 aquatic 25 agriculture 22 saliva 18 wastewater 16 terrestrial 14 ancient microbiome 8 marine 7 urogenital tract 6 soil 5 medium temperature 5 built environment 4 sludge 4 sewage 4 cropland 3 anaerobic 3 subsurface 2 airways 1 groundwater 1 full term birth 1 fresh water 1 contaminated 1 skin 1 waste 1 hospital 1