animal host 16,233 host-associated 16,233 digestive tract 16,224 intestine 16,205 mammalian host 15,926 human host 15,144 industrialized 13,088 adult 7,330 urban 2,596 infant 1,230 elderly 1,200 child 1,037 adolescent 520 rural 345 full term birth 273 non-industrialized 254 preterm birth 58 traditional agriculturalist 44 anthropogenic 41 aquatic 39 wastewater 31 terrestrial 27 hunter-gatherer 24 built environment 19 sewage 17 rumen 14 ancient microbiome 14 soil 9 skin 8 mouth 7 marine 7 sludge 5 agriculture 4 hospital 4 medium temperature 3 saliva 2 low temperature 2 pelagic 2 food 1 fermented food 1 fresh water 1 benthic 1 groundwater 1 subsurface 1 air 1 urogenital tract 1 very low temperature 1