animal host 8,117 host-associated 8,117 digestive tract 7,971 mammalian host 7,836 human host 7,174 intestine 6,999 industrialized 5,336 adult 2,243 infant 2,136 mouth 1,286 urban 805 elderly 802 saliva 784 child 745 rural 386 non-industrialized 346 preterm birth 287 full term birth 250 anthropogenic 233 aquatic 162 wastewater 162 terrestrial 154 sewage 150 adolescent 145 airways 116 built environment 114 skin 108 traditional agriculturalist 48 urogenital tract 34 hospital 25 sludge 21 medium temperature 18 low temperature 15 agriculture 15 ancient microbiome 15 hunter-gatherer 14 rumen 11 ancient dental calculus 8 food 7 anaerobic 7 cropland 7 fermented food 7 soil 4 very low temperature 3 wetland 2 paludal 2 lentic 2 air 1 high temperature 1 plant host 1