animal host 997 human host 997 host-associated 997 mammalian host 997 digestive tract 970 industrialized 920 mouth 882 adult 669 saliva 585 intestine 497 urban 256 child 217 anthropogenic 137 wastewater 136 aquatic 136 sewage 131 terrestrial 82 airways 79 built environment 78 adolescent 67 urogenital tract 23 low temperature 22 elderly 21 infant 11 medium temperature 10 non-industrialized 7 sludge 6 rural 5 preterm birth 5 skin 4 very low temperature 4 ancient dental calculus 2 ancient microbiome 2 hospital 1