animal host 5,785 host-associated 5,785 digestive tract 5,773 intestine 5,409 mammalian host 5,395 human host 2,407 adult 1,446 industrialized 1,398 child 734 rural 719 non-industrialized 660 rumen 456 infant 252 anthropogenic 222 urban 195 aquatic 185 elderly 181 traditional agriculturalist 177 terrestrial 146 hunter-gatherer 131 adolescent 110 wastewater 107 sludge 106 subsurface 56 fresh water 56 groundwater 53 agriculture 52 sewage 46 contaminated 40 anaerobic 32 mouth 26 built environment 21 saliva 18 soil 17 low salinity 17 medium temperature 15 food 14 marine 11 tundra 10 dairy product 9 low temperature 9 ancient microbiome 8 hospital 8 waste 7 insect host 6 urogenital tract 6 fermented food 5 mine 4 cropland 4 lentic 3 paludal 2 wetland 2 fluvial 1 medium salinity 1 permafrost 1 full term birth 1 lotic 1 skin 1 estuary 1 stream 1 brackish water 1 airways 1