host-associated 2,189 animal host 2,141 mammalian host 2,036 human host 2,002 digestive tract 1,847 industrialized 1,831 mouth 1,555 adult 1,087 saliva 1,070 intestine 902 terrestrial 851 anthropogenic 783 built environment 731 elderly 349 urban 331 child 322 skin 262 adolescent 100 soil 93 airways 87 infant 85 air 70 plant host 49 aquatic 44 rural 38 agriculture 36 rhizosphere 35 non-industrialized 27 fresh water 24 benthic 19 hospital 19 sediment 18 contaminated 18 lacustrine 15 phyllosphere 12 lake bed 12 marine 10 littoral 10 low salinity 9 tundra 9 permafrost 9 urogenital tract 8 lentic 7 insect host 7 stream 7 forest 6 wastewater 5 wetland 4 low temperature 4 medium temperature 4 paludal 4 sludge 4 very low temperature 4 plant litter 3 cropland 3 grassland 3 ancient microbiome 3 negative control 2 full term birth 2 mine 2 arid 2 subsurface 1 fluvial 1 coral reef 1 groundwater 1 rumen 1 lotic 1 ice 1 hunter-gatherer 1 sewage 1 high salinity 1 preterm birth 1