host-associated 2,539 animal host 2,399 mammalian host 2,103 human host 1,944 industrialized 1,766 digestive tract 1,363 terrestrial 1,268 skin 955 adult 915 intestine 830 mouth 756 anthropogenic 747 elderly 620 soil 605 built environment 556 aquatic 534 saliva 433 urban 241 lentic 189 fresh water 182 child 175 low salinity 146 plant host 141 wastewater 134 forest 128 lacustrine 127 sludge 121 marine 108 rhizosphere 103 airways 97 agriculture 97 wetland 67 paludal 67 very low temperature 63 hospital 61 infant 60 high salinity 58 benthic 56 sediment 55 grassland 53 tundra 52 arid 45 urogenital tract 43 permafrost 42 pelagic 39 cropland 39 adolescent 39 preterm birth 39 contaminated 34 anaerobic 34 medium temperature 30 rural 27 medium salinity 26 brackish water 24 ice 23 low temperature 23 non-industrialized 21 stream 20 subsurface 18 littoral 18 groundwater 16 lake bed 14 insect host 14 plant litter 12 lotic 10 very high salinity 7 saline water 6 traditional agriculturalist 5 sewage 5 phyllosphere 5 fluvial 5 salt marsh 5 hot spring 4 spring 4 estuary 3 ancient dental calculus 2 negative control 2 mine 2 sea floor 2 full term birth 2 waste 2 ancient microbiome 2 acidic 1