host-associated 39,035 animal host 38,710 digestive tract 38,283 mammalian host 37,195 intestine 36,130 human host 32,358 industrialized 26,412 adult 16,076 urban 4,987 aquatic 4,683 child 3,366 infant 2,840 elderly 2,743 mouth 2,636 terrestrial 2,433 rural 2,058 marine 1,826 non-industrialized 1,802 saliva 1,688 anthropogenic 1,645 fresh water 1,387 lentic 1,327 low salinity 1,224 adolescent 1,141 soil 1,015 lacustrine 770 wastewater 731 pelagic 705 built environment 656 rumen 640 high salinity 639 sludge 591 full term birth 545 traditional agriculturalist 448 medium salinity 400 brackish water 387 wetland 333 lotic 332 benthic 329 plant host 327 paludal 318 saline water 282 agriculture 275 hunter-gatherer 261 subsurface 254 very low temperature 243 preterm birth 235 groundwater 232 stream 231 airways 221 sediment 217 estuary 213 rhizosphere 203 fluvial 202 low temperature 187 sewage 176 medium temperature 143 spring 126 skin 124 contaminated 122 urogenital tract 118 permafrost 116 littoral 116 forest 105 cropland 101 arid 101 microaerobic 97 ice 96 very high salinity 89 insect host 86 tundra 79 hot spring 76 anaerobic 70 alkaline 69 sea floor 67 grassland 62 very high temperature 60 hospital 58 ancient microbiome 52 plant litter 51 hydrothermal vent 50 food 49 phyllosphere 47 mine 46 coral reef 45 fermented food 25 dairy product 24 lake bed 19 briny water 17 mangrove 15 high temperature 13 acidic 10 ancient dental calculus 9 waste 8 salt marsh 6 negative control 5 stream bed 2 air 1