host-associated 28,501 animal host 27,909 digestive tract 26,887 mammalian host 26,360 intestine 24,965 human host 23,703 industrialized 17,550 adult 9,666 aquatic 7,338 terrestrial 5,706 infant 5,277 anthropogenic 3,677 marine 3,459 urban 3,287 mouth 2,428 built environment 2,425 child 2,177 soil 2,091 fresh water 1,982 elderly 1,890 low salinity 1,762 lentic 1,719 preterm birth 1,637 rural 1,588 saliva 1,478 non-industrialized 1,413 pelagic 1,380 high salinity 1,011 lacustrine 996 wastewater 912 benthic 721 adolescent 604 plant host 588 lotic 552 medium salinity 529 sludge 527 skin 526 wetland 525 forest 515 brackish water 506 paludal 503 full term birth 468 agriculture 412 very low temperature 402 rumen 394 subsurface 384 stream 363 groundwater 353 traditional agriculturalist 347 sewage 337 rhizosphere 333 fluvial 315 sediment 304 low temperature 290 estuary 260 saline water 258 hospital 254 contaminated 237 spring 234 airways 228 grassland 223 permafrost 212 sea floor 208 insect host 199 very high temperature 169 littoral 168 hydrothermal vent 167 cropland 164 medium temperature 161 phyllosphere 154 microaerobic 139 hunter-gatherer 139 ice 126 mine 121 arid 106 tundra 106 alkaline 88 coral reef 83 acidic 82 food 77 hot spring 67 fermented food 61 plant litter 59 ancient microbiome 49 very high salinity 44 anaerobic 43 lake bed 38 air 26 urogenital tract 23 mangrove 22 stream bed 21 briny water 21 ancient dental calculus 18 dairy product 16 high temperature 12 salt marsh 11 waste 8 negative control 3 breast milk 1