host-associated 52,999 animal host 52,318 mammalian host 49,642 digestive tract 49,374 intestine 46,605 human host 44,106 industrialized 34,471 adult 19,189 aquatic 9,085 terrestrial 8,424 infant 8,346 urban 6,369 anthropogenic 5,507 marine 4,345 child 4,322 elderly 4,020 built environment 3,776 mouth 3,190 soil 3,125 rural 2,701 non-industrialized 2,534 fresh water 2,372 lentic 2,189 preterm birth 2,146 low salinity 2,114 skin 1,972 saliva 1,871 pelagic 1,702 high salinity 1,401 adolescent 1,290 full term birth 1,161 lacustrine 1,133 wastewater 1,047 benthic 938 wetland 800 paludal 766 lotic 726 forest 703 plant host 686 rumen 668 sludge 647 agriculture 611 traditional agriculturalist 582 medium salinity 571 brackish water 545 subsurface 532 very low temperature 487 groundwater 461 sediment 443 stream 420 airways 411 sewage 393 low temperature 391 hospital 390 urogenital tract 372 rhizosphere 371 fluvial 367 spring 358 hunter-gatherer 357 permafrost 356 saline water 349 grassland 315 contaminated 288 sea floor 276 estuary 269 very high temperature 247 insect host 242 cropland 236 hydrothermal vent 231 littoral 210 medium temperature 206 arid 203 phyllosphere 190 tundra 187 food 159 ancient microbiome 148 microaerobic 141 mine 136 ice 133 hot spring 127 fermented food 127 coral reef 113 very high salinity 108 alkaline 103 ancient dental calculus 97 acidic 92 air 83 anaerobic 83 lake bed 65 plant litter 65 dairy product 47 stream bed 43 mangrove 34 salt marsh 33 briny water 21 high temperature 17 negative control 12 waste 8 breast milk 1