host-associated 39,004 animal host 38,694 digestive tract 38,281 mammalian host 37,193 intestine 36,128 human host 32,356 industrialized 26,412 adult 16,076 urban 4,987 aquatic 4,349 child 3,366 infant 2,840 elderly 2,743 mouth 2,636 terrestrial 2,233 rural 2,058 non-industrialized 1,802 marine 1,774 saliva 1,688 anthropogenic 1,602 fresh water 1,204 adolescent 1,141 lentic 1,092 low salinity 1,043 soil 887 wastewater 722 pelagic 697 built environment 646 rumen 640 lacustrine 631 sludge 587 full term birth 545 high salinity 535 traditional agriculturalist 448 medium salinity 397 brackish water 384 lotic 319 plant host 312 benthic 293 wetland 264 agriculture 262 hunter-gatherer 261 paludal 250 saline water 246 subsurface 236 preterm birth 235 very low temperature 232 stream 228 airways 221 groundwater 215 estuary 211 fluvial 201 sediment 197 rhizosphere 188 low temperature 178 sewage 173 medium temperature 138 skin 124 urogenital tract 118 spring 115 contaminated 113 littoral 109 forest 101 cropland 99 microaerobic 97 ice 96 permafrost 94 insect host 86 tundra 78 anaerobic 69 hot spring 65 sea floor 65 alkaline 64 hospital 58 grassland 55 very high temperature 53 ancient microbiome 52 plant litter 51 hydrothermal vent 50 food 49 arid 49 phyllosphere 47 mine 39 coral reef 35 very high salinity 33 fermented food 25 dairy product 24 lake bed 19 mangrove 14 briny water 14 high temperature 13 ancient dental calculus 9 waste 8 negative control 5 acidic 3 salt marsh 2 stream bed 2 air 1