host-associated 26,562 animal host 26,076 digestive tract 25,134 mammalian host 24,769 intestine 23,299 human host 22,723 industrialized 16,751 adult 9,114 aquatic 6,705 infant 5,159 terrestrial 4,420 urban 3,192 marine 3,160 anthropogenic 3,053 mouth 2,428 child 1,955 built environment 1,931 fresh water 1,818 elderly 1,807 low salinity 1,618 preterm birth 1,616 lentic 1,550 rural 1,518 saliva 1,478 soil 1,428 non-industrialized 1,352 pelagic 1,238 lacustrine 962 high salinity 923 wastewater 903 benthic 658 adolescent 577 sludge 516 lotic 503 medium salinity 496 skin 488 plant host 482 brackish water 477 full term birth 455 wetland 399 paludal 380 subsurface 351 stream 345 sewage 336 groundwater 324 agriculture 324 very low temperature 322 traditional agriculturalist 317 rumen 298 fluvial 295 sediment 282 forest 281 rhizosphere 280 low temperature 250 saline water 248 estuary 240 airways 226 contaminated 223 spring 205 hospital 203 sea floor 198 insect host 187 grassland 185 very high temperature 167 hydrothermal vent 166 littoral 151 medium temperature 149 microaerobic 139 permafrost 137 hunter-gatherer 121 mine 118 cropland 114 phyllosphere 112 ice 98 alkaline 86 acidic 79 arid 69 tundra 67 food 60 coral reef 55 plant litter 54 ancient microbiome 48 fermented food 45 anaerobic 41 hot spring 39 very high salinity 37 lake bed 34 urogenital tract 22 air 22 stream bed 21 mangrove 19 ancient dental calculus 18 dairy product 15 briny water 15 salt marsh 9 waste 8 high temperature 8 negative control 3 breast milk 1