host-associated 38,305 animal host 38,287 digestive tract 38,050 mammalian host 36,979 intestine 36,003 human host 32,194 industrialized 26,284 adult 15,987 urban 4,943 child 3,333 infant 2,833 elderly 2,721 mouth 2,522 rural 2,053 non-industrialized 1,797 saliva 1,659 adolescent 1,135 aquatic 1,083 rumen 636 terrestrial 584 anthropogenic 551 full term birth 545 traditional agriculturalist 448 lentic 410 fresh water 376 low salinity 295 hunter-gatherer 261 wastewater 251 preterm birth 233 marine 222 airways 217 lacustrine 213 sludge 187 soil 162 benthic 155 built environment 137 sewage 132 subsurface 124 wetland 123 sediment 120 urogenital tract 118 paludal 117 groundwater 113 high salinity 92 skin 86 agriculture 85 lotic 81 saline water 69 spring 67 contaminated 64 anaerobic 53 low temperature 51 ancient microbiome 46 sea floor 43 pelagic 43 permafrost 43 very high temperature 42 hydrothermal vent 41 microaerobic 41 tundra 41 alkaline 39 hospital 36 food 34 very low temperature 33 medium temperature 32 hot spring 26 fermented food 24 mine 23 littoral 22 plant host 20 brackish water 19 medium salinity 19 rhizosphere 17 stream 16 fluvial 14 very high salinity 12 ice 11 forest 10 dairy product 10 cropland 9 insect host 8 waste 8 high temperature 7 mangrove 6 coral reef 5 ancient dental calculus 5 negative control 5 estuary 5 lake bed 5 phyllosphere 2 air 1 acidic 1 arid 1