host-associated 19,292 animal host 19,122 mammalian host 18,515 digestive tract 18,479 human host 17,609 intestine 16,835 industrialized 13,886 adult 6,549 infant 3,861 mouth 2,575 child 2,025 terrestrial 1,980 urban 1,923 anthropogenic 1,751 saliva 1,735 elderly 1,514 built environment 1,322 aquatic 1,250 rural 846 non-industrialized 791 full term birth 647 adolescent 448 preterm birth 413 skin 407 lentic 406 soil 362 wastewater 342 fresh water 339 marine 312 low salinity 282 high salinity 240 sludge 236 lacustrine 208 plant host 172 airways 163 saline water 157 urogenital tract 147 very low temperature 141 agriculture 126 medium salinity 119 brackish water 114 rumen 103 pelagic 102 traditional agriculturalist 101 insect host 99 wetland 96 paludal 96 rhizosphere 93 low temperature 92 sewage 76 ice 71 air 70 estuary 69 hospital 65 contaminated 65 stream 61 tundra 57 medium temperature 56 cropland 55 subsurface 47 plant litter 46 fluvial 41 lotic 41 groundwater 39 permafrost 31 forest 31 benthic 29 sediment 26 phyllosphere 24 hunter-gatherer 21 littoral 20 anaerobic 20 food 17 lake bed 16 ancient microbiome 13 grassland 13 arid 11 very high salinity 10 mine 9 fermented food 9 alkaline 8 dairy product 8 briny water 6 microaerobic 5 negative control 4 waste 2 stream bed 2 acidic 1 coral reef 1 spring 1 hot spring 1 ancient dental calculus 1