host-associated 16,557 animal host 16,546 digestive tract 16,466 mammalian host 15,927 intestine 15,845 human host 12,903 industrialized 10,223 adult 5,423 child 1,540 urban 1,485 infant 1,302 rural 1,273 non-industrialized 1,165 elderly 905 mouth 557 rumen 405 saliva 401 aquatic 389 adolescent 335 anthropogenic 246 full term birth 189 terrestrial 171 traditional agriculturalist 154 fresh water 147 low salinity 125 wastewater 114 hunter-gatherer 104 lentic 97 preterm birth 95 sludge 92 marine 66 lacustrine 63 airways 58 sewage 53 high salinity 52 agriculture 47 insect host 47 subsurface 42 groundwater 40 saline water 40 soil 37 anaerobic 35 benthic 34 food 33 contaminated 27 built environment 24 medium temperature 23 sediment 23 ancient microbiome 21 alkaline 20 fermented food 17 dairy product 16 pelagic 16 urogenital tract 15 grassland 15 brackish water 13 low temperature 13 medium salinity 13 stream 12 mine 12 plant host 11 coral reef 10 estuary 9 cropland 9 rhizosphere 8 lotic 8 hospital 8 waste 7 littoral 6 wetland 6 paludal 6 tundra 5 very low temperature 5 spring 4 very high temperature 4 sea floor 4 fluvial 4 hydrothermal vent 4 forest 3 acidic 3 high temperature 2 lake bed 2 ice 2 very high salinity 1 stream bed 1 briny water 1 phyllosphere 1 permafrost 1