host-associated 35,149 animal host 35,148 digestive tract 34,973 mammalian host 34,208 intestine 33,173 human host 30,185 industrialized 24,740 adult 15,039 urban 4,708 child 3,090 infant 2,596 elderly 2,470 mouth 2,266 rural 1,821 non-industrialized 1,574 saliva 1,522 adolescent 1,092 rumen 605 full term birth 509 traditional agriculturalist 423 airways 206 preterm birth 200 hunter-gatherer 193 anthropogenic 192 aquatic 178 terrestrial 146 urogenital tract 117 wastewater 110 built environment 65 sewage 64 wetland 43 lentic 43 paludal 43 agriculture 43 skin 41 sludge 41 ancient microbiome 40 hospital 23 soil 17 medium temperature 13 marine 12 anaerobic 8 fresh water 6 low temperature 6 food 5 fermented food 5 cropland 4 subsurface 3 low salinity 3 insect host 3 groundwater 2 pelagic 2 contaminated 2 stream 1 plant host 1 benthic 1 air 1 phyllosphere 1 tundra 1 very low temperature 1 waste 1