host-associated 22,100 animal host 22,098 digestive tract 22,083 intestine 21,762 mammalian host 21,336 human host 18,755 industrialized 15,217 adult 8,523 urban 2,185 elderly 1,763 child 1,624 rural 1,582 non-industrialized 1,387 infant 854 adolescent 434 rumen 378 traditional agriculturalist 312 anthropogenic 200 full term birth 191 aquatic 139 hunter-gatherer 125 wastewater 121 sewage 101 terrestrial 94 built environment 55 sludge 45 preterm birth 31 ancient microbiome 28 fermented food 24 food 24 agriculture 23 medium temperature 22 anaerobic 19 low temperature 18 marine 11 hospital 11 grassland 10 skin 9 insect host 8 cropland 6 very low temperature 5 soil 4 fresh water 4 groundwater 4 subsurface 4 wetland 2 plant host 2 lentic 2 high temperature 2 paludal 2 contaminated 2