host-associated 2,572 animal host 2,567 digestive tract 2,556 intestine 2,546 mammalian host 2,457 human host 2,118 infant 1,168 industrialized 1,099 preterm birth 528 adult 381 rural 227 non-industrialized 220 child 181 anthropogenic 149 urban 147 terrestrial 141 full term birth 105 built environment 83 elderly 69 aquatic 67 adolescent 50 sludge 29 wastewater 28 agriculture 26 anaerobic 26 hunter-gatherer 22 food 21 fermented food 21 soil 18 sewage 11 traditional agriculturalist 11 lentic 10 rumen 10 paludal 9 wetland 9 cropland 8 tundra 8 fresh water 8 contaminated 7 plant host 6 medium temperature 6 low salinity 6 spring 5 hot spring 5 lotic 5 mine 5 ancient microbiome 4 marine 4 very low temperature 3 insect host 3 ice 3 subsurface 3 permafrost 3 rhizosphere 2 groundwater 2 high temperature 2 air 1 sediment 1 grassland 1 briny water 1 very high salinity 1 lake bed 1 lacustrine 1 forest 1