host-associated 2,569 animal host 2,564 digestive tract 2,553 intestine 2,543 mammalian host 2,456 human host 2,118 infant 1,168 industrialized 1,099 preterm birth 528 adult 381 rural 227 non-industrialized 220 child 181 urban 147 terrestrial 140 anthropogenic 140 full term birth 105 built environment 83 elderly 69 aquatic 63 adolescent 50 sludge 29 wastewater 28 agriculture 26 anaerobic 26 hunter-gatherer 22 soil 18 food 13 fermented food 13 sewage 11 traditional agriculturalist 11 rumen 10 lentic 10 wetland 9 paludal 9 fresh water 8 tundra 8 cropland 8 plant host 6 low salinity 6 contaminated 6 medium temperature 6 mine 5 ancient microbiome 4 marine 4 ice 3 permafrost 3 very low temperature 3 insect host 3 rhizosphere 2 groundwater 2 high temperature 2 subsurface 2 grassland 1 spring 1 hot spring 1 air 1 briny water 1 lotic 1 lake bed 1 very high salinity 1 lacustrine 1 forest 1 sediment 1