host-associated 1,122 animal host 1,109 mammalian host 1,104 digestive tract 1,103 intestine 1,100 human host 1,076 infant 672 industrialized 645 preterm birth 340 adult 206 urban 131 terrestrial 85 anthropogenic 62 built environment 56 elderly 51 rural 39 child 38 non-industrialized 33 full term birth 33 aquatic 22 soil 17 plant host 15 wastewater 10 rhizosphere 8 marine 8 sewage 8 traditional agriculturalist 8 adolescent 7 pelagic 6 arid 5 very low temperature 5 phyllosphere 5 skin 4 sludge 3 hospital 2 forest 2 airways 2 food 1 rumen 1 mouth 1 ancient microbiome 1 grassland 1 fermented food 1 saliva 1 lentic 1