host-associated 14,825 animal host 14,816 digestive tract 14,239 mammalian host 13,690 intestine 13,031 human host 11,676 industrialized 8,204 infant 4,061 adult 3,657 mouth 1,678 urban 1,294 elderly 1,149 child 1,091 saliva 1,055 preterm birth 1,022 anthropogenic 821 terrestrial 605 rural 597 non-industrialized 532 built environment 506 full term birth 378 aquatic 352 wastewater 299 urogenital tract 275 sewage 272 skin 239 adolescent 234 airways 174 food 98 fermented food 98 insect host 87 traditional agriculturalist 87 sludge 56 hospital 56 agriculture 52 hunter-gatherer 30 rumen 27 anaerobic 26 plant host 24 medium temperature 24 low temperature 22 ancient microbiome 21 soil 17 dairy product 15 fresh water 13 low salinity 12 very low temperature 11 phyllosphere 9 marine 8 cropland 8 ancient dental calculus 8 stream 7 benthic 6 sediment 6 mine 5 ice 4 contaminated 4 acidic 4 grassland 2 rhizosphere 2 forest 2 lentic 2 arid 2 wetland 2 paludal 2 high temperature 1 very high salinity 1 briny water 1 negative control 1 air 1