host-associated 21,428 animal host 21,127 mammalian host 20,407 human host 19,377 digestive tract 19,032 intestine 17,318 industrialized 15,490 adult 7,283 infant 4,053 terrestrial 3,900 anthropogenic 2,985 mouth 2,655 aquatic 2,640 built environment 2,340 elderly 2,096 child 2,056 urban 2,047 skin 1,818 saliva 1,754 fresh water 1,157 soil 1,130 lentic 1,074 low salinity 1,068 rural 858 non-industrialized 803 lacustrine 723 full term birth 652 preterm birth 548 marine 537 wastewater 472 adolescent 452 sludge 342 high salinity 316 plant host 304 medium salinity 272 brackish water 265 airways 264 hospital 250 agriculture 240 stream 236 wetland 234 paludal 234 forest 214 lotic 213 very low temperature 212 fluvial 203 rhizosphere 197 pelagic 186 saline water 175 estuary 168 urogenital tract 167 low temperature 161 cropland 111 insect host 110 tundra 107 traditional agriculturalist 104 rumen 104 permafrost 103 medium temperature 101 subsurface 96 sewage 90 contaminated 89 benthic 88 ice 86 sediment 84 groundwater 82 grassland 74 air 70 arid 62 anaerobic 58 littoral 56 plant litter 53 phyllosphere 33 food 23 hunter-gatherer 21 lake bed 19 very high salinity 17 mine 15 ancient microbiome 14 fermented food 12 alkaline 12 dairy product 11 acidic 8 negative control 8 spring 7 briny water 6 hot spring 6 salt marsh 5 microaerobic 5 waste 4 sea floor 3 stream bed 2 ancient dental calculus 2 coral reef 1 high temperature 1 very high temperature 1 hydrothermal vent 1