host-associated 4,488 animal host 4,323 digestive tract 4,254 mammalian host 4,061 intestine 3,923 aquatic 3,355 human host 2,651 marine 2,094 industrialized 2,042 terrestrial 1,629 pelagic 1,061 soil 1,052 adult 973 high salinity 719 lentic 686 anthropogenic 657 fresh water 653 low salinity 537 child 462 non-industrialized 372 benthic 357 wetland 342 rural 340 paludal 332 rumen 329 elderly 282 subsurface 275 sediment 256 groundwater 249 agriculture 244 lacustrine 209 lotic 208 medium salinity 207 brackish water 203 saline water 191 urban 183 sludge 174 plant host 166 grassland 157 spring 153 rhizosphere 153 microaerobic 136 wastewater 127 contaminated 126 infant 116 cropland 112 sea floor 106 permafrost 103 low temperature 87 very high temperature 86 mine 82 hot spring 80 hydrothermal vent 73 very low temperature 73 adolescent 71 medium temperature 71 tundra 71 forest 70 acidic 68 littoral 65 stream 63 estuary 61 very high salinity 60 alkaline 59 ancient microbiome 58 anaerobic 57 mouth 57 fluvial 55 ancient dental calculus 55 sewage 52 built environment 48 arid 46 food 45 hunter-gatherer 33 traditional agriculturalist 33 coral reef 32 fermented food 24 dairy product 21 skin 20 stream bed 20 lake bed 17 high temperature 11 mangrove 10 hospital 10 waste 8 insect host 8 salt marsh 4 briny water 4 phyllosphere 3 full term birth 2 plant litter 1 airways 1