aquatic 191 terrestrial 150 lentic 144 soil 117 fresh water 116 low salinity 111 lacustrine 77 wetland 77 paludal 74 benthic 35 sediment 35 permafrost 31 host-associated 26 low temperature 25 subsurface 25 groundwater 24 rhizosphere 24 plant host 24 anthropogenic 19 very low temperature 10 grassland 9 marine 9 contaminated 8 lotic 7 hot spring 5 alkaline 5 built environment 5 medium temperature 5 sludge 5 spring 5 wastewater 5 forest 4 medium salinity 3 brackish water 3 mangrove 3 high salinity 3 saline water 3 estuary 3 littoral 3 industrialized 2 mammalian host 2 digestive tract 2 human host 2 intestine 2 fluvial 2 animal host 2 mine 1 waste 1 high temperature 1 acidic 1