THERMOPHILIC BACTERIA AMONG ARCTIC, SUB-ARCTIC, AND ALPINE HABITATS

Although spore-forming bacilli are the most prevalent thermophiles, large numbers (290-1000 Colony Forming Units per g dry wet) of thermophilic actinomycetes were found in soils from parks in Reykjavik, Iceland. Soils from arctic Greenland and alpine Colorado exhibited low numbers of thermophilic microorganisms (0-20 and 1-19 CFUs per g dry wet, respectively), but generally supported between 103- and 106-times larger mesophile and psychotroph populations. Lagoon sediments from arctic Alaska generally possessed larger numbers of thermophilic bacteria than adjacent soils sampled during 1955-1957. Cultivated soils from Tromso, Norway, showed greater thermophilic populations than nearby undisturbed soils (250-24 000 vs. 0-6700 CFUs per g dry wt). In geothermal areas of Iceland, thermophiles generally ranged from 1500-23 000 CFUs per g dry wt; the ratios of thermophiles to mesophiles and psychotrophs were much more compressed than from previously mentioned habitats. Thermophilic bacteria also were found in all but one of the volcanic and nongeothermal soils from Iceland (9-1500 and 22-19 000 CFUs per g dry wt, respectively); a greater number of mesophiles and psychotrophs were generally present in each case. -from Authors