Properties of Thermus ruber Strains Isolated from Icelandic Hot Springs and DNA:DNA Homology of Thermus ruber and Thermus aquaticus.

Seventeen pink-pigmented strains of the genus Thermus were isolated from samples collected from thermal areas of Iceland. The strains were examined by using phenotypic characterization and DNA:DNA homology and were compared with recognized strains. Visually, the strains could be divided into three groups based on their pigmentation; however, spectroscopic studies of the pigments indicated little difference among them. Most strains required a vitamin supplement for growth and used fructose, maltose, mannose, or sucrose as the sole carbon source. In the presence of nitrate, two strains were able to grow under anaerobic conditions. The optimum growth temperature was 60 degrees C; growth did not occur at 30 or 70 degrees C.