The Taxonomy and Identification of Thermus

Abstract

Bacteria of the genus Thermus were first isolated in the late 1960s from hot springs in Japan and the USA. Thermus strains also appear to be widespread in neutral, hot, aqueous artificial environments such as domestic and industrial hot water systems and thermally polluted streams. The reference strains that have been used in taxonomic studies are listed in Table I. Isolates from sources in Yellowstone National Park were originally allocated to the type species, Thermus aquaticus (Brock and Freeze, 1969), of this new genus. Subsequently, sites in Yellowstone National Park were sampled for Thermus, but isolates were only obtained from sources between 55 °C and 80 °C and pH 6.0 to 10.5 (Munster et al., 1986). In Japan, early isolates were named “Flavobacterium thermophilum” (Oshima and Imahori, 1971), but validly redescribed as “Thermus thermophilus” (Oshima and Imahori, 1974). Other Japanese strains were given the invalid species names “Thermus flavus” (Saiki et al., 1972), and “Thermus caldophilus” (Taguchi et al., 1982), but these strains seem to belong to the T. thermophilus genospecies (see sections 5.2. and 6.1). Other terrestrial hot springs in Iceland were sampled (Cornetta et al., 1982b; Hudson et al., 1987a; Kristjansson and Alfredsson, 1983; Pask-Hughes and Williams, 1977). Extensive studies were also made of many New Zealand isolates, (Hudson et al., 1987a) and the validly named strain Thermus filiformis (Hudson et al., 1987b).