Thermus

Abstract

Ther'mus. Gr. adj.thermoshot; N.L. masc. n.Thermusto indicate an organism living in hot places.“Deinococcus‐Thermus” / Deinococci / Thermales / Thermaceae / ThermusStraight rods; the cell length is variable, 0.2–1.7 µm in width. Filaments are also formed; some strains have a stable filamentous morphology. Nonmotile; do not possess flagella. Endospores are not observed. Stain Gram‐negative. Most strains form yellow‐pigmented colonies; some strains are nonpigmented. Thermophilic, with an optimum growth temperature of about 65–75°C; most strains have a maximum growth temperature below 80°C, but some strains grow at slightly higher temperatures. The optimum pH for growth is about 7.0–8.5. Growth is chemoorganotrophic; some strains are mixotrophic using arsenic, sulfur or thiosulfate as electron donors. Aerobic with a strictly respiratory type of metabolism; some strains grow anaerobically with nitrate, nitrite, and iron as terminal electron acceptors; some strains can also reduce gold, chromate, and uranium under aerobic and anaerobic conditions. Oxidase positive, most strains are catalase positive. Strains generally require yeast extract or cofactors for growth. Sugars, amino acids, organic acids, and polyols are used as sole organic carbon and energy sources. Ornithine is the principal diamino acid of the peptidoglycan. Menaquinone 8 (MK‐8) is the predominant respiratory quinone. One major phospholipid and one major glycolipid dominate the polar lipid pattern on thin‐layer chromatography. Additional phospholipids and glycolipids are minor components. Phospholipids and glycolipids are primarily glycerol based, but some strains also possess 1,2‐long‐chain diol‐based lipids. Fatty acids are predominantlyiso‐andanteiso‐branched; branched‐chain 3‐hydroxy fatty acids are present in some strains. Found in hydrothermal areas with neutral to alkaline pH, also commonly isolated from man‐made thermal environments.DNA G + C content (mol%): 63–71 (Tm or HPLC).Type species:Thermus aquaticusBrock and Freeze 1969, 295AL.