Calidithermus

Abstract Ca.li.di.ther'mus. L. masc. adj. calidus , warm; Gr. masc. n. Thermus , a bacterial genus; N.L. masc. n. Calidithermus , a lukewarm Thermus . Deinococcota / Deinococci / Thermales / Thermaceae / Calidithermus The genus Calidithermus comprises four validly named species, Calidithermus chliarophilus , Calidithermus roseus , Calidithermus terrae , and Calidithermus timidus . These organisms form nonmotile rod‐shaped cells capable of forming lengthy filaments. Cells stain Gram‐negative and endospores are not observed. Colonies are yellow‐pigmented. The species of the genus Calidithermus are strictly aerobic and slightly thermophilic with optimum growth temperatures of 50–60°C. Growth is aerobic with a strictly respiratory type of metabolism, but all strains reduce nitrate to nitrite by nitrate reductase. Most strains also possess a nir K gene that codes for nitrite reductase. All strains possess the gene coding for lactate dehydrogenase. Possess cytochrome c oxidase and are catalase variable. The organisms are chemoorganotrophic. Growth factors are necessary for growth in minimal medium. Carbohydrates, amino acids, organic acids, and polyols are used as sole carbon and energy sources. The only respiratory quinone of this genus is menaquinone 8 (MK‐8). The polar lipid profile includes one major phospholipid (PL‐2) and two glycolipid variants (GL‐1a and GL‐1b). Major fatty acids are primarily iso‐ and anteiso‐branched; 2‐hydroxy and 3‐hydroxy fatty acids are also present. Found in hydrothermal areas. DNA G + C content (mol%) : 65.3–69.5 (genome). Type species : Calidithermus chliarophilus Raposo et al. 2019 VP .