Further descriptive information

This genus was created to accommodate the single species of moderate thermophile, Thiobacillus tepidarius. While this species showed many physiological similarities to Thiobacillus neapolitanus (now Halothiobacillus neapolitanus) (Wood and Kelly, 1985,1986), it was shown by 16S rRNA gene sequence analysis to be unrelated to that genus (Kelly and Wood, 2000). The properties, taxonomy, and differentiation of the genera of sulfur-oxidizing chemolith-oautotrophic Gram-negative rod-shaped bacteria are summarized in Tables 1 and 2 and Fig. 1 in the chapter on the genus Thio-bacillus which appear in Volume 2 Part C in this Manual.

List of species of the genus Thermithiobacillus

1. Thermithiobacillus tepidarius (Wood and Kelly 1985) Kelly and Wood 2000, 515VP (Thiobacillus tepidarius Wood and Kelly 1985, 436.)

tep.i.dar ius. L. n. tepidarium a warm bath fed by natural thermal water; M.L. adj. tepidarius warm-bathing (Thiobacillus).

Small rods, 0.5 X 1.0-2.0 |m. Motile by a single polar flagellum (5-10 | m in length). Gram negative, nonspore-forming. Colonies grown on thiosulfate agar at 43°C are small (1-2 mm), circular, convex and smooth and become white or yellow with precipitated sulfur. In liquid batch culture on thiosulfate, quantitative production oftetrathionate takes place before growth continues to effect complete oxidation to sulfate. Sulfur may be precipitated. pH drops to 4.5-5.0. Chemostat cultures do not accumulate intermediates during growth on sulfide, thiosulfate, tetrathionate, or trithionate. This organism oxidizes sulfide, thiosulfate, trithionate, tetrathionate, hexathionate, heptathionate, and sulfite, but not thiocyanate. Obligately chemolithotrophic and autotrophic. Uses ammonium salts as nitrogen source.

Aerobic. Optimum temperature: 43-45°C; range: 20-52°C (no growth at 15 or 55°C). Optimum pH: 6.8-7.5; range: 5.2-8.0. Isolated from the Great Roman Bath at the Temple of Sulis Minerva, Bath, Avon, England; distribution unknown. Member of the Gammaproteobacteria.

The mol% G + C of the DNA is: 66.6 (UV ratios; Bd).

Type strain: DSM 3134, ATCC 43215.

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