Thermithiobacillus

Abstract

Ther.mi.thi.o.ba.cil'lus. L. fem. n. therma, a warm or hot bath; Gr. neut. n. theîon, sulfur, brimstone (transliterated to L. neut. n. thium); L. masc. n. bacillus, a short rod, a short wand; N.L. masc. n. Thermithiobacillus, sulfur rodlet from a warm bath, or warm sulfur rodlet.

Proteobacteria / Acidithiobacillia / Acidithiobacillales / Thermithiobacillaceae / Thermithiobacillus

Cells are short, rapidly motile rods with a single polar flagellum, which can be 3–6 times longer than the cell. Gram‐stain‐negative. Endospores, exospores, and cysts are not produced. Obligate chemolithoautotrophs, using reduced inorganic sulfur species such as thiosulfate, polythionates, elementary sulfur (viz. α‐S8), and sometimes hydrogen sulfide, bisulfide, or d‐ or p‐block sulfide minerals such as galena (PbS). Heterotrophy, methylotrophy, and the so‐called C1 autotrophy are not observed. Carbon assimilated from CO2 via the transaldolase variant of the Calvin–Benson–Bassham cycle. Carboxysomes are used for CO2 concentration. No vitamin auxotrophy. Obligately respiratory, with molecular oxygen as the only known terminal electron acceptor, though nitrate is reduced to nitrite under air. Usually isolated from environments with high Ca2+ and/or Mg2+ ions. Usually has a high tolerance to Mg2+ ions. Most strains grow in the range of 20–52 °C, though some have a narrower range, and from pH 4.0–5.5 to pH 8.0–8.7. Most strains grow best without NaCl, but for one strain, the optimum is 350 mM (2% w/v). The major respiratory quinone is ubiquinone‐8 (UQ‐8). Dominant fatty acids in thiosulfate‐grown cells are usually palmitic acid (C16:0), palmitoleic acid (C16:1), vaccenic acid (C18:1), and ω‐cyclohexylmargaric acid (C17:0 cyclo). The dominant polar lipids in the same cells are cardiolipin, phosphatidylethanolamine, phosphatidylglycerol, and aminoglycolipids. The G + C fraction of genomic DNA is around 58.5–67.0 mol%. Form IAc (carboxysomal) and Form IC (cytoplasmic) d‐ribulose 1,5‐bisphosphate carboxylase/oxygenase are used, as are forms aa 3 and cbb 3 cytochrome c oxidase and the bd‐I ubiquinol oxidase.

DNA G + C content (mol%): 58.5–67.0.

Type species: Thermithiobacillus tepidarius (Wood and Kelly 1985) Kelly and Wood 2000, 515VP (Thiobacillus thioparus Wood and Kelly 1985, 436).