Page:Bergey's manual of determinative bacteriology.djvu/106

 ::2. Final pH, 1.0 or less,
 * a. Nitrate utilized.


 * aa. Nitrate not utilized.

II. Thiosulfate oxidized with increased alkalinity.

1. Thiobacillus thioparus Beijerinck, 1904. (Arch. d. Sci. Exact, et Nat. Haarlem, Sér. 2, 9, 1904, 153; also see Cent. f. Bakt., II Abt., 11, 1904, 593.)

thi.o′par.us. Gr. noun thium sulfur; L.v. paro to produce; M.L. adj. thioparus sulfur-producing.

Thin, short rods, 0.5 by 1.0 to 3.0 microns, averaging 0.5 by 1.7 microns. Motile. Starkey (Soil Sci., 39, 1935, 209) reports the isolation of cultures (C) that he regards as practically identical with this species though they were non-motile and of coccoid form. Gram-negative.

Thiosulfate liquid medium: Pellicle consists of cells and free sulfur. Medium becomes turbid. pH drops to 4.5.

Thiosulfate agar colonies: Small (1 to 2 mm in diameter) circular, whitish yellow due to precipitated sulfur. Turn brown in old cultures.

No growth on organic media.

Optimum reaction, close to neutrality. Growth occurs between pH 7.8 and 4.5.

Strictly autotrophic. Derives its energy by the oxidation of thiosulfate to sulfate and sulfur without the intermediate formation of tetrathionate. Also oxidizes elemental sulfur. Does not oxidize hydrogen sulfide or sulfides.

Utilizes nitrate and ammonium salts as sources of nitrogen.

Aerobic.

Source: Canal water, mud and soil.

Habitat: Presumably widely distributed.

2. Thiobacillus ferrooxidans Temple and Colmer, 1951. (Iron oxidizing bacterium, Colmer, Temple and Hinkle, Jour. Bact., 59, 1950, 317; Temple and Colmer, Jour. Bact., 62, 1951, 605.)

fer.ro.o'xi.dans. L. noun ferrum iron; Gr. adj. oxys sharp, acid; M.L. v. oxido to oxidize or make acid; M.L. part. adj. ferrooxidans iron-oxidizing.

Description prepared by Dr. Kenneth L. Temple, Morgantown, West Virginia.

Short rods, 0.5 by 1.0 micron, with rounded ends. Occur singly or in pairs, rarely in chains. Motile, presumably polar flagellate. Gram-negative.

Thiosulfate agar colonies: Very thin and small with irregular margins, becoming whitish in center upon aging.

Thiosulfate liquid medium: Uniform turbidity; delicate pellicle in two or three weeks.

Ferrous agar: Colonial appearance varies with ferrous-iron content of agar: on low to moderate iron concentration, an amber zone reveals the presence of microscopic colonies which become lobed and coated with hydrated ferric oxide; on high ferrous iron concentration, growth is abundant becoming heavily encrusted with hydrated ferric oxide.

Ferrous liquid medium: Clear, rapidly turning amber to reddish brown due to production of ferric iron; ferric hydrate precipitated. Pellicle composed of cells and ferric hydrate.

Nitrogen sources: Utilizes ammonia; nitrate to a lesser extent.

Aerobic.

Optimum pH, between 2.5 and 5.8. No growth above pH 6.0. There is some step-wise adaptation to a lower pH than 2.5.

Strictly autotrophic, deriving its energy from the oxidation of thiosulfates or inorganic ferrous iron. Sulfur not appreciably utilized.

Distinctive characters: The pH range approaches that of Thiobacillus thiooxidans but does not extend below pH 2.0, and elemental sulfur is not appreciably used. Thiosulfate is oxidized rapidly but both liquid and agar