84 



ORDER I. PSEUDOMONADALES 



2. Final pH, 1.0 or less, 

 a. Nitrate utilized. 



7. Thiohacilhis concretivonis. 

 aa. Nitrate not utilized. 



8. Thiobacillus thiooxidans . 

 II. Thiosulfate oxidized with increased alkalinity. 



9. Thiobacillus trautweinii. 



1. Thiobacillus thioparus Beijerinck, 

 1904. (Arch. d. Sci. Exact, et Nat. Haar- 

 lem, Ser. 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 con- 

 sists of cells and free sulfur. Medium be- 

 comes 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 forma- 

 tion of tetrathionate. Also oxidizes ele- 

 mental 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 bacter- 

 ium, Colmer, Temple and Hinkle, Jour. 

 Bact., 59, 1950, 317; Temple and Colmer, 

 Jour. Bact.,6^, 1951,605.) 



fer.ro.o'xi.dans. L. noun Jerrum iron; 

 Gr. adj. oxys sharp, acid; M.L. v. oxido to 



oxidize or make acid; M.L. part. adj. Jer- 

 rooxidans 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 flagel- 

 late. Gram -negative. 



Thiosulfate agar colonies: Very thin and 

 small with irregular margins, becoming 

 whitish in center upon aging. 



Thiosulfate liquid medium: Uniform tur- 

 bidity; 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 hy- 

 drated ferric oxide; on high ferrous iron 

 concentration, growth is abundant becom- 

 ing heavily encrusted with hydrated ferric 

 oxide. 



Ferrous liquid medium: Clear, rapidly 

 turning amber to reddish brown due to pro- 

 duction of ferric iron; ferric hydrate pre- 

 cipitated. Pellicle composed of cells and 

 ferric hydrate. 



Nitrogen sources: Utilizes ammonia; ni- 

 trate 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 inor- 

 ganic ferrous iron. Sulfur not appreciably 

 utilized. 



Distinctive characters: The pH range ap- 

 proaches 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 



