86 



ORDER I. PSEUDOMONADALES 



Distinctive characters: Develops in inor- 

 ganic media and oxidizes thiosulfate and 

 sulfur to sulfate. Media with slightly alka- 

 line reactions most favorable for growth. 



Source: Isolated from coprolite rock ma- 

 terial from Triassic period (Arizona). 



Habitat: Unknown. 



5. Thiobacillus denitrificans Beijer- 

 inck, 1904. (Beijerinck, Cent. f. Bakt., II 

 Abt., 11, 1904, 597; Sulfomonas denitrificans 

 Orla-Jensen, Cent. f. Bakt., II Abt., 22, 

 1909, 314.) 



de.ni.tri'fi.cans. L. pref. de off, removed; 

 M.L. noun niter saltpeter, nitrate; M.L. v. 

 nitrifico to make nitrate, to nitrify; M.L. 

 denitrifico to denitrify; M.L. part. adj. de- 

 nitrificans denitrifying. 



Short rods, 0.5 by 1 to 3 microns. Motile 

 by means of a single polar flagellum (Tjulpa- 

 nova-Mossevitch, Arch. d. Sci. Biol., 

 U.S.S.R.,SO, 1930, 203). 



Inorganic broth: Growth with production 

 of gas, predominantly nitrogen. 



Thiosulfate agar colonies: Thin; clear or 

 weakly opalescent. 



Optimum reaction: Neutral or slightly 

 alkaline. 



Autotrophic, utilizing carbon from COo , 

 carbonates and bicarbonates. Considered to 

 be strictly autotrophic by Lieske (Ber. d. 

 deutsch. botan. Gesell., 30, 1912, 12) and 

 facultatively by Tjulpanova-Mossevitch (op. 

 cit., 30, 1930, 203). Beijerinck stated (Kon. 

 Akad. V. Wetenschappen Amsterdam, 42, 

 1920, 899) that whereas the organism de- 

 veloped initially in an inorganic medium, it 

 lost the autotrophic habit bj^ cultivation in 

 an organic medium. 



Facultatively anaerobic. Can live in the 

 absence of free O2 in the presence of nitrate. 



Distinctive characters: Oxidizes thiosul- 

 fate to sulfate under anaerobic conditions 

 using nitrate as the hydrogen acceptor which 

 is reduced to N2 . Also oxidizes sulfide, ele- 

 mental sulfur and dithionate. 



Habitat: Canal and river water, salt 

 water, soil, peat, composts and mud. 



6. Thiobacillus neapolitanus Parker, 

 nom. nov. (Neue Gruppe von Schwefelbak- 

 terium, Nathansohn, Mitt. Zool. Sta., 

 Neapel, 15, 1902, 655; Thiobacillus X, 

 Parker, Jour. Gen. Microbiol., 8, 1953, 344.) 



ne.a.po.li.ta'nus. L. adj. neapolitanus 

 pertaining to Naples. 



Short rods, 0.5 by 1.0 to 1.5 microns. Non- 

 motile. Gram-negative. 



Thiosulfate agar colonies: Small (1 to 2 

 mm in diam.) circular, convex; whitish yel- 

 low due to precipitated sulfur. 



Thiosulfate liquid medium; Uniform tur- 

 bidity with pellicle which contains free 

 sulfur. pH drops to 3.0. 



Sulfur liquid medium: Very slight, uni- 

 form turbidity. 



Optimum pH, about 6.0; growth occurs 

 between pH 8.5 to 3.0. 



Temperature relations: Optimum, 28° C; 

 slow growth at 10° and 37° C; death occurs 

 at 55° C. 



Strictly autotrophic. Derives energy by 

 the oxidation of thiosulfate, tetrathionate, 

 elemental sulfur and hydrogen sulfide. 

 Thiosulfate is oxidized to tetrathionate, 

 sulfate and sulfuric acid; tetrathionate is 

 oxidized to sulfate and sulfuric acid while 

 free sulfuric acid only is formed from ele- 

 mental sulfur and hydrogen sulfide. Utilizes 

 atmospheric CO 2 as a source of carbon. 

 • Nitrogen sources: Ammonium; nitrate- 

 and nitrite-nitrogen. 



Aerobic. 



Comments: It has not been clear until re- 

 cently (Parker, Jour. Gen. Microbiol., 8, 

 1953, 344) that this organism is a species 

 separate from Thiobacillus thioparus Beijer- 

 inck. The isolation and detailed study of an 

 organism from concrete identical in most 

 respects with Nathansohn 's description of 

 his isolate but different from Beijerinck's 

 and Starkey's description of Thiobacillus 

 thioparus makes it clear that two separate 

 species are involved. Thiobacillus neapoli- 

 tanus produces tetrathionate and sulfate 

 from thiosulfate and oxidizes HoS and tetra- 

 thionate whereas Thiobacillus thioparus 

 produces sulfur and sulfate from thiosulfate 

 and does not oxidize H2S or tetrathionate. 



Source: Originally isolated by Nathan- 

 sohn from sea water at Naples, Italy. Iso- 

 lated by Parker from early stages of the cor- 

 rosion of concrete sewers and other concrete 

 structures. 



Habitat: Presumably widely distributed 

 in soil and water, including sea water. 



7. Thiobacillus concretivorus Parker, 



