78 ORDER I. PSEUDOMONADALES 



Discussion : In spite of the fact that reaction would be helpful in clarifying this 



several able bacteriologists have studied situation. If the species is to be accepted as 



this species and the actinomycete that has a non-motile but related to polar-flagellate 



similar physiology, several important points bacteria, it must be Gram-negative. If an 



actinomycete, it would be Gram -positive. 

 Lantzsch reports the organism he studied 



are left in doubt; the most important of 



these is whether Beijerinck was right ii 



thinking the actinomycete something dis , , . , ,. , ^ , , ^ 



^. . r \- T> 11 T h i,-i „>. (which was an actinomj^cete) to be Gram- 



tinct from his Bacillus ohgocarbophilus, or ^ j / 



whether Lantzsch (Cent. f. Bakt., II Abt., Positive. 



57, 1922, 309) was right in thinking of them as Source: Isolated from garden soil. 



but stages in the growth cycle of a single Habitat: Presumably widely distributed 



species. Definite data in regard to the Gram in soil. 



FAMILY III. THIOBACTERIACEAE JANKE, 1924.* 



(Allgem. Tech. Mikrobiol., Dresden and Leipzig, I Teil, 1924, 68.) 



Thi.o.bac.te.ri.a'ce.ae. M.L. neut.n. Thiobacterium type genus of the family; -aceae 

 ending to denote a family; M.L. fem.pl.n. Thiobacteriaceae the Thiobacterium family. 



Coccoid, straight or curved rod-shaped bacteria. Oxidize sulfur compounds, usually de- 

 positing free sulfur granules within or without the cells. Never filamentous. Colorless sulfur 

 bacteria that are sometimes embedded in gelatinous pellicles or in gelatinous bladder-like 

 colonies. Polar flagellate when motile. Presumably Gram-negative. Found in places where 

 hydrogen sulfide occurs or may oxidize free sulfur, thiosulfates or related compounds. 



While all of the species placed in this family have been described as colorless sulfur bac- 

 teria, they are still inadequately known and may not all deserve to be designated as sulfur 

 bacteria. It is hoped that placing them together in one family will cause comparative studies 

 to be made. 



The type genus is Thiobacterium Janke. 



Key to the genera of family Thiobacteriaceae. 

 I. Free sulfur granules deposited within or without the cells. Usually found in sulfurous 

 waters or soil. 



A. Cells coccoid or straight rods. 



1. Non-motile so far as known. ^ 



Genus I. Thiobacterium, p. 79. 



2. Motile by means of polar flagella so far as known. 



a. Cells rod-shaped, very large. 



Genus II. Macromonas, p. 80. 

 aa. Cells round to ovoid, large. 



Genus III. Thiovuhim., p. 81. 



B. Cells large, curved rods, somewhat pointed. 



Genus IV. Thiospira, p. 82. 

 II. Oxidize free sulfur, thiosulfates and related sulfur compounds to sulfates. Autotrophic 

 or facultatively autotrophic. 



Genus V. Thiohacillus, p. 83. 



* Revision of Thiobacteriaceae Janke prepared by Prof. Dr. Alexander Janke, Technische 

 Hochschule, Vienna, Austria, December, 1954, with the assistance of Prof. Robert S. Breed, 

 Cornell University, Geneva, New York. 



