228 ORDER I. PSEUDOMONADALES 



Distinctive characters: By catalytic ac- of even minute traces of ferrous iron medium 



tion, this species increases by several fold to an acid thiosulfate medium may cause 



the amount of sulfuric acid normally formed decomposition of the thiosulfate, evidenced 



by the atmospheric oxidation of pyritic by the development of turbidity due to the 



materials found in bituminous coal seams formation of colloidal sulfur; this purely 



and associated rock strata. chemical reaction involving thiosulfate 



maj^ easily be misinterpreted as a bacterial 

 oxidation of this same substrate. 

 Source: Isolated from bituminous coal 



Comment: This organism closely resem 

 bles Thiobacillus ferrooxidans and may, in 

 fact, be identical with it. However Temple 

 and Colmer (Jour. Bact., 59, 1950, 317) 

 report that Thiobacillus ferrooxidans oxi- "^^^« drainages and from waters receiving 

 dizes thiosulfate while Leathen and Braley ^^^^ discharges. 



(op. cit., 1954, 44) report that Ferrobacillus Habitat: Indigenous to bituminous coal 



ferrooxidans does not oxidize thiosulfate. regions. Frequently form relatively hard 

 Thelatter workers (personal communication, granules of ferric iron in which many 

 May, 1954) further report that the transfer bacteria are entrapped. 



FAMILY VII. SPIRILLACEAE MIGULA, 1894. 



(Migula, Arb. Bact. Inst. Karlsruhe, 1, 1894, 237; Spirillobacteriaccae Orla-Jensen, 

 Jour. Bact., 6, 1921, 264.) 



Spi.ril.la'ce.ae. M.L. neut.n. Spirillum type genus of the family; -aceac ending to denote 

 a family; M.L. fem.pl.n. Spirillaceae the Spirillum family. 



Cells simple, curved or spirally twisted rods. These frequently remain attached to each 

 other after transverse division to form chains of spirally twisted cells. Cells are rigid and 

 usually motile by means of a single flagellum (rarely two) or a tuft of polar flagella. Gram- 

 negative. Frequently oxidative in their physiology. Aerobic or facultatively anaerobic, 

 although a few strict anaerobes occur among the vibrios (Desulfovibrio and Vibrio). Largely 

 water forms, although some are parasitic or pathogenic on higher animals and man. 



Key to the genera of family Spirillaceae. 



I. Curved, vibrio-like rods that are rarely united into a complete ring. 



A. Cells curved; rods never united at the end into a ring-shaped cell. Usually possess 

 a single, polar flagellum. 



1. Curved rods that are not known to attack cellulose. 



a. Aerobic to anaerobic, heterotrophic vibrios. 



Genus I. Vibrio, p. 229. 

 aa. Anaerobic, facultatively autotrophic vibrios that produce hydrogen sulfide 

 or methane. 

 b. Reduce sulfates to hydrogen sulfide. 



Genus II. Desulfovibrio, p. 248. 

 bb. Reduce carbon dioxide to methane. 



Genus III. Methanobacterium, p. 250. 



2. Curved rods that attack cellulose. 



a. Vibrio-like cells. 



Genus IV. Cellvibrio, p. 250. 

 aa. Pointed, sickle-shaped cells. 



Genus V. Cellfalcicula, p. 252. 



B. Curved rods that join ends to form a complete ring. 



Genus VI. Microcyclus, p. 253. 



