982 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



Genus I. Sphaerotilus KiUzimj. 



(Kiitzing, Linnaea, 8, 1833, 385; Cladothrix Cohn, Beitr. z. Biol. d. Pflanz., 1, 

 Heft 3, 1875, 185.) From Greek sphaera, sphere. 



Attached, colorless threads, showing false branching, though this may be rare in 

 some species. Filaments consist of rod-shaped or ellipsoidal cells, surrounded by a 

 firm sheath. Multiplication occurs both by non-motile conidia and by motile swarm 

 cells, the latter with lophotrichous flagella. 



The type species is Sphaerotilus natans Kiitzing. 



1. Sphaerotilus natans Kiitzing. 

 (Kiitzing, Linnaea, <S, 1833, 385; not 

 Sphaerotilus natans Sack, Cent. f. Bakt., 

 II Abt., 65, 1925, 116; Cladothrix natans 

 Migula, in Engler and Prantl , Die natiirl . 

 Pflanzenfam. 1, la, 1895, 46.) From 

 Latin natans, swimming. 



Cells cylindrical, surrounded by a 

 sheath which is slimy in character, 2 to 

 3 microns in diameter. False branching 

 rare. 



Multiplication occurs through the 

 formation of coiaidia within the sheath 

 of the vegetative cells, from which they 

 swarm out at one end, swim about for a 

 time, then attach themselves to objects 

 and develop into delicate filaments. 

 Gelatin rapidly liquefied, requires 

 organic nitrogen, does not grow in the 

 ordinary peptone solution, grows best 

 with low concentrations of meat extract 

 (Zikes, Cent. f. Bakt., II Abt., 43, 1915, 

 529). 



The culture cultivated and described 

 as Sphaerotilus natans by Sack (Cent. f. 

 Bakt., II Abt., 65, 1925, 116) was identi- 

 fied as Bacillus mycotdeshy Haag {ibid., 

 69, 1926, 4). 



Source: Originally found in polluted 

 waters. May become a real nuisance in 

 sewage purification plants of the acti- 

 vated sludge type (Lackey and Wattie, 

 U. S. Pub. Health Ser., Pub. Health 

 Repts., 55, 1940, 975) and in streams pol- 

 luted with sulfite liquor from pulp and 

 paper mills (Lackey, Mimeographed 

 Kept. U. S. Pub. Health Ser., 1941). 



Habitat: Stagnant and running water, 

 especially sewage polluted streams. 



2. Sphaerotilus dichotomus (Cohn) 

 Migula. {Cladothrix dichotoma Cohn, 



Beitr. z. Biol. d. Pflanz., 1, Heft 3, 1875, 

 185; Migula, Syst. d. Bakt., ,?, 1900, 1033; 

 Sphaerotilus natans var. cladothrix 

 Butcher, Trans. Brit. Myc. Soc, 17, 

 1932, 112.) From Greek dicholomos, cut 

 in two parts, forked. 



The identity of this species as distinct 

 from Sphaerotilus Jiatans has been ques- 

 tioned. Cohn's description applied to 

 filaments 0.3 micron in diameter, while 

 all later authors have applied the name 

 to a much larger organism (2 to 4 microns 

 in diameter). 



Zikes (Cent. f. Bakt., II Abt., 43, 1915, 

 529) gives the following differential char- 

 acters: Cells smaller than Sphaerotilus 

 natans, 1.5 to 2.5 microns; false branch- 

 ing constant; grows best in high concen- 

 trations of meat extract; will grow in 

 ordinary peptone solutions; can utilize 

 inorganic nitrogen; liquefies gelatin 

 slowly. 



Source : Found by Cohn in water con- 

 taining Myconostoc. 



Habitat: Comparatively unpolluted 

 fresh water capable of sustaining algae. 



3. Sphaerotilus fluitans (Migula) Schi- 

 kora. {Streptolhrix fluitans Migula, in 

 Engler and Prantl, Die natiirl. Pflanzen- 

 fam., ^, la, 1895, 38; Schikora, Ztschr. f. 

 Fischerei, 7, 1899, 1-28; Chlamydothrix 

 fluitans Migula, Syst. d. Bakt., 2, 1900, 

 1033; Lcptothrix fluitans Chester, Man. 

 Determ. Bact., 1901, 370.) From Latin 

 fluitans, flowing, floating. 



Very thin attached filaments sur- 

 rounded by a soft sheath, from which 

 almost spherical conidia issue, usually 

 attaching themselves to the exterior of 

 the sheath, where the}' multiply. 



