212 ORDER I. PSEUDOMONADALES 



duces a blue color with concentrated sul- Source: Isolated from "Trapani" salt 



furic acid, thus suggesting a carotenoid. r..^^ • -d ,~.j , , 



,. 1 ui ■ -J- 1 , , , • "^"^ ^ cannery in Bergen (Norway) and 



Very soluble in pyridine; less soluble in = \ j / 



methanol, ethanol and chloroform; slightly 



from the water of the Dead Sea. 



soluble in acetone, very slightly so in ben- Habitat: Sea salt, sea-water brine and 



zol; insoluble in xylene and petroleum ether. salt lakes. 



FAMILY V. CAULOBACTERACEAE HENRICI AND 

 JOHNSON, 1935, EMEND. BREED.* 



(Includes the typical families and genera of Caulobacteriales (sic) Henrici and Johnson, 

 Jour. Bact., 29, 1935, 4 and ibid., 30, 1935, 83. The Order Caulobacterales Henrici and Johnson 

 was redefined as a Sub-order, Caidobacteriineae (sic), by Breed, Murray and Kitchens, Bact. 

 Rev., 8, 1944, 255. The present emendation reduces the Order Caulobacterales, as originally 

 defined, to the status of a family in the Sub -order Pseudomonadineae Breed, Murray and 

 Smith.) 



Cau.lo.bac.ter.a'ce.ae. M.L. neut.n. Caulobacter the type genus of the family; -aceae 

 ending to denote a family; M.L. fem.pl.n. Caulobacteraceae the Caulobacter famil}^ 



Non-filamentous, rod-shaped bacteria normally attached by branching or unbranching 

 stalks to a substrate. In one floating form the stalks are branched. Cells occur singly, in 

 pairs or in short chains. The cells are asymmetrical in that a stalk is developed at one end 

 of the cell or ferric hydro.xide or other material is secreted from one side of the cell to form 

 stalks. Cells are polar flagellate in the free-living state, non-motile in the attached forms. 

 Gram-negative. Multiply by transverse fission, the daughter cells remaining in place or 

 swimming away as swarm cells. Typically fresh- or salt-water forms. 



The family Caulobacteraceae, as here defined, includes the genera Caulobacter Henrici and 

 Johnson, Gallionella Ehrenberg, Siderophacus Beger and Nevskia Famintzin. 



The species in this family as presented here have close affinities with the species in the 

 family Pseudomonadaceae . In all cases where motility has been observed and stains made, 

 polar flagella have been found. It seems probable that when the life histories of these seden- 

 tary bacteria have been investigated, it will be found that practically all, if not all, of these 

 attached forms develop a motile stage. Such a stage permits the distribution of the species 

 in its environment. 



The stalked bacteria studied by Henrici and Johnson (op. cit., 30, 1935, 83) were of fresh- 

 water origin. Bacteria of this type are found, however, equally if not more abundantly in 

 marine habitats where they play their part in the fouling of underwater surfaces. ZoBell 

 and Upham (Bull. Scripps Inst, of Oceanography, LaJolla, California, 5, 1944, 253) summa- 

 rize this situation as follows: "Many of the bacteria found in sea water are sessile or peri- 

 phytic, growing preferential!}^ or exclusivelj^ attached to solid surfaces. The sessile habit 

 of marine bacteria is most pronounced when they are growing in very dilute nutrient solu- 

 tions, such as sea water, to which nothing has been added. . . . Most sessile bacteria appear 

 to attach themselves tenaciously to solid surfaces by exuding a mucilaginous holdfast. A 

 few have stalks. Some of the sessile bacteria grow on the walls of the culture receptacle 

 without clouding the medium itself.". 



The submerged-slide technique as employed by Henrici (Jour. Bact., 25, 1933, 277) and 



* Redefined and rearranged by Prof. Robert S. Breed, Cornell University, Geneva, New 

 York, December, 1953. Prof. Herbert Beger, Institut fiir Wasser-, Boden- und Lufthygiene, 

 Berlin-Dahlem, Germany, has given this section a further revision so as to include genera 

 and species not previously recognized in the Manual, February, 1954. 



