Page:Bergey's manual of determinative bacteriology.djvu/234

 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.

(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 sedentary 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 freshwater 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) summarize this situation as follows: "Many of the bacteria found in sea water are sessile or periphytic, 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 solutions, 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