by ZoBell and Allen (Proc. Soc. Exper. Biol, and Med., 30, 1933, 1409) has proved to be most useful for studying bacteria that live attached to a substrate.
The species included in Pasteuria Metchnikoff and Blastocaulis Henrici and Johnson reproduce by a curious form of fission or budding. They have been transferred to a new- Order, Hyphomicrobiales Douglas.
Key to the genera of family Caulobacteraceae.
I. Long axis of cell coincides with axis of stalk. Stalks slender.
Genus I. Caulobacter, p. 213.
II. Long axis of cell transverse to long axis of stalk. Stalks may be twisted and branched.
- A. Stalks are band-shaped or rounded. Contain ferric hydroxide.
- 1. Stalks band-shaped and twisted. Dumb-bell-shaped in cross section.
Genus II. Gallionella, p. 214.
- 2. Stalks horn-shaped, not twisted. Round in cross section.
Genus III. Siderophacus, p. 216.
B. Stalks lobose, composed of gum. Forming zoogloea-like colonies. Free-floating.
Genus IV. Nevskia, p. 216.
Genus I. Caulobacter Henrici and Johnson, 1935.
(Jour. Bact., 29, 1935, 4; ibid., 30, 1935, 83.)
Cau.lo.bac'ter. L. noun caulis a plant stem or stalk; M.L. noun bacter masculine form of Gr. neut.n. bactrum a rod; M.L. mas.n. Caulobacter stalk rod.
Stalked, curved, rod-shaped bacteria, the long axis of the elongated cells coinciding with the long axis of the stalks. Young cells motile by means of a single polar flagellum. Old cells attached to submerged objects by a stalk that is a continuation of the cell. A holdfast is developed at the distal end. Multiplication of cells is by transverse binary fission. Periphytic, growing upon submerged surfaces.
The type species is Caulobacter vibrioides Henrici and Johnson emend. Bowers et al.
1. Caulobacter vibrioides Henrici and Agar colonies: Surface colonies up to 5 Johnson, 1935, emend. Bowers et al., 1954. mm in diameter, round, smooth, slightly (Henrici and Johnson, Jour. Bact., 30, 1935, raised, glistening, finely granular in the 83; Bowers, Weaver, Grula and Edwards, center, grayish white, with center and re- Jour. Bact., 68, 1954, 194.) verse side becoming brownish yellow. Sub- vib.ri.oi'des. L.v. vibro to vibrate; M.L. surface colonies dense, brownish yellow, noun Vibrio name of a genus; Gr. noun lenticular, up to 0.5 mm in diameter and 1.0 eidus shape, form; M.L. adj. vibrioides re- mm in length, sembling a vibrio. Agar slant: Growth filiform, grayish Cells elongated, curved, vibrio-like, with white, glistening, viscid, rounded ends, 0.5 to 1.2 by 1.5 to 3.0 mi- Broth: Moderate turbidity with slightly crons; filamentous forms occasionally pro- viscid sediment, duced. Young cells actively motile with a Litmus milk: Unchanged, single polar flagellum; older cells develop p^^^^^^ kittle or no growth, a stalk at the flagellated end. The stalk has a central filament or tube and a membrane that is continuous with the cell wall. Organ- isms attached singly or in rosettes, with Indole not produced. Nitrites not produced from nitrates. No acid or gas from carbohydrates. stalks attached to a common holdfast. Usu- Requires riboflavin, phosphates, iron and ally surrounded by a slime layer. Gram- an organic source of energy for growth. Glu- negative. cose, maltose or casamino acids are used as Gelatin: Surface growth and filiform sources of carbon and energy; sodium bi- growth in stab without liquefaction. carbonate, sodium lactate, sodium acetate
