of a single, polar flagellum. Not acid-fast. Litmus milk : Slight growth with a neutral Gram-negative. to alkaline reaction; litmus slowly decolor- Gelatin: No liquefaction. ized; no peptonization. Peptone agar colonies: Small, round. Potato: No growth, smooth, gray, glistening. Indole not produced. Peptone agar slant: Growth is poor, Nitrites produced from nitrates, widely spread, colorless to whitish, trans- Congo red is weakly absorbed, lucent and resembles droplets of moisture. No growth at pH 4.5. Mannitol- calcium- glycerophosphate agar Optimum temperature, between 15° and slant: Weak growth resembling a film of 25° C. droplets of moisture. Distinctive characters: May be distin- Broth: Slightly turbid; no pellicle; very ^^j^j^^^ ^^^^^ Agrohacterium radiohacter small sediment. j * , j- ■ ^ ^ j^i r, xi -x, T'Tv-/^ A • 1 X 11 1 ^^^ ^- tumejaciens by weak growth on Broth with KInOs: Acid toward phenol , -,1 i -n i r • x , bouillon or bouillon agar, by forming star- Q^o +^.. r.A- ^. 001A KT 1 +1, like clusters on sea-water medium 2216, Sea-water medium 221b: Weak growth; . ' good formation of star-shaped clusters. by weak growth on calcium-glycerophos- Carrot agar: Very weak growth. P^^^^ ^^ar, by weak absorption of Congo Iron-manganese-carrot juice: Very weak ^'^d, by failure to grow on potato, by very development; no surface growth; no star- weak growth on carrot agar or Fe-Mn-carrot shaped clusters. juice and by forming star-like clusters on Iron -manganese -sea water-carrot juice: Fe-Mn-sea water-carrot juice. Good growth; thin, easily destroyed, sur- Source: Isolated from marine mud. face film; no star-shaped clusters. Habitat: Marine sources. Genus III. Chromobacteriuni Bergonzini, 1881.* (Cromobacterium (sic) Bergonzini, Ann. Societa d. Naturalisti in Modena, Ser. 2, 14, 1881, 153.) Chro.mo.bac.te'ri.um. Gr. noun chroma color; Gr. noun bacterium a small rod; M.L. neut.n. Chromobacteriuni colored rod. Rods which measure 0.4 to 0.8 by 1.0 to 5.0 microns. Motile by means of 1 to 4 or more flagella. Gram-negative. A violet pigment (violacein) is produced which is soluble in alcohol but not in water or chloroform. Grow on ordinary culture media, usuallj^ forming acid from glucose, sometimes from maltose and sucrose, but not from lactose. Gelatin is liquefied, sometimes slowly. Indole is not produced. Nitrites usually produced from nitrates; the nitrites are frequently further reduced to nitrogen and possibly nitrous oxide. Some strains grow well at 4° C. while others grow well at 37° C. with a maximum temperature of between 40° and 42° C. ; none grow at both 4° and 37° C. Usually saprophytic soil and water bacteria. Occasionally pathogenic to animals and man. The type species is Chromobacierium violaceum (Schroeter) Bergonzini. Discussion: The most characteristic feature of this group is its production of a violet pigment. The chemistry of this pigment has been well worked out by Tobie (Bull. Assoc. Diplomes Microbiol., Fac. Pharm. de Nancy, No. 18, 1939, 7). Since violacein appears to be chemically related to indigo, peritrichous organisms producing the latter pigment may tentatively be placed in this genus pending further study (Tobie, Jour. Bact., 35, 1938, 11). Cultures of violet bacteria are difficult to maintain in culture collections and are frequently
- Prepared by Prof. Robert S. Breed, New York State Experiment Station, Cornell Uni-
versity, Geneva, New York, from Cruess-Callaghan and Gorman, Scientific Proc. Royal Dublin Society, 21, 1935, 213, in January, 1938; further revision, July, 1955, with the as- sistance of Dr. Ethel T. Eltinge, Mount Holyoke College, South Hadley, Massachusetts, and Dr. W. C. Tobie, Old Greenwich, Connecticut.
