Colonies are smooth, but rough variants may occur; colonies are of butyrous
consistency and are easily emulsified in water. Most strains produce the violet
pigment violacein, but nonpigmented strains may be encountered, and  subcultures
of pigmented strains often contain partially or completely unpigmented colonies.
Growth in nutrient broth produces a violet ring at the surface with a fragile pellicle.
Violacein is produced in media containing tryptophan. Beta-hemolytic on blood agar.
Growth temperature range is 10-40 ºC, 30-35 ºC optimum. Optimum pH 7-8 (no
growth below pH 4). Grows in 2% NaCl, but not in 4% NaCl media. Grows on TSI, TSA
MacConkey agar, and in nutrient broth. Facultative anaerobe.
Cultural characteristics
Biochemical characters
Phylum Proteobacteria, Class Betaproteobacteria, Order Neisseriales, Family Chromobacteriaceae, Genus Chromobacterium,
Chromobacterium violaceum
Bergonzini 1880 - type species of the genus.

Old synonyms:
Chromobacterium janthinum (Zopf) Ford 1927, Chromobacterium manilae (Krasil'nikov) Leifson 1956,
Chromobacterium laurentium (Migula) Leifson 1956.
Gram-negative, round-ended, coccoid rods, 0.6-0.9 x 1.5-3.0 μm. Motile by a single
polar flagellum and, usually, one or more subpolar or lateral flagella. Capsule is not
produced. Usually contains poly-beta-hydroxybutyrate crystals (80% of strains are
Occurs in soil and water and is common in tropical and subtropical climates. Produce thea monocyclic beta-lactam antibiotic
Susceptible to chloramphenicol (10 μg), chlortetracycline (10 μg), furazolidone (50 μg), kanamycin (30 μg), neomycin (10 μg), nalidixic
acid (30 μg), nitrofurantoin (200 μg), oxytetracycline (10 μg) & sulfafurazole (100 μg).
Resistant to O/129 agent by disc diffusion method (50 μg), ampicillin (25 μg), cephaloridine (25 μg), colistin sulfate (10 μg), penicillin G
(1.5 U), streptomycin (10 μg) & sulfafurazole, 500 μg.
Occasionally causes serious pyogenic or septicemic infections of mammals, including humans (producing fever, sepsis, skin
lesions, localized abscesses in liver, lung, spleen, skin, lymph nodes, and brain).
Pathogenic bacteria of carp have been characterized as closely resembling
C. violaceum.
  1. Tone Tonjum, 2005. Order IV. Neisseriales ord. nov. In:  Bergey’s Manual of Systematic Bacteriology, Second edition, Vol two, part
    C The Alpha-, Beta-, Delta-, and Epsilonproteobacteria, George M. Garrity (Editor-in-Chief), pp 774-863.
  2. Euzeby (J.P.): Necessary corrections according to Judicial Opinions 16, 48 and 52. Int. J. Syst. Bacteriol., 1998, 48, 613.
  3. Euzeby (J.P.): List of Bacterial Names with Standing in Nomenclature: a folder available on the Internet. Int. J. Syst. Bacteriol.,
    1997, 47, 590-592. (List of Prokaryotic names with Standing in Nomenclature.
  4. Yang CH, Li YH. Chromobacterium violaceum infection: a clinical review of an important but neglected infection. J Chin Med
    Assoc. 2011 Oct;74(10):435-41. doi: 10.1016/j.jcma.2011.08.013. Epub 2011 Oct 19.
  5. M Ravish Kumar. Chromobacterium violaceum: A rare bacterium isolated from a wound over the scalp. Int J Appl Basic Med Res.
    2012 Jan-Jun; 2(1): 70–72. doi: 10.4103/2229-516X.96814.
  6. Ching-HueiYang. Nonpigmented Chromobacterium violaceum bacteremic cellulitis after fish bite. Journal of Microbiology,
    Immunology and Infection, Volume 44, Issue 5, October 2011, Pages 401-405.
Positive results for arginine dihydrolase, catalase, chitin digestion, casein hydrolysis, HCN production, egg yolk reaction, gelatin
hydrolysis, oxidase, Tween 80 hydrolysis, urease (negative in API NE), acid production from D-fructose, gluconate, D-glucose,
glycerol, glycogen, D-mannose & trehalose. Can utilize as sole carbon source: citrate (negative in API NE), fumarate, lactate, malate,
pyruvate & succinate.

Negative results for esculin hydrolysis, H
2S production (in TSI medium), indole production, lysine decarboxylase, methyl red test,
ornithine decarboxylase, starch hydrolysis, Voges-Proskauer test, acid production from: L-arabinose, D-cellobiose, D-galactose,
N-acetyl-glucosamine, myo-inositol, lactose, D-maltose, D-mannitol, melezitose, D-raffinose, D-sorbitol & D-xylose. No utilization of

Variable results for nitrate reduction (usually positive), nitrite reduction (usually negative), acid production from inulin (usually
negative), starch (usually positive) & sucrose (usually negative). Variable (usually positive) utilization of acetate and propionate.
Chromobacterium violaceum
(c) Costin Stoica
Culture media
Biochemical tests
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