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 1. Identifying Characteristics

• Facultative aerobes.
• Coccobacilli to slender rods.
• 0.4-1.0 um x 0.7-6.0 um in size.
• No resting stages or spores are known.
• Cells stain gram negative.
• If motile, by peritrichous flagella.
• Chemoorganotrophic.
• No unusual structures formed.
• Colonies are usually yellow, orange, and red to brown pigmented which are not soluble in media.
• Nonfermentative.
• Indole produced by all but one species.
• Oxidase positive.
• Catalase positive.
• The percent G+C ranges from 31-42%
• Phosphotase positive.
• Some fix nitrogen.
• Highly antibiotic resistant.
• Opportunistic pathogen.

In the above picture the tube on the left shows the characteristic alkaline reaction of yellow Flavobacterium colonies. The tube on the right is positive for indole(red band seen at the surface of the agar). A nonfermentative bacillus that produces both yellow pigment and indole can be presumptively identified as Flavobacterium species.

2. TAXONOMIC DESCRIPTION

Flavobacterium are found in soil, water, plants, food stuffs and almost every water systems including distilled water lines and dental chair spray units. They can also survive in intravenous anesthetics, eyes, urine, and stool samples. Most species are yellow pigmented rods. Motility is not observed in hanging drop. Some strains form spreading colonies. Some species are acid producing. Flavobacterium are nonfermentative gram-negative bacilli. All but one species produces indole which is a unique characteristics among non fermenters. They are chemoorganotrophs which have respiratory metabolism. Some strains are holotolerant. Flavobacterium are fastidious microbes and some strains are pathogenic to humans and animals.

There are three hundred and twelve strains of Flavobacterium. Two hundred and fifty of these strains are acid producing. The acid producing strains include the species meningosepticum, the strain which causes the deadly disease meningitis.

3. Isolation and Ecology

Selective media are available and, on isolation, Flavobacterium colonies may be yellow, orange, and red to brown pigmented with a fruity odor. The colonies are often circular, smooth and shiny. x

Flavobacterium are very common and are found in soil, plants, animals, food stuffs, and almost all water systems. In hospitals they are found in incubators, water baths, drinking fountains, and cold humidifiers. They can also survive in intravenous anesthetics. Flavobacterium occur in 0.1-1.0% of all blood cultures and 0.01% of all urine cultures. They can be found living in the eyes of animals. When being cultured they can thrive in everything from blood agar medium to basal medium. In soils Flavobacterium are concentrated around in the rhizosphere, the layer of soil immediately surrounding roots.

Some species of Flavobacterium are capable of degrading pentachlorophenol and other similar compounds. This is an example of the bioremediation capabilities of this genus.

4. ADDITIONAL SOURCES OF INFORMATION

Gilardi, G.L. 1985. Nonfermentative Gram-Negative Rods. Marcel Dekker, Inc.. New York.

Joklik, Willett, and Amos. 1984. Zinsser Microbiology. Appleton-Century-Crafts. Connecticut.

Koneman, E., Allen, S., and V.R. Dowell, Jr.. 1983. Color Atlas and Textbook of Diagnostic Microbiology. Lippineott Company. Pennsylvania.

Krieg, N. 1984. Bergey's Manual of Systematic Bacteriology. Williams and Wilkins. Maryland.

Metting, B. 1993. Soil Microbiology Ecology. Marcel Dekker, Inc..New York.

O'Leary, W. 1989. Practical Handbook of Microbiology. CRC Press, Inc.. Florida.

5. LINKS TO OTHER SITES ON FLAVOBACTERIUM

These sites contain additional information on the genus Flavobacterium.

Antigens and antisera used in serological tests to identify flavobacterium species. This is the NEOFORMA Guide to Microbiology, click on the Microbiology link and then enter Flavobacterium as the keyword.

Information on Flavobacterium as a non-fermenter.

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