GLUCONOBACTER

9 plus species including:

SPECIES

Gluconobacter oxydans

MICROSCOPIC APPEARANCE

Gram Stain: Gram-variable, more than likely negative.
Morphology: Ellipsoidal to rod-shaped. Occurring singly, in pairs, and sometimes in short chains.
Size: 0.5-1.0 micrometers by 2.6-4.2 micrometers.
Motility: Motile and non-motile. When motility occurs, cells have 3-8 polar flagella.
Capsules: None.
Rods: None.
Other: Enlarged, irregular cell forms (involution) may occur.

MACROSCOPIC APPEARANCE

Large, slimy, pale colonies. Typically the strains are circular, raised or convex, regularly edged, milky white to yellowish. Depending upon the culture medium, strains may produce pink or dark brown pigments.

KEY BIOCHEMICAL REACTIONS

METABOLIC PROPERTIES

Obligately aerobic, having a strict respiratory type of metabolism with oxygen as the terminal electron acceptor. Chemoorganotrophic. Oxides ethanol into acetic acid. However, no acid production or growth occurs on starch. Gluconobacter strains prefer sugar-enriched environments. All Gluconobacter strains require growth factors in the presence of D-Mannitol as the primary carbon source. In media with no carbon source no growth occurs.

HABITAT

Widely distributed in vegetation, flowers, spoilage organisms in wine, beer, bakers yeast, honey bees, and soft drinks.

PATHOGENICITY

Gluconobacter strains are not known to have any pathogenic effect towards man or animals. They are capable of causing a bacterial rot of apples and pears which is accompanied by various shades of browning. The bacteria enter the apples through wounds in the cuticula and apple tissue. Strains of G. oxydans are also the causative agent of "pink disease" of pineapple fruit; the disease fruit turns pink or pink-brown to deep brown after heating. (2)

RECOMMENDED MEDIA

For culture: GYC Standard Medium. (1)
For selective isolation: None described.
For maintenance: GYC Standard Medium and Mannitol Medium for up to 3 months. (1) Lyophilization is recommended for long-term storage.

INCUBATION

Temperature: 25-30 degrees C, with all growth ceasing beyond 37 degrees C.
Time: 24-48 hours.
Atmosphere: Aerobic.
Optimum pH: 5.5-6.0.

REFERENCES

1. Holt, J.G., et al. 1994. Bergey's Manual of Determinative Bacteriology , 9th ed. Williams & Wilkins, Baltimore, MD.

2. Holt, J.G., et al. 1986. Bergey's Manual of Systemic Bacteriology , Vol. I & II. Williams & Wilkins, Baltimore, MD.

3. The Oxoid Vade-Mecum of Microbiology . 1993. Unipath Ltd., Basingstoke, UK.

4. Murray, P.R., et al. 1995. Manual of Clinical Microbiology , 6th ed. American Society for Microbiology, Washington, D.C.

5. Internet: www.hardlink.com/ Bacterial Database Search, February, 1998.

6. Hensyl, B.R., et al. 1990. Stedman's Medical Dictionary , 25th ed. Williams & Wilkins, Baltimore, MD.

7. Koneman, et al. 1997. Color Atlas and Textbook of Diagnostic Microbiology , 5th ed. Lippincott, Philadelphia, PA.


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