Acetobacter oeni

Genus/species: Acetobacter oeni

Gram Stain: Negative

Morphology:

  • Cell: Motile, non-spore forming rods with peritrichous flagella (0·8–0·9x3·6–5·1 µm).
  • Colony: Colonies on YEDC are circular, convex, cream, opaque and usually 1–2 mm in diameter within 4 days growth at 28 °C.
  • Liquid Growth: Film former

Physiological Traits: 
Produces 5-ketogluconic acid from glucose; utilizes glycerol; ethanol or methanol can be used as carbon sources.


Ecological Traits: 
Acetic acid bacteria (AAB) occur in sugary environments in nature such as fruits and flowers. They are especially well suited for fruits that produce ethanol as they rot. Their acidic end product in the presence of ethanol provides AAB with an environment with little competition from other microbes. It is these qualities that make them prolific in areas where alcohol is produced.


Distinguishing Features: 
5-Keto-D-gluconic acid (+), 2-Keto-D-gluconic acid (-), Growth in ammonium with ethanol (-), Growth in presence of 10 % ethanol (+), Growth on carbon sources: Glycerol (+), Maltose (-), Methanol (-), Growth on YE + 30 % D-glucose (-), Catalase, Oxidase (-). 
The key features that distinguish A. oeni from other acetic acid bacteria are the production of 5-Keto-D-gluconic acid and not 2-Keto-D-gluconic acid and growth in presence of 10 % ethanol.

Role in wine: 
A. oeni is a spoilage organism that can lead to the production of volatile acids (namely acetic acid) in a wine.


Sensitivities:
 SO2: X

Sorbate:

DMDC:

pH:

Acids:

Ethanol:

Anaerobiosis: X

Heat: X

References:

  • H. Konig et al. (eds.), Biology of Microorganisms on Grape, in Must and in Wine, Springer-Verlag Berlin Heidelberg 2009, pg. 31-44