Genus/species: Gluconacetobacter intermedius
Gram Stain: Gram negative
Morphology:
Cell: ellipsoidal to rod-shaped
Colony: Pale; forms a zone of clearing on calcium carbonate medium
Liquid Growth: thick pellicle formed
Physiological Traits:
Strictly aerobic. Growth substrates are ethanol, glucose, and glycerol. Most strains do not utilize sucrose. Oxidize ethanol to acetic acid. Grow well on MRS medium and may be mistaken for an acetic acid bacterium.
Ecological Traits:
Damaged fruit, nectar of flowers, sugarcane mealy bugs, tea fungus, and beverages such as cider, wine, and beer.
Distinguishing Features:
- Growth on Carr and Passmore medium
- Growth on 30% (w/v) D-glucose medium
- Cellulose formation
- Possesses ubiquinone Q-10 as major quinone
Role in wine:
Gluconacetobacter sp. are present on damaged fruit and within the winery. At high levels Gluconacetobacter are considered a spoilage organism, because they produce volatile acidity.Gluconacetobacter sp. produce acetic acid and oxidize ethanol. Gluconacetobacter sp. are usually present on fermenting fruit so they are known to accompany yeast and insects likeDrosophila sp.
Sensitivities:
- SO2: 0.7-1 mg/L molecular
- Sorbate: No
- DMDC: 200 mg/L
- pH : < 2.3 (optimum 4.0-6.0)
- Acids: >10% acetic acid
- Ethanol >9.5-11%
- Anaerobiosis:No
- Heat: > 37ºC (optimum 28-30 ºC)