Acetobacter lovaniensis

Genus/species (alias): Acetobacter lovaniensis (Acetobacter pasteurianis subsp. lovaniensis)

 

Gram Stain: Negative

Morphology: 

  •  Cellellipsoidal, rod-shaped cells, often with a slight bends, sized between 0.6-0.9 x 1.0-1.4 um.
  •  Colony: colonies tend to be pale in color, small and raised.
  • Liquid Growth:Acetobacter can be flocculent and can form a pellicle.

Physiological Traits:

It can survive for a limited time without oxygen, but is obligately aerobic for metabolic activity.  It oxidizes actetate, lactase, ethanol and glucose to gluconate. 2-ketogluconate and 5-ketogluconate are not produced.  It is catalase positive.  Does not produce acid from d-fructose, l-sorbose, d-mannitol, d-sorbitol, glycerol, sucrose, or lactose. Acid production from d-mannose, d-galactose, l-arabinose, and d-xylose is strain dependent.

Ecological Traits:

Three of the most commonly studied strains of A. lovaniensis were isolated from vinegar, a mushroom from Thailand, and the type strain from sewage on soil in Belgium.  It is commonly found on fruits, flowers, vinegars, and in fermented foods and drinks.

Distinguishing Features:

Role in wine:

Like most Acetobacter species it can be common as both a grape flora, on ripe berry surface, particularly if damaged, and as part of the winery flora. While obligately aerobic, it can survive for some period of time in wine and oxidizes ethanol to acetic acid and ethyl acetate.  If substrates are not exhausted, may continue activity after ML has finished, in bottle.  Common control methods include use of SO2, avoidance of excessive oxygen and sanitation.

Sensitivities:

  • SO2:Sensitive to free SO2 in wine at typical levels
  • Sorbate: Unknown   
  • DMDC: Unknown
  • pH: Optimum 4.0-6.0
  • Acids: Unknown 
  • Ethanol: Unknown
  • Anaerobiosis: Unknown  Heat Optimum at close to 30 degrees Celsius.

References:

König H., G. Unden and J. Fröhlich.  2009.  Biology of Microorganisms on Grapes, in Must, and in Wine.  Springer, New York.