Genus/species: Acetobacter tropicalis
Gram Stain: Negative
- Cell: rods that are 0.5-0.7 by 1.8-2.0 micrometers in size. They occur in singles, chains, or in pairs.
- Colony: circular, convex, shiny, and not pigmented.
- Liquid Growth: dispersed
No growth on mannitol. Colonies are positive for catalase activity. Bacteria oxidize ethanol to acetic acid. Oxidizes acetate and lactate to CO2 and water. Production of D-gluconate and 2-keto-D-gluconate from D-glucose, also produces acid from glucose. No oxidase activity detected in colonies. Forms gamme-pyrones from both D-glucose and D-frusctose. Performs ketogenesis from glycerol. Acetobacter tropicalis grows in the temperature range 20 to 37 degrees Celsius and from pH 3.5 to 8.0. Grows well in presence of 5% D-glucose and 2 to 7% ethanol.
Found mainly in tropical regions, hence its name. Was first found in Indonesia in many plants. Isolated frequently from coconut.
Acetobacter tropicalis can be differentiated from other species using the following characteristics. It produces 2-Keto-D-gluconic acid from D-glucose. Acetobacter tropicalis is unable to grow using ammonium as a nitrogen source with ethanol as the carbon source. It can use both glycerol and maltose as a carbon source, but no growth using methanol as a carbon source. It will not grow on YE+30% (w/v) D-glucose. Catalase test will be positive, and it has between a 55.6-56.2 G+C content of DNA.
Role in wine:
Acetobacter tropicalis is an acetic acid bacteria, so it converts ethanol to acetic acid, using acetaldehyde as an intermediate. Identified in spoiled wine (rare).
- SO2: Sensitive
- Sorbate: Can utilize sorbic acid
- DMDC: Sensitive
- pH: Sensitive at 3.0 and below and at 9.0 and above
- Acids: Require acids as growth factors
- Ethanol: Does best in 2-7%
- Anaerobiosis: Obligate aerobe
- Heat: Killed below 20 and above 40 degrees Celsius
Bartowski, Eveline and Henschke, Paul. “Acetic Acid Bacteria Spoilage of Bottled Red Wine – A Review.” Journal of Food Microbiology, June 2008, pages 60-70.