Acetobacter

acetobacter, genus within the family of acetic acid bacteria (AAB) capable of spoiling wine by converting it ultimately into vinegar. They are found on all grapes but especially rot-affected grapes. Acetobacter can survive only in oxygen and are also one of the very few groups of bacteria which can live in the high-acid (low ph) environment of wine (although see also lactic acid bacteria).

Ideal conditions for the growth of acetobacter are temperatures between 30° and 40 °C (86° and 104 °F), relatively high pH values of between 3.5 and 4.0, low alcohol concentrations, absence of sulfur dioxide, and generous supplies of oxygen. For these reasons, safe winemaking favours low storage temperatures, good levels of acidity and alcohol, use of appropriate levels of sulfur dioxide as a disinfectant and, to minimize oxygen contact, barrels, vats, and tanks kept full at all times, that is with minimum ullage. If this last cannot be avoided, the stored wine is blanketed with carbon dioxide, nitrogen, or an inert gas mixture.