|Mother of vinegar from a wine vinegar pot|
As their name implies, these bacteria transform alcohol, for instance from wine, into acetic acid. From what I read during a quick overview of the literature, common acetic acid bacteria include species of the genera Acetobacter and Gluconobacter.
Both Acetobacter and Gluconobacter operate under aerobic conditions, but interestingly only Acetobacter can fully process the organic acid into water and CO2; Gluconobacter cannot proceed further than acetic acid. Nevertheless, Acetobacter strains are often preferred for vinegar production because they are better acid producers. But obviously, I do not know for sure what species is (are) present in my father's vinegar pots!
The acetic acid bacteria are great to make vinegar, but they can cause oenological problems in wine making. The acetic acid bacteria are naturally present on grapes and in the freshly pressed juice, but their number tend to decrease during the alcoholic fermentation (Joyeux, 1984). During the wine making conditions are kept anaerobic so acetic acid bacteria usually cannot grow; however, acetic acid bacteria can survive and proliferate if temperature and oxygenation are not tightly controlled. Usually wine is not filter-sterilized prior to be put into bottles, so a small number of acetic acid bacteria can still be in there. If the wine is stored for a long time in improper conditions (for instance a corked bottle standing upright), acetic acid bacteria can form a biofilm in the oxic zone and spoil the wine…
Wine vinegar is only one type among many types of vinegar that are produced in the world: cider, fruit, malt, rice and many other starting materials can be used to make vinegar. Just pick up your favorite one!
|Vineyards in Signy, Switzerland|
- Joyeux A., Lafon-Lafourcade S. and P. Ribéreau-Gayon (1984). Evolution of acetic acid bacteria during fermention and storage of wine. Applied and Environmental Microbiology. Vol.48, pp. 153-156.