From Distillers Wiki
According to The Alcohol Textbook:
A genus of Gram-negative, aerobic bacteria compirising ellipsoidal to rod-shaped cells as singles, pairs or chains. Otherwise known as acetic acid or vinegar bacteria, they are able to oxidize ethanol to acetic acid. They may be responsible for loss of yield in ethanol production if a fermented mash is agitated or aerated excessively.