Which microorganism is used to produce vinegar?

Acetobacter is a genus of bacteria used to produce vinegar by converting ethanol into acetic acid in the presence of oxygen. This aerobic oxidation gives vinegar its characteristic sour taste and aroma, usually after yeast has first fermented sugars into alcohol.

Species such as Acetobacter aceti have long been associated with vinegar production from wine, cider and other alcoholic liquids. The bacteria thrive at the liquid’s surface, where oxygen is available, and can form a thin community or film. Their ability to tolerate acidic conditions allows them to continue working as acetic acid accumulates.

The process is often called acetic fermentation, although it is chemically an oxidation rather than the alcohol fermentation performed by yeast. Louis Pasteur demonstrated the microbial basis of acetic fermentation in 1864, helping overturn the idea that vinegar formed through a purely chemical transformation. A common mix-up is naming Saccharomyces, which produces the alcohol needed first but does not normally make vinegar itself. More broadly, several acetic-acid-bacteria genera can contribute to vinegar production, but Acetobacter is the standard canonical answer.