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【English Name】Acetic Acid Bacteria

Aerobic bacteria that oxidize alcohol to acetic acid are collectively called acetic acid bacteria. They are Gram-negative bacteria classified in the phylum Proteobacteria, with the genera Acetobacter and Gluconacetobacter being their representatives.

The role acetic acid bacteria play in sushi culture is fundamental. Rice vinegar and grain vinegar, indispensable to vinegared rice, are all born through fermentation processes in which acetic acid bacteria are involved. In other words, without acetic acid bacteria the flavor of sushi could not exist.

Acetic acid bacteria possess strong acid tolerance and can grow even under acidic conditions below pH 5.0. Their optimal growth environment is said to be in the pH 5.4-6.3 range. In nature, they live widely in places such as wounds on fruit where yeast produces alcohol and in flower nectar. Owing to their aerobic nature, they show the characteristic behavior of forming a film on the surface of liquids as they multiply.

Beyond vinegar production, acetic acid bacteria are also active in the manufacture of diverse fermented foods such as nata de coco and kombucha (a fermented tea-based drink). Species capable of producing cellulose are also known, and their application to industrial materials is being researched. Academic research on this group of bacteria was triggered in 1864 when the French bacteriologist Pasteur identified the genus Acetobacter.