Acetic acid bacteria

Abstract

Acetic acid bacteria (AAB) are considered one of the most common wine spoilage microorganisms and a threat for the oenologists. Their ability to transform most of the sugars and alcohols into organic acids produces easily the transformation of glucose into gluconic acid in damaged grapes and ethanol or glycerol into acetic acid or dihydroxyacetone in wines. As a result of their strictly aerobic metabolism and high dependence to oxygen, acetic acid bacteria population is highly reduced during the must fermentation, with only few strains able to survive. However, wine aeration and oxygen exposure during oenological practices after alcoholic fermentation can activate their metabolism and increase their population with risks of acetic acid production. Inappropriate long-term wine storage and bottling conditions may also activate the acetic acid production. Good cellar practices such as high hygiene, microbiological control, oxygen restriction and reduction of porous surfaces reduce considerably the risks of wine spoilage by acetic acid bacteria.