Respiratory Chains and Bioenergetics of Acetic Acid Bacteria

Abstract

Publisher Summary The chapter discusses the respiratory chains and bioenergetics of acetic acid bacteria. Acetic acid bacteria are obligate aerobes and well known as “vinegar producers.” They produce acetic acid from ethanol by two sequential catalytic reactions of membrane-bound alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Besides alcohols and aldehydes, acetic acid bacteria are able to oxidize various sugars and sugar alcohols such as D-glucose, glycerol, and D-sorbitol. Such oxidation reactions are called “oxidative fermentations”, because they involve incomplete oxidation of alcohols or sugars accompanied by accumulation of the corresponding oxidation products in huge amounts in the growth medium. Bacteria capable of effecting oxidative fermentations are called “oxidative bacteria,” of which the most prominent are acetic acid bacteria. Acetic acid bacteria are also important for the fermentation industries to produce biomaterials such as vinegar and L-sorbose. Acetic acid bacteria are classified into two genera, Gluconobacter and Acetobacter of the family Acetobacteraceae. Gluconobacter species catalyze highly active oxidation reactions on ethanol or D-glucose— including also oxidative reactions on sugars such as D-gluconic acid, D-sorbitol, and glycerol. By contrast, Acetobacter species have a highly active ethanoloxidizing system but not enzymes for sugar oxidation. The respiratory chain in Acetobacter spp. has ubiquinone, cytochrome b , cytochrome c , and a terminal ubiquinol oxidase, which is either cytochrome a 1 or cytochrome o .