The genome of acetic acid bacteria

Abstract

Acetic acid bacteria are strictly aerobic, acidophilic organisms that are famous for their rapid incomplete oxidations. They are the elicitors of various wine faults, mainly the formation of vinegar taste due to direct oxidation of ethanol to acetic acid with acetaldehyde as an intermediate. The complete genome sequence of Gluconobacter oxydans 621H provided rich information on the physiology and biochemistry of acetic acid bacteria. The direct oxidations are done by membrane-bound PQQ or flavin dependent enzyme systems with their active sites facing towards the periplasm. The membrane-bound dehydrogenases feed the electrons derived from the oxidations directly into a short electron transport chain that translocates relatively few protons. Besides the membrane-bound dehydrogenases the organism has an additional set of dehydrogenases located in the cytoplasm. They may function mainly in carbon assimilation. The intermediary metabolism seems to be specialized in providing building blocks for biosynthesis. An Entner-Doudoroff pathway and the pentose-phosphate cycle are present; Glycolysis is incomplete due to a missing phosphofructokinase. As succinate thiokinase and succinate dehydrogenase are missing, there is no closed TCA cycle. Furthermore, there is no possibility for the formation of phosphoenolpyruvate from pyruvate and therefore there is no gluconeogenesis from acetate or lactate. © 2009 Springer-Verlag Berlin Heidelberg. All rights reserved.