Glucose-dehydrogenase-mediated Solute Transport and ATP Synthesis in Acinetobacter calcoaceticus

Laboratory of Microbiology and Enzymology, Delft University of Technology, Julianalaan 67a, 2628 BC Delft, The Netherlands Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands ABSTRACT SUMMARY: Evidence is presented that in Acinetobacter calcoaceticus oxidation of glucose to gluconate by the periplasmic quinoprotein glucose dehydrogenase (EC 1.1.99.17 ) leads to energy conservation. Membrane vesicles prepared from cells grown in carbon-limited chemostat culture exhibited (1) a high rate of glucose-dependent oxygen consumption and gluconate production, (2) glucose-mediated cytochrome reduction, (3) uncoupler sensitive, glucose-dependent generation of a membrane potential and (4) glucose-driven accumulation of amino acids. Furthermore, oxidation of glucose to gluconate by whole cells was associated with ATP synthesis. These results confirm and extend previous observations that periplasmic glucose oxidation can act as a driving force for energy-requiring processes. It is therefore concluded that the incomplete oxidation of glucose by bacteria may serve as an auxiliary energy-generating system. Present address: Unilever Research Laboratory, Department of Bioprocessing, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands.