Applied Microbial and Cell Physiology

Applied Microbiology and Biotechnology

, Volume 86, Issue 1, pp 311-317

Open Access This content is freely available online to anyone, anywhere at any time.

An intracellular pH gradient in the anammox bacterium Kuenenia stuttgartiensis as evaluated by 31P NMR

  • Wouter R. L. van der StarAffiliated withDepartment of Biotechnology, Delft University of TechnologyDeltares
  • , Cor DijkemaAffiliated withBiophysics, Wageningen University and Research Centre
  • , Pieter de WaardAffiliated withWageningen NMR Centre, Wageningen University and Research Centre
  • , Cristian PicioreanuAffiliated withDepartment of Biotechnology, Delft University of Technology
  • , Marc StrousAffiliated withMax Planck Institute for Marine MicrobiologyCenter for Biotechnology, University of Bielefeld Email author 
  • , Mark C. M. van LoosdrechtAffiliated withDepartment of Biotechnology, Delft University of Technology

Abstract

The cytoplasm of anaerobic ammonium oxidizing (anammox) bacteria consists of three compartments separated by membranes. It has been suggested that a proton motive force may be generated over the membrane of the innermost compartment, the “anammoxosome”. 31P nuclear magnetic resonance (NMR) spectroscopy was employed to investigate intracellular pH differences in the anammox bacterium Kuenenia stuttgartiensis. With in vivo NMR, spectra were recorded of active, highly concentrated suspensions of K. stuttgartiensis in a wide-bore NMR tube. At different external pH values, two stable and distinct phosphate peaks were apparent in the recorded spectra. These peaks were equivalent with pH values of 7.3 and 6.3 and suggested the presence of a proton motive force over an intracytoplasmic membrane in K. stuttgartiensis. This study provides for the second time—after discovery of acidocalcisome-like compartments in Agrobacterium tumefaciens—evidence for an intracytoplasmic pH gradient in a chemotrophic prokaryotic cell.

Keywords

Anammox Kuenenia stuttgartiensis Internal pH In vivo NMR Nuclear magnetic resonance spectroscopy 31P NMR