title: Oxidation of Molecular Hydrogen by a Chemolithoautotrophic Beggiatoa Strain.
abstract: A chemolithoautotrophic strain of the family Beggiatoaceae, Beggiatoa sp. strain 35Flor, was found to oxidize molecular hydrogen when grown in a medium with diffusional gradients of oxygen, sulfide, and hydrogen. Microsensor profiles and rate measurements suggested that the strain oxidized hydrogen aerobically when oxygen was available, while hydrogen consumption under anoxic conditions was presumably driven by sulfur respiration.Beggiatoa sp. 35Flor reached significantly higher biomass in hydrogen-supplemented oxygen-sulfide gradient media, but hydrogen did not support growth of the strain in the absence of reduced sulfur compounds. Nevertheless, hydrogen oxidation can provide Beggiatoa sp. 35Flor with energy for maintenance and assimilatory purposes and may support the disposal of internally stored sulfur to prevent physical damage resulting from excessive sulfur accumulation. Our knowledge about the exposure of natural populations of Beggiatoa ceae to hydrogen is very limited, but significant amounts of hydrogen could be provided by nitrogen fixation, fermentation, and geochemical processes in several of their typical habitats such as photosynthetic microbial mats and submarine sites of hydrothermal fluid flow.
  
  
  OBJECTIVE
  Reduced sulfur compounds are certainly the main electron donors for chemolithoautotrophic Beggiatoa ceae, but the traditional focus on this topic has left other possible inorganic electron donors largely unexplored. In this paper, we provide evidence that hydrogen oxidation has the potential to strengthen the ecophysiological plasticity of Beggiatoa ceaein several ways. Moreover, we show that hydrogen oxidation by members of this family can significantly influence biogeochemical gradients and therefore should be considered in environmental studies.
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany akreutzm@mpi-bremen.de heide.schulz-vogt@io-warnemuende.de.
authors.forename: Anne-Christin
authors.initials: AC
authors.lastname: Kreutzmann
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany Leibniz Institute for Baltic Sea Research Warnemuende (IOW), Rostock, Germany akreutzm@mpi-bremen.de heide.schulz-vogt@io-warnemuende.de.
authors.forename: Heide N
authors.initials: HN
authors.lastname: Schulz-Vogt
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D053524:Beggiatoa / Q000254:growth & development / Q000378:metabolism*; D018533:Biomass; D052837:Chemoautotrophic Growth; D003470:Culture Media / Q000737:chemistry; D006859:Hydrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D013440:Sulfides / Q000378:metabolism
chemical_list: D003470:Culture Media; D013440:Sulfides; D006859:Hydrogen