title: Kinetic model of hydrogen generation by Rhodobacter sphaeroides in the presence of NH ions.
abstract: OBJECTIVE
  To examine the effects of ammonium ion concentration and illumination intensity on the effectivness of the hydrogen generation process of Rhodobacter sphaeroides.
  
  
  RESULTS
  In all experiments the amount of evolved hydrogen, biomass growth, concentration of ammonium ions, pH and chemical oxygen demand were measured. A nonstructural kinetic model was applied in description of biomass growth, the amount of evolved hydrogen and consumption of organic compounds and ammonium ions. An increase of ammonium ions concentration resulted in a decrease of maximal specific hydrogen potential production. At higher ammonium ion concentrations, no hydrogen evolution was observed. The efficiency of malic acid conversion into hydrogen and the PHB content in the biomass were the highest with lower concentrations of nitrogen compounds.
  
  
  CONCLUSIONS
  The presence of ammonium ions inhibits hydrogen photogeneration. A good agreement between the experimental data and model simulations were obtained. In all cases, hydrogen evolution started after an exhaustion of ammonium ions and the increase was proportional to the C/N ratio in the medium. The accumulation of PHB competes with the hydrogen evolution process while the conversion of acids into biomass was limited at higher levels of hydrogen generation.
  
  
  CONCLUSIONS
  Confirmation of the suitability of the selected model for kinetic studies of hydrogen photoevolution.
authors.affiliation: A. Mickiewicz University, Poznań 60-780 , Poland.
authors.forename: M
authors.initials: M
authors.lastname: Waligórska
authors.forename: K
authors.initials: K
authors.lastname: Seifert
authors.forename: K
authors.initials: K
authors.lastname: Górecki
authors.forename: M
authors.initials: M
authors.lastname: Moritz
authors.forename: M
authors.initials: M
authors.lastname: Laniecki
mesh_terms: D018533:Biomass; D019149:Bioreactors; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006885:Hydroxybutyrates / Q000032:analysis; D007700:Kinetics; D008027:Light; D008293:Malates / Q000378:metabolism; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism; D011091:Polyesters / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012242:Rhodobacter sphaeroides / Q000254:growth & development* / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
chemical_list: D006859:Hydrogen; D006885:Hydroxybutyrates; D008293:Malates; D010100:Oxygen; D011091:Polyesters; D000644:Quaternary Ammonium Compounds; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C030298:malic acid