title: Experimental and modeling analysis of Synechocystis sp. PCC 6803 growth.
abstract: OBJECTIVE
  The influence of different parameters such as temperature, irradiance, nitrate concentration, pH, and an external carbon source on Synechocystis PCC 6803 growth was evaluated.
  
  
  METHODS
  4.5-ml cuvettes containing 2 ml of culture, a high-throughput system equivalent to batch cultures, were used with gas exchange ensured by the use of a Parafilm™ cover. The effect of the different variables on maximum growth was assessed by a multi-way statistical analysis.
  
  
  RESULTS
  Temperature and pH were identified as the key factors. It was observed that Synechocystis cells have a strong influence on the external pH. The optimal growth temperature was 33°C while light-saturating conditions were reached at 40 µE·m⁻²·s⁻¹.
  
  
  CONCLUSIONS
  It was demonstrated that Synechocystis exhibits a marked difference in behavior between autotrophic and glucose-based mixotrophic conditions, and that nitrate concentrations did not have a significant influence, probably due to endogenous nitrogen reserves. Furthermore, a dynamic metabolic model of Synechocystis photosynthesis was developed to gain insights on the underlying mechanism enabling this cyanobacterium to control the levels of external pH. The model showed a coupled effect between the increase of the pH and ATP production which in turn allows a higher carbon fixation rate.
authors.affiliation: IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
authors.forename: Miguel
authors.initials: M
authors.lastname: Lopo
authors.forename: Arnau
authors.initials: A
authors.lastname: Montagud
authors.forename: Emilio
authors.initials: E
authors.lastname: Navarro
authors.forename: Isabel
authors.initials: I
authors.lastname: Cunha
authors.forename: Andrea
authors.initials: A
authors.lastname: Zille
authors.forename: Pedro Fernández
authors.initials: PF
authors.lastname: de Córdoba
authors.forename: Pedro
authors.initials: P
authors.lastname: Moradas-Ferreira
authors.forename: Paula
authors.initials: P
authors.lastname: Tamagnini
authors.forename: Javier F
authors.initials: JF
authors.lastname: Urchueguía
mesh_terms: D052818:Autotrophic Processes; D001431:Bacteriological Techniques / Q000379:methods / Q000592:standards; D061249:Batch Cell Culture Techniques / Q000379:methods*; D002244:Carbon / Q000378:metabolism; D052836:Heterotrophic Processes; D006863:Hydrogen-Ion Concentration; D008027:Light; D050296:Microbial Viability; D008954:Models, Biological; D015999:Multivariate Analysis; D009566:Nitrates / Q000378:metabolism; D010788:Photosynthesis; D046939:Synechocystis / Q000254:growth & development* / Q000378:metabolism; D013696:Temperature
chemical_list: D009566:Nitrates; D002244:Carbon