Detalle de: Experimental and Modeling Analysis of Synechocystis sp. PCC 6803 Growth

<i>Background/Aims:</i> The influence of different parameters such as temperature, irradiance, nitrate concentration, pH, and an external carbon source on <i>Synechocystis </i>PCC 6803 growth was evaluated. <i>Methods:</i> 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. <i>Results:</i> Temperature and pH were identified as the key factors. It was observed that <i>Synechocystis</i> 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. <i>Conclusion:</i> It was demonstrated that <i>Synechocystis</i> 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 <i>Synechocystis</i> 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.