Supplementary Material for: Experimental and Modeling Analysis of <i> Synechocystis </i>sp. PCC 6803 Growth

Background/Aims: 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. Conclusion: 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.研究背景与目的：评估温度、光照强度、硝酸盐浓度、pH值及外源碳源等不同参数对集胞藻（Synechocystis PCC 6803）生长的影响。 方法：采用容积为4.5mL的比色皿，内装2mL培养液，构建了等同于分批培养模式的高通量培养体系，使用Parafilm™封口膜以保障气体交换。通过多变量统计分析，评估了各变量对菌株最大生长量的影响。 结果：研究确定温度与pH值为关键调控因素。观测发现，集胞藻细胞可显著调控外界环境的pH值。该藻株的最适生长温度为33℃，当光照强度达到40 µE·m⁻²·s⁻¹时进入光饱和状态。 结论：研究证实，集胞藻在自养与以葡萄糖为碳源的混养条件下表现出显著的代谢行为差异；硝酸盐浓度对其生长无显著影响，这可能源于其内源氮储备。此外，本研究构建了集胞藻光合作用的动态代谢模型，以解析该蓝细菌调控外界pH水平的潜在机制。该模型揭示了pH升高与ATP生成之间的耦合效应，而这一效应可进一步提升碳固定速率。