Department of Environmental Sciences, Louisiana State University, Baton Rouge, Louisiana, 70803, USA.
J Phycol. 2022 Oct;58(5):703-718. doi: 10.1111/jpy.13278. Epub 2022 Aug 5.
The marine cyanobacterium Synechococcus elongatus was grown in a continuous culture system to study the interactive effects of temperature, irradiance, nutrient limitation, and the partial pressure of CO (pCO2) on its growth and physiological characteristics. Cells were grown on a 14:10 h light:dark cycle at all combinations of low and high irradiance (50 and 300 μmol photons ⋅ m ⋅ s , respectively), low and high pCO (400 and 1000 ppmv, respectively), nutrient limitation (nitrate-limited and nutrient-replete conditions), and temperatures of 20-45°C in 5°C increments. The maximum growth rate was ~4.5 · d at 30-35°C. Under nutrient-replete conditions, growth rates at most temperatures and irradiances were about 8% slower at a pCO of 1000 ppmv versus 400 ppmv. The single exception was 45°C and high irradiance. Under those conditions, growth rates were ~45% higher at 1000 ppmv. Cellular carbon:nitrogen ratios were independent of temperature at a fixed relative growth rate but higher at high irradiance than at low irradiance. Initial slopes of photosynthesis-irradiance curves were higher at all temperatures under nutrient-replete versus nitrate-limited conditions; they were similar at all temperatures under high and low irradiance, except at 20°C, when they were suppressed at high irradiance. A model of phytoplankton growth in which cellular carbon was allocated to structure, storage, or the light or dark reactions of photosynthesis accounted for the general patterns of cell composition and growth rate. Allocation of carbon to the light reactions of photosynthesis was consistently higher at low versus high light and under nutrient-replete versus nitrate-limited conditions.
海洋蓝细菌聚球藻在连续培养系统中生长，以研究温度、光照、营养限制和 CO 分压 (pCO2) 对其生长和生理特性的相互影响。细胞在光照时间为 14:10 的光暗循环中生长，光照强度分别为低（50 μmol 光子 ⋅ m ⋅ s-1）和高（300 μmol 光子 ⋅ m ⋅ s-1），pCO2 分别为低（400 ppmv）和高（1000 ppmv），营养限制（硝酸盐限制和营养充足条件）和温度为 20-45°C，每 5°C 增加一次。最大生长速率约为 30-35°C 时的 4.5 · d-1。在营养充足的条件下，大多数温度和光照下的生长速率在 pCO2 为 1000 ppmv 时比 400 ppmv 时慢约 8%。唯一的例外是 45°C 和高光强。在这些条件下，1000 ppmv 时的生长速率约高 45%。在固定相对生长速率下，细胞的碳氮比与温度无关，但在高光强下高于低光强。在营养充足与硝酸盐限制条件下，所有温度下光合作用-光照曲线的初始斜率都高于高光强；在高光强和低光强下，所有温度下的初始斜率都相似，除了 20°C 时，高光强下抑制了初始斜率。一个浮游植物生长模型，其中细胞碳被分配到结构、储存或光合作用的光或暗反应中，解释了细胞组成和生长速率的一般模式。与高光强和硝酸盐限制条件相比，低光强下光合作用的光反应分配的碳始终更高。
