Cell and Molecular Biology Program, Colorado State University, 1005 Campus Delivery, Fort Collins, CO, 80523, USA.
Proteomics and Metabolomics Facility, Colorado State University, 2021 Campus Delivery, Fort Collins, CO, 80523, USA.
Plant J. 2019 Jul;99(2):379-388. doi: 10.1111/tpj.14320. Epub 2019 Apr 26.
Cyanobacteria are a model photoautotroph and a chassis for the sustainable production of fuels and chemicals. Knowledge of photoautotrophic metabolism in the natural environment of day/night cycles is lacking, yet has implications for improved yield from plants, algae and cyanobacteria. Here, a thorough approach to characterizing diverse metabolites-including carbohydrates, lipids, amino acids, pigments, cofactors, nucleic acids and polysaccharides-in the model cyanobacterium Synechocystis sp. PCC 6803 (S. 6803) under sinusoidal diurnal light:dark cycles was developed and applied. A custom photobioreactor and multi-platform mass spectrometry workflow enabled metabolite profiling every 30-120 min across a 24-h diurnal sinusoidal LD ('sinLD') cycle peaking at 1600 μmol photons m sec . We report widespread oscillations across the sinLD cycle with 90%, 94% and 40% of the identified polar/semi-polar, non-polar and polymeric metabolites displaying statistically significant oscillations, respectively. Microbial growth displayed distinct lag, biomass accumulation and cell division phases of growth. During the lag phase, amino acids and nucleic acids accumulated to high levels per cell followed by decreased levels during the biomass accumulation phase, presumably due to protein and DNA synthesis. Insoluble carbohydrates displayed sharp oscillations per cell at the day-to-night transition. Potential bottlenecks in central carbon metabolism are highlighted. Together, this report provides a comprehensive view of photosynthetic metabolite behavior with high temporal resolution, offering insight into the impact of growth synchronization to light cycles via circadian rhythms. Incorporation into computational modeling and metabolic engineering efforts promises to improve industrially relevant strain design.
蓝藻是一种模式光合自养生物，也是可持续生产燃料和化学品的底盘。然而，关于昼夜循环自然环境中的光合自养代谢的知识还很缺乏，这对提高植物、藻类和蓝藻的产量具有重要意义。在这里，我们开发并应用了一种全面的方法来描述模型蓝藻集胞藻 PCC 6803（S. 6803）在正弦昼夜光：暗周期下的多种代谢物，包括碳水化合物、脂质、氨基酸、色素、辅因子、核酸和多糖。定制的光生物反应器和多平台质谱工作流程使我们能够在 24 小时的正弦 LD（“sinLD”）周期中每隔 30-120 分钟进行一次代谢物分析，该周期在 1600μmol 光子 m sec 时达到峰值。我们报告了广泛的正弦 LD 周期内的震荡，其中 90%、94%和 40%的鉴定出的极性/半极性、非极性和聚合代谢物分别显示出统计学上显著的震荡。微生物生长显示出明显的滞后、生物量积累和细胞分裂生长阶段。在滞后阶段，氨基酸和核酸在每个细胞中的积累量达到高水平，然后在生物量积累阶段降低，这可能是由于蛋白质和 DNA 的合成。不溶性碳水化合物在昼夜过渡时每个细胞显示出急剧的震荡。强调了中心碳代谢中的潜在瓶颈。总之，本报告提供了具有高时间分辨率的光合作用代谢物行为的综合视图，为通过昼夜节律对光周期的生长同步化的影响提供了深入的了解。将其纳入计算模型和代谢工程努力有望改善工业相关菌株的设计。
