Timpmann Kõu, Rätsep Margus, Freiberg Arvi
Institute of Physics, University of Tartu, Tartu, Estonia.
Estonian Academy of Sciences, Tallinn, Estonia.
Front Chem. 2023 Oct 16;11:1231431. doi: 10.3389/fchem.2023.1231431. eCollection 2023.
Photosynthesis is a vital process that converts sunlight into energy for the Earth's ecosystems. Color adaptation is crucial for different photosynthetic organisms to thrive in their ecological niches. Although the presence of collective excitons in light-harvesting complexes is well known, the role of delocalized excited states in color tuning and excitation energy transfer remains unclear. This study evaluates the characteristics of photosynthetic excitons in sulfur and non-sulfur purple bacteria using advanced optical spectroscopic techniques at reduced temperatures. The exciton effects in these bacteriochlorophyll -containing species are generally much stronger than in plant systems that rely on chlorophylls. Their exciton bandwidth varies based on multiple factors such as chromoprotein structure, surroundings of the pigments, carotenoid content, hydrogen bonding, and metal ion inclusion. The study nevertheless establishes a linear relationship between the exciton bandwidth and Q singlet exciton absorption peak, which in case of LH1 core complexes from different species covers almost 130 nm. These findings provide important insights into bacterial color tuning and light-harvesting, which can inspire sustainable energy strategies and devices.
光合作用是一个至关重要的过程，它将阳光转化为地球生态系统所需的能量。颜色适应性对于不同的光合生物在其生态位中茁壮成长至关重要。尽管光捕获复合物中集体激子的存在已为人所知，但离域激发态在颜色调谐和激发能量转移中的作用仍不清楚。本研究使用先进的光学光谱技术在低温下评估了硫和非硫紫色细菌中光合激子的特性。这些含细菌叶绿素的物种中的激子效应通常比依赖叶绿素的植物系统中的激子效应要强得多。它们的激子带宽因多种因素而异，如色素蛋白结构、色素周围环境、类胡萝卜素含量、氢键和金属离子包含情况等。然而，该研究建立了激子带宽与Q单重态激子吸收峰之间的线性关系，对于来自不同物种的LH1核心复合物，这种关系涵盖了近130纳米。这些发现为细菌颜色调谐和光捕获提供了重要见解，可启发可持续能源战略和设备。
