Photosynthetic micro-organisms are equipped with molecular machineries that are designed to transform light into chemical or bioenergy, and help shape and balance the ecosystem of all life forms on earth. Recently, aquatic ecosystems have been disrupted by climate change, which leads to the frequent occurrence of harmful algal blooms (HABs). HABs endanger drinking water resources and harm the fishing and coastal recreation industries. Despite its urgency, mechanistic understanding of how key biophysical and biochemical parameters impact algal growth is largely unexplored. In this article, we developed a microscope-based light gradient generator for studies of photosynthetic micro-organisms under well-defined light intensity gradients. This technology utilized a commercially available microscope, allowed for controlled light exposure and imaging of cells on the same microscope platform, and can be integrated with any micrometer-scale device. Using this technology, we studied the role of light intensity in the growth of photosynthetic micro-organisms. A parallel study was also carried out using a 96-well plate. Our work revealed that the growth rate of the microalgae/cyanobacteria was significantly regulated by the light intensity and followed Monod or van Oorschot kinetic models. The measured half-saturation constants were compared with those obtained in macro-scale devices, and indicated that shading, light spectrum, and temperature may all play important roles in the light sensitivity of photosynthetic micro-organisms. This work highlighted the importance of analytical tools for quantitative understanding of biophysical parameters in the growth of photosynthetic micro-organisms, and knowledge learned will be critical in the design of future technologies for managing algal blooms or optimizing bioenergy production.

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用于光合微生物定量生长研究的基于显微镜的光梯度生成

光合微生物配备了分子机器，旨在将光转化为化学或生物能，并帮助塑造和平衡地球上所有生命形式的生态系统。近年来，水生生态系统受到气候变化的破坏，导致有害藻华（HABs）的频繁发生。HABs 危及饮用水资源，危害渔业和沿海休闲产业。尽管其紧迫性，但对关键生物物理和生化参数如何影响藻类生长的机械理解在很大程度上尚未得到探索。在本文中，我们开发了一种基于显微镜的光梯度发生器，用于研究明确定义的光强度梯度下的光合微生物。该技术利用了市售显微镜，允许在同一显微镜平台上对细胞进行受控的曝光和成像，并且可以与任何微米级设备集成。利用这项技术，我们研究了光强在光合微生物生长中的作用。还使用 96 孔板进行了平行研究。我们的工作表明，微藻/蓝细菌的生长速率受光强度的显着调节，并遵循 Monod 或 van Oorschot 动力学模型。将测得的半饱和常数与宏观设备中获得的半饱和常数进行了比较，表明遮光、光谱和温度都可能对光合微生物的光敏感性起重要作用。