紫外线(UV)辐射(315-400nm)是到达地球表面的太阳紫外线辐射的主要组成部分。然而,UV-A对光合生物的积极作用的潜在机制尚未阐明。在这项研究中,我们研究了UV-A辐射对生长的影响,光合能力,和可食用蓝细菌Nostocsphaeroides的代谢组。暴露于5-15Wm-2(15-46µmol光子m-2s-1)UV-A和4.35Wm-2(20µmol光子m-2s-1)可见光16天显着增加了生长速率和生物量生产。分别,与非UV-A适应的细胞相比。此外,适应UV-A的细胞表现出细胞烟酰胺腺嘌呤二核苷酸磷酸(NADP)池的1.8倍增加,光合能力增加(58%),光合效率(24%),QA再氧化,光系统I丰富,和循环电子流(87%),这进一步导致光诱导的NADPH生成(31%)和ATP含量(83%)的增加。此外,适应UV-A的细胞显示核酮糖-1,5-二磷酸羧化酶/加氧酶活性增加2.3倍,表明它们的固碳能力增加。基于气相色谱-质谱的代谢组学进一步揭示了UV-A辐射对能量储存碳代谢的上调,糖积累的增加证明了这一点,脂肪酸,和柠檬酸盐在UV-A适应的细胞中。因此,我们的结果表明,UV-A辐射增强了蓝藻N.spaeroides的能量流和碳同化。IMPORTANCE紫外线(UV)辐射对光自养生物产生有害影响;然而,一些研究证明了紫外线辐射的积极影响,特别是UV-A辐射(315-400nm),关于初级生产力。因此,了解与UV-A辐射对初级生产力的促进作用相关的潜在机制可以促进UV-A在CO2封存中的应用,并促进光生物学的发展。在这项研究中,我们使用了蓝细菌Nostocsphaeroides,人类作为食品和药品的使用已有1700多年的历史,探讨其光合驯化对UV-A辐射的响应。根据我们的知识,这是第一项研究证明UV-A辐射通过增强能量流和碳同化来增加N.spaeroides的生物量产量。我们的发现为UV-A介导的光合适应提供了新的见解,并为在未来的CO2中性框架中应用UV-A辐射优化光吸收能力和增强CO2封存提供了科学依据。圆形,可持续的生物经济。
Ultraviolet (UV) A radiation (315-400 nm) is the predominant component of solar UV radiation that reaches the Earth\'s surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible
cyanobacterium Nostoc sphaeroides. Exposures to 5-15 W m-2 (15-46 µmol photons m-2 s-1) UV-A and 4.35 W m-2 (20 μmol photons m-2 s-1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%-30% and 15%-56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography-mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the
cyanobacterium N. sphaeroides.IMPORTANCEUltraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315-400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the
cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy.