Solar spectral management for natural photosynthesis: from photonics designs to potential applications

Advancements of astaxanthin production in Haematococcus pluvialis: Update insight and way forward

The global market demand for natural astaxanthin (AXT) is growing rapidly owing to its potential human health benefits and diverse industry applications, driven by its safety, unique structure, and special function. Currently, the alga Haematococcus pluvialis (alternative name H. lacustris) has been considered as one of the best large-scale producers of natural AXT. However, the industry's further development faces two main challenges: the limited cultivation areas due to light-dependent AXT accumulation and the low AXT yield coupled with high production costs resulting from complex, time-consuming upstream biomass culture and downstream AXT extraction processes. Therefore, it is urgently to develop novel strategies to improve the AXT production in H. pluvialis to meet industrial demands, which makes its commercialization cost-effective. Although several strategies related to screening excellent target strains, optimizing culture condition for high biomass yield, elucidating the AXT biosynthetic pathway, and exploiting effective inducers for high AXT content have been applied to enhance the AXT production in H. pluvialis, there are still some unsolved and easily ignored perspectives. In this review, firstly, we summarize the structure and function of natural AXT focus on those from the algal H. pluvialis. Secondly, the latest findings regarding the AXT biosynthetic pathway including spatiotemporal specificity, transport, esterification, and storage are updated. Thirdly, we systematically assess enhancement strategies on AXT yield. Fourthly, the regulation mechanisms of AXT accumulation under various stresses are discussed. Finally, the integrated and systematic solutions for improving AXT production are proposed. This review not only fills the existing gap about the AXT accumulation, but also points the way forward for AXT production in H. pluvialis.

Omics exploration of Tetraselmis chuii adaptations to diverse light regimes

Microalgae are significantly influenced by light quality and quantity, whether in their natural habitats or under laboratory and industrial culture conditions. The present study examines the adaptive responses of the marine microalga Tetraselmis chuii to different light regimes, using a cost-effective filtering method and a multi-omics approach. Microalgal growth rates were negatively affected by all filtered light regimes. After six days of cultivation, growth rate for cultures exposed to blue and green filtered light was 67%, while for red filter was 83%, compared to control cultures. Transcriptomic analysis revealed that the usage of green filters resulted in upregulation of transcripts involved in ribosome biogenesis or coding for elongation factors, exemplified by a 2.3-fold increase of TEF3. On the other hand, a 2.7-fold downregulation was observed in photosynthesis-related petJ. Exposure to blue filtered light led to the upregulation of transcripts associated with pyruvate metabolism, while photosynthesis was negatively impacted. In contrast, application of red filter induced minor transcriptomic alterations. Regarding metabolomic analysis, sugars, amino acids, and organic acids exhibited significant changes under different light regimes. For instance, under blue filtered light sucrose accumulated over 6-fold, while aspartic acid content decreased by 4.3-fold. Lipidomics analysis showed significant accumulation of heptadecanoic and linoleic acids under green and red light filters. Together, our findings indicate that filter light can be used for targeted metabolic manipulation.

Noble Metal Plasmon-Molecular Catalyst Hybrids for Renewable Energy Relevant Small Molecule Activation

Significant endeavors have been dedicated to the advancement of materials for artificial photosynthesis, aimed at efficiently harvesting light and catalyzing reactions such as hydrogen production and CO2 conversion. The application of plasmonic nanomaterials emerges as a promising option for this purpose, owing to their excellent light absorption properties and ability to confine solar energy at the nanoscale. In this regard, coupling plasmonic particles with molecular catalysts offers a pathway to create high-performance hybrid catalysts. In this review, we discuss the plasmonic-molecular complex hybrid catalysts where the plasmonic nanoparticles serve as the light-harvesting unit and promote interfacial charge transfer in tandem with the molecular catalyst which drives chemical transformation. In the initial section, we provide a concise overview of plasmonic nanomaterials and their photophysical properties. We then explore recent breakthroughs, highlighting examples from literature reports involving plasmonic-molecular complex hybrids in various catalytic processes. The utilization of plasmonic materials in conjunction with molecular catalysts represents a relatively unexplored area with substantial potential yet to be realized. This review sets a strong basis and motivation to explore the plasmon-induced hot-electron mediated photelectrochemical small molecule activation reactions. Utilizing in situ spectroscopic investigations and ultrafast transient absorption spectroscopy, it presents a comprehensive template for scalable and sustainable antenna-reactor systems.

Spectral-conversion film potential for greenhouses: Utility of green-to-red photons conversion and far-red filtration for plant growth

Although green (G, 500 to 600 nm) and far-red (FR, 700 to 800 nm) light play important roles in regulating plant growth and development, they are often considered less useful at stimulating photosynthesis than red (R, 600 to 700 nm) and blue (B, 400 to 500 nm) light. Based on this perception, approaches to modifying the transmission of greenhouse glazing materials include (1) conversion of G photons from sunlight into R photons and (2) exclusion of the near-infrared (>700 nm) fraction of sunlight. We evaluated these approaches using simulated scenarios with light-emitting diodes to determine how partial and complete substitution of G with R light and exclusion of FR light affected the growth of lettuce and tomato grown indoors. The substitution of G with R light had little or no effect on fresh and dry mass of tomato. However, with the presence of FR light, fresh and dry mass of lettuce increased by 22-26% as G light was increasingly substituted with R light. In tomato, excluding FR inhibited plant height, leaf area, and dry mass by 60-71%, 10-37%, and 20-44%, respectively. Similarly, in lettuce, excluding FR inhibited plant diameter, leaf length, and dry mass by 15-23%, 23-33%, or 28-48%, respectively. We conclude that the spectral conversion of G-to-R photons can promote plant growth in at least some crop species, such as lettuce, while the exclusion of FR decreases crop growth and yield.