ABSTRACT Microalgal biomass has good potential as a raw material for animal feed, especially fish, being an alternative source of protein and fatty acids. Adopting microalgae for animal feed is a promising solution for addressing food security challenges. The Kingdom of Saudi Arabia (KSA) is planning a sustainable development of 100,000 ha of microalgal biomass production to be used as a raw material for animal feed. KSA is an ideal location for such production due to its abundant sunlight, flat land, CO2 resources, and nitrogen (N) and phosphorus (P) availability. This work reviews relevant information and maps industrial waste streams, mainly from thermo-power, desalination, wastewater treatment plants and petroleum refineries that could potentially be used as nutrient sources (C, N and P) in KSA. KSA has substantial potential for large-scale microalgal biomass production using industrial waste streams as nutrient sources. Analysis of the data presented here leads to the prediction that KSA could potentially produce up to 3,168,000 t year‒1 of land-based microalgal biomass and potentially uptake approximately 5,702,000 tons of CO2. This approach not only supports animal feed production but also extends carbon use, so it is not released immediately into the atmosphere, aligning with national sustainability goals.

ABSTRACT Microalgae are cell factories rich in biochemicals that can be used as a feedstock for applications such as medicines, nutraceuticals, food, feed and bioenergy. Developing economical and efficient cultivation media is a major challenge in microalgal biomass production, as efficient upstream cultivation processes are crucial for continuous biomass resource supply. Nano-based fertilisers are being developed and currently used in agricultural cultivation for greater efficacy compared to conventional chemical fertilisers. Use of nanotechnology in microalgal biotechnology is in its infancy, and use of nano-based media for microalgal cultivation is yet to be explored. In this study, a novel nano-based cultivation medium named nano-JAPH medium was formulated and standardized. The efficacy of nano-JAPH medium was tested at different nutrient concentrations and validated through laboratory-scale trials with the microalgae, Chlorella vulgaris, Chlorococcum humicola, Oocystis crassa, Scenedesmus quadricauda and Synechococcus aeruginosus. The pilot-scale outdoor trials using nano-JAPH medium were carried out subsequently with Chlorella vulgaris in a suspended cultivation system and with a polyculture microalgal consortium in an immobilized cultivation system against modified NMR commercial medium as control. The results showed that nano-JAPH medium resulted in significantly higher areal biomass productivity (10.545 g m‒2 d‒1 in suspended and 2.9 g m‒2 d‒1 in attached systems) compared to those in control with 42.3% and 13.2% increase, respectively. This study shows that the novel nano-JAPH medium can be effectively used to increase microalgae biomass productivity and facilitate commercial microalgae mass culture through sustained supply of nutrients.

ABSTRACT Phenylketonuria is an autosomal genetic disorder characterized by a deficiency of phenylalanine hydroxylase, leading to the accumulation of phenylalanine in the blood instead of its metabolism and excretion. This accumulation can result in intellectual disabilities in infants. Phenylalanine ammonia lyase (PAL; EC 4.3.1.24) was originally identified from plants, and today its cyanobacterial type is considered as a candidate to help in the treatment of phenylketonuria. In this study, three isolates of the cyanobacterium Anabaena variabilis from the Karaj Azad University collection were cultured in BG-11 culture medium under appropriate light conditions, including 24-h artificial illumination. Following growth for 3–4 weeks, the cells were lysed via sonication, and protein was extracted from the lysate. The extract yielded the PAL enzyme, which catalyses the conversion of phenylalanine into cinnamic acid. The concentration of cinnamic acid was quantified at 285 nm with a spectrophotometer. Enzyme activity was assessed at three temperatures relevant to physiological and environmental conditions, 25°C, 37°C and 40°C, for 30 and 60 min. Additionally, since tyrosine serves as another substrate for PAL, yielding fumaric acid, its activity was measured at a wavelength of 270 nm from pH 2 to pH 12. Variable enzyme activities at different pH levels and temperatures over both time intervals showed the sensitivity of the enzyme to temperature and pH. To further characterize the enzyme, the molecular weight of PAL extracted from Iranian cyanobacteria was compared against published data for the SDS-PAGE method, confirming a molecular weight consistent with the literature of 60–70 kDa. HPLC showed that levels of cinnamic acid in the cyanobacterial extract were very low before adding phenylalanine and they were much higher after addition of phenylalanine.

ABSTRACT The co-cultivation of seaweeds with bivalve shellfish is a potential strategy for protecting bivalve crops against anthropogenic coastal acidification and hypoxia. We co-cultivated seaweeds and bivalves using a succession of seaweed species according to season (winter, Saccharina latissima → spring, Ulva spp. → summer, Gracilaria spp.) together with eastern oysters (Crassostrea virginica) and blue mussels (Mytilus edulis). Bivalves and seaweeds were deployed in two estuaries that contrasted in trophic state, one mesotrophic and one eutrophic. In all five experiments in the mesotrophic system, co-cultivation with seaweeds significantly increased weight- and/or shell-based growth of bivalves (p < 0.05). Growth rate increases for C. virginica were modest, with weight-based growth improving by 17–21% and shell-based growth improving by 3–27% with seaweed co-culture of all macroalgal species. For M. edulis, the effect was large; co-culture with S. latissima caused 47% and 114% increases in shell- and weight-based growth rates, respectively. In the four experiments in the eutrophic estuary, co-culture with seaweeds did not significantly improve bivalve growth. Seaweed cultivation significantly improved water quality metrics (increased pH and dissolved oxygen (DO); p < 0.05 in all cases) in and around the seaweed sites at both locations, although increases in pH and DO were modest, and even in control treatments, there were no prolonged periods of harmful pH or DO levels. An abundance of macroalgal detritus may have bolstered the diets of co-cultivated bivalves in the mesotrophic estuary, a hypothesis supported by lower chlorophyll a concentration, and therefore lower planktonic food levels, at that site. Given that seaweeds display species-specific allelopathic effects against phytoplankton, it is also possible that the presence of seaweeds altered the phytoplankton community to the benefit of the bivalves. Regardless, the findings here demonstrate that co-cultivation with seaweeds can accelerate the growth of bivalves.

ABSTRACT The Microalgae Museum (MiMu) was a free one-day pop-up event held in the Glasgow Botanic Gardens. The purpose was for algal enthusiasts, scientists, students, artists and entrepreneurs to collaborate and to raise public awareness by celebrating the magnificent world of microalgae. While the concept of MiMu is a museum, the only museum glass present on this day was on the greenhouse walls and the coverslips of a microscope slide. This was a conscious decision when selecting Glasgow Botanic Gardens as a venue. All the displays, visitors, and volunteers were themselves under glass, creating the feeling of being an active part of the exhibition. The focus was on interactivity and direct engagement, with the aim of providing that sense of wonder. This was achieved by showcasing the important roles that algae play in the environment and highlighting their numerous applications. For instance, algae are pivotal in global scale biogeochemical cycles, energy transfer, and oxygen production, while they have huge potential for sustainable production of food, clean water, energy, raw materials and chemical building blocks. Microscopes allowed people to observe living microalgae. Biodesign and engineering were demonstrated through biophotovoltaic cells producing energy, and skin-care products were showcased using an algal–bacterial biofilm. Algal art was displayed as a spiral steel headdress etched with algal designs, and as a scientific abstract written in beautiful medieval script. MiMu provided a forum for phycologists to cross-fertilize ideas and inspire each other. It also fostered research and business development opportunities, and created opportunities for public awareness and engagement, through a fun, in-person event suitable for all ages. Over 300 visitors engaged in the different activities and left inspired by the enthusiasm of the volunteers and the diversity of algae. During post-event meetings, it was agreed among those involved that the MiMu should become a recurring event.

ABSTRACT Hyperpigmentation is a common skin condition resulting from uncontrolled melanin production or accumulation. Commercial skin-whitening products have been reported to cause undesirable skin effects, limiting safe treatment options. Microalgae are increasingly explored as sustainable sources for cosmetic applications due to their diverse bioactive properties and versatility. Chlorella vulgaris, a green microalga, is regarded as a promising source of beneficial compounds, particularly in cosmeceuticals. In this study, pigmentation-related targets were identified from public databases, and network pharmacology techniques were employed, including protein–protein interaction (PPI) network construction using STRING and visualization in Cytoscape. Enrichment analysis was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The interactions between hub targets and C. vulgaris compounds retrieved from PubChem were investigated via molecular docking and molecular dynamics simulations. Hub genes TYRP1, TYR, TP53, SLC45A2, CTNNB1, and MC1R were identified as significant regulators of melanocyte differentiation and melanogenesis-associated pathways. Molecular docking highlighted four hit compounds namely 7,22-ergostadienol acetate (CID: 14056082), dehydroergosterol acetate (CID: 69827569), ergosterol acetate (CID: 6436903), and [(3S,10S,13 R,14 R,17 R)-17-[(E,2 R,5 R)-5-ethyl-6-methylhept-3-en-2-yl]-10,13-dimethyl 2,3,4,12,14,15,16,17-octahydro-1 H-cyclopenta[a]phenanthren-3-yl] acetate (PubChem CID: 162856537), which showed favourable binding affinities with the core gene targets. Molecular dynamics revealed that these compounds could bind stably to SLC45A2, CTNNB1, and MC1R, suggesting potential depigmenting effects of C. vulgaris. While these findings provide a theoretical framework for microalgae-derived depigmentation agents, the study is based solely on in silico predictions and relies on currently available compound–target databases, which may not encompass the full chemical diversity of C. vulgaris. Therefore, further validation through phytochemical characterization, in vitro assays, and in vivo studies is essential to confirm the therapeutic potential of these compounds for pigmentation-related skin disorders.

ABSTRACT Lectins are carbohydrate-binding proteins involved in diverse biological processes with potential biotechnological and biomedical applications. Seaweeds are promising sources of novel lectins with unique structures and glycan specificities. This study screened 21 Indonesian seaweed species for lectin occurrence and partially characterized their biochemical properties and glycan-binding specificities. The extraction of the lectins was performed using phosphate-buffered saline, followed by precipitation with 75% (NH4)2SO4. The haemagglutination activity (HA) assay, utilizing both native and enzyme-treated animal and human erythrocytes, revealed that all seaweed samples contained haemagglutinins. This includes 12 species that have not previously been screened for lectins. Lectins from some red and green seaweeds exhibited substantial HA against trypsin-treated chicken erythrocytes. The glycan-binding specificities of the lectin-rich fraction (LF) were determined through a haemagglutination inhibition (HAI) assay, which employed nine monosaccharides and 12 glycoproteins. No inhibition was observed with any of the monosaccharides tested, indicating that the lectins did not recognize or bind to simple sugars. In contrast, most LFs bound to glycoproteins, with the highest inhibition by fetuin, thyroglobulin and mucin, which are glycoproteins bearing N-glycans, O-glycans or complex and high mannose-type N-glycans. The HA of most LFs decreased markedly under acidic conditions and showed a slight reduction in alkaline conditions. A sharp decline in HA was observed at temperatures above 70°C, while the activity was unaffected by the presence or absence of divalent cations. The study identified previously unreported seaweed species as potential sources of lectins, warranting further investigation.

ABSTRACT Blue light therapy is increasingly used to treat various skin conditions like acne, psoriasis and neonatal hyperbilirubinemia. Yet, excessive blue light exposure can also negatively impact human health by disrupting circadian rhythms, generating free radicals and damaging skin barrier function. Quantifying personal blue light exposure is therefore essential for optimizing therapeutic efficacy while preventing side effects. However, current blue light dosimetry techniques require complex, expensive instrumentation, making routine monitoring impractical. In this feasibility study, we explored the potential for developing a blue-light dosimeter that uses the colour changes of photodegraded microalgae to measure blue light doses relevant for phototherapy. Two fibre-coupled light-emitting diodes (LEDs), one emitting at 415 nm and the other at 455 nm, were used. A strain of the green microalga Schizochlamys sp. (Chlorophyceae) exhibited a photobleaching response upon blue light irradiation, with colour changes quantitatively linked to exposure dose. This approach enables real-time monitoring and assessment of blue light exposure in a variety of contexts, including the workplace, the home and healthcare facilities, in a cost-effective and user-friendly way.

ABSTRACT Despite underpinning entire polar and temperate coastal ecosystems, kelp is rarely examined in standard ecotoxicology test batteries, and no universally accepted testing guidelines exist despite the growing regulatory interest in macroalgal tests. Declines in kelp populations, linked increasingly to pollution and other anthropogenic stressors, reinforce an urgent need to quantify contaminant effects on kelp health and survival. Reliable and consistent kelp cultivation protocols are therefore essential for generating ecotoxicological data that both addresses critical gaps in environmental risk assessment and provides alternatives to vertebrate testing in toxicology. The microscopic kelp life stages present a particular opportunity for reproducible assays at recognized bottlenecks in the life cycle, where kelp is often most sensitive to environmental stressors. This review consolidates laboratory cultivation techniques for three key species: Laminaria hyperborea, L. digitata, and Saccharina latissima, drawing on published literature and practitioner interviews. Protocols are outlined for spores, gametophytes, juvenile sporophytes, and mature sporophytes, with an emphasis on managing life stage transitions. Key parameters include temperature (5–15°C), nutrient enrichment (F2P), and precise control of light intensity, wavelength, and photoperiod. Strategies to address challenges such as contamination, genetic drift, and long-term culture maintenance are identified, alongside a discussion of emerging efforts to standardize kelp bioassays. The synthesis supports a broader and more robust use of kelp-based assays, which will strengthen our capacity to assess and understand pollution risks to kelp forests, and advance conservation and sustainable management of coastal ecosystems.

ABSTRACT Wild seaweeds and associated habitats are the basis of the world’s seaweed industry, yet they lack adequate global conservation protection. A review of the industry’s global distribution, production and species based on available datasets and literature searches revealed that seaweed wild harvesting and aquaculture were reported in 82 countries on five continents. However, analysis of key datasets (FAO and Phyconomy) revealed reporting inconsistencies within the industry. Widespread uncertainty as to which species are used and the quantities produced by the industry has implications for wild stock sustainability, biosecurity, product provenance and safety. This points to the need for greater standardization and wild stock protection by the industry. Analysis of the industry’s global distribution in relationship to Marine Protected Areas revealed c. 50% of aquaculture and wild harvesting sites were close to conservation areas. This presents farmers and harvesters with a potential opportunity to strategically develop the MPA concept to protect wild stocks and secure the long-term future of this industry.