Phycology, Volume 5, Issue 4 (December 2025) – 13 articles

Microcystis aeruginosa, a kind of cyanobacterium, can lead to water blooms under specific conditions and it is harmful to human and ecological security due to the toxins produced by certain strains. Artemisinin, which is derived from Artemisia annua Linn, has a strong allelopathic effect on algae. Artesunate is a water-soluble derivative of artemisinin. We investigated the effect of artesunate on M. aeruginosa, including growth and key photosynthetic parameters (Fv/Fm, φPSII). Our findings demonstrate that artesunate inhibits the growth of M. aeruginosa by damaging the photosynthetic center of photosystem II (PS II), and this inhibitory effect is enhanced with increasing concentration. At the concentration of 200 mol/L, the maximum inhibition rate was 41.62% for FACHB-315 and 43.19% for FACHB-927 after 96 h. After 24 h of exposure, the φPSII of the two strains decreased significantly (p < 0.01). These results could inform further studies on the use of artesunate to control cyanobacterial growth in water bodies and provide theoretical support for the application of artemisinin derivatives in treating water blooms. Full article

The growing demand for sustainable bioprocesses highlights microalgae as a promising source of renewable feedstock. However, high energy use for artificial lighting limits the commercial viability of photobioreactor systems. This study proposes an energy-optimized framework for cultivating Mychonastes homosphaera using LED illumination. The optimization was performed using Response Surface Methodology (RSM) with a Face-Centered Central Composite Design (FCCCD) to assess the interactive effects of light intensity, duration, airflow rate, and nitrogen concentration on biomass and lipid productivity. The performance of LED wavelengths was compared for biomass, lipid productivity, and energy consumption. RSM models were statistically significant (p < 0.01), and ANOVA had a high coefficient of determination (R²) for all LEDs. Maximum biomass productivity was 512.0 ± 12.23 mg L⁻¹ day⁻¹ with cool-white, followed by pink (401.33 ± 10.48), blue (342.66 ± 3.53), and red (189.6 ± 1.36). Cool-white consumed the least energy (228.6 Wh day⁻¹) to produce the maximum biomass, compared to blue (235.05 Wh day⁻¹), pink (240.0 Wh day⁻¹), and red (240.0 Wh day⁻¹). Lipid content was highest under red (22.84%), followed by pink (17.39%), blue (15.82%), and cool-white (8.96%). However, lipid productivity was highest under pink (69.8 mg L⁻¹ day⁻¹), followed by blue (54.2 mg L⁻¹ day⁻¹), cool-white (45.86 mg L⁻¹ day⁻¹), and red (43.3 mg L⁻¹ day⁻¹). Full article

Clay minerals and other flocculants are used to mitigate the effects of some species that produce harmful algal blooms due to their physical and chemical characteristics. In this study, we applied calcium bentonite clay (Bca) and zeolite (Ze) to flocculate and remove cells of the dinoflagellate Gymnodinium catenatum (Graham), a producer of paralyzing toxins. The flocculants were characterized by scanning electron microscopy (SEM) in combination with an energy-dispersive X-ray spectroscopy (EDS) microanalysis system. During experiments, Bca and Ze were suspended in distilled water, deionized water, and seawater at concentrations of 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 4.0 gL⁻¹. The percentage of removal efficiency (RE%) of biomass indicators of G. catenatum was calculated. The cell number and concentration of chlorophyll a and peridinin were analyzed using high-performance liquid chromatography (HPLC-UV and HPLC-DAD). The external effects on cells of G. catenatum were recorded. As a result, the maximum RE% of Bca was 79% with respect to the total number of cells, chlorophyll a was 69% and peridinin of 73%. The RE% of Ze was less than 40%. In the matrix of sedimented Bca, malformation of cells was observed, inhibiting their swimming, as well as death and rupture of cells with temporary cyst formation after 72 h. We conclude that Bca, suspended in deionized and distilled water, was more efficient in flocculating cells of G. catenatum. Full article

The beneficial effects of algae on plant growth are widely known, so the combination of coconut fiber with algae waste from a species such as Caulerpa prolifera, which is an invasive species in the Mar Menor, could become an ideal substrate for leafy vegetable cultivation. The aim of this study was to evaluate the effect of an “algae waste + coconut fiber” combination in different proportions on the cultivation of iceberg lettuce. The proportions studied consisted of 0% algae waste + 100% coconut fiber (0% AW), 50% algae waste + 50% coconut fiber (50% AW), 75% algae waste + 25% coconut fiber (75% AW), and 100% algae waste + 0% coconut fiber (100% AW). Physiological parameters were evaluated. The results obtained showed that the mixture of algae waste and coconut fiber is a great alternative in the production of iceberg lettuce, since the proportion of 50% AW considerably improved the size of the lettuce (54.4%), the total phenol concentration (24.8%), the antioxidant activity (28.2%), the total sugars (14.1%) and reduced its nitrate concentration (24.6%), with respect to the 0% AW plants. These findings support the feasibility of reusing Caulerpa prolifera as a bio-enriched substrate for high-quality lettuce production. Full article

High-mountain microalgae exhibit remarkable adaptability to extreme environments, making them promising candidates for sustainable biorefineries. We evaluated how photoperiod (12:12, 18:6, 24:0 h) and LED spectra (cool white, full spectrum, red–blue 4:1) affect growth and metabolite formation in Chlorella sp. UFPS019 and Scenedesmus sp. UFPS021. Biomass peaked in Chlorella under red–blue 18:6 (≈1.8 g L⁻¹) and in Scenedesmus under red–blue 24:0 (≈1.7 g L⁻¹), revealing species-specific responses. Carbohydrate fractions were maximized under red–blue 12:12 in both species, and continuous light (24:0) depressed carbohydrate content—most notably under full spectrum. Protein content was highest under red–blue 18:6 in Chlorella sp. and under red–blue 12:12–18:6 in Scenedesmus sp. Lipid fractions increased with light duration, peaking under red–blue 18:6–24:0 in Chlorella and under red–blue 18:6–24:0—with Cool White 24:0 also high—in Scenedesmus sp. Although extended illumination favored lipids, intermediate photoperiods (12:12–18:6) provided better productivity-to-energy trade-offs and broader metabolic profiles. These results show that tuning spectral composition and photoperiod to species-specific physiology enables the targeted, energy-aware production of proteins, carbohydrates, or lipids; red–blue at intermediate durations is a robust, energy-efficient regime, whereas longer exposures can be used strategically when lipid enrichment is prioritized. Full article

Macroalgal polysaccharides represent a diverse group of structurally complex biopolymers with significant potential in biomedicine and functional food applications. This review provides a comprehensive examination of their structural features, biological activities, and molecular targets, with an emphasis on precision applications. Key polysaccharides such as alginates, carrageenans, fucoidans, ulvans, and laminarans are highlighted, focusing on their unique chemical backbones, degrees of sulfation, and branching patterns that underlie their bioactivity. Special attention is given to their roles in modulating inflammation, oxidative stress, apoptosis, gut microbiota, and metabolic pathways. Comparative assessment of extraction strategies, structure–function relationships, and bioactivity data highlights the importance of tailoring polysaccharide processing methods to preserve bioefficacy. Emerging insights from computational modelling and receptor-binding studies reveal promising interactions with immune and apoptotic signalling cascades, suggesting new therapeutic opportunities. Finally, the review outlines challenges related to standardisation, scalability, and regulatory approval, while proposing avenues for future research toward clinical translation and industrial innovation. By integrating structural biology, pharmacology, and nutraceutical sciences, this work underscores the potential of macroalgal polysaccharides as precision agents in health-promoting formulations and next-generation functional foods. Full article

Microalgae cultivation offers a sustainable approach for nutrient recovery from municipal effluents and the production of valuable biomass, although efficient harvesting remains challenging. This study evaluated the adaptation of the microalgal consortium MC-10 in a sequential batch system through reinoculation of its flocculating fraction to enhance harvesting efficiency and mineral recovery. The consortium was initially cultivated under high ionic stress to promote cell aggregation. Laboratory preadaptation using secondary municipal effluents was then conducted, followed by an outdoor evaluation. In the initial propagation stage, flocculation efficiency reached 98%. Using municipal effluents, flocculation values of 99% were obtained, with a 149% increase in flocculating biomass under laboratory conditions, and 84% flocculation with a 125% increase in biomass production under outdoor conditions, demonstrating the consortium’s stability under environmental fluctuations and its suitability for biomass harvesting. The resulting biomass showed high potential as a biofertilizer due to its mineral content (47% dry weight, DW) and acid solubility (83%), indicating high nutrient bioavailability. Additionally, it contained a total carotenoid concentration of 451 μg/g DW, adding antioxidant value. These findings support the use of microalgae cultivation for the valorization of municipal effluents through the production of easily harvestable biomass with potential for reintegration into agricultural systems. Full article

Industrial wastewater can serve as a low-cost nutritional source for sustainable microalgal biomass production. This study investigated the biomass of Chlorella vulgaris var. vulgaris TISTR 8261 grown in untreated wastewater collected from four food industry factories in Phra Nakhon Sri Ayutthaya Province, Thailand. Among them, wastewater from a processed food production plant (PFPP) supported the highest algal growth. Supplementation with 17.4 mM sodium acetate significantly improved algal biomass yield. Further optimization with 3.7 mM NH₄Cl, 1.0 mM KH₂PO₄, 0.2 mM MgSO₄, and a moderate concentration of trace minerals enhanced the specific growth rate and chlorophyll concentration. Scaled-up cultivation in 3.5 L culture bottles in optimized PFPP yielded a maximum biomass yield of 8.436 ± 0.378 g L⁻¹, comparable to 6.498 ± 0.436 g L⁻¹ in standard TAP medium. Biomass composition analysis after 15 days of cultivation revealed 42.70 ± 1.40% protein, 17.10 ± 1.60% carbohydrate, and 1.90 ± 0.10% lipid on a dry weight basis. These findings demonstrate that optimized PFPP wastewater can effectively support high-density cultivation of C. vulgaris var. vulgaris TISTR 8261, yielding nutritionally rich biomass, and offering a cost-effective and environmentally sustainable strategy for industrial-scale microalgal production. Full article

Taxonomic clarity within the genus Antithamnion is critical for understanding its molecular phylogeny and biodiversity. Here we report Antithamnion hubbsii for the first time from the Korean coast. This finding highlights the need to re-evaluate its relationship with the previously reported, morphologically very similar A. nipponicum in this region, raising the question of whether the newly identified A. hubbsii represents a local variant of A. nipponicum or a recently introduced invasive species via nearby ports. Specimens collected from Gangneung were analyzed using plastid-encoded rbcL and psaA genes, confirming their identity as A. hubbsii. Morphological features such as indeterminate lateral axes, oppositely arranged pinnae and pinnules, and distinctive adaxial gland cells supported this identification. Molecular analyses revealed minimal divergence between A. hubbsii and A. nipponicum (1–3 bp in rbcL, none in psbA), and contrasting results from different species delimitation methods. Phylogenetic analyses nevertheless placed the Korean specimens in a strongly supported A. hubbsii/A. nipponicum clade. Taken together, our results suggest that the North American invasive A. nipponicum and the Korean A. hubbsii may represent a single species with broad intraspecific variation. Definitive resolution will require molecular analyses of the type specimens of both taxa. Full article

Colaconema daviesii has been described as an epi-endophyte of red algae. However, it has also been observed in vitro to colonize thalli of Macrocystis pyrifera, a giant kelp classified as a foundational organism of coastal marine ecosystems. This study aimed to determine, through co-cultivations, how C. daviesii affects the early stages of M. pyrifera, specifically gametophyte and sporophyte development. Determined were growth, oogonia formation, and gametophyte fertility, as well as sporophyte growth rate and survival. The results showed that the presence of C. daviesii negatively altered oogonia production and gametophyte fertility. Moreover, the survival of young sporophytes in co-cultures decreased. These findings demonstrate that the early developmental stages of M. pyrifera could be susceptible to infestation by a filamentous red alga, with negative consequences on fitness. Full article

This study uses industrial wastewater from an aluminum factory to evaluate the phycoremediation efficiency of two green microalgal strains, Dictyosphaerium sp. and Tetradesmus obliquus. The industrial wastewater contained high levels of pollutants, including COD, ammonium, nitrate, phosphate, and heavy metal ions (Al³⁺, Cu²⁺, Cr³⁺, Zn²⁺, Mn²⁺, Cd²⁺). Four biomass conditions were tested: free-living cells (active living cells), immobilized cells (entrapped within alginate), dried biomass (non-living dried cells), and acid-treated dried biomass (chemically modified for enhanced adsorption). Both strains demonstrated significant pollutant removal, with living biomass (free and immobilized) achieving the highest nutrient and organic pollutant removal, and non-living biomass (dried and acid-treated) being more efficient for rapid heavy metal removal. Tetradesmus obliquus showed superior performance across most parameters, while Dictyosphaerium sp. exhibited the highest aluminum removal (99.4%, reducing Al from 481.2 mg/L to 10.2 mg/L). These findings highlight the potential of microalgae-based approaches and support species-specific strategies for cost-effective and sustainable phycoremediation of industrial wastewater. Full article

Harmful algal blooms (HABs) caused by toxic species such as Pseudo-nitzschia hasleana pose significant risks to marine ecosystems and human health. This study investigates the effects of heating rate on the fluorescence temperature curves (FTCs) of P. hasleana and compares them with non-toxic species (Phaeodactylum tricornutum and Picochlorum maculatum) to design a reliable detection method. An increasing heating rate leads to a change in the temperature spectrum of the fluorescence of the studied algae and to increasing differences between them. During the study, the FTCs were measured in the temperature range of 20–80 °C and at heating rates of 1, 2, 3, and 6°/min. The results showed that P. hasleana exhibited a distinct local fluorescence maximum at 45–55 °C when heated at a rate of 3 °C/min or more, which was absent in non-toxic species. Additionally, rapid heating (6 °C/min) preserved fluorescent pigment–protein complexes, yielding four-fold higher fluorescence intensity at 70–80 °C compared to slower rates. There were no such changes for the microalgae P. maculatum and P. tricornutum. The results of this study make it possible to increase the efficiency of detecting hazardous microalgae using non-invasive optical monitoring methods. These findings demonstrate that controlled heating protocols can enhance the species-specific identification of toxic microalgae, offering a practical tool for early HAB detection. Full article

Sustainable plant-based materials are becoming more popular as a substitute for those of animal origin for the encapsulation of compounds. Among different techniques, microencapsulation is widely used to protect bioactives and keep them intact to reach the desired target area. In this work, microencapsulation of oils by spray-drying using alternative vegan materials was proposed to mitigate oxidative degradation of oils. The determination of the best combination and ratio for different vegan wall materials (pectin, inulin, pea protein, and modified corn starch) was first developed using high-oleic sunflower oil enriched with β-carotene. In terms of efficiency, the best wall materials were pectin and inulin (P:I) in a 1:1 ratio, achieving 67.26 ± 0.78%. This ratio also obtained the best morphological results for shape and size studied by SEM (scanning electron microscopy) and DLS (dynamic light scattering). Additionally, the antioxidant activity of the oil enriched with β-carotene was studied, obtaining an IC5O of 0.15 mg/mL. Moreover, when Schizochytrium sp. was used instead of sunflower oil, as a docosahexaenoic acid (DHA)-enriched plant-based oil, the best results were also obtained for the P:I mixture, but at a ratio of 1:5. In all cases, the preservation of fatty acid profiles was achieved, giving insights for the potential use of alternative materials. The synergy between the use of antioxidants and encapsulation provides an effective method to avoid oxidation of edible oils. This work demonstrates the possibility of encapsulating carotenoid-enriched microalgae oil with vegan materials, improving its stability and bioavailability. Full article