Search Results (595)

Phycobiliproteins are water-soluble photosynthetic pigments extracted mainly from microalgae and cyanobacteria with many potential biotechnological applications, such as healthy food colorants, nutraceuticals, fluorescent tags, or non-toxic therapeutic agents. We have recently devised a green innovative two-step ultrasound-based process (named UltraBlu) to obtain blue phycocyanin (a phycobiliprotein) with a high-purity grade from the cyanobacterium Limnospira platensis. To assess the possibility of a wider use of the method, this study evaluates the UltraBlu process on an organism of a different taxonomic domain, the red microalga Porphyridium cruentum, for extracts rich in B-phycoerythrin (B-PE), the main phycobiliprotein produced by this organism. The UltraBlu process is characterized by the extraction of phycobiliproteins decoupled from biomass cell lysis, although the process is entirely carried out in an aqueous medium. Conversely, cell lysis is integrated with the purification step and is carried out by ultrasonication in ammonium sulfate solution before the pigment extraction/recovery step. B-PE, significantly purer than that obtained via conventional one-step direct ultrasound-assisted extraction, was recovered within a few hours from fresh biomass, only isolating the B-PE extract from the leftover biomass by centrifugation. Yields generally exceeded 9%, approaching the highest pigment contents reported for P. cruentum in the literature. Full article

Maintaining sustainable production of healthy and nutritious food represents a major global challenge. Cultivated meat could reduce the environmental impact of livestock production, but it remains costly, largely due to the expense of fetal bovine serum, a common cell culture media supplement. Algal and cyanobacterial proteins, particularly phycobiliproteins, represent promising sustainable sources of potentially bioactive peptides that may contribute to the development of serum-reduced or serum-free culture media. This study investigated the potential of hydrolysates prepared using the protein extracts of the red alga Porphyra haitanensis and the cyanobacterium Arthrospira platensis as functional supplements for cell cultivation in a low-serum environment. Twelve hydrolysates were generated by treating protein extracts from Arthrospira platensis and Porphyra haitanensis with six proteolytic enzymes: pepsin, trypsin, chymotrypsin, subtilisin, thermolysin and proteinase K. The effects of these hydrolysates were studied in three cell models of mammalian (CHO-K1), avian (QM7), and fish (MACK1) origin. The effects of hydrolysates on cell viability, proliferation, and antioxidant activity were evaluated. A. platensis–chymotrypsin hydrolysate significantly improved QM7 cell viability compared to control in both 80% reduced-serum and tryptose phosphate broth conditions (p ≤ 0.0001). Additionally, peptide composition analysis and identification of amino acid sequences provided preliminary insights into potentially bioactive chromopeptides associated with the maintenance and promotion of cellular growth. Algae/cyanobacteria-derived hydrolysates positively regulated cell viability and proliferation in serum-reduced conditions, although effects were dependent on the algal species, enzymatic treatment, and cell type. These findings highlight their potential as sustainable supplements for alternative cell culture media. Full article

Cyanobacteria offer a sustainable and environmentally friendly method of light-driven biosynthesis of chemicals with minimal environmental impact, making them an extremely attractive proposition in alleviating society’s dependency on fossil fuels. To fully exploit cyanobacteria as a chassis to meet society’s demands for energy and chemical production, genetic modification is a crucial step in improving productivity through the expression of heterologous and novel biosynthetic pathways. Genome mining was carried out with the aim of identifying potential recE and recT homologues to improve the efficiency of genetic manipulation. Two promising candidate homologues of recT and cas4 (recE homologue) were identified from the cyanobacterium Aphanocapsa feldmanni. Expression of these candidates increased recombination efficiency 3-fold, generating mutants with the expected genotypes and phenotypes, which were comparable to mutants created with conventional knockout protocols using suicide vectors. These results indicate that cyanobacteria possess recombination homologues that can be re-purposed to improve the efficiency of genome engineering to accelerate cyanobacteria for strain development. Full article

Interactions between cyanobacteria and eukaryotic algae are traditionally viewed as favoring cyanobacteria, which are often the dominant competitors in freshwater ecosystems. However, increasing evidence suggests that eukaryotic algae also possess effective chemical defenses capable of suppressing cyanobacterial proliferation. In this study, the anti-cyanobacterial potential of a methanolic biomass extract of the green microalga Chlorella vulgaris against the bloom-forming cyanobacterium Microcystis aeruginosa was investigated. Optical density measurements revealed the inhibition of cyanobacterial growth, with extract concentrations of 0.4–1.6 mg mL⁻¹ significantly reducing biomass accumulation. The lowest concentration (0.2 mg mL⁻¹) stimulated the accumulation of phycobiliproteins, whereas concentrations of 0.8–1.6 mg mL⁻¹ significantly decreased phycobiliprotein content, indicating progressive physiological impairment. The results suggest that the highest extract concentration applied may also cause alteration in phosphate acquisition. Lipid profiling of the Chlorella biomass showed that 97% of the extractable lipids consisted of methanol-soluble fatty acids, with C18 fatty acids predominating among the 20 identified compounds. These metabolites are reported to possess allelopathic activity and therefore represent plausible contributors to the observed inhibition. These findings support that anti-cyanobacterial activity may represent a widespread ecological trait of Chlorella and potentially other green microalgae, providing a promising foundation for environmentally friendly cyanobacterial bloom management. Full article

The pet food industry is undergoing a significant transformation, driven by the growing trend of companion animal humanization and increasing concerns over the environmental sustainability of conventional protein and lipid sources. Consumers now seek diets that not only meet basic nutritional requirements but also offer preventive health benefits. Microalgae, including Arthrospira (Spirulina, a kind of cyanobacterium), Chlorella, Schizochytrium, and Euglena gracilis, have emerged as versatile biological platforms capable of addressing both functional and sustainability challenges. These microorganisms produce high-quality proteins, omega-3 long-chain polyunsaturated fatty acids (particularly docosahexaenoic acid, DHA), natural pigments, and immunomodulatory polysaccharides. This review synthesizes findings from peer-reviewed studies on the application of microalgae in pet nutrition, covering dogs, cats, and aquatic companion animals. We examine how algal ingredients influence gut microbiota, for instance, by enriching beneficial genera such as Turicibacter and Peptococcus, enhance vaccine responses and mucosal immunity, support cognitive function in aging pets, and contribute to weight management. Particular attention is given to Euglena gracilis and its paramylon (β-1,3-glucan), a pathogen-associated molecular pattern that engages the Dectin-1 pathway to train innate immunity and has demonstrated antiviral activity through host defense mechanisms. The review also surveys the patent landscape, highlighting trends in palatability enhancement, hypoallergenic formulations, and novel delivery formats. Key challenges remain, including ingredient standardization, safety validation, palatability optimization, and consumer acceptance. We outline a translational roadmap that prioritizes well-designed clinical trials in target species and processing methods that preserve bioactivity. Collectively, the evidence positions microalgae, and Euglena gracilis in particular, as promising candidates for next-generation functional pet foods that deliver health benefits alongside ecological sustainability. Full article

Cyanobacteria are essential primary producers in aquatic ecosystems. Silver nanoclusters (Ag NCs) are emerging ultrasmall nanomaterials with broad applications; however, they inevitably enter aquatic environments. This study investigated the nanotoxicity of Ag NCs on model cyanobacterium Synechococcus elongatus PCC 7942 (Syn7942), revealing concentration-dependent growth inhibition with a 72 h half-maximal effective concentration of 1.19 mg L⁻¹. Ag NCs internalized into Syn7942 cells severely impaired the photosynthetic machinery, evidenced by reduced chlorophyll a content and suppressed photochemical reactions, leading to impaired electron transport. This photosynthetic dysfunction resulted in substantial reactive oxygen species generation and lipid peroxidation, as indicated by elevated levels of malondialdehydes. Although the activities of key antioxidant enzymes were enhanced, oxidative damage ultimately overwhelmed the cellular defense capacity. Furthermore, quantitative analysis of silver ions (Ag⁺) release coupled with comparative toxicity assays of Ag⁺ and Ag NCs confirmed that the toxicity originates from the Ag NCs themselves, rather than from the released Ag⁺. Transcriptional level analysis revealed that Ag NCs altered the expression of genes involved in photosynthesis and metal detoxification. Collectively, this study reveals a unique toxicity mechanism for Ag NCs distinct from that for Ag NPs and Ag⁺, highlighting the potential ecological risks posed by ultrasmall nanomaterials. Full article

Nodularin is a cyanobacterial toxin predominantly produced by Nodularia spumigena Mertens. This cyanobacterium has been associated with fish, bird, and animal deaths, and the toxin can contaminate fish and shellfish intended for human consumption. With climate change, blooms of Nodularia spumigena are becoming more frequent and more widespread, meaning that the risk this cyanobacterium poses to human health must be evaluated. However, toxicity information is scarce, meaning that data from the closely related toxin class, microcystins, are currently used instead. In the current study, the LD₅₀ of nodularin-R by intraperitoneal injection was found to be 50 µg/kg, consistent with previous reports. For the first time, the LD₅₀ of nodularin-R by oral administration was determined using the voluntary consumption of laced cream cheese (7.5 mg/kg), which is similar to that reported for microcystin-LR (10.9 mg/kg). The use of microcystin toxicology data in food safety assessments for nodularin, therefore, seems reasonable—but it is critical that an oral repeated-dose study is performed on nodularin to better understand the risk posed by this toxin through chronic exposure. Full article

Sulfate is a natural major ion commonly found in the environment. Various anthropogenic activities can lead to the discharge of sulfate in high concentrations, causing negative effects on aquatic organisms. While chronic toxicity of sulfate for brackish water species was established, acute toxicity data were scarce. In this study, we tested the acute toxicity of sulfate to seven Baltic Sea species and, together with the literature data, derived the fifth percentile hazardous concentration (HC5) through a species sensitivity distribution (SSD) with 12 species. Acute sulfate sensitivity varied across taxa, with fish and crustaceans being much more sensitive than bivalves, algae, rotifers and bacteria, which led to a bimodal SSD. The most sensitive species tested were whitefish (Coregonus lavaretus) and vendace (Coregonus albula) during fertilization, and the most tolerant were cyanobacterium Synechococcus sp. and bacterium Aliivibrio fischeri. Acute HC5 using the model-averaging approach was 2489 (1016–3990) mg/L sulfate. With a Predicted No Effect Concentration of 1011 mg/L, the upper limit of the 95% confidence interval for the estimated percentage of species affected was below 5%. This new data contributes to the development of the maximum allowable concentration for the sulfate environmental quality standard in the northern Baltic Sea. Full article

Algal cultivation has attracted significant attention due to CO₂ biocapture and potential for biofuel generation. Enormous generation of waste polymer often poses an environmental problem due to non-biodegradability. This study comprehensively analyses the thermal degradation characteristics of blue–green alga, Leptolyngbya subtilis JUCHE1 (LS) and waste textile polyester (WTP) and their mixtures (LS1P3 (1:3); LS1P1 (1:1); LS3P1 (3:1)) during co-pyrolysis. The interaction between LS and WTP during co-pyrolysis has been assessed through the verification of synergism using different blending ratio and through the comparison of the corresponding values of the Comprehensive Pyrolysis Index (CPI). The composite, LS1P3, exhibited the highest synergism and the maximum value of CPI. Isoconversional models (FWO, Starink, Bosewell and Tang) have been used to predict the activation energies (E_a). Thermodynamic parameters, namely, heat of reaction (ΔH), Gibbs free energy change (ΔG) and entropy change (ΔS), have also been determined for all. The average value of E_a for LS1P3 is also the lowest (96.015 kJ/mol) among all composites. The Master plot method identifies that there is a shift of reaction mechanism from phase boundary type (R2 and R3) for LS and WTP to a P2-type acceleratory reaction rate mechanism for LS1P3. The lowest average value of ΔH and the highest values of ΔG and ΔS for LS1P3 co-pyrolysis also support the least consumption of energy and the highest favorability under present conditions. The product yield distribution of co-pyrolysis in the isothermally operated conditions (450 °C) also establishes the superiority of LS1P3. Yields of pyro-oil and pyro-gas are the highest among all composites. The study ensures the future application prospects of co-pyrolysis of LS and WTP as a means for generation of energy resources (pyro-oil and pyro-gas) and chemicals (pyro-char). Full article

Natural dyes are attracting increasing attention owing to their environmental compatibility and safety profile, particularly in contrast to synthetic dyes, which may contain hazardous compounds posing risks to human health and ecosystems. In this study, crude phycocyanin extract from the cyanobacterium Limnothrix planctonica (KU.B3) was evaluated as a natural blue color for textile screen printing. The investigation encompassed the optimization of curing temperatures and assessment of colorfastness under simulated-use conditions, including washfastness, lightfastness, and rubfastness. The results indicated that a curing temperature of 110 °C represented the practical upper limit for maintaining phycocyanin chromophore stability during the screen printing process. Among the additive compound evaluated, copper sulfate conferred the greatest resistance to UV-induced fading; the compound-treated fabric retained a K/S value of 0.83 ± 0.03 following 5 h of UV exposure, representing a decline of approximately 16% compared with approximately 25% in the untreated control. However, washfastness was poor across all treatment conditions (grey scale score 1), indicating that under the binder system investigated in this study phycocyanin may be more suitable for decorative rather than washable textile applications. Full article

Spirulina, a cyanobacterium recognized for its nutritional and environmental advantages, has emerged as a potential ingredient for sustainable diets. Consumer acceptance remains limited despite its benefits, particularly due to sensory challenges and limited prior awareness. This study aimed to investigate knowledge, consumption patterns, and attitudes toward Spirulina among a Brazilian sample. A cross-sectional online questionnaire distributed via social media and public spaces yielded 933 valid responses, categorized into three groups based on prior awareness and consumption history. Results indicated limited prior awareness and low consumption, with more than half of consumers having tried Spirulina only once. Education, income, generation, and health-related behaviors were associated with knowledge and consumption, although most effect sizes were small. Knowledge of Spirulina was concentrated on nutritional attributes, whereas environmental and technological attributes were less widely recognized. Health and environmental benefits were most often rated as increasing willingness to consume Spirulina, while self-reported barriers included taste, smell, and issues related to powdered and capsule forms. Preferred applications were in familiar food categories such as baked goods and powdered mixes. These findings indicate that Spirulina occupies a niche position among respondents and suggest the relevance of sensorially acceptable formulations, tailored communication strategies, and inclusive educational efforts. Full article

Fruits and vegetables are among the most widely consumed products; however, their processing by both industry and households generates substantial peel waste, leading to significant environmental concerns. This study aimed to assess fruit and vegetable peels as an eco-friendly source of natural cyanbactericidal compounds for controlling toxic algal blooms. Aqueous Extract (AE), Ethyl Acetate Extract (EAE), and Ethanol Extract (EE) of five fruit and vegetable peels (Avocado, tomato, mango, eggplant, and potato) were screened for their inhibitory effects on Microcystis aeruginosa using both paper disc diffusion and microdilution techniques. Therefore, the extracts of avocado peel, the most bioactive of the five peels, were selected for further testing in a batch bioassay. The inhibitory effect appeared to be dose-dependent. The maximum inhibition rate (98%) was recorded following an 8-day exposure period at the dose (MIC = 0.8 mg/mL) for both the AE and EAE. Thus, the EE showed significant potential, particularly at the highest concentration (MIC = 0.2 mg/mL), where inhibition peaked at 92% on day 8. Accordingly, all treated groups demonstrated a significant decrease in primary photosynthetic pigments and phycobiliproteins in comparison to the control groups. In conclusion, avocado peel extracts show the most potent inhibition in batch bioassay. These extracts could constitute a promising strategy to valorize avocado peel waste as a sustainable cyanobactericidal agent to suppress the proliferation of M. aeruginosa blooms in eutrophic aquatic ecosystems. Full article

Ketoprofen (KET) is a non-steroidal anti-inflammatory drug frequently detected in surface waters and effluents, with the potential to impact trophic base organisms. This study evaluated the toxicity of KET, in its active pharmaceutical ingredient (API) form and in four commercial formulations (KET-1, KET-2, KET-3, and KET-4), on two freshwater species: the cyanobacterium Microcystis novacekii and the microalga Chlorella vulgaris. Cell growth assays, performed under acute (4 days) and chronic (14 days) conditions, showed that the API KET was the most toxic compound, especially for M. novacekii, with a chronic EC50 of 1.35 mg/L. The commercial formulations presented distinct toxicity profiles, suggesting the influence of excipients and synergistic or antagonistic interactions. For C. vulgaris, low acute toxicity was observed, with increased chronic effects at high concentrations and possible hormetic response at low doses. Risk quotient (RQ) calculations, based on environmental concentrations of KET, indicated low risk in surface and drinking water, but high risk in untreated hospital and wastewater treatment plant effluents, especially for M. novacekii. The results show that the complete formulation, exposure time, and target species are critical factors in the ecotoxicological risk assessment of pharmaceuticals in freshwater environments. Full article

Cyanobacteria, the only prokaryotic oxygenic phototrophs, rely on sophisticated regulatory networks, including those mediated by small RNAs (sRNAs) to cope with environmental fluctuations. Here, we delineate the sRNA landscape of Synechocystis sp. PCC 6803 under short- and long-term ammonium stress, revealing a significant proportion of antisense RNAs (asRNAs). Functional characterization identified three asRNAs (sll0312-as, sll0873-as, and slr1667-as) as key regulators of ammonium stress tolerance, implicating their targets (sll0312, sll0873, and slr1667) as new players in nitrogen fluctuation acclimation. The sll0944-as and sll1515-as were also identified, revealing an additional regulatory layer targeting known carbon/nitrogen metabolism regulators. Mechanistically, we characterized the ammonium-induced asRNA ssr0692-as, demonstrating that it represses pirA translation via direct 5′UTR interaction. This finding, integrated with the known role of the nitrogen limitation-responsive sRNA NsiR4 targeting the same region, supports a synergistic model wherein these two sRNAs precisely modulate PirA protein levels—and thus the downstream nitrogen flux—across varying nitrogen availability. Together, our findings expand the functional repertoire of cyanobacterial sRNAs and elucidate a dynamic post-transcriptional mechanism to fine-tune nitrogen metabolism in response to fluctuating nutrient conditions. Full article

Phycocyanin, a phycobiliprotein derived from the cyanobacterium Limnospira (Arthrospira) platensis (commonly known as Spirulina), is recognized for its antioxidant, immunomodulatory, and bioactive properties. This research aims to develop a new cosmetic ingredient based on phycocyanin incorporated into a high-lipid matrix, such as shea butter. A comprehensive characterization of the cytotoxicity and anti-inflammatory activity of this new bioactive phycocyanin–protein complex in human THP-1 monocytic cells was performed. For this purpose, cytocompatibility was evaluated using MTT assays at concentrations ranging from 10 to 0.0006% v/v. Anti-inflammatory activity was measured under LPS-induced inflammatory stress by measuring IL-6 and IL-8 secretion using ELISA in PMA-differentiated THP-1 cells treated with non-cytotoxic concentrations (0.04, 0.02, and 0.01% v/v). A crucial finding was the absence of anti-inflammatory activity at 0.01% v/v, indicating a minimum effective concentration threshold and, consequently, effective doses. The results of this research indicate that the phycocyanin and shea butter ingredients demonstrate strong cytocompatibility at relevant cosmetic doses and significant anti-inflammatory activity, supporting their suitability for formulations targeting skin sensitivity, erythema reduction, and post-inflammatory recovery. Full article