Search Results (498)

Light intensity and spectral quality play crucial roles in microalgal growth and biochemical biosynthesis. This study investigates the effects of different light intensities (3000, 8000 and 15,000 lux) and colors (red, white, yellow and green) on the growth and metabolites of Nephroselmis sp. Moderate intensity (8000 lux) of white light is sufficient to produce this microalga. The colors of light strongly affect the parameters of the growth of Nephroselmis under each light intensity (p < 0.05). The yellow and green light supported the highest growth rates for the three intensities. Blue and green light at 15,000 Lux stimulates high levels of chl-a corresponding to antenna size 2.80 and 2.46. Nephroselmis illuminated with red light synthesizes carotenoids reaching 13 µg mL⁻¹ at 15,000 lux. This latter for each color stops the proliferation of Nephroselmis, and cells shift their metabolism towards the accumulation of protein. Nephroselmis accumulates more protein, followed by carbohydrates, lipids and polyphenols. Nephroselmis exhibited the highest protein (64% D.W) content when cultured under white light, and the green at 15,000 lux enhanced their production. Nephroselmis is rich in carbohydrates, which accounted for more than 20% D.W under all combinations of light intensities and colors. The accumulation of polyphenols and carotenoids under high-intensity red and white light may reflect an oxidative stress response, suggesting their role as protective antioxidants. The capacity of Nephroselmis sp. to thrive and synthesize valuable metabolites under variable light regimes underscores its potential as a robust candidate for the production of various molecules. Full article

Due to widespread use of silver nanoparticles (AgNPs), the assessment of their potential harm to microalgal photosynthesis is crucial, as microalgae, together with cyanobacteria, contribute to approximately 50% of global oxygen production. This study investigated photosynthetic pigments, photosynthetic rate, chlorophyll a fluorescence, and the expression of photosynthesis-related genes and proteins in green alga Chlorella vulgaris after 72 h exposure to citrate- and cetyltrimethylammonium bromide (CTAB)-stabilized AgNPs, as well as silver ions (AgNO₃), at concentrations allowing 75% cell survival (EC₂₅). All treatments impaired photosynthetic performance. The most pronounced decreases in chlorophyll fluorescence parameters and photosynthetic rate, alongside elevated energy dissipation, were observed after exposure to AgNP-CTAB and AgNO₃. AgNP-citrate had milder effects and induced compensatory responses, reflected in an increased performance index and upregulation of photosynthesis-related proteins. AgNP-CTAB induced the strongest downregulation of gene and protein expression, likely due to its higher EC₂₅ concentration and cationic surface promoting interaction with photosynthetic structures. Although AgNO₃ caused fewer molecular changes, it significantly disrupted photosynthetic function, suggesting a direct effect of Ag⁺ ions on photosynthesis-related proteins. Overall, the results highlight the role of AgNPs’ surface coatings and dosage in determining their phytotoxicity, with photosystem disruption and oxidative stress emerging as key mechanisms of action. Full article

Microalgal biomass has emerged as a valuable and nutrient-rich source of novel plant-based foods of the future, with several demonstrated benefits. In addition to their green and health-promoting characteristics, these foods exhibit bioactive properties that contribute to a range of physiological benefits. Photoautotrophic microalgae are particularly important as a source of food products due to their ability to biosynthesize high-value compounds. Their photosynthetic efficiency and biosynthetic activity are directly influenced by light conditions. The primary goal of this study is to track the changes in the light requirements of various high-value microalgae species and use advanced systems to regulate these conditions. Artificial intelligence (AI) and machine learning (ML) models have emerged as pivotal tools for intelligent microalgal cultivation. This approach involves the continuous monitoring of microalgal growth, along with the real-time optimization of environmental factors and light conditions. By accumulating data through cultivation experiments and training AI models, the development of intelligent microalgae cell factories is becoming increasingly feasible. This review provides a concise overview of the regulatory mechanisms that govern microalgae growth in response to light conditions, explores the utilization of microalgae-based products in plant-based foods, and highlights the potential for future research on intelligent microalgae cultivation systems. Full article

In recent years, microalgae have gained significant biotechnological importance as a sustainable source of various metabolites of industrial interest. Among these, paramylon, a polysaccharide produced by the microalga Euglena gracilis, stands out for its diverse applications in biomedicine and pharmaceuticals. E. gracilis is an adaptable secondary eukaryote capable of growing photoautotrophically, heterotrophically and mixotrophically. During photoautotrophic growth, varying light conditions impact biomass and paramylon production. To investigate the effects of varying illumination more thoroughly, we designed and built a modular photobioreactor that allowed us to simultaneously evaluate the photoautotrophic growth of E. gracilis under twelve different light conditions: seven single-spectrum lights (ultraviolet, royal blue, blue, green, red, far-red, and infrared) and five composite-spectrum lights (3000 K, 10,000 K, and 30,000 K white lights, amber light, and “Full-spectrum” light). The 24-day growing kinetics were recorded, and the growth parameters were calculated for each light regime. Both growth curves and pigment composition present differences attributable to the light regime used for cell culture. Additionally, photosynthetic and respiratory machinery functionality were proven by oximetry. Finally, our results strongly suggest that the far-red component enhances paramylon production during the stationary phase. Full article

Biomass-derived growth stimulants are widely recognized as green and economical solutions that can significantly enhance microalgae culture efficiency and optimize the biomanufacturing process of target products. In this paper, we investigated the effect of ethanol synergized with guaiacol (GA) on biomass and β-1,3 glucan accumulation in edible microalgae, namely Euglena gracilis. The ethanol-induced mixotrophic mode significantly increased biomass and paramylon production by 12.68 and 6.43 times, respectively, compared to the autotrophic control group. GA further exerted toxic excitatory effects (hormesis) on top of ethanol mixotrophic nutrition. At the optimal concentration of 10 mg·L⁻¹ GA, chlorophyll a, carotenoids, and paramylon production increased by 8.96%, 11.75%, and 16.67%, respectively, compared to the ethanol-treated group. However, at higher concentrations, the biomass and paramylon yield decreased significantly. This study not only establishes an effective combinatorial strategy for enhancing paramylon biosynthesis but also provides novel insights into the hormesis mechanism of phenolic compounds in microalgae cultivation. The developed approach demonstrates promising potential for sustainable production of high-value algal metabolites while reducing cultivation costs, which could significantly advance the commercialization of microalgae-based biorefineries in food and pharmaceutical industries. Full article

The growing concern for environmental sustainability has led to an increased interest in biodegradable materials derived from renewable resources. This study explores the innovative use of residual biomass from the green photosynthetic microalga Chlamydomonas reinhardtii, left over after polysaccharide extraction, as a natural filler in the development of the compostable protein-based material SP-Milk^®. The microalgal biomass was characterized using Fourier transform infrared spectroscopy (FTIR) and UV-Visible Spectroscopy to assess its chemical and structural composition. Subsequently, it was incorporated into a biodegradable protein matrix, and the resulting biocomposites were evaluated for mechanical and thermal properties. The results demonstrate that the incorporation of algal filler improves the mechanical strength and elasticity of the material while reducing its glass transition temperature, highlighting its potential for use in sustainable applications as a possible substitute for conventional plastics. The biocomposite materials developed, based on the protein-based material SP-Milk^® and residual microalgal biomass, are environmentally friendly, contributing to the reduction in pollution and the risks associated with plastic accumulation. Thus, this study offers a simple, effective, and sustainable strategy for the valorization of microalgal biomass, enabling the production of biodegradable materials with enhanced mechanical performance, suitable for applications such as sustainable packaging within a circular economy framework. Full article

Microalgal–bacterial consortia are the environmentally sustainable biotechnological strategy to enhance the potential of microalgae. Understanding the regulatory mechanisms that enable bacteria to adapt to culture conditions of each bioprocess is crucial to ensure a successful synergic interaction. Thus, the present study evaluated the transcriptomic response of microalgal growth-promoting bacteria (MGPB) A. brasilense separately co-cultured with both green microalgae Scenedesmus sp. and Chlorella sorokiniana during CO₂ fixation from biogas through a microarray-based approach. The transcriptome profiling revealed a total of 416 differentially expressed genes (DEGs) in A. brasilense: 228 (140 upregulated and 88 downregulated) interacting with Scenedesmus sp. and 188 (40 upregulated and 148 downregulated) associated with C. sorokiniana. These results support the modulation of signal molecules: indole-3-acetic acid (IAA), riboflavin, and biotin, during co-cultivation with both microalgae. The findings suggest that the metabolic A. brasilense adaptation was mainly favored during the mutualistic interaction with Scenedesmus sp. Finally, a valuable contribution is provided to the biotechnological potential of the microalga–Azospirillum consortium as an environmentally sustainable strategy to improve the bio-refinery capacity of these microalgae and biogas upgrading by valorizing CO₂ of these gaseous effluent. Full article

The integration of renewable energy with circular economy strategies offers effective pathways to reduce greenhouse gas emissions while enhancing local energy independence. This study analyses three real-world projects implemented in Spain that exemplify this synergy. LIFE Smart Agromobility converts pig manure into biomethane to power farm vehicles, using anaerobic digestion and microalgae-based upgrading systems. Smart Met Value refines biogas from a wastewater treatment plant in Guadalajara to produce high-purity biomethane for the municipal fleet, demonstrating the viability of energy recovery from sewage sludge. The UNDERGY project addresses green hydrogen storage by repurposing a depleted natural gas reservoir, showing geochemical and geomechanical feasibility for seasonal underground hydrogen storage. Each project utilises regionally available resources to produce clean fuels—biomethane or hydrogen—while mitigating methane and CO₂ emissions. Results show significant energy recovery potential: biomethane production can replace a substantial portion of fossil fuel use in rural and urban settings, while hydrogen storage provides a scalable solution for surplus renewable energy. These applied cases demonstrate not only the technical feasibility but also the socio-economic benefits of integrating waste valorisation and energy transition technologies. Together, they represent replicable models for sustainable development and energy resilience across Europe and beyond. Full article

The knowledge about the potential toxic effects of microplastics (MPs) combined with herbicides at lower trophic levels is still largely unknown. The present study aimed to evaluate the potential toxic effects of polyethylene terephthalate (PET) and polyamide (PA), isolated or combined with the pesticide glyphosate (GLY), on the microalgae Arthrospira platensis. For this, microalgae were exposed to control, GLY (3 μg/L), PET (0.5 and 1 mg/L), PA (0.5 and 1 mg/L), and the respective mixtures of each MP with GLY, for 12 days. The photosynthetic pigment content, phytochemicals, antioxidants, and enzymatic activity were determined. Cell growth was significantly enhanced on day 4 in the GLY+PA1 group (~80%), compared to the control. At day 12, biomass was significantly higher in the GLY (~25%) and GLY+PET0.5 (~26%) groups relative to the control. Significant effects on the enzymatic and detoxification mechanisms were observed, including increased SOD (PET0.5, p = 0.011) and CarE (GLY, PA and GLY+PA, p < 0.01), and decreased GST in combined exposures, which support stress-induced enzymatic activation and adaptive biochemical responses. Significant effects on phytochemicals and antioxidant activity were also observed, with PET0.5 significantly reducing total carotenoids (~65%), and flavonoids (p < 0.001) and ortho-diphenols (p < 0.05) being decreased in all exposure groups, in comparison to the control group. The decrease in flavonoids and ortho-diphenols, important antioxidant molecules, suggests the depletion of these key compounds under stress. DPPH scavenging activity, a measure of antioxidant potential, was inhibited in the GLY+PA groups, indicating compromised antioxidant defense. Results confirmed that combined stressors elicit distinct and sometimes deleterious responses not predicted by single exposures. Our findings highlight that the combined exposure to glyphosate and MPs significantly disrupts antioxidant defenses and enzymatic activity in A. platensis, indicating potential risks to primary producers in aquatic ecosystems and underscoring the ecological implications of co-contaminant stressors. In fact, the results indicate that MPs can modify herbicide toxicity, posing enhanced risks to microalgal physiology and potentially affecting primary productivity and nutrient cycling in aquatic ecosystems. In turn, negative effects of MPs on microalgae can have serious consequences for food webs, food security, and ecological health. Full article

This study presents a biomonitoring study of surface waters in the Krynka River basin, encompassing three major regional reservoirs: Khanzhenkovskoe, Olkhovskoe, and Zuyevskoe. These water bodies face significant anthropogenic pressure from mining effluents, industrial discharges, and domestic wastewater. Key pollutants identified are surfactants (SAAs), sulfates, phenols, chlorides, and manganese, with chemical oxygen demand (COD) exceeding regulatory limits. The research was conducted in September 2024. Based on the Specific Combinatorial Water Pollution Index, surface waters in the studied objects can be characterized as slightly polluted. To assess the negative impact of the identified pollutants on hydrobionts, the species composition of phytoplankton of the studied water bodies was analyzed. In the Olkhovskoe Reservoir and Olkhovaya River, cyanobacterial blooms (Oscillatoria agardhii G.) were observed, altering biodiversity in the Krynka River and Zuyevskoe Reservoir. Phytoplankton genera Synedra, Amphiprora, and Navicula—established bioindicators of aquatic ecosystem health—were dominant in Khanzhenkovskoe Reservoir, signaling nutrient enrichment and organic pollution. Changes in the species composition and structure of phytoplankton in the Krynka River, its tributaries and reservoirs, indicate a change in the level of saprobic water bodies from β to α-mesosaprobic, which indicates both the general level of surface water pollution and the accumulation of pollutants along the course of the river. The paper presents the results of fluorimetric analysis of photosynthetic activity of natural phytoplankton cells and demonstrates the possibility of using fluorescence induction curves for regular monitoring measurements. Fluorescence parameters indicate a general deterioration of photosynthetic activity of natural phytoplankton. The growth of Oscillatoria agardhii in the waters of the Olkhovskoe Reservoir and of green microalgae in the Zuevskoe Reservoir led to an increase in the fluorescence quantum yield (F_v/F_m) and the total photosynthetic activity index (PI), which makes it possible to use these parameters as indicator parameters reflecting the intensity of “blooming” of various phytoplankton species. Full article

Microalgae have long been recognized for their potential in biofuel production and wastewater treatment, but their broader capabilities remain underexplored. This opinion paper presents a case for a significant shift in how microalgae are conceptualized from biomass producers to dynamic, multifunctional systems that can serve as environmental nano-factories. It highlights emerging research on the role of microalgae in heavy metal sequestration, the green biosynthesis of metal nanoparticles, and the cascading valorization of residual biomass through environmentally sustainable extraction methods. Together, these applications offer a unified platform for pollution mitigation and the production of valuable materials. The paper also examines recent progress in synthetic biology, bioreactor design, and microbial consortia that could support this transition. At the same time, it acknowledges key challenges, including issues of scalability, regulatory acceptance, and process integration. Strategic recommendations are proposed to advance this field and align it more closely with circular economy models. By reimagining microalgae as living nano-factories, this paper outlines a path forward for developing integrated, sustainable technologies that simultaneously address environmental and industrial challenges. Full article

Conventional methods for extracting bioactive compounds from microalgae rely on organic solvents that are both polluting and potentially harmful to human health. In recent years, a noticeable shift has emerged toward greener extraction alternatives that are more environmentally friendly and sustainable. This review highlights various green extraction techniques, compounds, and yields obtained from different microalgal species for a range of applications and provides a comparison between the yields of conventional and green extraction methods. Green extraction methods have shown yields that are comparable to, or even exceed, those of conventional techniques, although they are predominantly studied for the extraction of lipids and pigments. This review aims to provide an overview of the current state of green extraction applied to microalgae, and to outline future research perspectives in this emerging field. Full article

Biorefinery is gaining attention as a promising approach to valorize natural resources and promote a circular bioeconomy. This study aimed to recover high-value molecules, such as xanthophylls and polar lipids with nutraceutical applications, through enzymatic pretreatment and sequential pressurized liquid extraction (PLEseq), by reusing the residual biomass of Nannochloropsis gaditana after each processing step. Remarkably, pure glycolipids (102.95 ± 1.10 mg g⁻¹ dry weight) were obtained immediately after enzymatic pretreatment, facilitating their easy recovery. Furthermore, two alternative sequential extraction processes were successfully developed, using ethanol and water as green solvents at varying temperatures and in different orders. The most effective PLEseq conditions yielded up to 48 mg mL⁻¹ of carbohydrates using water at 50 °C, and up to 44 mg mL⁻¹ of proteins via subcritical water extraction at 100 °C, prior to conventional lipid extraction with ethanol to produce various concentrated extracts. In the inverted PLEseq process—starting with ethanol extraction followed by successive water washes—isolated and purified fractions of lutein and astaxanthin were obtained, contributing to the complete depletion of the residual biomass. Overall, the development of an integrated and sequential biorefinery protocol that enables the extraction of multiple high-value compounds holds significant potential for application in the food industry. Full article

Mesoporous silica nanoparticles (MSNs) functionalized with silane quaternary ammonium compounds (SiQACs) were synthesized and utilized as carriers for thymus essential oil (TO), a green bio-antifouling agent. The synthesis of MSNs functionalized with SiQACs was carried out in a single step, with clear advantages in terms of simplicity of the process, high yield (94%) and saving of reagents and solvents for the MSN purification. After loading with TO, this innovative dual-action antifouling system was able to integrate the intrinsic biocidal properties of SiQACs with the release of TO from MSN pores, resulting in an engineered material with prolonged efficacy. The antifouling compounds incorporated into the nanoparticles accounted for 42% of the total weight. The biocidal performance was evaluated by monitoring the growth inhibition of Chlorella sorokiniana, a microalga commonly associated with stone biodeterioration. Additionally, these nanoparticles were embedded in a commercial silane-based protective coating and applied to tuff stone samples to assess their ability to mitigate biofilm formation over extended periods. Results demonstrated the system’s high potential for durable protection against microbial colonization and biofilm growth on stone surfaces. Full article

Olyokma Nature Reserve, where we conducted our research, is in Eastern Siberia in the middle taiga zone in an area characterized by continuous permafrost. This is the only protected area in the region with a complete reserve regime, where there is no human activity. Here, we studied 14 different types of water bodies located along the Olyokma River valley, 13 of which were studied for the first time. For some of the studied water bodies, a high content of biogenic elements was noted, which may be associated with the characteristics of permafrost water bodies, which are under nutrient release from permafrost thaw. The concentration of several biogenic elements, including ammonium, nitrates and phosphates, increases in the water of the lakes toward the bottom of the river valley. In the composition of various communities of these water bodies, including both planktonic and non-planktonic, we identified 246 species and varieties of microalgae. The abundance and biomass of phytoplankton, as well as the number of species, decreased down the river valley. At the same time, at the upper stations there were more diatoms; while at the stations down the valley, green algae came to the fore; and even lower down, cyanobacteria prevailed. At the lower stations, the indicators of microalgae development were minimal. In accordance with the bioindicative properties of microalgae, a decrease in the trophic status of water bodies was noted down the river valley, which, in our opinion, is a characteristic feature of the waters of an undisturbed catchment basin in the permafrost area. This indicates that the studied aquatic ecosystem changes within a set of environmental and biological indicators, that is, it exists in natural conditions for this catchment basin. Research on the territory of Olyokma Nature Reserve allowed us to obtain information on natural transformation and removal of nutrients in permafrost catchments, while excluding the likelihood of anthropogenic impact on these processes. Full article