Search Results (1,479)

Indoor microalgae production under artificial illumination is constrained by facility footprint and energy demand, making biomass output per area the central design objective. Single-layer thin-layer cascade (TLC) systems are geometrically limited to a surface-to-footprint ratio (SF) of at most 1.0 m² m⁻². This study presents a stacked thin-layer cascade (STLC) photobioreactor validated at two scales sharing the same six-channel architecture: a laboratory-scale unit (2 L) and a pilot-scale unit (250 L). Both units achieved an SF well above the single-layer ceiling (3.65 and 4.2 m² m⁻²), demonstrating that vertical stacking is an inherent structural solution to the geometric limitation of open thin-layer cascade systems, independent of scale. Both units operated reliably for 11 to 13 days across a 125-fold difference in working volume, converging to comparable transitional Reynolds numbers and confirming that the film hydrodynamics central to the STLC concept remain consistent by design across scale. Footprint-normalized productivity reached 3.41 g DW m⁻² d⁻¹ at laboratory scale and 6.11 g DW m⁻² d⁻¹ at pilot scale, with pilot-scale protein reaching 42.1% DW prior to nitrogen depletion. Growth kinetics differed between scales, reflecting light/dark cycling regime, initial biomass density, and retention tank geometry as distinct, tunable operational variables. Closing the residual productivity gap requires jointly increasing photon flux density and standing biomass density, since low-density operation causes a large fraction of incident light to pass through the culture unabsorbed regardless of irradiance. Full article

Modern biological wastewater treatment technologies should not only effectively remove organic compounds and nutrients but also enable the recovery of biomass suitable for further valorization. The aim of this study was to compare activated sludge (AS), a Chlorella sp. monoculture (MA), and a microalgal–bacterial consortium (M-BC) for the treatment of model dairy wastewater and to assess the methane potential of the recovered biomass. AS provided the highest organic matter removal efficiency, reducing COD and BOD₅ concentrations to 141.4 ± 7.6 mg O₂/L and 32.3 ± 1.7 mg O₂/L, respectively, corresponding to removal efficiencies of 94.3 ± 0.3% and 98.1 ± 0.1%. The M-BC variant achieved the highest nitrogen and phosphorus removal efficiencies, at 90.3 ± 0.6% and 90.0 ± 0.6%, respectively. The system based solely on MA was less effective from a treatment perspective, but the resulting biomass had the highest volatile solids content and the highest methane potential. In this case, cumulative CH₄ production after 20 days was 255.1 ± 12.3 mL CH₄/g VS. The corresponding values were 230.2 ± 15.9 mL CH₄/g vs. for M-BC and 189.5 ± 6.3 mL CH₄/g vs. for AS. The Gompertz model, however, indicated the most favorable digestion kinetics for M-BC biomass, with an R_max of 26.8 ± 1.8 mL CH₄/g VS·d and a lag phase of 0.53 ± 0.08 d. Full article

The extremophilic microalga Galdieria sulphuraria has shown considerable potential for the treatment of acid mine drainage (AMD) while producing biomass for value-added applications. However, biological metal removal alone is limited, and efficient biomass harvesting under highly acidic conditions remains a major challenge. This study developed an integrated treatment approach with potential sustainability benefits by cultivating Galdieria sulphuraria in AMD followed by simultaneous biomass harvesting and dissolved metal removal using calcium polysulfide (CaSx). Galdieria sulphuraria successfully grew in undiluted Berkeley Pit water (BPW), a representative AMD, demonstrating its adaptability to highly acidic and metal-rich conditions. During cultivation, only partial removal of dissolved metals was achieved, indicating that biological treatment alone was insufficient for effective AMD remediation. Conventional flocculants, ferric chloride and chitosan, achieved only moderate harvesting efficiencies (54–56%) and showed negligible contribution to metal removal. In contrast, CaSx achieved a maximum biomass harvesting efficiency of 98.7% after a 60min settling-time experiment. In a separate dosage experiment, Zn removal reached nearly 100% at 2.95 g L⁻¹ of CaSx, while Mn removal increased with CaSx dosage and reached 78% at 7.36 g L⁻¹. Control experiments with BPW in the absence of microalgae showed comparable metal removal, indicating that Zn and Mn removal using CaSx treatment was primarily driven by chemical processes. The enhanced treatment was consistent with sulfide-mediated precipitation of dissolved metals and the increase in solution pH, which promoted the formation of dense biomass aggregates. CHN, SEM, EDX, and XRD analyses consistently demonstrated that CaSx transformed the recovered material from predominantly organic microalgal biomass into a mineral-enriched biomass composite. This study demonstrates that integrating Galdieria sulphuraria cultivation with CaSx-assisted biomass harvesting and dissolved metal removal provides a potential approach for sustainable AMD remediation while generating a mineral-enriched biomass. Full article

Today, waste is viewed as a renewable energy source and a potential supplier of new bioproducts. Microalgae are essential in wastewater treatment, and the anaerobic digestion (AD) of the harvested biomass leads to the production of biomethane. However, the process of producing methane from algae requires energy-intensive pretreatment steps. This study investigates the potential of carbon nanotubes (CNTs) and granular activated carbon (GAC) to enhance methane production through AD of untreated Chlorella sorokiniana and Tetradesmus obliquus biomass. Indicators of process stability included organic acid, total ammonia nitrogen concentrations, methane production data, and microbial community structure and dynamics. The results suggest that adding CNTs (2.0 and 4.0 g L^–1) and GAC (4.0 g L^–1) following the acclimatization stage is an effective strategy to enhance the utilization of produced organic acids and promote long-term methane production from the tested biomass. Additionally, the significance of the bacterial genus Ruminofilibacter in biomass hydrolysis has been emphasized. Among methanogens, there was a decrease in the relative abundance of Methanosarcina, while the relative abundances of Methanothrix and Methanoculleus increased by day 12 in CNTs/GAC-added experiments, during which substantial differences in methane production were observed. This proposed approach has the potential to promote environmentally sound waste management and enhance the production of renewable energy. Full article

Phycobiostimulants derived from macroalgae, microalgae, and cyanobacteria are increasingly used to improve crop performance. However, their effects vary across products, crops, and environments. In this review, we propose a biomass–process–composition–mechanism–efficacy (BPCME) framework to systematically trace this variability. Biomass provenance, including taxonomic identity, cultivation conditions, physiological state, and harvest timing, defines the initial biochemical potential, whereas processing and formulation determine the molecular profile delivered to the plant. The current findings indicate that phycobiostimulants act mainly by modulating endogenous signaling networks, hormone crosstalk, redox regulation, metabolic reprogramming, and rhizosphere and plant–microbiome responses rather than by direct nutrient or hormone replacement. Agronomic performance is further moderated by the genotype, dose, application route, developmental stage, soil conditions, and environmental stress. To improve reproducibility, we propose a phycobiostimulant quality-by-design (QbD) framework that integrates candidate critical biomass attributes and process parameters, chemical fingerprints, biological potency, and batch equivalency. Cascading algal biorefineries and precision application strategies can improve resource efficiency while helping to define the conditions for reliable field performance. Progress towards precision phycobiostimulants will require the experimental linking of product identity and mechanism to reproducible potency across batches and agronomic environments. Full article

Microalgae in high-rate algal pond (HRAP) systems sustain elevated rates of photosynthetic carbon fixation and nutrient assimilation compared with natural aquatic ecosystems, owing to their optimized operating conditions, such as shallow depth, continuous mixing, and high light and nutrient availability. HRAPs offer a low-cost option for wastewater treatment and CO₂ sequestration, yet their combined performance under tropical conditions, particularly when treating landfill leachate, remains poorly documented. This case study reports the operation of a single pilot-scale HRAP treating undiluted constructed-wetland effluent receiving landfill leachate in Valle del Cauca, Colombia, monitored over one continuous experimental run to jointly assess water-quality performance, daytime CO₂ uptake, and the resident algal community. The pond was operated continuously at 0.14 m³ d⁻¹, and physicochemical variables (pH, dissolved oxygen, conductivity, and redox potential) were monitored three times per week. Carbon fixation was estimated from a daytime inorganic-carbon mass balance (influent and effluent carbon, gas exchange, and respiration) combined with static-chamber measurements. The system effectively removed the soluble organic fraction of the leachate (soluble COD of 22.2%; soluble BOD₅ of 58.9%), whereas the apparent increases in total COD, total BOD₅, and suspended solids were attributable to in-pond microalgal biomass production. Under tropical sunlight, the pond fixed approximately 33.1 g C d⁻¹ (95% CI 14.8–51.5), acting as a net CO₂ sink during daylight hours. Sixteen algal taxa, mainly from the Chlorophyceae and Chlamydophyceae, were identified by morphological keys, several of which have not been previously reported in leachate-treatment systems. As an unreplicated pilot-scale case study without a parallel control, the quantitative estimates should be interpreted as system-specific rather than generalizable; nonetheless, the results provide a field reference for CO₂ biofixation and leachate treatment in tropical HRAPs and a basis for future controlled, replicated studies. Full article

Water purification is the most crucial process for recirculating aquaculture systems (RASs), while microalgae exhibit significant potential for nutrient removal from aquaculture wastewater. Four microalgal species with removal capacities for ammonia nitrogen (NH₄⁺-N), nitrite nitrogen (NO₂-N) and total phosphorus (TP) were isolated and identified from the land-based RASs, namely, Kirchneriella cornuta HY-1, Desmodesmus abundans HY-1, Coccomyxa sp. HY-1 and Oocystis sp. HY-1. The growth kinetics were characterized through measurements of cell density, chlorophyll content, and dry biomass in the in situ wastewater. Based on zeta potential, the flocculation efficiencies of seven agents were evaluated. Preservation parameters were optimized under nutrient-supplemented conditions with protective agents. Under large-scale culture conditions, over a 7-day period, the highest NH₄⁺-N removal efficiency of 87.20 ± 0.56% was achieved by C. sp. HY-1, the highest NO₂-N removal efficiency (85.63 ± 2.56%) was obtained by O. sp. HY-1, and the maximum TP removal efficiency (71.19 ± 3.35%) was exhibited by K. cornuta HY-1. Moreover, the harvest period could be reached after about 14 days of cultivation. FeCl₃ was identified as the optimal harvesting flocculant for all four species. Optimal preservation conditions were determined as 25 °C and 31.25 μmol·m⁻²·s⁻¹ for D. abundans HY-1, C. sp. HY-1, and O. sp. HY-1, and 25 °C and 18.75 μmol·m⁻²·s⁻¹ for K. cornuta HY-1. This work provides theoretical guidance for large-scale microalgal production and confirms the technical feasibility of microalgae-driven in situ wastewater remediation. Full article

Algal biomass and algal-derived preparations have attracted increasing interest in livestock nutrition because of their potential to modulate the gut microbiota, which plays a crucial role in animal health, immunity, and growth performance. This review focuses primarily on microalgae and cyanobacterial preparations, while also considering selected macroalgae relevant to livestock feeding, without restricting its scope to marine sources. In this narrative review, we summarize recent advances in the physicochemical properties and biological activities of key algal components, such as polysaccharides, polyunsaturated fatty acids, and carotenoids. We assess evidence for changes in potentially beneficial bacteria, including Lactobacillus and Bifidobacterium, and for inhibitory effects against selected pathogenic bacteria, including Salmonella and pathogenic strains of Escherichia coli. We also examine proposed links between these compounds, microbial short-chain fatty acid and bile acid metabolism, and host immune and growth responses. This review discusses practical applications of algal biomass and algal-derived preparations in livestock production, with a focus on inclusion levels and safety assessments. Effects are evaluated in relation to the source organism, preparation, and animal model, rather than assumed to be shared across algal groups. Current challenges and future research directions are also identified to facilitate the efficient utilization of algal resources in sustainable animal husbandry. This review identifies the evidence supporting specific feeding applications and distinguishes observed animal responses from proposed mechanisms. Full article

The continuous increase in carbon dioxide (CO₂) has intensified the need for sustainable technologies to mitigate greenhouse gas emissions. Carbon Capture and Utilization (CCU) represents a promising strategy to convert captured CO₂ into valuable products, contributing to climate change mitigation and the circular economy. This review provides an overview of the main carbon management pathways, including Carbon Capture and Storage (CCS), Carbon Capture, Utilization and Storage (CCUS), and CCU, with a focus on biological CCU (bio-CCU) based on microalgae and carbonic anhydrases (CAs). Particular attention is given to the role of CAs as highly efficient biocatalysts that accelerate CO₂ hydration, enhancing inorganic carbon availability. Recent advances in enzyme immobilization technologies and support materials are examined, highlighting their potential to improve enzyme stability, reusability, and process performance. Furthermore, the integration of immobilized CAs with microalgal cultivation systems is explored as an emerging strategy in which CAs facilitate inorganic carbon availability and delivery, potentially enhancing its photosynthetic fixation by microalgae and biomass productivity. Building on previous studies on microalgal bio-CCU and CA-assisted carbon capture, this review provides an integrated perspective on CA immobilization strategies, support materials, and their potential implementation in microalgal bio-CCU systems, highlighting how enzyme immobilization can connect enzymatic CO₂ conversion with microalgal carbon fixation and contribute to sustainable CO₂ valorization and environmental remediation. Full article

Microalgae endemic to desert ecosystems possess exceptional stress-resistance traits; however, the physiological and molecular drought-adaptation mechanisms of desert-dwelling Chlorella remain largely uncharacterized. Herein, we combined physiological–biochemical assays, ultrastructural observation, transcriptomics and metabolomics to dissect drought responses in Taklamakan-desert-origin Chlorella sp. under polyethylene glycol 6000 (PEG-6000)-simulated mild (10%), moderate (20%), and severe (30%) drought stress, with mechanistic focus on moderate-drought conditions. Moderate drought repressed algal biomass (−26.32%), chlorophyll a (−24.40%), maximum photosystem II quantum yield (Fv/Fm, −16.55%) and effective quantum yield of photosystem II (ΦPSII, −24.35%). Malondialdehyde (MDA) accumulated (+50.69%), alongside elevated activities of superoxide dismutase (SOD, +156.74%) and catalase (CAT, +11.61%). Compatible solutes, including proline, soluble sugars, total protein and total lipid, increased significantly by 39.00%, 39.36%, 26.35% and 23.06%, respectively (p < 0.05). Moderate drought triggered cell swelling, partial cell-wall rupture and prominent enlargement of intracellular starch granules and lipid droplets. Transcriptomic profiling demonstrated up-regulation of transcription–translation and DNA-repair machinery, ATP-binding cassette (ABC) transporters, abscisic acid (ABA)/jasmonic acid (JA) signaling, and biosynthetic pathways for protective metabolites, whereas catabolic pathways and mitogen-activated protein kinase (MAPK) signaling were suppressed. Untargeted metabolomics further validated accumulation of trehalose, stress-protective amino acids, vitamins and functional lipids, while chloroplast-membrane-related metabolites and catabolic intermediates declined. This multi-omics study systematically reveals physiological and molecular regulatory cascades underlying drought tolerance in desert Chlorella sp., providing candidate genes and metabolites to support microalgal resource exploitation for arid-zone applications. Full article

The untapped genetic diversity of extremophilic microalgae provides distinctive physiological and biochemical traits with potential to support Sustainable Development Goal (SDG) 6 (Clean Water and Sanitation), SDG 7 (Affordable and Clean Energy), and SDG 15 (Life on Land). This review examines the diversity, stress-adaptation mechanisms, and biotechnological potential of extremophilic microalgae, with emphasis on their roles in resource recovery, carbon utilization, and bioproduct generation. Their ability to maintain cellular functions under extreme salinity, pH, temperature, radiation, and nutrient conditions enables their cultivation in environments that may be unsuitable for conventional production systems and facilitates the accumulation of lipids, pigments, carbohydrates, proteins, and other bioactive metabolites. These characteristics create opportunities to couple wastewater treatment, carbon capture and utilization, and biomass valorization within circular bioprocesses. However, laboratory-scale demonstrations should not be equated with established environmental or commercial benefits, as strain-specific physiological requirements, energy demand, process control, harvesting, downstream processing, and resource inputs can constrain scale-up. The review therefore emphasizes the need to evaluate extremophilic microalgal systems using integrated techno-economic and life-cycle approaches rather than biological productivity alone. Future advances will depend on combining multi-omics, metabolic engineering, adaptive cultivation, process optimization, and predictive modeling to identify robust strains and cultivation strategies. Such integration could accelerate the translation of extremophile-based bioprocesses into resource-efficient and economically credible applications for environmental sustainability. Full article

The transition toward sustainable energy systems requires the identification of renewable biomass resources capable of replacing fossil fuels while minimizing environmental impacts. Among microalgae, diatoms are an attractive feedstock for advanced biofuel production due to their rapid growth, high photosynthetic efficiency, and remarkable lipid accumulation capacity. This study investigated the diversity, spatial distribution, and bioenergy potential of diatom communities in the Nador Lagoon (Marchica), Morocco, one of the largest Mediterranean coastal lagoons. Samples were collected at 13 sampling stations during three sampling campaigns in March, April, and June 2024, using both qualitative and quantitative approaches. Diatom identification was performed by microscopic observation, while abundance was estimated using the Utermöhl sedimentation method. Species richness, frequency of occurrence, presence–absence patterns, hierarchical cluster analysis, and principal component analysis (PCA) were used to characterize the diatom community. A total of 22 diatom taxa belonging to 11 taxonomic orders were identified. The total recorded diatom abundance was 23,360 cells mL⁻¹, with Bacillariales contributing the highest relative abundance (38.87%), followed by Rhizosoleniales (15.92%), Chaetocerotales (13.36%), and Naviculales (11.64%). Rhizosoleniales and Fragilariales were the most represented orders in terms of species richness, with four taxa each. Eight taxa with biofuel-related potential reported in the scientific literature were identified, among which Chaetoceros decipiens and Pseudo-nitzschia sp. occurred at six sampling stations, while Nitzschia sigma occurred at five stations. Hierarchical clustering and PCA revealed consistent patterns of spatial co-occurrence among these taxa. These findings highlight Nador Lagoon as a valuable reservoir of indigenous diatom diversity and provide a basis for prioritizing native taxa for future isolation, cultivation, biochemical characterization, and biofuel-related evaluation. Full article

The western part of north-eastern China is mostly covered by soda soil, which has a significant impact on the growth, breeding and production of crops. The present study investigates the physiological responses and metabolic adaptation of Chlamydomonas reinhardtii P.A.Dangeard (C. reinhardtii) under different types of alkaline stress and the potential application to soda soil improvement and plants in response to alkaline stress. The soda–saline soil was treated with C. reinhardtii for 5 and 120 days, respectively, and the chemical properties of the soil were determined. The microalga was cultured for a period of 12 days, with and without an alkaline medium, and then the metabolic profiles of the microalgae were then analyzed by metabolomics. Results showed that C. reinhardtii exhibited a high level of tolerance to 40 mM NaHCO₃, pH 8.3, and pH 10.3 with an increase in incubation time. Moreover, C. reinhardtii has been demonstrated to ameliorate selected physicochemical properties of soda–saline soil by reducing soil pH, electrical conductivity (EC), and the contents of CO₃²⁻ and HCO₃⁻ by 40–100% (w/w, wet biomass) addition for 120 cultivation days, respectively. It was demonstrated that rice seedlings were less affected by alkaline stress in the presence of C. reinhardtii. Furthermore, C. reinhardtii has the capacity to adapt to alkaline environments by regulating key pathways such as cofactor biosynthesis, glycerophospholipid metabolism, amino acid biosynthesis, purine metabolism, carbon metabolism, tropane, piperidine, and pyridine alkaloid biosynthesis. This adaptation is characterized by the accumulation of metabolites, including saccharides, amino acids and organic acids. These interact with high pH, CO₃²⁻ and HCO₃⁻ ions. This study elucidates that C. reinhardtii has the capacity to improve soda–saline soil and respond well to diverse alkaline stresses, attributable to its intricate metabolic profile. Full article

Selenium (Se) biofortification of microalgae is a promising strategy for producing functional biomass with enhanced nutritional value. This study evaluates the effect of sodium selenite (Na₂SeO₃) supplementation to the culture medium on the biochemical profile of Limnospira platensis cultivated under intensive growth conditions with an elevated CO₂ concentration (3 vol.%). Two consecutive cultivation experiments were conducted using Na₂SeO₃ supplementations of 10, 20, 40, and 80 mg/L along with a control (0 mg/L). In the second experiment, biomass previously cultivated at 20 mg/L served as the inoculum to evaluate the response of a pre-adapted culture. Biomass productivity, protein, carbohydrate, lipid, pigment, CHNS composition, Se accumulation, and macro- and microelement contents were determined. Maximum biomass productivity (0.369 g·L⁻¹·day⁻¹) was obtained at 10 mg/L. The most severe disruptions to biochemical and elemental parameters occur at 80 mg/L. This concentration triggers a statistically significant reduction in protein content (down to 46.98% in the first experiment), an accumulation of mercury, an elevation in carbohydrates, and a corresponding shift in the C/N ratio. The second experiment demonstrated enhanced metabolic stability of the pre-adapted culture, including preservation of protein content under high selenium stress and normalization of copper accumulation, indicating the adaptive capacity of L. platensis to prolonged selenium exposure. The concentration of Se in the biomass grown under 0 (control), 10, 20 and 80 mg/L of Na₂SeO₃ was 0.5, 88.7, 394.0 and 762.0 mg/kg, respectively. Overall, a method for producing L. platensis biomass with a controlled Se content has been demonstrated. Based on these findings, Na₂SeO₃ concentrations of 10–40 mg/L are recommended for producing Se-enriched biomass, balancing productivity, nutritional quality, and elemental safety. The nutritional efficacy of the biomass obtained using this method should be the subject of future research. Full article

Sweet Basil (Ocimum basilicum L.) is a widely valued plant species with multiple applications, including use as a culinary herb and condiment, essential oil extraction, and traditional medicine. The present study aimed to evaluate the growth, photosynthetic pigments, and gas exchange of sweet basil plants under blue light supplementation and microalgae-based bioinput application. The experiment was conducted in a completely randomized design in a 4 × 2 factorial arrangement, comprising three blue light treatments (blue light was provided by LED lighting, dark blue glossy reflective laminate, and light blue glossy reflective laminate) plus a control, and bioinput application (presence and absence). The bioinput was prepared from Chlorella vulgaris microalgae biomass. Indirect blue light delivered by the dark blue reflective laminate, combined with C. vulgaris bioinput application, promoted the greatest increases in plant height, stem diameter, number of leaves, shoot dry matter, root dry matter, and total dry matter. Both direct blue light (LED) and indirect blue light (dark blue and light blue reflective laminates), in combination with microalgae bioinput application, significantly enhanced photosynthetic pigment contents—including chlorophyll a, total chlorophyll, and carotenoids—as well as transpiration, instantaneous carboxylation efficiency, stomatal conductance, and net photosynthetic assimilation rate. The multivariate analyses confirmed that blue light supplementation and C. vulgaris bioinput application act synergistically, promoting a distinct and superior physiological profile in sweet basil plants. These findings establish the combined use of blue light—direct or indirect—with Chlorella vulgaris microalgae bioinput as a promising and sustainable strategy for enhancing growth and photosynthetic performance of O. basilicum L. in protected cultivation systems. Full article