Search Results (617)

Microalgae represent some of the most promising eukaryotic platforms in biotechnology due to their rapid growth, simple cultivation requirements, reliance on sunlight as a primary energy source, and ability to synthesize high-value bioactive compounds. These characteristics have made microalgae attractive candidates in various fields, including biofuel production, carbon capture, and pharmaceutical development. However, several technical limitations have limited their large-scale use as sustainable biofactories. A paradigm shift is currently occurring thanks to the genetic manipulation of microalgae, driven by CRISPR-Cas technology. Significant progress has been made in the model species Chlamydomonas reinhardtii, particularly in the targeted and efficient insertion of foreign DNA. Despite this progress, key challenges remain, and further optimization of CRISPR-Cas methodologies is needed to fully unleash the genetic potential of this organism. This review provides an overview of the convergence of CRISPR-Cas technologies in microalgae research, highlighting their impact on genetic studies, metabolic engineering, and industrial applications. It summarizes recent advances in microalgal genome editing through CRISPR systems, outlines current technical challenges, and highlights future directions for improving the implementation of this innovative technology in microalgal biotechnology. Full article

Microalgal production has garnered increasing interest from both researchers and industry due to the wide range of biomass applications in food, feed, cosmetics, and pharmaceuticals. The successful cultivation of microalgae requires not only adequate supply of nutrients but also large volumes of water. The development of green technologies aimed at sustainable microalgae biomass production is expanding, though it presents several technological challenges. Recycling spent culture media and nutrients has emerged as a promising strategy to reduce water consumption and cultivation costs while supporting environmentally friendly practices. In this review, we first highlight the role of macro- and micronutrients in microalgal growth, then examine physicochemical and physical treatments for optimizing medium reuse, discuss the economic aspects of microalgae production, and outline key technologies for sustainable cultivation. The review underscores the potential of medium recycling to significantly lower costs and environmental impact, paving the way for a more sustainable and economically viable microalgae industry. Full article

Microalgae are extremely diverse photosynthetic organisms, adapted to live in different habitat conditions, from freshwater to marine environments. This adaptability is also associated with the ability to produce several metabolites. Polyunsaturated aldehydes (PUAs), first identified in 1999 in Thalassiosira gravida and Skeletonema costatum, are known to influence the development of their predators, having teratogenic effects and blocking their development. PUAs have shown several activities, such as antitumor, antimicrobial and antiparasite. Another relevant compound is pheophorbide a (PPBa), a chlorophyll degradation product, which has previously shown properties useful to be considered as a photosensitizer in photodynamic therapy, demonstrating cytotoxic effects on various tumor cell lines. It has also been shown to have activity against some bacteria and fungi. Considering the growing problem of multi-antibiotic resistance of human pathogenic bacteria and the increasing market demand for new drugs, the aim of our work was to screen two PUAs, i. e., 2,4-octadienal and trans,trans-2,4-decadienal, and PPBa against a panel of human pathogenic bacteria and fungi: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus fumigatus. The antimicrobial activity was evaluated through MIC (Minimum Inhibitory Concentration) and MFC/MBC (Minimum Fungicidal/Bactericidal Concentration), demonstrating that the two PUAs had a greater antimicrobial activity than PPBa on both bacteria and fungi, except for P. aeruginosa, where the antimicrobial activity was low. The compound 2,4-Octadienal showed extremely high antifungal activity, especially against the fungus A. fumigatus, where the MIC and MFC were 0.001 µL/mL and 0.004 µL/mL, respectively. These results are shedding light on the antimicrobial activity of microalgal compounds and their possible applications for different human infection diseases. Full article

Subtropical climate in Florida offers a unique opportunity for sustainable biofuel production using native microalgae cultivated in untreated wastewater. This study bioprospected oleaginous microalgal consortia from a wastewater holding tank at the Thomas P. Smith Water Reclamation Facility in Tallahassee, Florida, aiming to identify strains capable of both nutrient remediation and lipid accumulation. Using Fluorescence-Activated Cell Sorting (FACS), chlorophyll-containing cells were isolated and cultured on BG-11 media. Shotgun metagenomics revealed that the most robust consortia—labeled C3, C4, and C9—were dominated by Chlamydomonas, Acutodesmus, and Volvox spp., alongside diverse bacterial, fungal, and archaeal communities. Functional gene analysis indicated active pathways for photosynthesis, lipid biosynthesis, and nutrient assimilation. In microcosm experiments, these consortia achieved up to 100% ammonia, 95% phosphorus, and 89% nitrate removal, outperforming control treatments. Lipid screening confirmed significant accumulation, with consortium C9 showing the highest yield. These findings underscore the potential of native microalgal consortia for integrated wastewater treatment and biofuel production, advancing circular bioeconomy strategies for subtropical regions. Full article

The agro-industrial sector in Indonesia produces significant amounts of nutrient-rich waste and wastewater, which pose environmental risks but also present opportunities for valorization within a circular bioeconomy. Microalgae provide a promising solution for transforming these wastewaters into valuable products such as biomass for bioenergy, biofertilizers, or pigments, all while helping to remediate pollutants. This review synthesizes current knowledge on the use of major Indonesian agro-industrial effluents, specifically palm oil mill effluent (POME), byproducts from cassava and sugarcane, and soybean residues, as substrates for microalgal biomass production and cultivation. Furthermore, various cultivation strategies are summarized, including autotrophic, heterotrophic, and mixotrophic methods, as well as the use of open ponds, photobioreactors, and hybrid systems. These cultivation processes influence biomass yield, metabolite production, and nutrient removal. Reported studies indicate high removal efficiencies for organic loads, nitrogen, and phosphorus, along with considerable production of lipids, proteins, pigments, and biofuels. Yet, effluent pretreatment, concerns about heavy metal and pathogen contamination, high downstream processing costs, and biosafety issues remains as challenges. Nonetheless, the application of microalgal cultivation into Indonesia’s agro-industrial wastes treatment can provide the dual benefits of waste mitigation and resource recovery, helping to advance climate goals and promote rural development. Full article

In this study, two native microalgae, Chlorella sp. MC18 (CH) and Scenedesmus sp. MJ23-R (SC) were cultivated in bubble column photobioreactors for wastewater treatment. Domestic wastewater (DWW) was used as the main culture medium, alone (100%) and blended (10%) with vinasse, whey, or agro-food waste (AFW), respectively. Both species thrived in 100% DWW, achieving significantly high removal efficiencies for chemical oxygen demand, total nitrogen, and total phosphorus. Mineral removal exceeded 90% in all blended systems, highlighting the strong nutrient uptake capacity of both strains. The maximum specific growth rate (µ_max) in 100% DWW was higher for SC than in standard BG11 medium, and supplementation with vinasse, whey, or AFW further increased µ_max for both species. Blending DWW significantly enhanced microalgal biomass and lipid production compared to 100% DWW. Lipid production (max., 374 mg L⁻¹), proximate lipid composition (max., 30.4%), and lipid productivity (max., 52.9 mg L⁻¹ d⁻¹) significantly increased in all supplemented cultures relative to DWW alone, demonstrating the potential of co-substrate supplementation to optimize microalgal cultivation. This study contributes to reducing the water footprint and fills a gap in the bioprocessing potential of algae-based systems, highlighting wastewater blending as a circular economy-aligned approach that supports sustainable bioprocesses and resource recovery. Full article

Microalgae are unicellular, industrially important organisms that are used extensively in a range of industrial, environmental, and biorefinery applications. They can produce lipids, carbohydrates, and possibly additional vital bioactive substances. The increasing popularity of artificial intelligence (AI) in microalgae research can be attributed to its algorithms’ ability to manage the complexity of unexpected biosystems. In the case of microalgae-based biorefineries, AI technology can also help uncover system dynamics and uncertainties, provide helpful predictive analytics, and expedite the optimisation process. AI is used in microalgal cultivation to optimise carbon capture, biomass production, and conditions for growth. Additionally, it is employed for genome editing, automated monitoring, and lipid accumulation enhancement. However, its uses are broad and constantly growing. Furthermore, critical environmental parameters in microalgae culture, including temperature, light intensity, pH, dissolved oxygen, and nutrient levels, may be continually monitored and controlled by internet of things (IoT)-based devices. This review comprehensively summarises the latest applications of AI technology in the field of microalgae cultivation and the role of IoT-based automatic control. Full article

This study assessed the potential of Chlorella vulgaris to biosequester carbon dioxide (CO₂) and produce microalgal biomass using real exhaust gases from a municipal heating plant. Experiments were conducted in vertical tubular photobioreactors (V-PBRs) in three series: a control with atmospheric air as the CO₂ source (S1), exhaust gases containing SO_x (S2), and fully desulphurised exhaust gases (S3). The highest productivity of C. vulgaris was recorded in S3, where 2120 ± 123 mg VS/L was achieved with an exponential growth rate of 281.0 ± 16.2 mg VS/L·d. The presence of SO_x in the gases caused the culture to die off as early as day 8 of the cultivation cycle, resulting in a decrease in biomass concentration and acidification of the culture medium. In S2, compared to the other experimental series, significantly lower organic carbon, lipid, and sugar contents were also observed in the microalgal biomass. However, protein content remained stable regardless of the CO₂ source tested. Carbon Dioxide Utilisation Efficiency (CO₂UE) was 53.8% (S1), 24.1% (S2), and 41.4% (S3), respectively. The results indicate that the presence of SO_x in exhaust gases negatively affects the growth and survival of C. vulgaris, while its removal improves both biomass productivity and CO₂ sequestration efficiency. The research demonstrates the potential for integrating microalgae cultivation with industrial CO₂ emission management. Full article

Microalgae hold significant potential as nature-based solutions in agriculture, offering benefits such as nitrogen fixation, enhanced nutrient cycling, stimulation of beneficial microbes, strengthening soil structure, and carbon sequestration. Yet, despite their potential, the role of microalgae, particularly through their interactions with soil systems, remains largely underexplored. Their ability to generate bioactive substances such as phytohormones, amino acids, and extracellular polymeric substances (EPS) fosters soil aggregation, nutrient availability, water retention, biological soil crust, and soil restoration, which ultimately supports plant growth and productivity. Moreover, the thermochemical conversion of microalgal biomass into biochar offers an effective strategy to improve carbon sequestration while simultaneously enriching soil nutrient content, thereby increasing crop productivity. While microalgae-based products often demonstrate strong efficacy under laboratory and greenhouse conditions, their performance in the field remains constrained by soil physicochemical properties, ecological incompatibility, competition with native microbial communities, and environmental variability, leading to inconsistent outcomes and highlighting the need for soil-specific, field-relevant strategies. Furthermore, the lack of standardized and cost-effective cultivation, formulation, and processing, along with low biomass yield and energy-intensive production, continues to limit their large-scale adoption in agricultural systems. Therefore, this narrative review aimed to discuss the mechanisms of coupling microalgal biomass and biochar to enhance soil health and crop growth, while also addressing field-performance constraints. It provides a balanced view of the potential and challenges of microalgae-based technologies for sustainable soil management and crop productivity. Overall, microalgae possess significant potential to improve soil health, increase crop yields, and contribute to sustainable agriculture that can withstand climate challenges. Full article

Although AI-mediated approaches provide promising support for bioengineering using training datasets, their application in microalgal research remains limited. In this study, ChatGPT-4.0, an easily accessible AI model, was employed to optimize culture conditions and evaluate the industrial potential of the isolated diatom Gedaniella flavovirens. Culture optimization was conducted using response surface methodology, in which pH, temperature, and salinity were selected as independent variables. ChatGPT assisted in determining the design and suggested a face-centered central composite design. The optimal conditions for biomass production were determined to be pH 8.30, 23 °C, and 34.24 psu. Analysis of variance revealed significant quadratic effects (p < 0.05), indicating curvature in the response surface. Fatty acid profiling showed high levels of palmitoleic acid, palmitic acid, and eicosapentaenoic acid. Pigment analysis further indicated a high abundance of fucoxanthin, diadinoxanthin, and diatoxanthin. Based on the analyzed compounds, ChatGPT suggested potential applications of the algal strain across various industrial sectors. The most relevant application was identified as aquafeed, as the strain contains metabolites known to enhance pigmentation, growth, and immune responses in aquaculture species. Overall, this study demonstrates ChatGPT-mediated bioengineering as a practical strategy for optimizing culture conditions and evaluating the industrial potential of novel microalgal strains. Full article

Microalgae are used as dietary supplements for humans and animals, due to their excellent nutritional profile. This research aims to characterize Spirugrass^®, a co-product obtained after the extraction of phycocyanin from Limnospira platensis, and to evaluate whether a stabilization treatment involving high-pressure processing (HPP) affects its proteomic profile. The research also aims to evaluate the possible use of Spirugrass^® as feed integration for honeybee health. Proteins were extracted and fractionated using size exclusion chromatography (SEC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The iron content was measured using atomic absorption spectrometry (AAS). Samples of Spirugrass^® were subjected to HPP at 600 MPa for five minutes and the effect on the integrity of the protein profile was analyzed. Finally, nine groups of 30 newly emerged honeybees were supplemented with Spirugrass^® in a controlled laboratory experiment. SDS-PAGE and SEC enabled the assessment of the quality and integrity of the Spirugrass^® proteome, which contains 80% of the proteins found in the algal biomass, including phycocyanin. The phycocyanin purity indices were 2.07 ± 0.14 and 0.72 ± 0.13 for the L. platensis and Spirugrass^® extracts, respectively. Spirugrass^® maintains a consistent iron content of 261 ± 15 μg/g dry weight, equivalent to 74% of the iron present in the algal biomass. In both L. platensis and Spirugrass^®, iron was predominantly bound to high-molecular-mass proteins, including phycocyanin. Following HPP treatment, differences in the protein profiles were observed, which suggests partial protein degradation. Preliminary data obtained with honeybees are encouraging, as no mortality or adverse effects were observed and Spirugrass^® can be considered a promising candidate as feed supplement. Overall, the presence of consistent levels of soluble proteins, as well as protein-bound iron, suggests that Spirugrass^® could be used in animal nutrition. Full article

Postharvest operations are cost intensive in microalgae production, and when electrocoagulation–electroflotation (EC/EF) with aluminum anodes is used, aluminum can remain associated with biomass and wash streams; hence, a selective postwash process is needed. Accordingly, this study defined an operational window for aluminum desorption that preserves the energetic advantage of EC/EF. A response-surface design (I-optimal/CCD) was used to evaluate the effects of the EDTA concentration (1–100 mM), contact time (5–20 min), mixing speed (100–300 rpm), and pH (6–10) on EC/EF-harvested Chlorella sp. biomass, with ANOVA and model diagnostics supporting adequacy. EDTA concentration and mixing emerged as significant factors, whereas time and pH acted mainly through interactions; moreover, quadratic terms for EDTA and mixing indicated diminishing returns at high levels. Consequently, the surface predicted an optimum near EDTA ≈ 65 mM, time ≈ 20 min, pH 10, and 100 rpm, corresponding to ~97% aluminum removal. Importantly, a confirmation run under these conditions across eight chlorophyte strains consistently achieved >95% removal, revealing narrow dispersion yet statistically distinguishable means. Taken together, coupling EC/EF with an EDTA postwash operation in the identified window effectively limits aluminum carry-over in microalgal biomass and, therefore, provides a reproducible basis for downstream conditioning and potential recirculation within biorefinery schemes. Full article

Acylpyruvate derivatives represent a promising yet underexplored class of compounds for modulating microalgal growth and metabolism. Inspired by the metabolic role of pyruvate and the diverse bioactivity of its acylated analogs, this study investigates the structure–activity relationship of a diverse library of 55 acylpyruvate-derived compounds for stimulation of the green microalga Chlorella vulgaris. The library, encompassing 12 chemotypes including acylpyruvic acids, their esters, and various heterocyclic derivatives, was screened for effects on C. vulgaris growth. Six compounds were identified as active ones that enhanced biomass production in a preliminary microassay. Notably, four of these active compounds were direct acylpyruvate derivatives, highlighting this scaffold as the most promising one. Conversely, a specific subclass, 1,4-benzoxazin-2-ones, exhibited potent, dose-dependent algicidal activity. Detailed assessment of the active compounds under scaled-up culture conditions revealed that while their effect on overall cell density was limited, several compounds significantly enhanced the intracellular content of valuable metabolites: one increased chlorophyll content by 17%, another elevated carotenoids by 40%, and a third boosted neutral lipid accumulation by 44%. Furthermore, control experiments confirmed that the bioactivity of p-ethoxybenzoylpyruvates, which showed the best biological activity, is inherent in the intact framework and is not mediated by their hydrolysis products. Our findings underscore the potential of acylpyruvates as versatile tools for the enhancement of metabolite production in microalgae and as potent candidates for the development of algicides. Full article

Auxenochlorella pyrenoidosa, a promising edible bioresource, can be efficiently and safely cultivated using exogenous phytohormones to enhance its productivity. This study employed multi-omics analysis to systematically investigate the effects and mechanisms of exogenous trans-Zeatin (tZ) on the growth and metabolism of A. pyrenoidosa. Results demonstrated that 10 mg/L tZ significantly promoted algal growth, increasing biomass by 166 ± 3.35% at 72 hours (h), while concurrently elevating cellular soluble protein (SP), carbohydrate (CHO), and chlorophyll a (Chla) content. tZ also strengthened the antioxidant defense system, evidenced by reduced reactive oxygen species (ROS) levels, enhanced activities of antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)), upregulation of glutathione metabolism, and decreased lipid peroxidation product (malondialdehyde (MDA)). Furthermore, tZ activated key metabolic pathways, including nitrogen metabolism, photosynthetic carbon fixation, and porphyrin biosynthesis, leading to the accumulation of arginine and polyamines, etc. This study reveals that tZ promotes microalgal growth by coordinately regulating carbon–nitrogen metabolic networks and antioxidant systems, providing a theoretical foundation for phytohormone-augmented microalgae cultivation technologies. Full article

Torrefaction, a mild thermochemical pretreatment process, generates the fuel-torrefied biomass along with non-condensable and condensable gases. The latter can be condensed to yield a dark, viscous liquid called torrefaction condensate (TC). In this study, we investigated the effect of TC on growth and exopolysaccharide (EPS) production by the green microalgae Chlamydomonas reinhardtii, a well-known model organism. Aspen wood pellets were torrefied at different temperatures, and the condensate formed at each temperature was analyzed. Based on the GC-MS analysis, 225 °C TC was selected and used for the cultivation of C. reinhardtii. Results show that at 2 mL/L and 2.5 mL/L concentrations, TC negatively impacts growth, EPS production, as well as the composition of amino acids, lipids, and fatty acids n of C. reinhardtii. However, C. reinhardtii gradually adapted to TC and attained the growth patterns comparable to the control, showing the resilience of the culture. The biochemical and antioxidant properties of the EPS showed significant differences to that of the control. Therefore, cultivating these microalgae in TC suggests a new microalgal biorefinery approach through the utilization of low-value TC for the production of value-added products, such as EPS. Full article