Search Results (65)

Phosphorus is a key macronutrient central to the processes of energy and information storage and exchange in the cell. Single-celled photosynthetic organisms, including microalgae, accumulate intracellular reserves of phosphorus (mostly in the form of polyphosphate) essential for the maintenance of cell homeostasis during fluctuations of external phosphorus availability. The polyphosphate reserves in microalgal cells are formed by polyphosphate polymerases—a ubiquitous enzyme family represented mainly by prokaryotic (PPK-type, typical of prokaryotes, e.g., cyanobacteria) and VTC-type polyphosphate polymerases harbored by eukaryotic microalgae, although certain species possess both PPK and VTC types of the enzyme. This enzyme is important for the environmental fitness of microalgae dwelling in diverse habitats, as well as for the efficiency of microalgae-based systems for the biocapture of phosphate from waste streams and for upcycling this valuable nutrient to agricultural ecosystems via biofertilizer from microalgal biomass. This review summarizes the recent progress in the field of structure, regulation, and functioning of VTC in microalgae. In conclusion, biotechnological implications and perspectives of VTC as a target of microalgal cell engineering and bioprocess design for improved phosphate bioremoval efficiency and culture robustness are considered. Full article

Three-dimensional bioprinting integrating living cells and bioactive materials enables the fabrication of scaffold structures supporting diverse cellular growth and metabolism. Microalgae are among the most promising microbial platforms for the construction of photosynthetic cell factories, while the current industrial-scale cultivation of microalgae remains predominantly dependent on traditional liquid submerged systems, imposing limitations on commercial viability due to both process and economic constraints. Encapsulation of microalgae within bioactive matrices combined with 3D bioprinting to fabricate customized structures has been explored to address the limitations of submerged cultivation, which are expected to expand microalgal applications and establish new research directions in microalgal biotechnology. This review analyzes both matrices and methods of 3D bioprinting, summarizing the advancement of microalgae-based 3D bioprinting into six main domains including living building materials, biophotovoltaics, photosynthetic biosynthesis, bioremediation, tissue engineering, and food engineering. Lastly, synthetic biology-informed perspectives are provided on future developments of 3D bioprinting technologies and their potential in microalgal research. Full article

Microalgae, with their unparalleled capabilities for sunlight-driven growth, CO₂ fixation, and synthesis of diverse high-value compounds, represent sustainable cell factories for a circular bioeconomy. However, industrial deployment has been hindered by biological constraints and the inadequacy of conventional genetic tools. The advent of CRISPR-Cas systems initially provided precise gene editing via targeted DNA cleavage. This review argues that the true transformative potential lies in moving decisively beyond cutting to harness CRISPR as a versatile synthetic biology “Swiss Army Knife”. We synthesize the rapid evolution of CRISPR-derived tools—including transcriptional modulators (CRISPRa/i), epigenome editors, base/prime editors, multiplexed systems, and biosensor-integrated logic gates—and their revolutionary applications in microalgal engineering. These tools enable tunable gene expression, stable epigenetic reprogramming, DSB-free nucleotide-level precision editing, coordinated rewiring of complex metabolic networks, and dynamic, autonomous control in response to environmental cues. We critically evaluate their deployment to enhance photosynthesis, boost lipid/biofuel production, engineer high-value compound pathways (carotenoids, PUFAs, proteins), improve stress resilience, and optimize carbon utilization. Persistent challenges—species-specific tool optimization, delivery efficiency, genetic stability, scalability, and biosafety—are analyzed, alongside emerging solutions and future directions integrating AI, automation, and multi-omics. The strategic integration of this CRISPR toolkit unlocks the potential to engineer robust, high-productivity microalgal cell factories, finally realizing their promise as sustainable platforms for next-generation biomanufacturing. Full article

The escalating climate crisis and the imperative to transition from a fossil fuel-dependent economy demand transformative solutions for sustainable energy and carbon management. Biological CO₂ capture and utilization (CCU) using microalgae represents a particularly compelling approach, capitalizing on microalgae’s high photosynthetic efficiency and remarkable product versatility. This review critically examines the principles and recent breakthroughs in microalgal CO₂ bioconversion, spanning strain selection, advanced photobioreactor (PBR) design, and key factors influencing carbon sequestration efficiency. We explore diverse valorization strategies, including next-generation biofuel production, integrated wastewater bioremediation, and the synthesis of value-added chemicals, underscoring their collective potential for mitigating CO₂ emissions and achieving comprehensive resource valorization. Persistent challenges, such as economically viable biomass harvesting, cost-effective scale-up, and enhancing strain robustness, are rigorously examined. Furthermore, we delineate promising future prospects centered on cutting-edge genetic engineering, integrated biorefinery concepts, and synergistic coupling with waste treatment to maximize sustainability. By effectively bridging carbon neutrality with renewable resource production, microalgae-based technologies hold considerable potential to spearhead the circular bioeconomy, accelerate the renewable energy transition, and contribute significantly to achieving global climate objectives. Full article

Polyamines play a pivotal role in regulating the growth and metabolic adaptation of microalgae, yet their integrative regulatory roles remain underexplored. This review advances a comprehensive perspective of microalgae growth, integrating polyamine dynamics, amino acid metabolism, and redox balance. Polyamines (putrescine, spermidine, and spermine) biology in microalgae, particularly Chlamydomonas reinhardtii, is reviewed, exploring their critical function in modulating cell cycle progression, enzymatic activity, and stress responses through nucleic acid stabilization, protein synthesis regulation, and post-translational modifications. This review explores how the exogenous supplementation of polyamines modifies their intracellular dynamics, affecting growth phases and metabolic transitions, highlighting the complex regulation of internal pools of these molecules. Comparative analyses with Chlorella ohadii and Scenedesmus obliquus indicated species-specific responses to polyamine fluctuations, linking putrescine and spermine levels to important tunable metabolic shifts and fast growth phenotypes in phototrophic conditions. The integration of multi-omic approaches and computational modeling has already provided novel insights into polyamine-mediated growth regulation, highlighting their potential in optimizing microalgae biomass production for biotechnological applications. In addition, genomic-based modeling approaches have revealed target genes and cellular compartments as bottlenecks for the enhancement of microalgae growth, including mitochondria and transporters. System-based analyses have evidenced the overlap of the polyamines biosynthetic pathway with amino acids (especially arginine) metabolism and Nitric Oxide (NO) generation. Further association of the H₂O₂ production with polyamines metabolism reveals novel insights into microalgae growth, combining the role of the H₂O₂/NO rate regulation with the appropriate balance of the mitochondria and chloroplast functionality. System-level analysis of cell growth metabolism would, therefore, be beneficial to the understanding of the regulatory networks governing this phenotype, fostering metabolic engineering strategies to enhance growth, stress resilience, and lipid accumulation in microalgae. This review consolidates current knowledge and proposes future research directions to unravel the complex interplay of polyamines in microalgal physiology, opening new paths for the optimization of biomass production and biotechnological applications. Full article

Microalgae have evolved a diverse carotenoid profile, enabling efficient light harvesting and photoprotection. Previous studies have demonstrated the feasibility of genome editing in the green algal model species Chlamydomonas reinhardtii, leading to significant modifications in carotenoid accumulation. By overexpressing a fully redesigned β-carotene ketolase (bkt), the metabolic pathway of C. reinhardtii was successfully redirected toward astaxanthin biosynthesis, a high-value ketocarotenoid with exceptional antioxidant properties, naturally found in only a few microalgal species. In this study, a tailor-made double knockout targeting lycopene ε-cyclase (LCYE) and zeaxanthin epoxidase (ZEP) was introduced as a background for bkt expression to ensure higher substrate availability for bkt enzyme. The increased zeaxanthin availability resulted in a 2-fold increase in ketocarotenoid accumulation compared to the previously engineered bkt1 or bkt5 strain in the UVM4 background. Specifically, the best Δzl-bkt-expressing lines reached 2.84 mg/L under low light and 2.58 mg/L under high light, compared to 1.74 mg/L and 1.26 mg/L, respectively, in UVM4-bkt strains. These findings highlight the potential of rationally designed microalgal host strains, developed through genome editing, for biotechnological applications and high-value compound production. Full article

As of 2024, approximately 81.5% of global energy consumption is still derived from non-renewable fossil fuels, such as coal, oil, and natural gas. This highlights the urgent need to transition to alternative energy sources amid the escalating climate crisis. Cyanobacteria and microalgae have emerged as promising biocatalysts in microbial fuel cells (MFCs) for eco-friendly energy production, owing to their photosynthetic abilities and resilience in regard to various environmental conditions. This review explores the potential of cyanobacteria and microalgae to drive bioelectricity generation via metabolic and extracellular electron transfer processes, leveraging their ability to fix carbon and nitrogen, while thriving in challenging environments. Bioengineering and electrode design advances are integrated to enhance the electron transfer efficacy and constancy of cyanobacteria-based MFCs. This approach addresses the growing demand for carbon-neutral energy and can be applied to wastewater treatment and bioremediation scenarios. By synergizing biological innovation with sustainable engineering techniques, this review establishes cyanobacteria and microalgal-driven MFCs as a scalable and eco-friendly platform for next-generation energy systems. The findings lay the groundwork for further exploration of the role of cyanobacteria and microalgae in bridging the gap between renewable energy production and environmental stewardship. Full article

Microalgae are microscopic unicellular organisms that inhabit marine, freshwater, and moist terrestrial ecosystems. The vast number and diversity of microalgal species provide a significant reservoir of biologically active compounds, highly promising for biomedical applications. Diatoms are unicellular eukaryotic algae belonging to the class Bacillariophyceae. They possess intricately structured silica-based cell walls, which contain long-chain polyamines that play important roles in the formation of silica. Long-chain polyamines are uncommon polyamines found only in organisms that produce biosilica. Diatomite, which is a marine sediment of the remains of the silica skeleton of diatoms, could be an abundant source of biogenic silica that can easily be converted to silica particles. This concise review focuses on the biofabrication of polyamine-based nanosilica from diatoms and highlights the possibility of utilizing diatom biosilica as a nanocarrier for drug and siRNA delivery, bioimaging, and bone tissue engineering. The challenges that may affect diatom production, including environmental stresses and climate change, are discussed together with the prospect of increasing diatom-based biosilica production with the desired nanostructures via genetic manipulation. Full article

It has been demonstrated that microalgal bioactive chemicals have beneficial health effects, including cardiovascular protection, antihypertensive, anti-obesity, antioxidative, and anticancer properties. However, the functional food industry has encountered numerous challenges in utilizing microalgal biomass due to species diversity, biomass variations, and cultivation parameters. Microalgae, as novel foods, are rich in a variety of bioactive compounds. Over the past decade, significant advances in genetic engineering techniques have facilitated the accumulation of specific value-added chemicals in many model microalgae. The food industry is interested in obtaining preservative chemicals from microalgae biomass, which can enhance the production of bioactive compounds under controlled conditions. Several microalgae species have been successfully used as natural resources, meeting both nutritional and technological criteria when added to meals or animal feeds. Our study aimed to evaluate the effects of incorporating Spirulina platensis in yogurt, which increased antioxidant activity by 35% in 2% Spirulina yogurt, and Chlorella vulgaris in bread products, which increased antioxidant activity by 40% in 2% Chlorella bread. Full article

Marine phytoplankton is an emerging source of immunomodulatory bioactive lipids (BLs). Under physiological growth conditions and upon stress challenges, several eukaryotic microalgal species accumulate lipid metabolites that resemble the precursors of animal mediators of inflammation: eicosanoids and prostaglandins. Therefore, marine phytoplankton could serve as a biotechnological platform to produce functional BLs with therapeutic applications in the management of chronic inflammatory diseases and other clinical conditions. However, to be commercially competitive, the lipidic precursor yields should be enhanced. Beside tailoring the cultivation of native producers, genetic engineering is a feasible strategy to accrue the production of lipid metabolites and to introduce heterologous biosynthetic pathways in microalgal hosts. Here, we present the state-of-the-art clinical research on immunomodulatory lipids from eukaryotic marine phytoplankton and discuss synthetic biology approaches to boost their light-driven biosynthesis. Full article

This review evaluates the feasibility of using microalgal culture for sustainable energy production, emphasizing microbial fuel cells (MFCs) and biophotovoltaics (BPVs). This study’s uniqueness is rooted in its thorough examination of recent developments (2014–present) in microalgal strain selection, bioreactor design, and electrode materials. Furthermore, this review combines microalga cultivation with wastewater treatment, highlighting its importance. Notably, it examines advanced methodologies, such as the use of genetic engineering to enhance microalgal traits, nanotechnology to optimize electrode efficacy, and artificial intelligence (AI) to optimize bioelectrochemical systems. In addition, this study identifies possible future research avenues by examining microalga–bacterium consortia and cascaded biobattery systems. Consequently, the incorporation of case studies illustrating microalga biobatteries’ practical applications in low-power devices and wastewater treatment underscores the technology’s promise. Similarly, this study examines significant problems with enhancing farming methods, reconciling cost and yield, and integrating renewable energy sources with the grid, offering vital insights for academics and policymakers. Ultimately, this review emphasizes the need for economical cultivation methods, waste stream utilization, and scalable bioreactor designs, thereby considerably advancing sustainable energy options. Full article

The treatment of wastewater using microalgae is regarded as a green and potential technology. However, its engineering application has been largely hindered because of the limitation of microalgae separation and harvesting. Therefore, immobilization technology has been widely used to embed microalgae for wastewater treatment. In this paper, sodium alginate (SA) and polyvinyl alcohol (PVA) as the common immobilized carriers were used to immobilize ankistrodesmus falcatus for simulated slaughtering wastewater (SSW) treatment. The experimental results of the mass transfer and adsorption of immobilized carriers were found to show that the mass transfer of SA-SiO₂ gel balls (SS-GB) was better than PVA-SA gel balls (PS-GB) and that the adsorption of PS-GB was better than SS-GB. When immobilizing microalgae with the two kinds of carriers, it was found that SA-SiO₂ microalgal spheres (SS-MS) were better than PVA-SA microalgal spheres (PS-MS) for the maintenance of microalgal cell activity and that PS-MS were better than SS-MS for the resistance to biodegradation. This is because the carrier of PS-MS had a thick shell and dense structure, while the carrier of SS-MS had a thin shell and loose structure. The results of SSW treatment by PS-MS and SS-MS were found to show that the total phosphorus (TP) removal rates of PS-MS and SS-MS were 90.31% and 86.60%, respectively. This indicates that the TP removal effect of PS-MS was superior to that of SS-MS. The adsorption kinetics simulation showed that the adsorption of TP onto PS-GB was controlled by chemisorption and that the adsorption of TP onto SS-GB was controlled by physical adsorption. The chemical oxygen demand (COD) and ammonium nitrogen (NH₄⁺-N) removal of PS-MS were 9.30% and 10.70%, respectively, and the COD and NH₄⁺-N removal of SS-MS were 54.60% and 62.08%, respectively. This indicates that the COD and NH₄⁺-N removal effect of SS-MS were superior to PS-MS. This is the result of the combined action of the degradation by microalgal cells and adsorption by the carrier. Full article

Microalgae biotechnology has taken the world by storm. However, despite its great potential promise, it still cannot be considered a fully consolidated technology due to a crucial challenge: the low rates of biomass productivity. To overcome this hurdle, photobioreactors have been developed as an innovative solution, promising to increase the efficiency of microalgae cultures by providing optimized conditions. However, the results obtained with these systems do not always meet initial expectations, and their large-scale implementation faces complex technical challenges. In light of this, the present review addresses the main aspects related to the design and engineering of photobioreactors, highlighting their potentialities and limitations in overcoming the critical challenges of microalgal biotechnology. Furthermore, we discuss the current technological readiness level and the commercial readiness index of microalgae-based bioproducts from the perspective of industrial-scale production. Full article

The urgent need to address environmental issues associated with the use of conventional fossil fuels has driven the rapid evolution of the global energy landscape. This review explores the background and significance of 3-G biofuel production, emphasizing the shift towards sustainable alternatives amidst escalating greenhouse gas emissions. While various renewable energy sources have gained prominence, biofuels have emerged as a promising solution for the transportation and industrial sectors, particularly from microalgal biomass. The rationale for focusing on microalgal biomass is based on its technical and environmental advantages. Unlike traditional feedstocks, microalgae boast a high lipid content, enhancing biofuel production efficiency. Their rapid growth rates and efficient carbon dioxide sequestration make microalgae frontrunners in scalable and sustainable biofuel production. This review aims to comprehensively analyze recent breakthroughs in 3-G biofuel production from microalgal biomass, filling gaps in the existing literature. The topics covered included species diversity, cultivation techniques, harvesting, pretreatment, lipid extraction methods, and biofuel production pathways. Genetic engineering, downstream processing, energy-efficient practices, and emerging trends, such as artificial intelligence and cross-disciplinary collaboration, will be explored. This study aims to consolidate recent research findings, identify challenges and opportunities, and guide future directions in microalgal biomass-based biofuel production. By synthesizing unpublished research, this review seeks to advance our knowledge and provide insights for researchers to foster sustainable and efficient 3-G biofuel production. Full article

The rapid expansion of global urbanization and industrialization has significantly increased the discharge of municipal wastewater, leading to issues of carbon emissions and energy consumption when using traditional biological treatment processes. This study proposes an innovative process that couples iron coagulation with microalgal–bacterial granular sludge (MBGS), with optimization and regulation based on operational conditions. The study found that the coagulation performance achieved optimal levels at an iron concentration of 25 mg/L and an anionic polyacrylamide concentration of 1 mg/L, which could remove approximately 61% of the organics and over 90% of phosphorus from raw wastewater. By relying on heterotrophic microorganisms, such as Proteobacteria, Bacteroidota, and Chloroflexi, along with the synergistic interaction between algae and bacteria, the subsequent MBGS process could further effectively remove organics over the day-night cycles. Moreover, the addition of inorganic carbon sources of NaHCO₃ increased the abundance of denitrification-related genes, reduced the accumulation of nitrite within MBGS, and led to effective total nitrogen removal. These results indicate that the iron coagulation–MBGS coupling process can efficiently treat municipal wastewater, offering potential for environment-sustainable pollutant removal with reduced energy consumption. These findings provide valuable insights for the practical engineering application of MBGS in wastewater treatment systems aiming for carbon-neutral wastewater treatment. Full article