Carbon Fixation Research Articles

Screening of Bacteria Promoting Carbon Fixation in Chlorella vulgaris Under High Concentration CO2 Stress

The cooperation between microalgae and bacteria can enhance the carbon fixation efficiency of microalgae. In this study, a microalgae-bacteria coexistence system under high-concentration CO2 stress was constructed, and the bacterial community structure of the entire system was analyzed using the 16S rDNA technique. Microbacterium sp., Bacillus sp., and Aeromonas sp. were screened and demonstrated to promote carbon fixation in Chlorella vulgaris HL 01 (C. vulgaris HL 01). Among them, the Aeromonas sp. + C. vulgaris HL 01 experimental group exhibited the most significant effect, with an increase of about 24% in the final biomass yield and a daily carbon fixation efficiency increase of about 245% (day 7) compared to the control group. Continuous cultivation of microalgae and bacterial symbiosis showed that bacteria could utilize the compounds secreted by microalgae for growth and could produce nutrients to maintain the vitality of microalgae. Detection of extracellular organic compounds of microorganisms in the culture broth by excitation-emission matrix spectral analysis revealed that bacteria utilized the aromatic proteinaceous compounds and others secreted by C. vulgaris HL 01 and produced new extracellular organic compounds required by C. vulgaris HL 01. The metabolic organic substances in the liquids of the experimental groups and the control group were analyzed by liquid chromatography-mass spectrometry, and it was found that 31 unique organic substances of C. vulgaris HL 01 were utilized by bacteria, and 136 new organic substances were produced. These differential compounds were mainly organic acids and their derivatives, benzene compounds, and organic heterocyclic compounds, etc. These results fully demonstrate that the carbon fixation ability and persistence of C. vulgaris HL 01 are improved through material exchange between microalgae and bacteria. This study establishes a method to screen carbon-fixing symbiotic bacteria and verifies that microalgae and bacteria can significantly improve the carbon fixation efficiency of microalgae for high-concentration CO2 through material exchange, providing a foundation for further research of microalgae-bacterial carbon fixation.

Enrichment of electrotrophic microorganisms from contrasting shallow-sea hydrothermal environments in bioelectrochemical reactors

IntroductionHydrothermal vents are inhabited by electrotrophic microorganisms, which are capable of oxidizing extracellular compounds, such as metals, to power their metabolisms. However, their diversity is poorly known, especially in shallow-sea hydrothermal vents where it has not been extensively studied. Bioelectrochemical reactors can be used to investigate such electrotrophic diversity by providing an electrode as an electron donor.MethodsHere, a total of 60 different reactors were set up and inoculated with either a microbial community coming from the shallow, acidic (ca. pH 5.5) and hot (ca. 120°C) hydrothermal system of Panarea, Aeolian islands, Italy, or the shallow, alkaline (pH 11) and mild (40°C) hydrothermal system of Prony Bay, New Caledonia.ResultsWith the alkaline sample, no electrical current increase was seen in any of the 15 reactors operated for 6 days under Prony hydrothermal conditions (pH 10, 30–75°C). By contrast, a 6-fold increase on average was observed in reactors operated under the Panarea hydrothermal fluid conditions (pH 4.5–7, 75°C). A Multi-Factor Analysis revealed that the overall bioelectrochemical performances of these reactors set them apart from all the other Panarea and Prony conditions, not only due to their higher current production but also archaeal abundances (measured through qPCR). Most reactors produced organic acids (up to 2.9 mM in 6 days). Still, coulombic efficiencies indicated that this might have been due to the (electro) fermentation of traces of yeast extract in the medium rather than CO2 fixation. Finally, microbial communities were described by 16S metabarcoding and ordination methods, and potential electrotrophic taxa were identified. In Panarea reactors, higher growth was correlated with a few bacterial genera, mainly Bacillus and Pseudoalteromonas, including, for the former, at higher temperatures (55°C and 75°C). In reactors reproducing the Prony Bay hydrothermal conditions, known facultative methylotrophs, such as Sphingomonas and Methylobacterium, were dominant and appeared to consume formate (provided as carbon source) but no electrons from the cathode.ConclusionThese results provide new insights into the distribution and diversity of electrotrophs in shallow-sea hydrothermal vents and allow the identification of potential novel biocatalysts for Microbial Electrosynthesis whereby electricity and carbon dioxide are converted into value-added products.

Modification of intracellular metabolism by expression of a C-terminal variant of phosphoribulokinase from Synechocystis sp. PCC 6803.

Phosphoribulokinase (PRK) is a key enzyme in the Calvin cycle of cyanobacteria required for CO2 fixation and enhancing intracellular PRK activity will contribute to altering the metabolic state. In Synechocystis sp. PCC 6803, PRK activity is inhibited by the small protein CP12 and intramolecular disulfide bonds in its C-terminal loop. This study aimed to increase PRK activity by expressing a mutant PRK that inhibitory Cys residues (positions 229 and 235) in the C-terminal loop were replaced with Ser. The engineered strain showed increased PRK activity under photomixotrophic conditions. Metabolomic analysis revealed that this strain accumulates organic acids downstream of glycolysis and the tricarboxylic acids cycle, highlighting its potential for producing chemicals using these metabolites as precursors. These findings suggest that preventing disulfide bond formation in the PRK C-terminal loop enhances its activity, providing a promising approach for metabolic engineering in cyanobacteria.

Long-Term in vivo Observation of Maize Leaf Xylem Embolism, Transpiration and Photosynthesis During Drought and Recovery.

Plant water transport is essential to maintain turgor, photosynthesis and growth. Water is transported in a metastable state under large negative pressures, which can result in embolism, that is, the loss of function by the replacement of liquid xylem sap with gas, as a consequence of water stress. To avoid experimental artefacts, we used an optical vulnerability system to quantify embolism occurrence across six fully expanded maize leaves to characterize the sequence of physiological responses (photosynthesis, chlorophyll fluorescence, whole-plant transpiration and leaf inter-vein distance) in relation to declining water availability and leaf embolism during severe water stress. Additionally, we characterize the recovery of leaf function in the presence of sustained embolism during a 6-day recovery period. Embolism formation occurred after other physiological processes were substantially depressed and were irreversible upon rewatering. Recovery of transpiration, net CO2 assimilation and photosystem II efficiency were aligned with the severity of embolism, whereas these traits returned to near pre-stress levels in the absence of embolism. A better understanding of the relationships between embolism occurrence and downstream physiological processes during stress and recovery is critical for the improvement of crop productivity and resilience.

The application of shrub willow chip organic amendments impacts soil microbial community dynamics.

Incorporating shrub willow chips into soil may improve the chemical, physical and biological properties of soils with low organic matter but the impact on soil microbial communities and their dynamics is not known. We assessed changes in the soil microbial communities in response to willow chip applied at increasing rates (0, 20, 40 and 60 Mg ha-1) in a potato-barley cropping system. Bacterial and fungal community diversity, relative abundance, and potential functions were assessed using amplicon sequencing of 16S and ITS rRNA genes at six time points. High rates (40 and 60 Mg ha-1) of willow chips had no effect on bacterial alpha diversity but significantly decreased fungal alpha diversity (Shannon) while increasing fungal richness (Chao-1). At rates of 40 Mg ha⁻¹ and higher, the relative abundance of copiotrophic bacterial groups increased, while that of copiotrophic fungal groups decreased. The relative abundance of the most dominant microbial phyla and genera varied over time, with copiotrophic groups declining and oligotrophic groups increasing. High willow chip application rates increased bacterial molecular markers related to carbon fixation and degradation, nitrogen fixation, and phosphorus solubilization, while decreasing markers related to cellobiose transport and denitrification. This study demonstrates the ability of willow chips to influence the microbial community composition and potential function over time.

Persistent functional and taxonomic groups dominate an 8,000-year sedimentary sequence from Lake Cadagno, Switzerland

Most of our knowledge of deep sedimentary life comes from marine environments; however, despite their relatively small volume, lacustrine sediments constitute one of the largest global carbon sinks and their deep sediments are largely unexplored. Here, we reconstruct the microbial functional and taxonomic composition of an 8,000-year Holocene sedimentary succession from meromictic Lake Cadagno (Switzerland) using shotgun metagenomics and 16S rRNA gene amplicon sequencing. While younger sediments (<1,000 years) are dominated by typical anaerobic surface sedimentary bacterial taxa (Deltaproteobacteria, Acidobacteria, and Firmicutes), older layers with lower organic matter concentrations and reduced terminal electron acceptor availability are dominated by taxa previously identified as “persistent populations” within deep anoxic marine sediments (Candidatus Bathyarchaeia, Chloroflexi, and Atribacteria). Despite these dramatic changes in taxonomic community composition and sediment geochemistry throughout the sediment core, higher-order functional categories and metabolic marker gene abundances remain relatively consistent and indicate a microbial community capable of carbon fixation, fermentation, dissimilatory sulfate reduction and dissimilatory nitrate reduction to ammonium. As the conservation of these metabolic pathways through changes in microbial community compositions helps preserve the metabolic pathway connectivity required for nutrient cycling, we hypothesize that the persistence of these functional groups helps enable the Lake Cadagno sedimentary communities persist amidst changing environmental conditions.

Estimation of light utilisation and antioxidative protection in an alpine plant species (Soldanella alpina L.) during the leaf life cycle at high elevation.

Photosynthesis, electron transport to carbon assimilation, photorespiration and alternative electron transport, light absorption of the two photosystems, antioxidative protection and pigment contents were investigated in S. alpina leaves. S. alpina is an alpine snow-bed plant which can be found with green leaves after snowmelt. At least 24% of the leaves were formed at the beginning of the vegetation period in the previous year and survived two consecutive vegetation periods under contrasting environmental conditions. In leaves still covered by snow (SNOW), the parameters of antioxidative protection and carbon assimilation were lower than in leaves from the previous vegetation period (NEW) or several weeks after snowmelt (OLD). Directly after snowmelt, antioxidative protection was strongly but transitionally increased. The senescence of leaves did not depend on antioxidative scavenging capacity. Lower carbon assimilation was not related to increases in alternative electron flow (ETRalt) in SNOW leaves. In the second vegetation period, light absorption by PSII decreases in favour of PSI in OLD leaves. This allows OLD leaves to keep the electron transport chain more oxidised and to support photorespiration with increased ATP synthesis by cyclic electron transport around PSI. This study describes how the leaves of a unique plant can cope with contrasting environmental conditions.

Increasedchloroplast occupancy in bundle sheath cells of ricehap3Hmutants revealed by Chloro-Count: a new deep learning-based tool.

There is an increasing demand to boost photosynthesis in rice to increase yield potential. Chloroplasts are the site of photosynthesis, and increasing their number and size is a potential route to elevate photosynthetic activity. Notably, bundle sheath cells do not make a significant contribution to overall carbon fixation in rice, and thus, various attempts are being made to increase chloroplast content specifically in this cell type. In this study, we developed and applied a deep learning tool, Chloro-Count, and used it to quantify chloroplast dimensions in bundle sheath cells of OsHAP3H gain- and loss-of-function mutants in rice. Loss of OsHAP3H increased chloroplast occupancy in bundle sheath cells by 50%. When grown in the field, mutants exhibited increased numbers of tillers and panicles. The implementation of Chloro-Count enabled precise quantification of chloroplasts in loss- and gain-of-function OsHAP3H mutants and facilitated a comparison between 2D and 3D quantification methods. Collectively, our observations revealed that a mechanism operates in bundle sheath cells to restrict chloroplast occupancy as cell dimensions increase. That mechanism is unperturbed in Oshap3H mutants but loss of OsHAP3H function leads to an increase in chloroplast numbers. The use of Chloro-Count also revealed that 2D quantification is compromised by the positioning of chloroplasts within the cell.

Mechanistic impact of Gracilaria bailinae extracts on photosynthesis and metabolism in Phaeodactylum tricornutum

In the intricate realm of aquatic ecosystems, biotic interactions play pivotal roles in shaping the physiological responses and survival strategies of microorganisms. This study investigates the effects of Gracilaria bailinae on photosynthesis and metabolism on the diatom Phaeodactylum tricornutum and the ecological significance. Our results reveal considerable suppression by G. bailinae on both its light-dependent and light-independent reactions of photosynthesis in P. tricornutum. A pronounced decline in carbon fixation was observed causing. the diatom to prioritize its carbon flux towards carbohydrate synthesis for its cellular energy needs. At high G. bailinae concentrations a marked reduction in lipid content indicated their importance as emergency energy sources. This response in lipid mobilization under photosynthetic stress is an evolutionary strategy for environmental adaptation. In addition, G. bailinae-induced stress amplified lysosomal activity in the diatom. Such an upsurge in oxidative stress appears to fast-track cellular death. We conclude that the ROS production, induced by G. bailinae, acts as a linchpin in mediating stress responses, thereby significantly reconfiguring the metabolism in the diatom. This study not only elucidates the physiological countermeasures of microalgae against biotic stressors but it also underscores the complex interactions between aquatic microorganisms.

Physiological and transcriptomic analysis of purple flowering stalks (Brassica campestris var. purpurea) under cadmium stress and exogenous glutathione application.

Glutathione (GSH) has a beneficial effect on the response of plants to cadmium (Cd) stress. The physiological and molecular processes by which glutathione influences Cd tolerance in purple flowering stalks (a Brassica vegetable) remain unclear. The aim of this study was to investigate the role of exogenous GSH in alleviating Cd toxicity in purple flowering stalks. On day 10 of the Cd stress treatment, spraying of GSH resulted in an increase in the net photosynthetic rate by 18.48%; enhanced antioxidant enzyme activities and the endogenous GSH and ascorbic acid contents; reduced the malondialdehyde and proline content 32.45% and 24.65%, respectively; and reduced the Cd content in the roots by 2.93%. On day 5, the transcriptome analysis showed that the application of GSH up-regulated the expression of 27 genes in the photosynthetic pathway. In contrast, GSH application led to the down-regulation of most genes involved in GSH metabolism, sulfur metabolism, and arginine and proline metabolism. These findings will aid future studies of the response of purple flowering stalks to Cd stress.

Ozone exposure alters nutrients and stoichiometric ratios in different organs of four urban tree species despite limited negative effects on leaf physiology and plant growth and biomass

To better understand the effects of ground-level ozone (O3) on nutrients and stoichiometry in different plant organs, urban tree species Celtis sinensis, Cyclocarya paliurus, Quercus acutissima, and Quercus nuttallii were subjected to a constant exposure to charcoal-filtered air (CF), nonfiltered air (NF), or NF + 40, 60, or 80 nmol O3 mol–1 (NF40, NF60, and NF80) starting early in the summer of the growing season. At the end of summer, net CO2 assimilation rate (A), stomatal conductance (gs), leaf mass per area (LMA), and/or leaf greenness (SPAD) either were not significantly affected by elevated O3 or were even higher in some cases during the summer compared with the CF or NF controls. LMA was significantly lower in autumn only after the highest O3 exposures. Compared to NF, NF40 caused a large increase in gs across species in late summer and more K and Mn in stems. At the end of the growing season, nutrient status and stoichiometric ratios in different organs were variously altered under O3 stress; many changes were large and often species-specific. Across O3 treatments, LMA was primarily associated with C and Mg levels in leaves and Ca levels in leaves and stems. NF40 enriched K, P, Fe, and Mn in stems, relative to NF, and NF60 enhanced Ca in leaves relative to CF and NF40. Moreover, NF resulted in a higher Ca/Mg ratio in leaves of Q. acutissima only, relative to the other O3 regimes. Interestingly, across species, O3 stress led to different nutrient modifications in different organs (stems + branches vs leaves). Thus, ambient and/or elevated O3 exposures can alter the dynamics and distribution of nutrients and disrupt stoichiometry in different organs in a species-specific manner. Changes in stoichiometry reflect an important defense mechanism in plants under O3, and O3 pollution adds more risk to ecological stoichiometries in urban areas.

Response of an obligate CAM plant to competition and increased watering intervals.

Climate change has exacerbated precipitation variability, profoundly impacting vegetation dynamics and community structures in arid ecosystems. There remains a notable knowledge gap regarding the ecological effects of altered precipitation on crassulacean acid metabolism (CAM) plants and their interactions with other photosynthetic types. This study investigated the response of the typical obligate CAM plant Orostachys fimbriata to extended watering intervals (WI4-WI8) and various competitive patterns (M1-M4) with the C3 grass Melilotus officinalis and the C4 grass Setaria viridis through greenhouse experiments. The results showed that: (1) In species mixtures, CAM plants had slightly reduced the total biomass (TB) compared to monocultures, yet maintained competitiveness by increasing the root-to-shoot biomass (R:S) ratio, stabilizing plant height, and sustaining their photosynthetic rates. (2) As watering intervals increased, CAM plants adapted by further elevating the R:S ratio, reducing height, and decreasing aboveground biomass. However, their height, CO2 assimilation rate, and above- and below-ground biomass were significantly suppressed, particularly when coexisting with C4 plants. More extreme watering regime caused a 47.6% decrease in TB of CAM plants in M4, while C3 and C4 grasses declined by 53.2% and 37.8%, respectively. (3) Given the predicted extension of drought intervals and the intensification of individual rainfall events under future climate conditions, the competitive pressure from C4 plants with high drought tolerance and resource acquisition advantages may limit the expansion potential of CAM plants in drylands. This study enhances the understanding of adaptive mechanisms of CAM plants competing and coexisting with grasses under variable environments, providing scientific bases for predicting arid ecosystem dynamics.

Catalytic Activity of Microcystis aeruginosa in Fe-Co-MOFs System for Efficient CO2 Fixation and High-Value Conversion

Catalytic Activity of Microcystis aeruginosa in Fe-Co-MOFs System for Efficient CO2 Fixation and High-Value Conversion

Mechanism of pore structure on carbonation properties of cement with high carbon fixation capacity

Mechanism of pore structure on carbonation properties of cement with high carbon fixation capacity

Identifying bacterial fixation pathway of mediating soil carbon stock changes along tropical forest restoration

The mechanism mediating carbon accumulation changes along ropical forest restoration remains unclear. Here, we identified how functional bacteria, litter input, and abiotic variables control soil organic carbon stock changes along an age-chronosequence of tropical forest restoration. Over 51-yr recovery, significant increases in total organic carbon stocks (∼1.7 fold) were strongly associated with increases in copy number of carbon fixation bacterial genes (cbbL) (∼2.6 fold). The direct pathways of cbbL abundance, microbial and mineral-associated organic carbon explained 76 % of carbon stock variation. In contrast, litter carbon, soil water, and bulk density indirectly regulated carbon stocks through affecting cbbL abundance (68 %) and microbial carbon level (29 %). Furthermore, cbbL abundance had a higher contribution (71 %) to carbon fraction transformation than microbial carbon level (19 %). We suggest that tropical forest restoration controls carbon stocks primarily via direct bacterial fixation pathway mediated by litter carbon and physical soil variables. Our results are helpful to further understand the mechanism of tropical forest restoration regulating carbon transformation and accumulation.

Microbial drivers of biogeochemical cycles in deep sediments of the Kathiawar Peninsula Gulfs of India.

Deep marine sediments are rich in microbial diversity, which holds metabolic repertoire to modulate biogeochemical cycles on a global scale. We undertook the environmental microbiome inhabiting the Gulf of Kathiawar Peninsula as a model system to understand the potential involvement of the deep marine sediment microbial community and as a cohort in the carbon, nitrogen, and sulfur biogeochemical cycles. These gulfs are characterized by dynamic tidal variations, diverse sediment textures, and nutrient-rich waters, driven by coastal processes and the interaction between natural coastal dynamics and anthropogenic inputs that shape its microbial community diversity. Our findings suggest that carbon fixation was carried out by Gamma-proteobacteria with CBB cycle-related genes or by microbial participants with Wood-Ljungdahl pathway-related genes. Microbial communities involved in nitrogen metabolism were observed to be rich and diverse, and most microbial communities potentially contribute to the nitrogen cycle via processing nitrogen oxides. Bacteria belonging to the KSB1 phylum were also found to fix nitrogen. The sulfur cycle was spread throughout, with Verrucomicrobiota phylum being a major contributor. The varying napAB genes, significantly lower in the Gulf of Kutch compared to the Gulf of Cambay and the Arabian Sea, mediated nitrate reduction. Dynamics between these pathways were mutually exclusive, and organic carbon oxidation was widespread across the microbial community. Finally, the proteobacteria phylum was highly versatile and conceivably contributed to biogeochemical flux with exceptionally high abundance and the ability to form metabolic networks to survive. The work highlights the importance of critical zones and microbial diversity therein, which needs further exploration.

Light-Driven Carbon Fixation Using Photosynthetic Organelles in Artificial Photosynthetic Cells.

Building an artificial photosynthetic cell from scratchhelps to understandthe working mechanismsof chloroplasts.It is a challenge to achieve carbon fixation triggered by photosynthetic organelles in an artificial cell. ATP synthase and photosystem II (PSII)are purified and reconstituted onto the phospholipid membrane to fabricate photosynthetic organelles. With the integration of phycocyanin, the ATP production yield increases by 2.51-fold due to the enhanced light harvesting capability. The carbon fixation pathway is established by converting α-oxoglutarate to acetyl-CoA and oxaloacetate with cascade enzyme reactions including the isocitratedehydrogenase (IDH), aconitase (ACO), and ATP citrate lyase (ACL).The photosynthetic organelles,phycocyanin,and carbon fixation pathway are encapsulatedinto giant unilamellar vesiclesto obtain artificial photosynthetic cells, which convert α-oxoglutarate to acetyl-CoA and oxaloacetate inside artificial cells upon light irradiation. The acetyl-CoA and oxaloacetatearethe most important intermediate products in the cellularmetabolic networks for the synthesis of cholesterol and fatty acids. Our results provide a way for efficient light energy conversion to produce ATP and fix CO2, and pave the path to buildautonomous artificial cells with more complicated metabolic networks.

A Theoretical Study on the Mechanism of Bifunctional Brønsted Acid/Base-Catalyzed CO2-Fixation Reaction with Homoallylic Amine.

The reaction mechanism and the enantioselectivity of the Brønsted acid/base (trans-stilbene diamine, simplified by BAM)-catalyzed CO2 fixation with homoallylic amine have been investigated using density functional theory (DFT) calculations. The proposed mechanism involves the initial activation of the amine by the Brønsted acid, followed by the nucleophilic attack of the amine on CO2 to form a carbamate intermediate. The Brønsted base subsequently deprotonates the carbamate intermediate to form the cyclic carbamate product, regenerating the Brønsted acid catalyst. The C-O cyclization is the enantio-determining step. The hydrogen bond network formed by the catalyst and substrate, similar to an enzyme pocket, plays a key role in stereoselectivity. In addition, the energy decomposition analysis (EDA) confirms that hydrogen bonding is driven by orbital and electrostatic attractions. The more Brønsted basic BAM catalyst (OMe at the quinoline 7-position) exhibits enhanced enantioselectivity.

Conformational dynamics of a multienzyme complex in anaerobic carbon fixation.

In the ancient microbial Wood-Ljungdahl pathway, carbon dioxide (CO2) is fixed in a multistep process that ends with acetyl-coenzyme A (acetyl-CoA) synthesis at the bifunctional carbon monoxide dehydrogenase/acetyl-CoA synthase complex (CODH/ACS). In this work, we present structural snapshots of the CODH/ACS from the gas-converting acetogen Clostridium autoethanogenum, characterizing the molecular choreography of the overall reaction, including electron transfer to the CODH for CO2 reduction, methyl transfer from the corrinoid iron-sulfur protein (CoFeSP) partner to the ACS active site, and acetyl-CoA production. Unlike CODH, the multidomain ACS undergoes large conformational changes to form an internal connection to the CODH active site, accommodate the CoFeSP for methyl transfer, and protect the reaction intermediates. Altogether, the structures allow us to draw a detailed reaction mechanism of this enzyme, which is crucial for CO2 fixation in anaerobic organisms.

Microalgae-based flue gas CO2 sequestration for cleaner environment and biofuel feedstock production: a review.

Anthropogenic CO2 emissions are the prime cause of global warming and climate change, promoting researchers to develop suitable technologies to reduce carbon footprints. Among various CO2 sequestration technologies, microalgal-based methods are found to be promising due to their easier operation, environmental benefits, and simpler equipment requirements. Microalgae-based carbon capture and storage (CCS) technology is essential for addressing challenges related to the use of industrial-emitted flue gases. This review focuses on the literature concerning the microalgal application for CO2 sequestration. It highlights the primary physiochemical parameters that affect microalgal-based CO2 biofixation, including light exposure, microalgal strain, temperature, inoculum size, pH levels, mass transfer, CO2 concentration, flow rate, cultivation system, and mixing mechanisms. Moreover, the inhibition effect of different flue gas components including NOx, SOx, and Hg on growth kinetics is discussed to enhance the capacity of microalgal-based CO2 biofixation, along with deliberated challenges and prospects for future development. Overall, the review indicated microalgal-based flue gas CO2 fixation rates range from 80mg L-1day-1 to over 578mg L-1day-1, primarily influenced by physiochemical parameters and flue gas composition. This article summarizes the mechanisms and stages of microalgal-based CO2 sequestration and provides a comprehensive review based on international interest in this green technology.