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Excessive carbon dioxide (CO 2) emissions into the atmosphere have become a dire threat to the human race and environmental sustainability. The ultimate goal of net zero emissions requires combined efforts on CO 2 sequestration (natural sinks, biomass fixation, engineered approaches) and reduction in CO 2 emissions while delivering economic growth (CO 2 valorization for a circular carbon bioeconomy, CCE). We discuss microalgae-based CO 2 biosequestration, including flue gas cultivation, biotechnological approaches for enhanced CO 2 biosequestration, technological innovations for microalgal cultivation, and CO 2 valorization/biofuel productions. We highlight challenges to current practices and future perspectives with the goal of contributing to environmental sustainability, net zero emissions, and the CCE. Carbon capture, storage, and utilization are crucial to ensure carbon valorization into valuable bioenergy and bioproducts. Carbon dioxide (CO 2) biosequestration by microalgae contributes to net zero emissions. Microalgae are promising due to non-interference with agriculture, thus supporting food security, promoting energy security, and posing fewer environmental issues. Using flue gas for microalgal cultivation and CO 2 sequestration is promising. Genetic engineering of microalgal species and technology innovations could improve microalgal photosynthesis efficiency for CO 2 biosequestration and biorefineries. Microalgal biorefineries contribute to sustainable carbon management and the bioeconomy. [ABSTRACT FROM AUTHOR]

Arthrospira (Spirulina) spp. has long been consumed as a dietary supplement that provides rich natural nutrients consisting of 60–70% proteins including essential amino acids, vitamins, and some minerals. The currently available Spirulina products in the market are mainly hot and spray-dried and their nutritional values are significantly compromised due to degradation of the heat-sensitive bioactive components. This commentary provides a critical view on the differences in main nutritional composition between dried and fresh living Arthrospira. In addition, the current R&D advances in the development of fresh living Arthrospira as a dietary supplement including the cultivation system, preservation and storage, product development, nutritional and functional properties and food safety were critically discussed. Fresh living Arthrospira can better maintain their nutritional, functional, and health values, and therefore could be developed for a new range of Arthrospira derived products. However, the cultivation system that could ensure the food safety and long-term storage technologies to preserve the cell viability in different product formulations are still under development for expanding the commercial applications. • Arthrospira is an ideal dietary supplement due to its high nutritional value and health benefits. • Functional and nutritional value of Arthrospira become significantly compromised during the drying process. • Fresh living Arthrospira retains its full nutritional value and is a better dietary supplement. • Challenges in the development of fresh living Arthrospira are cultivation cost, storage and safety. • Future perspectives on food safety and commercial applications are proposed. [ABSTRACT FROM AUTHOR]

Micro- and nanoplastics (MNPs) have been found to occur intensively in aquatic environments, along with other conventional pollutants (Po) such as heavy metals, pesticides, pharmaceuticals, etc. However, our understanding of how MNPs and Po interact on aquatic primary producers is fragmented. We performed a quantitative meta-analysis based on 933 published experimental assessments from 44 studies to examine the coupled effects of MNPs and Po on microalgae. Although the results based on interaction type frequency (the proportion of each interaction type in all results) revealed dominantly additive interactions (56%) for overall physiological performance, an overall antagonistic effect was observed based on the mean interaction effect sizes. A higher proportion of antagonistic interaction type frequency was found in marine species compared to fresh species. The antagonistic effects were particularly significant for growth, oxidative responses, and photosynthesis, which could be attributed to the adsorption effect of MNPs on Po and thus the decreasing concentrations of pollutants in the medium. Larger-sized, negatively charged or uncharged and aged MNPs had higher proportions of antagonistic effects compared to smaller-sized, positively charged and virgin MNPs, due to their stronger adsorption capacity to Po. This study provides a comprehensive insight into the interactive effects of MNPs and Po on microalgae. [Display omitted] • More studies show additive interactions between microplastics and pollutants on algae. • An overall antagonistic effect is observed based on the mean interaction effect size. • Larger-sized and aged microplastics have higher proportions of antagonistic effects. • Negatively charged microplastics had the highest proportion of antagonism. • Microplastics could alleviate the harm of pollutants by their absorption capacity. [ABSTRACT FROM AUTHOR]

The pursuit of carbon neutrality confronts the twofold challenge of meeting energy demands and reducing pollution. This review article examines the potential of gasifying plastic waste and biomass as innovative, sustainable sources for hydrogen production, a critical element in achieving environmental reform. Addressing the problem of greenhouse gas emissions, the work highlights how the co-gasification of these feedstocks could contribute to environmental preservation by reducing waste and generating clean energy. Through an analysis of current technologies, the potential for machine learning to refine gasification for optimal hydrogen production is revealed. Additionally, hydrogen storage solutions are evaluated for their importance in creating a viable, sustainable energy infrastructure. The economic viability of these production methods is critically assessed, providing insights into both their cost-effectiveness and ecological benefits. Findings indicate that machine learning can significantly improve process efficiencies, thereby influencing the economic and environmental aspects of hydrogen production. Furthermore, the study presents the advancements in these technologies and their role in promoting a transition to a green economy and circular energy practices. Ultimately, the review delineates how integrating hydrogen production from unconventional feedstocks, bolstered by machine learning and advanced storage, can contribute to a sustainable and pollution-free future. [Display omitted] • ML enhances hydrogen yield from plastic waste and biomass gasification. • Co-gasification of waste boosts emission reduction and energy sustainability. • Review highlights innovative, eco-friendly hydrogen storage solutions. • Economic viability of gasification methods affirmed for green economic transition. • Future research direction for hydrogen production via gasification. [ABSTRACT FROM AUTHOR]

Microbial biosensor which integrates different types of microorganisms, such as bacteria, microalgae, fungi, and virus have become suitable technologies to address limitations of conventional analytical methods. The main applications of biosensors include the detection of environmental pollutants, pathogenic bacteria and compounds related to illness, and food quality. Each type of microorganisms possesses advantages and disadvantages with different mechanisms to detect the analytes of interest. Furthermore, there is an increasing trend in genetic modifications for the development of microbial biosensors due to potential for high-throughput analysis and portability. Many review articles have discussed the applications of microbial biosensor, but many of them focusing only about bacterial-based biosensor although other microbes also possess many advantages. Additionally, reviews on the applications of all microbes as biosensor especially viral and microbial fuel cell biosensors are also still limited. Therefore, this review summarizes all the current applications of bacterial-, microalgal-, fungal-, viral-based biosensor in regard to environmental, food, and medical-related applications. The underlying mechanism of each microbes to detect the analytes are also discussed. Additionally, microbial fuel cell biosensors which have great potential in the future are also discussed. Although many advantageous microbial-based biosensors have been discovered, other areas such as forensic detection, early detection of bacteria or virus species that can lead to pandemics, and others still need further investigation. With that said, microbial-based biosensors have promising potential for vast applications where the biosensing performance of various microorganisms are presented in this review along with future perspectives to resolve problems related on microbial biosensors. [Display omitted] • Microbial biosensors are simple, rapid, robust compared to conventional methods. • Wide applications have been discovered, e.g., environmental, food monitoring. • Engineered microbes have great potential for high-throughput and portable analysis. • Microbial biosensors are advantageous in ethical issues perspective. • The challenges and future perspectives of microbial biosensor are discussed. [ABSTRACT FROM AUTHOR]

Bibliometric network analysis has revealed that the widespread distribution of microplastics (MPs) has detrimental effects on marine organisms; however, the combined effects of MPs and climate change (e.g., warming) is not well understood. In this study, Prorocentrum donghaiense , a typical red tide species in the East China Sea, was exposed to different MP concentrations (0, 1, 5, and 10 mg L−1) and temperatures (16, 22, and 28 °C) for 7 days to investigate the combined effects of MPs and simulated ocean warming by measuring different physiological parameters, such as cell growth, pigment contents (chlorophyll a and carotenoid), relative electron transfer rate (rETR), reactive oxygen species (ROS), superoxide dismutase (SOD), malondialdehyde (MDA), and adenosine triphosphate (ATP). The results demonstrated that MPs significantly decreased cell growth, pigment contents, and rETR max , but increased the MDA, ROS, and SOD levels for all MP treatments at low temperature (16 °C). However, high temperatures (22 and 28 °C) increased the pigment contents and rETR max , but decreased the SOD and MDA levels. Positive and negative effects of high temperatures (22 or 28 °C) were observed at low (1 and 5 mg L−1) and high MP (10 mg L−1) concentrations, respectively, indicating the antagonistic and synergistic effects of combined warming and MP pollution. These results imply that the effects of MPs on microalgae will likely not be substantial in future warming scenarios if MP concentrations are controlled at a certain level. These findings expand the current knowledge of microalgae in response to increasing MP pollution in future warming scenarios. [Display omitted] • MPs-induced oxidative stress inhibited the growth of Prorocentrum donghaiense. • Warming increased the photosynthetic pigment contents (Chl- a and Caro) and rETR max. • Warming alleviated the lipid peroxidation (MDA) caused by MPs. • Warming enhanced the tolerance of cells to MPs at the lower MP concentrations. • Antagonistic and synergistic effects of warming and MPs were detected. [ABSTRACT FROM AUTHOR]

Abstract: We conducted an oceanographic census in 1959, 2002, and 2005 to evaluate changes in the temporo-spatial distribution and abundance of Lucifer intermedius and L. hanseni in the Changjiang estuary. In general, the abundance and frequency of occurrence (OF) for these two species were highest during the summer. We measured a significant change in the abundance and OF between years. The abundance and OF of L. intermedius increased from 3.7individualsm−3 and 66.67%, respectively, in 1959, to 8.93individualsm−3 and 85.19%, in 2002. In 1959, L. hanseni was only found during the summer (abundance: 0.01individualsm−3, OF: 3.70%). However, in 2002, this species was collected during all seasons except the winter. Furthermore, abundance (0.47individualsm−3) and OF (25.93%) were higher in 2002 than in 1959. Further increases in abundance and OF were measured during cruises during the spring of 2005. We hypothesize that global warming is responsible for the increase in abundance of L. intermedius and L. hanseni and the northward expansion of L. hanseni in the Changjiang estuary. Given our results, monitoring of both species may be useful to evaluate the effects of climate change. [Copyright &y& Elsevier]

The macro- and microalgae have been found to inhibit the growth and photosynthesis of one another due to allelopathic interactions between them. Sargassum fusiformis is a common and commercially cultivated seaweed in coastal waters of the East China Sea (ECS) and usually encounters dense harmful algal blooms (HABs) formed by dinoflagellates during their sexual reproduction period. In the present study, the effects of Prorocentrum donghaiense lipophilic extracted allelochemicals on the growth and photosynthesis of S. fusiformis zygotes were probed by fast chlorophyll fluorescence rise kinetics and chlorophyll a transient analysis (JIP-test). It was found that exposure to the allelochemicals led to decreased chlorophyll a content and photosynthetic rates of the zygotes in comparison to the ones in the control. In addition, using the JIP-test, it was found that the inhibitory effects of allelochemicals on photosynthesis of the zygotes were mainly exerted on the electron transport within PSII. The decrease of photosynthetic parameters such as V J , Mo, ϕ Po , ϕ o , ϕ Eo , PI, P TR , P ET in the zygotes exposed to the allelochemicals all revealed that the obstruction of electron transport, and the dominant decrease in P ET , both implied that inhibition on the dark reaction contributed to the highest photosynthetic reduction. In addition, some reaction centers (RCs) in the zygotes exposed to the allelocamicals were inactivated, which led to higher dissipation of excitation energy, as demonstrated by the significant enhancement of the photosynthetic parameter DIo/RC. All the results indicated that the lipophilic extracts contained the allelochemicals of P. donghaiense which could inhibit the growth and photosynthesis of S. fusiformis zygotes by damaging the electron acceptors and inactivating RCs, and finally block the electron transport. • Allelochemicals decreased the chlorophyll a content and photosynthetic rates of the zygotes. • Inhibitory effects of allelochemicals on photosynthesis of the zygotes were mainly exerted on electron transport. • Inhibition of the dark reaction resulted in the most photosynthetic reduction. • Allelochemicals led to inactivation of the RCs in the zygotes and more trapped energy was converted to heat dissipation. [ABSTRACT FROM AUTHOR]

During the growth period of economically cultured Sargassum fusiforme , offshore eutrophication and ammonium release from sediments, both induced by high temperatures, significantly affect the photosynthesis and growth of this seaweed. In the present study, S. fusiforme seedlings were treated with various ammonium-nitrogen (NH 4 +-N) gradients and light intensities to evaluate the effects of these treatments on algal photosynthesis and NH 4 +-N accumulation. The results showed that a certain concentration of NH 4 +-N (300 μmol L−1) increased the photosynthetic electron transport rate (rETR) and maximum photosynthetic rates (Pm) of the S. fusiforme seedlings, but a high NH 4 +-N (900 μmol L−1) reduced the light-saturated rETR , the maximum quantum yield, and Pm. Although the seedlings maintained high NH 4 +-N uptake rates under high ammonium concentration, the glutamate synthase and glutamine synthetase activities were adversely affected, indicating that the absorption and assimilation of NH 4 +-N were not synchronous. Under low light conditions, high ammonium concentrations significantly inhibited the electron transfer and photosynthetic rates of the seedlings and negatively impacted the photosynthetic pigment synthesis and photosynthetic product accumulation. Sargassum fusiforme seedlings displayed a degree of photosynthetic tolerance to the increased ammonium concentrations. However, excessively high ammonium concentrations caused stress to the S. fusiforme seedlings, and this could inhibit algal growth and even cause death by inhibition of the photosynthetic process. These results indicated the concentration effects of ammonium eutrophication on the marine cultivation of S. fusiforme. It also showed that ammonium tolerance of S. fusiforme could be enhanced by improving the light conditions under high ammonium concentrations. • Certain concentration of NH 4 +-N (300 μmol∙L-1) increased photosynthesis of S. fusiforme seedling. • S. fusiforme seedling had photosynthetic tolerance to increased ammonium concentrations. • However, excessively high ammonium (900 μmol∙L-1) stressed seedling growth by inhibition of its photosynthetic process. • Low light intensified the inhibition of high ammonium on seedling photosynthesis and photosynthetic product accumulation. [ABSTRACT FROM AUTHOR]

Photocatalysis is a potential technology for removing pollutants from water. As the recombination of the photogenerated electron-hole pairs can hinder the photocatalytic efficiency in the treatment of wastewater, the surface of the carrier is usually coated with a semiconductor. In this study, carbon microtube electrode prepared from corncob was coated with either titanium oxide (TiO 2) or bismuth phosphate (BiPO 4) and then used as a photocatalyst (C–TiO 2 or C–BiPO 4) to investigate the photodegradation of methylene blue (MB). The two photocatalysts, C–TiO 2 and C–BiPO 4 , were characterized by phase determination, microstructure observation, water contact angle measurement, and base site analysis. The influences of reaction time, stability, MB concentration, initial pH, and OH radicals quenching on the degradation of MB were also evaluated. The degradation of MB by C–TiO 2 and C–BiPO 4 was mainly dominated by OH radical oxidation. The carbon microtube increased both the mass transfer rate and the photogenerated electron-hole pairs separation rate, thereby increasing the photocatalysis of both C–TiO 2 and C–BiPO 4 as revealed by an increase in the rate of MB degradation. The rate constants obtained for the degradation of MB by C–TiO 2 and C–BiPO 4 at 20 °C were 9.739 × 10−7 mM min−1 and 1.111 × 10−7 mM min−1, respectively. The coating of TiO 2 and BiPO 4 on the surface of the carbon microtube electrode enhanced their photocatalytic performance, and therefore, C–TiO 2 and C–BiPO 4 could be developed into a novel material to be used in the photodegradation of dye pollutants. Image 1 • Bilayered carbon microtube electrode was synthesized from TiO 2 , BiPO 4 , and corncob. • Photocatalytic was dominated by OH radical oxidation. • Mass transfer and photogenerated electron-hole pairs separation increased by carbon microtube, photocatalysis rate increased. [ABSTRACT FROM AUTHOR]

While clay has been extensively studied for its ability to remove chlorophyll from vegetable oil, its effects and suitability on microalgae oil have received far less attention. In this study, three different clay types are evaluated and compared for their ability to dechlorophyllise microalgae oil. The clays involved are kaolinite, Fuller's earth and bentonite clay which are activated by acid treatment. Bentonite clay is found to remove chlorophyll effectively (76.04%) than kaolinite and Fuller's earth due to the presence of porous materials that facilitate adsorption. Additionally, the conditions of high temperature (79.69%) and ultrasound treatment (84.24%) demonstrate satisfactory chlorophyll removal efficiency. Another promising finding is that chlorophyll can be adsorbed on the clays without affecting the lipid composition in the microalgae extract significantly. Spent bleaching clay disposal is a growing issue that poses an environmental burden. Reusing bleaching clay can lower expenses and increase oil recovery. In a single sequential run, using spent bentonite clay yields the outcomes comparable to those of virgin bentonite clay. This finding offers a useful green and environmentally friendly approach to remove chlorophyll from microalgae oil feedstock. [Display omitted] • Chlorophyll adsorption rate of kalininite, Fullers earth and bentonite were tested. • Porosity and surface area of adsorbents were related to chlorophyll adsorption. • Bentonite clay exhibited high efficiency (76.04%) in chlorophyll removal. • High temperature and ultrasound treatment were pronounced in chlorophyll removal. • Spent study clay can be reused in another cycle with efficiency of 70.35%. [ABSTRACT FROM AUTHOR]

• Effects of backward flow on plankton were evaluated in river-lake ecosystem. • Cyanobacteria and total prokaryotes were homogenized by backward flow. • Cyanobacterial network stability was high but decreased with backward flow. • Homogenous selection increased in cyanobacteria and total prokaryotes at backward flow. • The response to backward flow was strong in cyanobacteria and weak in eukaryotes. River ecosystems face escalating challenges due to altered flow regimes from human activities, such as urbanization with hydrological modifications. Understanding the role of microbial communities for ecosystems with changing flow regimes is still incomplete and remains at the frontier of aquatic microbial ecology. In particular, influences of riverine backward flow on the aquatic biota remain largely unknown. Therefore, we examined the impact of backward flow on the cyanobacterial, total prokaryotic, and eukaryotic communities in the Changdougang River, which naturally flows into Lake Taihu, through environmental DNA metabarcoding. We analyzed the differences in community diversity, assembly, and ecological network stability among groups under backward, weak, and forward flow direction conditions. Non-metric multidimensional scaling showed higher variations in communities of groups across flow direction conditions than seasonal groups. Variations in alpha and beta diversity showed that cyanobacterial and total prokaryotic communities experienced strong homogenization under backward flow conditions, whereas the ecological uniqueness of the eukaryotic community decreased. Assembly of the three flow-related communities was primarily governed by drift and dispersal limitation in stochastic processes. However, in the cyanobacterial community, homogeneous selection in deterministic processes increased from 22.79 % to 42.86 % under backward flow, aligning with trends observed in the checkerboard score (C-score). More importantly, the topological properties of ecological networks and the degree of average variation revealed higher stability in the cyanobacterial community compared to total prokaryotic and eukaryotic communities. Considering the variations in cohesion, the network stability in the cyanobacterial community decreased under backward flow. Our findings emphasize the distinct and sequentially diminishing responses of cyanobacterial, total prokaryotic, and eukaryotic communities to backward flowing rivers. This knowledge is crucial for maintaining ecological health of rivers, assessing the complex ecological impacts on hydrological engineering, and formulating sustainable water management strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

The production of low-cost solid adsorbents for carbon dioxide (CO 2) capture has gained massive consideration. Biomass wastes are preferred as precursors for synthesis of CO 2 solid adsorbents, due to their high CO 2 adsorption efficiency, and ease of scalable low-cost production. This review particularly focuses on waste biomass-derived adsorbents with their CO 2 adsorption performances. Specifically, studies related to carbon (biochar and activated carbon) and silicon (silicates and geopolymers)-based adsorbents were summarized. The impact of experimental parameters including nature of biomass, synthesis route, carbonization temperature and type of activation methods on the CO 2 adsorption capacities of biomass-derived pure carbon and silicon-based adsorbents were evaluated. The development of various enhancement strategies on biomass-derived adsorbents for CO 2 capture and their responsible factors that impact adsorbent's CO 2 capture proficiency were also reviewed. The possible CO 2 adsorption mechanisms on the adsorbent's surface were highlighted. The challenges and research gaps identified in this research area have also been emphasized, which will help as further research prospects. [Display omitted] • Biomass-derived adsorbents for CO 2 capture were reviewed • Different carbon and silicon-based adsorbents were synthesized from biomass • Synthesis condition decides the physicochemical properties of adsorbents • Modification of adsorbents is needed for the improvement of CO 2 uptake • Biomass-derived CO 2 adsorbent with optimized operational condition is needed [ABSTRACT FROM AUTHOR]

Surfactants have always been a prominent chemical that is useful in various sectors (e.g., cleaning agent production industry, textile industry and painting industry). This is due to the special ability of surfactants to reduce surface tension between two fluid surfaces (e.g., water and oil). However, the current society has long omitted the harmful effects of petroleum-based surfactants (e.g., health issues towards humans and reducing cleaning ability of water bodies) due to their usefulness in reducing surface tension. These harmful effects will significantly damage the environment and negatively affect human health. As such, there is an urgency to secure environmentally friendly alternatives such as glycolipids to reduce the effects of these synthetic surfactants. Glycolipids is a biomolecule that shares similar properties with surfactants that are naturally synthesized in the cell of living organisms, glycolipids are amphiphilic in nature and can form micelles when glycolipid molecules clump together, reducing surface tension between two surfaces as how a surfactant molecule is able to achieve. This review paper aims to provide a comprehensive study on the recent advances in bacteria cultivation for glycolipids production and current lab scale applications of glycolipids (e.g., medical and waste bioremediation). Studies have proven that glycolipids are effective anti-microbial agents, subsequently leading to an excellent anti-biofilm forming agent. Heavy metal and hydrocarbon contaminated soil can also be bioremediated via the use of glycolipids. The major hurdle in the commercialization of glycolipid production is that the cultivation stage and downstream extraction stage of the glycolipid production process induces a very high operating cost. This review provides several solutions to overcome this issue for glycolipid production for the commercialization of glycolipids (e.g., developing new cultivating and extraction techniques, using waste as cultivation medium for microbes and identifying new strains for glycolipid production). The contribution of this review aims to serve as a future guideline for researchers that are dealing with glycolipid biosurfactants by providing an in-depth review on the recent advances of glycolipid biosurfactants. By summarizing the points discussed as above, it is recommended that glycolipids can substitute synthetic surfactants as an environmentally friendly alternative. [Display omitted] • Glycolipids provides an environmentally friendly alternative to synthetic surfactants. • Glycolipids are critically evaluated in terms of synthesis, functions and extraction. • Common applications of glycolipids in various industries are investigated. • State-of-the-art glycolipid applications introduced and discussed thoroughly. • Future possibilities and current challenges awaiting glycolipids are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Replace of natural foods with biosynthesis compounds for nutraceuticals production. • Microalgae-produced nutraceuticals provide better health treatment effects. • Review of application of nanotechnology on microalgae for enhanced production. • Nanotechnology improves harvesting efficiency to 90% and above. • High concentration of nanoparticles provides side effects to the microalgal cells. Nutraceutical supplements provide health benefits, such as fulfilling the lack of nutrients in the human body or being utilized to treat or cure certain diseases. As the world population is growing, certain countries are experiencing food crisis challenges, causing natural foods are not sustainable to be used for nutraceutical production because it will require large-scale of food supply to produce enriched nutraceutics. The high demand for abundant nutritional compounds has made microalgae a reliable source as they can synthesize high-value molecules through photosynthetic activities. However, some microalgae species are limited in growth and unable to accumulate a significant amount of biomass due to several factors related to environmental conditions. Therefore, adding nanoparticles (NPs) as a photocatalyst is considered to enhance the yield rate of microalgae in an energy-saving and economical way. This review focuses on the composition of microalgal biomass for nutraceutical production, the health perspectives of nutritional compounds on humans, and the application of nanotechnology on microalgae for improved production and harvesting. The results obtained show that microalgal-based compounds indeed have better nutrients content than natural foods. However, nanotechnology must be further comprehended to make them non-hazardous and sustainable. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microalgae have been exploited to produce healthcare and pharmaceutical products. • Microalgae species that are capable to produce metabolites are summarised. • Metabolites produced by microalgae were discussed with its benefits on health. • Future prospects for microalgae application are proposed and discussed. Microalgae are photoautotrophic microorganisms which comprise of species from several phyla. Microalgae are promising in producing a varieties of products, including food, feed supplements, chemicals, and biofuels. Medicinal supplements derived from microalgae are of a significant market in which compounds such as -carotene, astaxanthin, polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and polysaccharides such as –glucan, are prominent. Microalgae species which are commonly applied for commercial productions include Isochrysis sp. , Chaetoceros (Chlorella sp.), Arthrospira sp. (Spirulina Bioactive) and many more. In this present review, microalgae species which are feasible in metabolites production are being summarized. Metabolites produced by microalgae as well as their prospective applications in the healthcare and pharmaceutical industries, are comprehensively discussed. This evaluation is greatly assisting industrial stakeholders, investors, and researchers in making business decisions, investing in ventures, and moving the production of microalgae-based metabolites forward. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chlorophyll is important in assessing algae growth and producing nutraceuticals. • LR and ANN techniques are used to predict chlorophyll content in microalgae. • RMSE, prediction accuracy and R2 metrics are used as evaluation benchmarks. • Both prediction models are superior to conventional spectrophotometry method. • ANN with low RMSE is an efficient chlorophyll concentration prediction model. This study presented a novel methodology to predict microalgae chlorophyll content from colour models using linear regression and artificial neural network. The analysis was performed using SPSS software. Type of extractant solvents and image indexes were used as the input data for the artificial neural network calculation. The findings revealed that the regression model was highly significant, with high R2 of 0.58 and RSME of 3.16, making it a useful tool for predicting the chlorophyll concentration. Simultaneously, artificial neural network model with R2 of 0.66 and low RMSE of 2.36 proved to be more accurate than regression model. The model which fitted to the experimental data indicated that acetone was a suitable extraction solvent. In comparison to the cyan-magenta-yellow-black model in image analysis, the red–greenblue model offered a better correlation. In short, the estimation of chlorophyll concentration using prediction models are rapid, more efficient, and less expensive. [ABSTRACT FROM AUTHOR]

Macroalgae, with short growth cycles, and high CO 2 fixation capacity, are third-generation biomass mainstays that play an essential role as a global carbon sink. Macroalgal biochar plays a crucial role in soil improvement, pollutant adsorption, electrodes, and capacitors, and it has already contributed to both ecological and economic fields. However, the physicochemical properties of macroalgal biochar are challenging to control, and the way macroalgal biochar is pyrolyzed and activated largely determines its physicochemical properties and areas of application. In this study, five standard methods (conventional pyrolysis, hydrothermal carbonization, microwave pyrolysis, co-pyrolysis, and drying) for the pyrolysis of macroalgal biochar and two activation methods (physical and chemical) are reviewed to screen for optimal preparation and activation methods under different conditions and in different application contexts. The conventional pyrolysis process is mature and simple, but the yield is low, which is suitable for industrial production. Hydrothermal carbonization can reduce the content of alkali metals in biochar without prior drying. Microwave pyrolysis has low energy consumption and uniform product properties, which is suitable for biochar with high stability requirements. Co-pyrolysis is a low-cost pyrolysis method if suitable co-pyrolysis materials can be found. The drying ash content is high, but the surface performance is weak, which is generally used as pretreatment. From laboratory to practical applications, macroalgal biochar still needs to be investigated in terms of cost reduction, yield improvement, and optimization of preparation and activation methods. • The development of macroalgal biochar resources was reviewed. • Five common pyrolysis methods are compared. • Physical and chemical activation can improve the macroalgal biochar. • Doping with elements enhances its adsorption and electrochemical properties. • Analysis of risk assessment, long-term stability and economic value of macroalgal biochar are needed before practical use. [ABSTRACT FROM AUTHOR]