Search

The present work aims to evaluate the performance of a novel three-phase reactor Belt Conveyor Reactor BCR (with rotating sieve trays patent GB2567340B) as a photobioreactor compared with a traditional Airlift Bubble Column ALR, both influenced by the flow of the gas. Chlorella vulgaris was cultivated in these two photobioreactors using ambient air has a CO2 concentration of 0.038% with different aeration flowrates 0.145, 0.195, 0.24, and 0.29 vvm (gas volume per minute/liquid volume in the reactor).The maximum growth rate achieved on the 14th day of culture was 2.120 and 1.420 g/L for BCR, ALR respectively, with initial biomass concentrations of 0.2 g/L and aeration flow of 0.29 vvm. Moreover, the removal efficiency of carbon dioxide sequestration by the two photobioreactors is 40% for BCR and 25% for ALR. The innovative design succeeded in operational quality of agitation with high gas holdup inside the sieve trays to increase the biomass growth up to 50% higher than in the ALR. The maximum CO2 fixation for ALR was at about 18% at a specific aeration rate of 0.145 vvm in the bubbly regime. Whereas in the BCR can be reached about 38% with wide range operation condition of airflow rate 0.145–0.24 vvm due to well-distributed liquid due to rotating trays, and good gas–liquid mass transfer surface area.

In the microalgae harvesting process, which includes a step for dewatering the algal suspension, directly reusing extracted water in situ would decrease the freshwater footprint of cultivation systems. Among various algae harvesting techniques, membrane-based filtration has shown numerous advantages. This study evaluated the reuse of permeate streams derived from Scenedesmus obliquus (S. obliquus) biomass filtration under bench-scale and pilot-scale conditions. In particular, this study identified a series of challenges and mechanisms that influence the water reuse potential and the robustness of the membrane harvesting system. In a preliminary phase of this investigation, the health status of the initial biomass was found to have important implications for the harvesting performance and quality of the permeate stream to be reused; healthy biomass ensured better dewatering performance (i.e., higher water fluxes) and higher quality of the permeate water streams. A series of bench-scale filtration experiments with different combinations of cross-flow velocity and pressure values were performed to identify the operative conditions that would maximize water productivity. The selected conditions, 2.4 m·s−1 and 1.4 bar (1 bar = 105 Pa), respectively, were then applied to drive pilot-scale microfiltration tests to reuse the collected permeate as a new cultivation medium for S. obliquus growth in a pilot-scale photobioreactor. The investigation revealed key differences between the behavior of the membrane systems at the two scales (bench and pilot). It indicated the potential for beneficial reuse of the permeate stream as the pilot-scale experiments ensured high harvesting performance and growth rates of biomass in permeate water that were highly similar to those recorded in the ideal cultivation medium. Finally, different nutrient reintegration protocols were investigated, revealing that both macro- and micro-nutrient levels are critical for the success of the reuse approach.

Microbial nutrient recovery cell (MNRC) and microalgae-activated sludge (MAAS) are both the most attractive emerging methods of wastewater treatment technology due to their promising potential to revolutionize wastewater treatment systems. However, despite this giant stride both methods still have some limitations. To address some of these limitations such as energy cost-effectiveness and improved bio-resource recovery, this research integrated both MASS and MNRC for its feasibility studies and performance efficiency. Three sets of reactors including an MNRC-based reactor named microbial nutrient recovery cell (MNRC) reactor; and two MAAS photobioreactors (PBRs) at varying mix ratios of wastewater and pre-cultured microalgae; PBRI (80:20) and PBRII (70:30) were studied. Notably, the pre-cultured microalgae applied in the PBRs were inoculated with nutrients recovered from the MNRC encouragements representing the integrated MNRC-MAAS system. The outcome of microalgae preculture using recovered nutrients presents a chlorophyll concentration of 5.8 mg/L and dissolved (DO) saturation concentration of 14.33 mg/L with a person coefficient of correlation (r) of 0.99, The performance efficiency of the integrated MNRC-MAAS with PBRI(80:20) mix ratio by volume of Wastewater and Microalgae has a higher cumulative percentage removal efficiency of BOD5, NH4, NO3, and PO4 of 98.07 %, 92.05 % 88.07 %, and 90.96 % after 18 days hydraulic retention reactors compared to PBR(70:30) ratio. Consequently, The integrated MNRC-MAAS process has become an attractive alternative wastewater bioremediation with efficient resource recovery.

Systems biology is an interdisciplinary field that aims to understand complex biological processes at the system level. The data, driven by high-throughput omics technologies, can be used to study the underpinning mechanisms of metabolite production under different conditions to harness this knowledge for the construction of regulatory networks, protein networks, metabolic models, and engineering of strains with enhanced target metabolite production in microalgae. In the current study, we comprehensively reviewed the recent progress in the application of these technologies for the characterization of carotenoid biosynthesis pathways in microalgae. Moreover, harnessing integrated approaches such as network analysis, meta-analysis, and machine learning models for deciphering the complexity of carotenoid biosynthesis pathways were comprehensively discussed.

Density of microalgae is critical information for production of algae in a closed cultivation system since it can be used to optimally control their growth rate, biomass concentration and quality of the products. Given advancement in image processing techniques and thanks to low-cost camera sensors, image based methods are increasingly widely utilized to indirectly estimate the density. Advantages of the image based techniques include being less invasive and more nondestructive and biosecured. However, most of the existing techniques rely on averaging all pixels of a microalgae image, which may eliminate crucial information of their spatial correlation. Therefore, in this work we propose to exploit a convolutional neural network (CNN) to efficiently extract information from the microalgae images, which are then employed to regress the density. Interestingly, the proposed deep CNN regression model accepts the whole color image as its input while the density is calculated in the output. The proposed CNN regression architecture was validated in real-world experiments where the microalgal strain Chlorella vulgaris was cultured and their images were captured by our low-cost camera sensor system. The obtained results demonstrate that the averaged estimation accuracy of the proposed model is 99.45% (± 0.68%) while the R2 value between the density predictions and the ground truths is 0.9997, which is highly accurate and practical.

Selenium, an essential micronutrient with potent anticancer and antioxidant properties, the inorganic form of selenium is highly toxic, while organic and elemental nanoforms are more bioavailable and less toxic and have gained attention owing to their dietary and clinical relevance. This study aims to optimize conditions for the biosynthesis and production of elemental selenium nanoparticles for selenium supplements using marine microalgae, Nannochloropsis oceanica CASA CC201. The 10 mM precursor solution treated with 1 % of the algal extract (10:1 ratio of precursor and algal extract, respectively) was shown to be the optimal concentration for synthesizing highly stable selenium nanoparticles with a size of 183 nm and a zeta potential of −38.5 mV. AFM and TEM analysis suggest that the spherical-shaped nanoparticles with smooth surfaces were polydispersely distributed. The nanoparticles are well characterized using various analytical and advanced techniques, including Raman spectroscopy and X-ray photoelectron spectroscopy. FT-IR analyses reveal the presence of microalgae proteins and peptides as stabilizing and fabricating agents of Se-NPs to further understand the mode of bioreduction. The synthesized elemental nanoform (Se0) has been validated for its biological functions, showing enhanced radical scavenging activity (74 % in a concentration-dependent manner). Subsequently, algal-mediated selenite reduction and nanoparticle synthesis is an eco-friendly, non-toxic, and sustainable method for the large-scale production of highly stable Se-NPs for niche applications as dietary and feed supplements.

The present study investigated the embryonic development, growth, metamorphosis, locomotory patterns, and feeding behaviors of Paphia textile larvae, offering dietary suggestions based on observed patterns. The larvae were subjected to a dietary regimen consisting of nine microalgae species at various developmental stages (1, 4, 7, 10, 13, and 16 days post-hatching). One hour after each feeding session, their feeding patterns were carefully documented. To assess digestion, larvae that had consumed the microalgae were filtered, rinsed, and placed in filtered seawater. The embryonic development of P. textile encompassed distinct stages, including the fertilized egg, emergence of the first and second polar bodies, progression through the 2–32 cell stage, morula stage, blastula stage, gastrula stage, trochophore stage, and ultimately the D-larvae stage. Movement patterns revealed that the larvae primarily utilized their cilia for locomotion and feeding. From a transverse perspective, they moved clockwise, tracing an irregular circular path. Vertically, they exhibited spiral movements, ascending or descending as needed. As they entered the late stage, they transitioned to using reciprocal expansion of their axe feet for crawling and filtering food through their gills. Throughout their development, the larvae were fed a variety of microalgae species, including Chlorella vulgaris, Nannochloropsis oculata, Pavlova viridis, Dicrateria zhanjiangensis, and Isochrysis galbana. At 4 days old, they began consuming Dunaliella salina, and at 7 days, they incorporated Platymonas subcordiformis into their diet. By 10 days of age, they had expanded their food choices to include Chaetoceros muelleri. However, it was noted that larvae frequently suffered from indigestion or incomplete digestion when fed excessive amounts of C. vulgaris and N. oculata. Therefore, it is recommended to commence the larval culture of P. textile using P. viridis, D. zhanjiangensis, and I. galbana as the primary dietary sources. Furthermore, a feeding strategy emphasizing small, frequent meals is recommended to promote optimal digestion and larval health.

One of the challenges in the aquaculture industry is providing nutritionally balanced and environmentally sustainable live food for fish larvae. Therefore, the rearing techniques of fish larvae with preferred starter food should be given importance for obtaining optimal hatchery production. Nile tilapia, Oreochromis niloticus larvae just after yolk absorption (body length 0.950 ± 0.004 mm; body weight 6.00 ± 0.02 mg) were reared in laboratory conditions for 16 days, feeding with 6 different diets to know their effect on survival and growth. The diets were live Monoraphidium littorale (T1), live enriched copepods with M. littorale (T2), powdered M. littorale (T3), powdered enriched copepods (T4), live M. littorale + live enriched copepods (T5), and powdered M. littorale + powdered enriched copepods (T6). The proximate composition, amino acid profile and fatty acid content of both M. littorale and copepods were analyzed. The biochemical analysis of the dried powder of enriched copepods and M. littorale revealed that both of them are excellent sources of protein, amino acids, and lipids, especially with monounsaturated and polyunsaturated fatty acids. The O. niloticus larvae fed the T2 diet exhibited the most favourable outcomes, with significantly higher larval gain in weight and percent weight gain, in comparison to the larvae fed other diets (p

The planktonic Crustacea Daphnia are among the most employed organisms in ecotoxicology, mainly in regulatory assays that follow OECD/ISO protocols. The most common endpoint for acute testing (24–48 h) without feeding of organisms is usually monitored as mortality or immobilization. A rapid and physiologically and environmentally more relevant toxicity endpoint could be the impaired feeding of daphnids. Decreased feeding of test organisms upon exposure to toxicants has been used to evaluate sub-lethal effects occurring already in minutes to hours. This endpoint, however, has not been used systematically and the respective data are inconsistent due to heterogeneity of experimental design. The aim of this review is to evaluate the scientific literature where impaired Daphnia feeding has been used in ecotoxicological research. The search made in WoS (June 5, 2024) using combination of keywords “Daphni* AND feed* yielded 152 articles. Out of these 152 papers 46 addressed feeding of daphnids upon exposure to various toxicants (insecticides, heavy metals, pharmaceuticals, contaminated environmental samples and toxic cyanobacteria; in total 59 different chemicals/combinations). These 46 papers formed the basis of the critical analysis presented in the current review. For 18 chemicals it was possible to compare the sensitivity of the feeding and mortality endpoints. We conclude that although the feeding inhibition of Daphnia sp. did not prove systematically more sensitive than mortality/immobilization, it is a sub-lethal endpoint that allows rapid evaluation of toxic effects of chemicals to aquatic crustaceans – important and sensitive organisms in the aquatic food web.

The global community faces critical energy and environmental challenges, necessitating innovative solutions to ensure a sustainable future.In response to these challenges, this paper explores the potential of integrating microalgal biotechnology with renewable energy systems within buildings. This innovative approach could transform architecture into a ''bio-factory'' capable of producing food, energy, and other valuable products.The success of this concept hinges on developing highly efficient photobioreactors specifically designed for building integration. Optimizing these systems requires careful consideration of design parameters, growth rate models, and factors influencing performance within diverse urban environments.Furthermore, integrating these systems must prioritize productivity and aesthetics to promote urban self-sufficiency and a sustainable built environment. By utilizing microalgae and renewable energy sources, building-integrated photobioreactors offer a promising solution for reducing energy consumption and carbon footprints in modern buildings.

Microalgae are being recognized as the key contributor to sustainability in many sectors, starting from energy up to food industries. The microorganism has also been utilized as environmental remediator, capable of converting organic compounds into economically valuable biomass. To optimize the use of microalgae in these sectors, researchers have explored various approaches, of which is the use of bacteria. The interaction between bacteria and microalgae can potentially be harnessed, but its complexity requires extensive research. Herein, we present the bibliometric analysis on microalgal-bacterial interactions. The metadata of published literature was collected through Scopus database on August 4, 2023. The downloaded.csv file was uploaded to VOSViewer and biblioshiny for network visualization. We found that the research has gained a lot of attention from researchers since 2012 with an exponential increase of the publication number. The United States and China are leading the research with a strong collaboration. Based on the research sub-topic clusters, the interaction is mostly studied for wastewater treatment, biomass production, and algal bloom control. Updated reviews on this topic reveal that researchers are now focus on optimizing the efficacy of microalgae-bacteria system, investigating the modes of actions, and identifying challenges in its real-world implementation. The microalgal-bacterial interaction is a promising approach for microalgae utilization in wastewater treatment, biomass production, and algal bloom control.

Microalgae are increasingly recognized as promising sources of natural bioactive compounds. However, traditional extraction methods using volatile organic solvents (VOCs) pose environmental risks. This study explores renewable deep eutectic solvents (DES) as sustainable alternatives for extracting bioactive compounds from microalgae biomass, focusing on Chlorella vulgaris and Scenedesmus incrassatulus. Four DES systems, comprising choline chloride (ChCl) and glycerol, citric acid, urea, and glucose, were compared with three conventional solvents (ethanol, methanol, and water). Extraction efficiency was assessed based on total phenolic content (TPC), flavonoid content, and tannin content, followed by antioxidant activity evaluation using DPPH, CAT, and FRAP assays. Additionally, antibacterial activity of the DES extracts was determined against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 29213), and Bacillus subtilis (ATCC 3366) using disc diffusion and microplate dilution methods to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results reveal that DES, particularly choline chloride: citric acid, outperform conventional solvents in terms of polyphenol extraction efficiency, antioxidant activity, and antibacterial activity against both Gram-negative and Gram-positive bacteria. For instance, the citric acid-based DES (SIDES2) showed a TPC of 4.98 mg/g, while the conventional solvent ethanol exhibited a TPC of 3.27 mg/g. Additionally, SIDES2 exhibiting the highest DPPH scavenging activity of 75 %, compared to 60 % for ethanol. Furthermore, SIDES2 showed an MIC of 0.5 mg/ml against Staphylococcus aureus. This study underscores the potential of DES for sustainable extraction of natural antioxidants from microalgae biomass, contributing to the development of environmentally friendly extraction processes in various industries.

This study introduced an innovative pathway utilizing an algal anaerobic ammonium oxidation (ALGAMMOX) system to treat ammonium wastewater. Lake bottom sludge and anammox sludge were used to cultivate functional microorganisms and microalgae for nitrogen removal in an upflow reactor made of transparent materials. The results showed that the ALGAMMOX system achieved 87.40 % nitrogen removal when the influent NH4+-N concentration was 100 mg-N/L. Further analysis showed that anammox bacteria Candidatus Brocadia (8.87 %) and nitrosobacteria Nitrosomonas (3.74 %) were crucial contributors, playing essential roles in nitrogen removal. The 16S rRNA gene showed that the anammox bacteria in the sludge transitioned from Candidatus Kuenenia to Candidatus Brocadia. The 18S rRNA gene revealed that Chlamydomonas, Bacillariaceae and Pinnularia were the dominant microalgae in the system at a relative abundance of 7.99 %, 3.64 % and 3.14 %, respectively. This novel approach provides a theoretical foundation for ammonium wastewater treatment.

Phycoerythrin (PE) extraction from Porphyridium sp. was studied employing ultrasound-assisted extraction combined with aqueous mixtures of two imidazolium-based ionic liquids (ILs) simultaneously, marking a significant novelty. A face-centred central composite design and response surface optimised PE yield (EPE), considering the effects of ionic liquid concentration (IL), [Emim][EtSO4]/[Bmim][EtSO4] mass ratio (E/B), biomass concentration (BM), and time (t). Improvements in EPE by 300 % and 115 % were achieved compared to a phosphate buffer solution and the freeze-thaw method, respectively. Temperature and pH effects were examined independently, leading to the determination of optimal operating conditions: BM = 10 mg mL−1, IL = 18.6 wt%, E/B = 0.78/0.22, t = 10 min, T = 35 °C, and pH = 7.5. Results indicated the potential for reusing the ILs for at least five consecutive extraction cycles, maintaining an EPE of 94.2 % compared to fresh ones. This underscores the success and innovation of the developed technology in enhancing PE extraction from Porphyridium sp.

ABSTRACT: Heat stress can greatly challenge growth and meat quality of broiler chickens where research is looking for sustainable ingredients, such as microalgae, that could also alleviate its negative impacts. Thus, in the present study, 576 1-D-old chicks (Ross 308) were housed until commercial slaughtering (42 D) in 36 pens in 2 rooms of a poultry house, according to a full factorial design encompassing 2 room temperatures (standard vs. high), 2 sexes (females vs. males), and 3 dietary treatments, that is, diet C0 (control diet), diet C3, and diet C6 containing 0, 3, and 6%, respectively, of C. vulgaris meal replacing the same quantities of soybean meal. The highest inclusion level of C. vulgaris decreased feed intake (P < 0.001) and body weight (P < 0.0001) compared to the control diet; it increased yellow and red indexes (P < 0.0001) of the breast muscle, besides the proportion of n3 polyunsaturated fatty acids (PUFA) (P = 0.028). Heat stress decreased feed intake (P = 0.001), breast (P = 0.001) and p. major yields (P = 0.036), and increased meat pH (P= 0.008) and cooking losses (P < 0.001), umami (P = 0.021) and brothy flavor (P < 0.001), and the proportion of n3 PUFA rates (P = 0.027), while reducing the contents of several amino acids in the breast meat (P ≤ 0.05). Compared to females, males displayed higher feed intake and growth, and more favorable feed conversion (P < 0.001). Carcass and p. major yields were greater in females (P < 0.001) which also showed a higher occurrence of spaghetti meat compared to males (P < 0.001). In conclusion, C. vulgaris can be used to replace until 3% of soybean meal in diets for broiler chickens without negative implications, while positively affecting breast meat color according to consumers’ preferences. However, the microalgae inclusion did not mitigate the negative effects of a chronic heat stress on growth performance nor reduced the occurrence of any myopathies.

Mismanaged plastics, upon entering the environment, undergo degradation through physicochemical and/or biological processes. This process often results in the formation of microplastics (MPs), the most prevalent form of plastic debris (

Pollution of rivers is mainly caused by anthropogenic activities such as discharge of effluent from industrial facilities, maintenance of sewage/effluent treatment plants, and dumping of solid waste on river banks. This study dealt with the pollution issues of the Cooum River in the well-known city of Chennai in South India. Water samples from 27 locations were collected and analyzed for 12 elements, including Ba, B, and Al, as well as heavy metals such as Pb, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Cd. The samples showed levels of these elements that exceeded World Health Organization recommendations. Pearson correlation analysis revealed the inter-dependency among elements, and the contribution of each element based on factor loadings showed its percentage contribution compared to others. Water samples from six significant locations were chosen for remediation with three algae: Chlorella vulgaris, Scenedesmus dimorphus, and Phormedium sp. The uptake of pollutants led to the continuous growth of algae during the incubation period of 15 d, effectively removing heavy metals from the river water. The increasing levels of algal counts and the chlorophyll a content confirmed the algal growth during the incubation period, followed by a declining stage after the incubation period. The scanning electron microscopic images of algae before and after the remediation showed no remarkable modification of morphological patterns. This study showed that the uptake of heavy metals using algae is an effective water pollution remediation measure, making the process practicable in the field on a large scale in the near future.

Background: For use in specialized programs in the food, pharmaceutical, nutraceutical, cosmetic, and animal feed sectors, micro-algal biomass has been generated industrially. They can be grown in closed buildings, such as photobioreactors, or open structures. The utilization of biomass from microalgae for energy production is another crucial topic. Because of the world’s diminishing petroleum sources and the greenhouse gas emissions from gasoline lines, it is now obvious that fuels generated from petroleum are not sustainable. Results: Microalgae can produce a variety of unique, sustainable biofuels. These include biodiesel made from trans-esterification of microalgal lipids, bioethanol from fermentation of carbohydrates, methane created by anaerobic digestion of algal biomass, and biohydrogen produced by photobiological processes. The idea of using microalgae as a fuel source is not entirely novel. Conclusion: This analysis emphasizes the significance of recent and noteworthy advancements in the industrial usage of microalgae, with an emphasis on their biotechnological applications.

Microalgae are a diverse group of microorganisms with a wide range of physical characteristics and interactions with their surroundings. They hold great promise as strategic crops capable of producing substantial quantities of valuable biomolecules, such as protein and omega-rich oils, which have extensive applications across multiple industries. This perspective aims to provide an overview of recent advancements in the utilization of photobioreactors for the large-scale cultivation of microalgae. It also delves into the implications of this technology on factors such as land efficiency, environmental impact, and the biochemical composition of microalgae. In this manuscript, the potential solution to these challenges lies in the adoption of vertical semi-closed photobioreactors, which seamlessly integrate photobioreactor technology with principles of vertical farming. This perspective effectively underscores the pivotal role of photobioreactors in mitigating global climate change, as they contribute to processes such as carbon dioxide (CO2) sequestration, conversion of greenhouse gases into increased biomass production, enhancement of air quality, and the modulation of climatic parameters. Furthermore, photobioreactors have the capacity to boost the production of bioactive compounds and biomass yields. For future considerations, we propose that the application of microalgae kinetics should be employed to gain a deeper understanding of microalgae production. This knowledge forms a critical foundation for the design and optimization of photobioreactors and the manipulation of microalgae metabolites, thus offering a pathway toward sustainable and efficient microalgae-based bioprocessing.

Microplastic pollution has been deemed a serious environmental concern for many developing countries, including Vietnam. Thus, bioplastics produced from sustainable materials by microorganisms have been sourced as an alternative to mitigating microplastic pollution. This study conducted the screening of 47 strains of microalgae and cyanobacteria sourced from various locations and environmental conditions in Vietnam for the production of polyhydroxyalkanoates (PHAs) as a source of bioplastics. The experimental results demonstrate that 15 out of the total 47 screened microalgae and cyanobacteria strains could produce PHAs, and they exhibited diverse PHAs production despite being grown under the same incubation conditions. Furthermore, amongst these 15 strains, Arthrospira platensis NLHT3, Microcystis aeruginosa DTB1, Arthrospira platensis NLNA2, and Arthrospira platensis NBQN1 exhibited the highest PHAs accumulation rates of 4.18 %, 3.46 %, 3.01 %, and 2.82 % of cell dry weight, respectively. The analysis of polymer granules accumulated inside the cell biomass by transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR) confirms that the accumulated biopolymers were PHAs.

This study investigated ten electrode materials for electrocoagulation-flotation (ECF) of Chlorella vulgaris. Magnesium showed the highest separation efficiency (98.7 %), followed by aluminum (97.34 %), iron (94.42 %), copper (93.17 %), zinc (91.65 %), nickel (91.50 %), lead (90.31 %), titanium (87.14 %), brass (84.92 %), and stainless steel (78.8 %). ECF increased the pH of the medium from 8.48 to the highest 10.89 by the brass electrode. Separated medium from all electrode materials after the ECF process can be recycled for further microalgae cultivation, which could economize water resources and reduce costs. This study underscores the ECF's efficacy for efficient and sustainable biomass recovery, especially using magnesium electrodes.

Microalgae have been highlighted as a contributor to CO2 sequestration due to their efficient photosynthetic system. However, calculations on their actual potential for CO2 sequestration are often lacking. Here, we calculated the potential of microalgae for the capture of CO2 by integrating it with a large emitter (gas-based energy plant) and a low emitter (dairy farms), and also discussed if such integrated systems can be considered as carbon sequesters given that the final use of the biomass often quickly releases the captured CO2. Moreover, the CO2 footprint of microalgal systems is highlighted as a critical point of attention for future developments. Such considerations are of utmost importance to avoid false promises that ultimately harm this sector, as large investments are made following untruthful claims that, when proven wrong, result in a loss of interest. Finally, key definitions are proposed to improve clarity and help in such discussions.

Microalgae have emerged as a storehouse of biologically active components having numerous health benefits that can be used in the formulation of nutraceuticals, and functional foods, for human consumption. Among these biologically active components, functional triacylglycerols are increasingly attracting the attention of researchers owing to their beneficial characteristics. Microalgae are excellent sources of triacylglycerol containing omega-3 and omega-6 fatty acids and can be used by the vegan population as a replacement for fish oil. The functional triacylglycerols extracted using conventional processes have various drawbacks resulting in lower yield and inferior quality products. The non-thermal technologies are emerging as user-friendly and environment-friendly technologies that intensify the yield of final products and maintain the high purity of extracted products that can be used in food, cosmetic, pharmaceutical, and nutraceutical applications. The present review focuses on major non-thermal technologies that can probably be used for the extraction of high-quality functional triacylglycerols from microalgae.

The biogas production from microalgae has gained attention due to fast depleting of fossil fuels and oil reserves. This study evaluated the anaerobic co-digestion of microalgae in various concentrations with cow manure to enhance biogas production. The biogas production of each experiment was measured using the water displacement method. The results indicated that the addition of microalgae significantly enhanced biogas production. Particularly, high methane yield of Anabaena sp. 50 %, Chlorella sp. 50 %, control was 345 ± 2.88 mL CH4/g VS, 297.96 ± 0.49 mL CH4/g VS, 138.32 ± 0.50 CH4/g VS respectively. The slurry produced by 50 % Anabaena sp. biogas plant exhibited the greatest level of seed germination. The current study demonstrated that Sorgham bicolor had the highest seed germination rate (94.2 %) root and shoot length of all crops. Therefore, it is possible to employ Anabaena sp. (50 %) and Chlorella sp. (50 %) in the rapid production of biogas. Moreover, agricultural output would be increased by using biogas slurry.

Microalgae are a promising sustainable food source with high nutritional value and environmental benefits. This study investigated the presence of toxic metals and rare earth elements (REEs) in 68 microalgal-based food products and conducted a probabilistic risk assessment to evaluate potential health risks. The findings revealed high detection rates of REEs (80.96% to 100%) and heavy metals (83.82% to 100%), with REE concentrations ranging from 0.0055 to 0.5207 mg/kg. Heavy metals were detected at the following average concentrations: As (2.80 mg/kg) > Cr (1.27 mg/kg) > Pb (0.30 mg/kg) > Cd (0.20 mg/kg) > Hg (0.01 mg/kg). Carcinogenic risk analysis for Cd (3.004 × 10−3), Cr (1.484 × 10−3), and As (1.1283 × 10−2) indicated that 95th percentile values exceeded established safety thresholds (10−4). These findings highlight the critical need for stringent monitoring and the establishment of comprehensive regulatory frameworks for the safety of novel microalgae foods.

The recent fast development of the microalgae-related biotechnologies has enabled the availability of sustainable and nutrients-rich raw materials to be used as substitution of conventional sources in aquafeed formulation. However the cost of energy of the photobioreactors used to produce these microorganisms still constrained their wider inclusion into aquafeed compounds. By exploiting industrial waste outputs, Nannochloropsis sp. and Spirulina sp. were produced and utilised to formulate two experimental enrichments (LM1 and LM2). During a 60 days trial, their efficacy have been tested as Artemia metanauplii enrichments in the diet of European seabass (Dicentrarchus labrax) larvae, in comparison to a commercial control. Larvae were fed with isonitrogenous and isolipidic dietary treatments. Each dietary treatment presented a specific profile for the long chain polyunsaturated fatty acids ARA, DHA and EPA. Ratio of DHA/EPA in enriched Artemia of 4:1 as in the case of LM1 and LM2 in the presence of 1.4% of ARA (as a % on total fatty acid) guaranteed equal results to the control which displayed a ratio of DHA/EPA of 2:1 with 2.2% of ARA. No significant effects of the dietary treatments were detected in final survival, growth performance and incidence of skeletal anomalies. Regarding oxidative status, larvae fed with LM2 enrichment presented lower catalase activity than control larvae with no signs of oxidative damage, suggesting a potential antioxidant effect of LM2. The present study contributes to expanding the existing literature on successful utilisation of microalgae and cyanobacteria, used to produce valuable nutrients, in a perspective of circular nutrients economy.

Consumers increased demand for food products that promote health has compelled the food processing industry to develop food products that not only satiate hunger but also aid in the prevention of non-communicable diseases. Microalgae have emerged as a potential source of functional components like triacylglycerols containing essential fatty acids that could be used in the formulation of functional food products. These components help prevent non-communicable diseases due to their inherent characteristics like anti-oxidative, anti-cancer, anti-diabetic, anti-inflammatory, etc. The microalgae are concentrated sources of triacylglycerols containing essential fatty acids and are considered a potential replacer for fish oil in providing these functional ingredients also well accepted by the vegan. This review aims to cover the literature on the triacylglycerol content of microalgae with a focus on the functional triacylglycerol, the fatty acid composition of triacylglycerol extracted from different microalgal biomass, innovative extraction technologies for intensified extraction, the potential use of triacylglycerols from microalgae in the formulation of functional food products. Further, the present constraints and future prospectus in using microalgal triacylglycerol in functional food are also discussed.

Microplastics (MPs) are emerging contaminants that have harmful effects on ecosystems. Microalgae are important primary producers in aquatic environments, providing nutrients for various organisms. These microorganisms may be affected by MPs. Therefore, it is important to investigate the toxicity aspects of different MPs on Chlorella species. It can be seen that the BG-11 culture medium was the most commonly used medium in 40 % of the studies for the growth of Chlorella sp. Chlorella sp. grows optimally at a temperature of 25 °C and a pH of 7. Most studies show that Chlorella sp. can grow in the range of 3000–6000 lux. Moreover, various techniques have been used to analyze the morphological properties of MPs in different studies. These techniques included scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM), which were used in 65 %, 35 %, and 27 % of the studies, respectively. 53 % of the research has focused on the toxic effects of PS on Chlorella sp. Findings show that 41 % of the studies investigated MPs concentrations in the range of 10–100 mg/L, followed by 32 % of the studies in the range of 100–1000 mg/L. The studies found that MPs were used in a spherical shape in 45 % of the cases. The enzymes most affected by MPs were superoxide dismutase (SOD) and Malondialdehyde (MDA), accounting for 48 % of the studies each. Additionally, exposure to MPs increased the activity of enzymes such as SOD and MDA. In general, it can be concluded that MPs had a relatively high negative effect on the growth of Chlorella sp.

Chlorella vulgaris is a microalga rich in proteins with potential applications in food and feed industries. However, the presence of a cellulose-containing cell wall, which is a major barrier to protein extraction, together with fibroproteinaceous complexes, limits the bioaccessibility of nutritional and bioactive proteins and peptides from C. vulgaris biomass. Therefore, this study aimed to evaluate the effect of different mechanical/physical pre-treatments (bead milling, extrusion, freeze-drying, heating, microwave and sonication) combined or not with enzymatic treatments (commercial trypsin and pancreatin) on protein extraction and peptide formation from a C. vulgaris suspension. The amount of total protein and peptides released to the supernatant was quantified by Bradford and o-phthaldialdehyde assays, respectively. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis was used to analyse the extracted protein fractions. The results showed that extrusion caused a 3-fold increase in total peptides (p

Fatty acids are of particular interest for industrial applications of microalgal feedstock, as these have a wide array of different uses such as pharmaceuticals and biofuels. Fourier transform infrared (FTIR) spectroscopic techniques used in combination with multivariate prediction modeling are showing great potential as analytical methods for characterizing microalgal biomass. The present study investigated the use of diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) coupled with partial least squares regression (PLSR) to estimate fatty acid contents in microalgae. A prediction model for microalgal samples was developed using algae cultivated in both Bold's basal medium (BBM) and sterilized municipal wastewater under axenic conditions, as well as algal polycultures cultivated in open raceway ponds using untreated municipal wastewater influent. This universal prediction model was able to accurately predict microalgal samples of either type with high accuracy (RMSEP = 1.38, relative error = 0.14) and reliability (R2 > 0.92). DRIFTS in combination with PLSR is a rapid method for determining fatty acid contents in a wide variety of different microalgal samples with high accuracy. The use of spectral characterization techniques offers a reliable and environmentally friendly alternative to traditional labor intensive techniques based on the use of toxic chemicals.

The current study aimed to screen biofilm-/mat-forming and fast-growing algal communities from the Garhwal Himalayas, India. A total of 15 biofilm/mat-forming algal samples were collected, 8 biofilms out of these could be cultured and analyzed for their growth and development with time. Light microscopy was used to identify different types of cyanobacteria and algae present in the different collected biofilms/mats. Four biofilm and mat communities, namely biofilms #E, #F, #G, and #H, were found to have fast growth and were quick to colonize the substratum. Nylon net was identified as the most cost-effective and best-supporting material for biofilm development and biomass production. The study also found that increasing the harvesting frequency from the nylon net-enmeshed biofilms at least once a week would enhance the final biomass yield compared to harvesting the community once after a longer growth duration. Nevertheless, the findings reported here will be useful for researchers in developing phototrophic biofilm-based technology using nylon net, as it will be mechanically strong, supportive, and easy to handle.

Commercial microalgae cultivation is a dynamic field with ongoing efforts to improve efficiency, reduce costs, and explore new applications. We conducted a study to examine how different light exposure periods affect Chlorella vulgaris's growth. We employed a Phyto tank batch system of approximately 3.5 L with LED light control, controlled airflow, and sterilized bags, maintained at 22.0 ± 2.0 °C indoors. Various methods, including spectrophotometry, and cell counter were employed to monitor Chlorella vulgaris growth under different light exposure cycles. Additionally, quality analysis as feed source was employed by proximate, amino acid, beta-glucan, and microbial content analysis. The results revealed significant variations in C. vulgaris biomass production based on light exposure duration. Notably, the 16:8-h light-dark photoperiod exhibited the highest biomass concentration, reaching 6.48 × 107 ± 0.50 cells/mL with an optical density (OD) of 1.165 absorbance at 682 nm. The 12:12-h light-dark photoperiod produced the second-highest biomass concentration, with 2.305 × 106 ± 0.60 cells/mL at an OD of 0.489. Proximate analysis of dry algae powder revealed low lipid content (0.48 %), high protein content (37.61 %), variable ash concentration (average 10.75 %), and a significant carbohydrate fraction (51.16 %) during extended daylight and shorter dark periods. Amino acid analysis identified nine essential amino acids, with glutamic acid being the most abundant (17.7 %) and methionine the least (0.4 %). Furthermore, quality analysis and microbiological assays demonstrated that the C. vulgaris biomass is well-suited for fish and livestock use as a feed source and possibility as human nutraceuticals. These findings can be considered more environmentally friendly and ethically sound due to the absence of genetic modification.

Microalgae are new and sustainable sources of starch with higher productivity and flexible production modes than conventional terrestrial crops, but the downstream processes need further development. Here, ultrasonication (with power of 200 W or 300 W and duration of 10, 15, 20, or 25 min) was applied to simultaneously extract and modify starch from a marine microalga Tetraselmis subcordiformis for reducing the digestibility, and an aqueous two-phase system (ATPS) of ethanol/NaH2PO4 was then used to isolate the starches with varied properties. Increasing ultrasonic duration facilitated the partition of starch into the bottom pellet, while enhancing the ultrasonic power was conducive to the allocation in the interphase of the ATPS. The overall starch recovery yield reached 73 ∼ 87 % and showed no significant difference among the ultrasonic conditions tested. The sequential ultrasonication-ATPS process successfully enriched the starch with purities up to 65 % ∼ 88 %, which was among the top levels reported in microalgal starch isolated. Ultrasonication produced more amylose which was mainly fractionated into the interface of the ATPS. The digestibility of the starch was altered under different ultrasonic conditions and varied from different ATPS phases as well, with the one under the ultrasonic power of 200 W for 15 min at the bottom pellet having the highest resistant starch content (RS, 39.7 %). The structural and compositional analysis evidenced that the ultrasonication-ATPS process could exert impacts on the digestibility through altering the surface roughness and fissures of the starch granules, modulating the impurity compositions (protein and lipid) that could interact with starch, and modifying the long- and short-range ordered structures. The developed ultrasonication-ATPS process provided novel insights into the mechanism and strategy for efficient production of functional starch from microalgae with a potential in industrial application.

Microalgae has great potential in carbon sequestration and production of biofuel even with a low concentrations of CO2. In this paper, an Andrews based microalgae growth kinetic model and a novel and multiple nutrient supplementary scheme that significantly extends the carbon sequestration period and enhances growth rates of microalgae are proposed. First, the correlation between nutrient concentration and microalgal growth is constructed experimentally. The advanced growth kinetic model incorporating nitrogen and phosphorus consumption is developed. Then, the optimum cultivation conditions including initial nutrients concentration, nutrients supplementary interval and daily nutrients supplementary quantities are obtained in the conical flask reactor. The findings led to a novel nutrient supplementation strategy that initiates with a 0.2BC concentration, followed by a 0.3BC addition at 100 h, with subsequent supplements every 72 h. After adopting this supplementary strategy, the microalgae growth rate is increased by 42.9 % and the carbon sequestration rate is increased by 56.2 % compared with that of the original microalgae cultivation method in one cultivation cycle. Finally, the universal microalgae nutrients supplementary model is proposed in a piecewise model. It can be concluded from the model that in the first cultivation period, microalgae needs a higher affinity for nutrients and after nutrients supplementary, the sensitivity to nutrient inhibition is reduced. The paper is significantly helpful to improve the sustainability of the microalgae growth rate and the carbon sequestration rate.

Metabolomics, a recent addition to omics sciences, studies small molecules across plants, animals, humans, and marine organisms. Nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC–MS) are widely used in those studies, including microalgae metabolomics. NMR is non-destructive and highly reproducible but has limited sensitivity, which could be supplemented by joining GC–MS analysis. Extracting metabolites from macromolecules requires optimization for trustworthy results. Different extraction methods yield distinct profiles, emphasizing the need for optimization. The results indicated that the optimized extraction procedure successfully identified NMR and GC–MS-based metabolites in MeOH, CHCl3, and H2O extraction solvents. The findings represented the spectral information related to carbohydrates, organic molecules, and amino acids from the water-soluble metabolites fraction and a series of fatty acid chains, lipids, and sterols from the lipid fraction. Our study underscores the benefit of combining NMR and GC–MS techniques to comprehensively understand microalgae metabolomes, including high and low metabolite concentrations and abundances. • In this study, we focused on optimizing the extraction procedure and combining NMR and GC–MS techniques to overcome the low NMR sensitivity and the different detected range limits of NMR and GC–MS. • We explored metabolome diversity in a tropical strain of the small cells’ diatom Cheatoceros tenuissimus.

This study aimed to investigate the potential of Spirulina platensis (SP), a high protein content microalgae species, to be used as feedstock for a new type of solid biofuel technology, namely bio-coke. The SP bio-coke production was conducted at different formation temperatures of 130, 150 and 170 °C without any binder. The results showed that SP BIC 150, which was produced at the optimum formation temperature of 150 °C, exhibited the highest density and mechanical strength when compared with that of SP BIC 130 and SP BIC 170. This means that it strongly influenced its stable structure during the combustion process. With the strong structure of SP BIC 150, the breakdown of bio-coke can be prevented during flame combustion, thereby contributing to a longer char and total combustion time. The conversion of SP microalgae showed good potential to be used as an alternative renewable energy source in the future.

SUMMARY: Spirulina platensis is an emerging poultry diet source due to its essential nutrition and bioactive ingredients. Spirulina microalgae confers beneficial effects on broiler's growth performance, immune response, and antioxidant activity. We investigated the effect of Spirulina platensis on BCO lameness, one of the most driving factors for economic and animal well-being concerns in the poultry industry. Additionally, supplementation of Availa ZMC containing organic trace minerals – zinc, manganese, and copper – was shown to alleviate lameness by 20 to 25%. We hypothesized that pairing microalgae and organic trace minerals might confer a synergistic effect in reducing BCO. A 2 × 2 factorial study, with microalgae (5% Spirulina platensis and 5% Spirulina platensis plus 0.15% Availa ZMC) and without microalgae (0.15% Availa ZMC and a negative control diet), plus one BCO source group were applied to 1,320 one-day-old chicks with 5 replicates of 60 chicks per treatment for lameness assessment. No significant difference in lameness was observed between the negative control and BCO source group (60.0% vs. 54.5%, P = 0.56). Compared to the negative control, Availa ZMC significantly reduced lameness by 51.2% (60.0% vs. 29.3%, P < 0.001), while microalgae slightly increased lameness by 6.3% (60.0% vs. 63.8%, P = 0.1). Availa ZMC plus microalgae alleviated lameness by 16.7% (50.0% vs. 60.0%, P = 0.005) compared to the negative control, which was statistically lower than microalgae alone and higher than Availa ZMC alone. These findings suggested the inclusion of 5% Spirulina platensis did not reduce BCO lameness, while Availa ZMC significantly alleviated lameness. When combined, there was no significant interaction between Availa ZMC and microalgae in mitigating broiler lameness.

The world population is expected to reach 9.8 billion by 2050 according to a report by the United Nations. The global demand for alternative proteins from different sources, such as microalgae, mycoproteins, insects, cell-based, cultured meat, meat substitutes, dairy alternatives, and fungi-based proteins, is projected to reach USD 290 billion by 2035. Due to their similar characteristics, offered at a relatively more affordable cost than animal proteins, alternative plant-based proteins are experiencing significant global demand. In recent years, industrial production of microalgal biomass has received attention due to its rich content of quality proteins, lipids, fatty acids, and pigments, whose products are of commercial interest in the field of food technology and engineering. Microalgae can be grown easily in open and closed systems for biomass and high-value products. Spirulina and Chlorella have the outstanding ability to accumulate protein and have already been used in meat substitutes, food products, feed, nutraceuticals, and pharmaceuticals. Here, we review the current literature, including new insights into the patent landscape about algal protein wholistically for its quality, culture conditions, recovery, and potential applications for food uses, and discuss its potential to find alternative protein sources for global needs.

Photosynthesis is the natural eternal process of conversion of solar energy into Chemical energy by living chlorophyllous organisms. The direct conversion of sunlight into electrical current by using photosynthetic organisms has the potential to produce green energy. Conventional bio-photovoltaic cells have utilized unicellular photosynthetic microorganisms such as cyanobacteria and unicellular green algae. This study describes electricity generation through a quasi-solid-state device by utilizing live freshwater macroalgae. Here, we fabricated a simple bio-photovoltaic device with filamentous macroalgae Pithophora roettleri as photoactive materials. The filamentous alga Pithophora belonging to the family of green algae, is generally found growing at the bottom or forming dense mats on the surface of aquatic habitats. The algae were collected from a pond located in the neighbourhood and fabricated a device by sandwiching the algal biofilm between activated carbon-coated copper (Cu) and titanium oxide (TiO2) coated fluorine-doped tin oxide (FTO) coated glass slide. The fabricated optimized device has exhibited a considerable amount of photo-generated current and photo-generated voltage generation under the white light and UV light irradiation The optimized device (with 1 cm2 area) exhibits 10.19 μA short circuit photocurrent and 0.35 V open circuit photovoltage in white light (100 mW/cm2) irradiance and exhibits 1.25 mA photocurrent and 0.5 V photovoltage in UV light (365 nm LED with 20 mW/cm2 intensity). To understand applicability, 10 devices were connected in a series that delivered 5.53 V in outdoors under natural sunlight with 0.6 Sun intensity.

Microalgae is a sustainable biological resource since it can be used in biodiesel production, pharmaceutical development, nutritional supplements, carbon dioxide sequestration, and wastewater remediation. Due to its high lipid content and low carbon dioxide emissions, microalgae-derived biodiesel can replace fossil fuels. Microalgae biomass production involves cultivation, harvesting, and drying. To develop microalgae and produce high-quality biomass, culture procedures must be optimized. Microalgae cultivation is affected by a range of physical and chemical parameters, including light intensity (I), temperature (T), carbon dioxide (CO2), pH, dissolved oxygen (DO), and oxidation reduction potential (ORP). The objective of this study is to examine the impact of physico-chemical factors on the cultivation process of Synechococcus HS-9 in order to generate dry biomass. ANN and multi-objective genetic algorithms will also be used to optimize cultivation. The five main procedures of this study are: 1) preparation of the cultivation medium; 2) Synechococcus HS-9 inoculum and utilization of a photobioreactor; 3) inoculation; 4) cultivation and physical-chemical parameter data collection; and 5) prediction and optimization. The physico-chemical properties of Synechococcus HS-9 were measured during cultivation. The average values of these parameters were found to be 439 to 325 7 μmol m−2s−1 for light conditions and 190–200 μmol m−2s−1 for dark conditions. During cultivation, T ranged from 29 to 32 °C and CO2 from 82 to 84 ppm. Most pH levels are between 8 and 7.5. The dissolved oxygen (DO) concentration drops from 15 to 3 mg/l. The ORP also fluctuates, dropping from 170 mV to 155 mV and then rising to 180 mV. Based on multi-objective optimization, the optimal values for energy efficiency (ղ) and biomass concentration (C) are 0.043 % and 4.61 × 10−5 mg/ml, respectively. The optimal condition is achieved when the light intensity (I): 254.7 μmol m−2s−1, temperature (T): 29.7 °C, CO2 concentration: 83.4 ppm, pH: 8.6, dissolved oxygen (DO): 6.0 mg/l, and ORP: 149.1 mV.

Marine microbiota is garnering increasing interest as a potential source of novel foods with enhanced nutritional and functional properties. In this study, the proximate composition and antioxidant capacity of five haloarchaea and microalgae species from the Andalusian Atlantic shoreline (Halobacterium salinarum, Haloarcula hispanica, Dunaliella salina, C5 and C13, and Picochlorum spp) were compared to two freshwater species (Chlamydomonas reinhardtii and Chlorella sorokiniana). All the species studied exhibited high protein content and antioxidant activity, with noticeable variations in total mineral content and fatty acid profile. Among the four extraction methodologies tested to prepare functional extracts, forced aqueous extraction followed by protein hydrolysis resulted in significantly greater yields and antioxidant activity, while microalgae demonstrated higher activity compared to haloarchaea tested in the present study. In conclusion, the diverse species examined displayed high nutritional and functional value, showing great potential to be part of the human diet as rich sources of readily available protein and antioxidant compounds.

This study examined the effects of high-pressure homogenization (HPH) and ultrasonication pre-treatment on the structural and physicochemical properties of proteins extracted from defatted Nannochloropsis Oceania biomass (DNOB). HPH treatment was found to enhance the solubility of protein extracted from DNOB compared to ultrasound, where samples pretreated with three passes (3P) of HPH exhibited lower solubility than two passes (2P). The morphology of extracted samples was visualized by scanning electron microscopy, which HPH pre-treatment, especially with more passes, were able to breakdown DNOB into fragments. Alternatively, more holes were displayed on the surface of the extracts pretreated with ultrasound especially when higher amplitude applied. The particle size of extracts from HPH3P (129.5 µm) significant dropped from HPH2P (314.25 µm), where samples pretreated with ultrasound at 20 % amplitude (US20) also decreased in particle size compared to 40 % amplitude (US40), from 115.25 µm to 78.22 µm. Protein flexibility of DNOB extracts were enhanced by both HPH2P and HPH3P but decreased for ultrasound samples. β-sheets were found to be the most abundant protein secondary structure for all samples, where samples treated with HPH3P contained the highest percentage of β-sheets (72 %) than control, HPH2P, ultrasonication at 20 and 40 % amplitude (52–62 %). The high percentage of β-sheets found in HPH3P sample also contributed to its outstanding emulsifying properties which stood out among all, especially at concentrations over 1 mg/ml. Results obtained from this study helped to direct the application of DNOB extracts as functional food ingredient for future food innovation.

In recent years, the production of plastic has been estimated to reach 300 million tonnes, and nearly the same amount has been dumped into the waters. This waste material causes long-term damage to the ecosystem, economic sectors, and aquatic environments. Fragmentation of plastics to microplastics has been detected in the world's oceans, which causes a serious global impact. It is found that most of this debris ends up in water environments. Hence, this research aims to review the microbial degradation of microplastic, especially in water bodies and coastal areas. Aerobic bacteria will oxidize and decompose the microplastic from this environment to produce nutrients. Furthermore, plants such as microalgae can employ this nutrient as an energy source, which is the byproduct of microplastic. This paper highlights the reduction of plastics in the environment, typically by ultraviolet reduction, mechanical abrasion processes, and utilization by microorganisms and microalgae. Further discussion on the utilization of microplastics in the current technologies comprised of mechanical, chemical, and biological methods focusing more on the microalgae and microbial pathways via fuel cells has been elaborated. It can be denoted in the fuel cell system, the microalgae are placed in the bio-cathode section, and the anode chamber consists of the colony of microorganisms. Hence, electric current from the fuel cell can be generated to produce clean energy. Thus, the investigation on the emerging technologies via fuel cell systems and the potential use of microplastic pollutants for consumption has been discussed in the paper. The biochemical changes of microplastic and the interaction of microalgae and bacteria towards the degradation pathways of microplastic are also being observed in this review.

The textile industry is one of the most important and economically significant industries in the world. China is the largest textile producer, for countries such as India, Pakistan, Bangladesh and Malaysia this sector is of crucial importance and it is also a growing sector in Latin America. This industry is responsible for 10 % of annual global carbon emissions and 20 % of global wastewater. This figure is worrying as this wastewater is highly recalcitrant, which has led to research into different treatment methods that are efficient and can provide a sustainable solution to this problem. The aim of this literature review was to identify the existing methods for the treatment of dry scrubber wastewater (TWWT) and the effects of this wastewater and its composition, focusing on biological, chemical and physicochemical processes from the point of view of advantages and disadvantages. It was analyzed which are the most important scientific areas of TWWT and which countries are the most important in this field, as well as the primary pollutants and TWWT processes. Finally, this analysis provides a context for current trends in TWWT research. In general, coagulation methods have been found to be fast but present difficulties due to the use of toxic coagulants; advanced oxidation processes (AOPs) are positioned as very effective methods that can disinfect and decontaminate these effluents. Currently, biological systems coupled with AOPs are a growing trend. Microalgae and cyanobacteria processes coupled with AOPs have attracted great interest due to the possibility of obtaining high added value products through the biorefining of biomass.

Because of its low environmental impact and high production, microalgae bio-oil has quickly become a popular renewable fuel option. The process utilizes microalgae which are readily available in nature to produce an alternative to fossil fuel. Although microalgal bio-oil production mechanisms have been previously reviewed in recent studies, comparatively few of them emphasize the significance of algal bio-oil production through all available bio-oil conversion mechanisms from microalgae. Here we review the available and common bio-oil conversion processes from microalgae, bio-oil upgrading, and the commercial aspects of its utilization. The most efficient route to bio-oil production can be identified by analysing both the biomass feedstock and the final product. For example, pyrolysis can produce high-energy bio-oil, but it also produces large amounts of char and gas. Although hydrothermal liquefaction and gasification are more complex and costly, they have the potential to produce bio-oil with greater consistency. However, the expense of using bio-oil in a commercial context is a major concern. The cost of producing bio-oil from microalgae is typically higher than that of producing conventional fossil fuels. Several factors, including cost, availability, and necessary infrastructure, contribute to the uncertainty of bio-oil’s commercial feasibility. With the constant improvements in technology and government support, however, bio-oil has the potential to emerge as a viable alternative to conventional fossil fuels.

The research aimed to generate bioelectricity using pepper waste and the microalgae Spirulina sp by a double-chamber microbial fuel cell (dcMFC). A dcMFC was constructed with Cu and Zn electrodes, where organic waste and microalgae were placed in the anodic and cathodic chambers, respectively. Also, electrochemical parameters were measured for 35 days. Finally, possible electrogenic microorganisms were isolated and identified. It was possible to generate maximum values of current (6.04414 ± 0.2145 mA) and voltage (0.77328 ± 0.213 V). The maximum conductivity value was 134.1636 ± 7.121 mS/cm, while the internal resistance value was 83.784 ±7.147Ω. The values of power and current density reached were 584.45 ± 19.14 mW/cm 2 and 5.983 A/cm 2, respectively. The optimal operating pH was 4.59 ± 0.14. From the microbial growth on the anode, the yeast Yarrowia phangngaensis (1) and Pseudomonas stutzeri (2) were identified, which may be involved in the transfer of electrons to the electrode. In conclusion, it was possible to generate clean energy in a laboratory-scale dcMFC when pepper waste and Spirulina sp. were used. These results are promising because organic waste can generate sustainable and environmentally friendly energy.

Salt lakes are significant components of global inland waters. Salt lake (SL) water can provide precious mineral resource for microbial growth. The prospect of utilizing diluted SL water for cultivation of a terrestrial oil-producing microalga Vischeria sp. WL1 was evaluated under laboratory conditions. Based on the detected mineral element composition, the water from Gouchi Salt Lake was diluted 2, 4, 6 and 8 folds and used with supplementation of additional nitrogen, phosphorus and iron (SL+ water). It was found that 4 folds diluted SL+ water was most favorable for biomass and oil production. When cultivated in this condition, Vischeria sp. WL1 gained a biomass yield of 0.82 g L−1 and an oil yield of 0.56 g L−1 after 24 days of cultivation, which is comparable to the optimum productivity we previously established. In addition, total monounsaturated fatty acid contents (64.4∼68.1 %) of the oils resulted from cultures in diluted SL+waters were higher than that in the control (55.5 %). It was also noteworthy that in all these cultures the oil contents (652.0∼681.0 mg g−1) accounted for the most of the biomass, which are far more than the protein and starch contents. This study demonstrates the feasibility of using SL water as a cost-effective mineral resource to cultivate microalgae for biomass and oil production.

The augmented prevalence of Se (Se) pollution can be attributed to various human activities, such as mining, coal combustion, oil extraction and refining, and agricultural irrigation. Although Se is vital for animals, humans, and microorganisms, excessive concentrations of this element can give rise to potential hazards. Consequently, numerous approaches have been devised to mitigate Se pollution, encompassing physicochemical techniques and bioremediation. The recognition of Se volatilization as a potential strategy for mitigating Se pollution in contaminated environments is underscored in this review. This study delves into the volatilization mechanisms in various organisms, including plants, microalgae, and microorganisms. By assessing the efficacy of Se removal and identifying the rate-limiting steps associated with volatilization, this paper provides insightful recommendations for Se mitigation. Constructed wetlands are a cost-effective and environmentally friendly alternative in the treatment of Se volatilization. The fate, behavior, bioavailability, and toxicity of Se within complex environmental systems are comprehensively reviewed. This knowledge forms the basis for developing management plans that aimed at mitigating Se contamination in wetlands and protecting the associated ecosystems.

Microalgae play a significant impact in the biogeochemical cycle of Mn(II) in the aquatic ecosystem. Meanwhile, the inflow of biochar into the water bodies is bound to impact the aquatic organisms. However, the influence of biochar on the manganese transformation in algae-rich water has not drawn much attention. Thus, we studied the effects of rice straw biochar on manganese enrichment and oxidation by a common type of algae in freshwater (Scenedesmus quadricauda). The results showed that Mn(II) was absorbed intracellularly and adsorbed extracellularly by active algal cells. A significant portion of enriched Mn(II) was oxidized to amorphous precipitates MnO2, MnOOH, and Mn2O3. Moreover, the extracellular bound Mn(II) content in the coexistent system of algae and biochar increased compared with the pure Scenedesmus quadricauda system. Nevertheless, the intracellular Mn content was continually lowered as the biochar dose rose from an initial 0.2 to 2.0 g·L−1, suggesting that Mn assimilation of the cell was suppressed. It was calculated that the total enrichment ability of Scenedesmus quadricauda in the algae-biochar coexistent system was 0.31- 15.32 mg Mn/g biomass, more than that in the pure algae system. More importantly, with biochar in the algae system, the amount of generated MnOx increased, and more Mn(II) was oxidized into highly-charged Mn(IV). This was probably because the biochar could relieve the stress of massive Mn(II) on algae and support the MnOx precipitates. In brief, moderate biochar promoted the Mn(II) accumulation by algal cells and its oxidation activity. This study offers deeper insight into the bioconversion of Mn(II) by algae and the potential impact of biochar application to the aquatic system.

ABSTRACT: Modern broilers are highly susceptible to environmental and pathogenic threats, leading to gut disorders and poor nutrient utilization if not managed properly. Nutritional programming using several feedstuffs and coproducts to manage gut health has been studied. This study used microalgae as a functional compound and xylanase enzyme in broilers’ diets as a strategy to manage gut health. A total of 162 one-day-old unsexed Cobb 500 broiler chicks were randomly assigned to 1 of the 3 dietary treatments: a) corn-soybean meal-based control diet (CON), b) 3% microalgae (MAG), and c) MAG with xylanase enzyme (MAG+XYN). The chicks were reared for 35 days (d) on a floor pen system maintaining standard environment conditions to evaluate the effects of microalgae, with or without xylanase supplementation, on serum immunoglobulins, cecal short-chain fatty acids (SCFA) production, cecal microbial diversity, and metabolic pathways. No significant differences were found for serum immunoglobulin and cecal SCFA among the treatment groups (P > 0.05). Relative microbial abundance at the genus level showed that MAG and MAG+XYN groups had a diverse microbial community on d 3 and d 35. However, no bacterial genus had a significant difference (P > 0.05) in their relative abundance on d 3, but 16 genera showed significant differences (P < 0.05) in their relative abundance among the dietary treatments on d 35. Most of these bacteria were SCFA-producing bacteria. Moreover, MAG and MAG+XYN-fed broilers had better responses than CON groups for metabolic pathways (D-mannose degradation, pectin degradation I and II, β-1-4-mannan degradation, tetrahydrofolate biosynthesis, glutathione biosynthesis, glutathione-peroxide redox reactions, lactate fermentation to propionate, acetate, and hydrogen, etc.) both on d 3 and d 35. The results suggest that using microalgae, with or without xylanase, had no statistical impact on serum immunoglobulins and cecal SCFA production in broilers. However, an improvement in the cecal microbial diversity and metabolic pathways, which are essential indicators of gut health and nutrient utilization, was observed. Most of the improved metabolic pathways were related to fiber utilization and oxidative stress reduction.