Application Of Microalgae Research Articles

Water desalination of Chlorella vulgaris

Saltwater intrusion is a common phenomenon in Southern Vietnam, but salinization is becoming more serious due to the rising sea level related to climate change. Among potential methods for water desalination, the application of halophytic microalgae is gaining high interest. This study investigated the effect of Chlorella vulgaris (C. vulgaris) microalgae on reducing water salinity at different media (Bold Basal Medium and Sea Salt Medium) and in different salt concentrations (1 - 30 g/L). The results indicated that C. vulgaris microalgae had good growth in all mediums used and contributed to lowering the salt content from 20% to 40% after 15 days of cultivation.

Application of Microalgae in Environmental Field

Microalgae have attracted extensive attention in biodiesel, wastewater treatment, food health care, medicine and other fields due to their advantages of short generation cycle, no competition with crops for cultivated land and rich in lipid, protein and polysaccharide.Especially in the current situation of accelerating urbanization and deepening industrialization, the combination of microalgae cultivation and pollution control can not only deal with wastewater and waste gas generated by human activities, but also accumulate lipid, protein and polysaccharide by microalgae themselves, so as to realize the purose of recycling waste resources.

Total Phenolic Content and Antioxidant Capacity of <i>Dunaliella salina </i>Were Cultivated Under Stress Conditions on Salt Field Media

<i>Dunaliella salina</i> (<i>D. salina</i>) is a unicellular green microalga with a high β-carotene content and bioactive compounds that is essential for any study of the application of microalgae. The current research aimed to evaluate total phenolic content, and antioxidant capacity of <i>D. salina</i> CCAP 19/18 strain in RM1 and RM2 salt field media under various stress conditions including natural light, high salinity, and nitrogen starvation. As a result, after 17 days of being enrichment, in the RM1 medium, there was no significant difference in phenolic content under natural light, high salinity, and nitrogen starvation stresses, with p = 0.305. Similarly, the antioxidant capacity had no significant difference, which was p = 0.105 (natural light with high salinity), and p=0.428 (nitrogen starvation with high salinity). While in RM2 medium, the phenolic content and antioxidant capacity under nitrogen starvation stress far exceeded that of natural light and high salinity, with respective figures being 157.147 fg acid gallic/cell and 600.443%/cell and these figures had a significant difference (p<0.05). As a consequence, we could choose an appropriate medium for cultivating and harvesting algae in a large-scale pilot. These true potential extract ingredients in algae are fascinating for cosmetic industries or used for various health benefits such as nutraceuticals and medications against damaging causes, particularly free radicals.

Phenol phycoremediation by Haematococcus pluvialis coupled with enhanced astaxanthin and lipid production under rac-GR24 supplementation for enhanced biodiesel production

The present study evaluated the impact of rac-GR24 on biomass and astaxanthin production under phenol stress coupled with biodiesel recovery from Haematococcus pluvialis. Phenol supplementation showed negative impact on growth, where the lowest biomass productivity of 0.027 g L-1 day−1 was recorded at 10 µM phenol, while 0.4 µM rac-GR24 supplementation showed the highest recorded biomass productivity of 0.063 g L-1 day−1. Coupling 0.4 µM rac-GR24 at different phenol concentrations confirmed the potential of rac-GR24 to mitigate the toxic effect of phenol by enhancing yield of PSII yield, RuBISCo activity, and antioxidant efficiency, which resulted in improved phenol phycoremediation efficiency. In addition, results suggested a synergistic action by rac-GR24 supplementation under phenol treatment where rac-GR24 enhanced lipid accumulation, while phenol enhanced astaxanthin production. Dual supplementation of rac-GR24 and phenol showed the highest recorded FAMEs content, which was 32.6% higher than the control, with improved biodiesel quality. The suggested approach could enhance the economic feasibility of triple-purpose application of microalgae in wastewater treatment, astaxanthin recovery, and biodiesel production.

Application of microalgae Scenedesmus acuminatus enhances water quality in rice-crayfish culture.

Improper management of aquatic environments substantially restricts the development of the aquaculture industry. The industrialisation of the crayfish Procambarus clarkii, for example, is currently being limited by poor water quality. Research suggests that microalgal biotechnology has a great potential for water quality regulation. However, the ecological effects of microalgal applications on aquatic communities in aquaculture systems remain largely unknown. In the present study, 5L Scenedesmus acuminatus GT-2 culture (biomass 120gL-1) was added to an approximately 1,000m2 rice-crayfish culture to examine the response of aquatic ecosystems to microalgal application. The total nitrogen content decreased significantly as a result of microalgal addition. Moreover, the microalgal addition changed the bacterial community structure directionally and produced more nitrate reducing and aerobic bacteria. The effect of microalgal addition on plankton community structure was not obvious, except for a significant difference in Spirogyra growth which was inhibited by 81.0% under microalgal addition. Furthermore, the network of microorganisms in culture systems with the added microalga had higher interconnectivity and was more complex, which indicating microalgal application enhance the stability of aquaculture systems. The application of microalgae was found to have the greatest effect on the 6th day of the experiment, as supported by both environmental and biological evidence. These findings can provide valuable guidance for the practical application of microalgae in aquaculture systems.

Strain Screening and Conditions Optimization in Microalgae-Based Monosodium Glutamate Wastewater (MSGW) Treatment

The wastewater generated from monosodium glutamate production displays distinctive features of elevated salinity, organic content, as well as nitrogen and phosphorus concentrations, and its indiscriminate disposal poses a significant threat to water quality and can cause detrimental impacts on aquatic ecosystems. The application of microalgae for monosodium glutamate wastewater (MSGW) treatment can result in simultaneous wastewater purification and biomass recovery. In this study, the algae species capable of thriving in diluted MSGW were screened, and the wastewater composition and growth conditions were optimized to obtain high algal biomass and nutrient removal rate. Among the tested species, Chlorella sp. FACHB-30 demonstrated superior potential for MSGW treatment and achieved a maximum specific growth rate of 0.28 d−1 and the highest COD removal rate of 61.50% over a 20-day cultivation period with trace metals supplementation in the wastewater. Moreover, the cultivation of Chlorella sp. FACHB-30 yielded considerable reductions in total phosphate (69.09%), total nitrogen (26.93%), and NH4+-N (51.91%) levels in the wastewater. The optimum conditions for achieving maximum algal density and highest nutrient removal were determined as light intensity of 150 μmol m−2s−1, inoculation concentration of 1 × 105 cells mL−1, and an iron concentration of 10−5 mol L−1. Finally, under the optimized conditions, the removal rates of total phosphate, total nitrogen, NH4+-N, and COD were determined to be 87.60%, 68.05%, 75.89%, and 77.96%, respectively. The findings of this study highlight the potential for enhancing the nutrient removal efficiency of microalgae-based MSGW treatment through the implementation of a combined approach that involves the selection of tolerant strains, optimization of cultivation conditions, and refinement of wastewater composition.

Rheological and physicochemical properties of Spirulina platensis residues-based inks for extrusion 3D food printing

Novel food matrices (such as microalgae, plants, fungi, and microbial proteins) with high protein content and biological value, good amino acid profile, and functionality have been explored. Phycocyanin and active polysaccharides extracted from Spirulina platensis are used as food additives, treatment of colitis, as well as obesity prevention. However, most of the remaining Spirulina platensis residues are mainly used as fish feed at present. 3D food printing is one of the promising development techniques used in the food industry. The aim of this study was to develop a novel 3D printing material of Spirulina platensis residues with shear thinning characteristics, high viscosity and rapid recovery. The effects of moisture content and pretreatment method on the rheological properties of Spirulina platensis residues were clarified. Scanning electron microscopy was used to observe the microstructure and texture profile analysis was used to determine the texture characteristics of Spirulina platensis residues, rheology was used to determine the key 3D printing factors such as viscosity and modulus of Spirulina platensis residues. More importantly, the printing process could be realized under ambient conditions. The development of microalgae residue ink promoted the high-value and comprehensive utilization of microalgae, and also broadened the application of microalgae in the food field.

Transcriptional analysis reveals induction of systemic resistance in tomato treated with Chlorella microalgae

The application of algae-based products has been reported to promote plant growth and yield of tomato plants, especially by enhancing flowering. However, how microalgae (MA) affect plants at the molecular level remains elusive. The aim of this study was to elucidate the effects of live microalgae application on plant photosynthesis and the transcriptome of the unopened flower buds of tomato plants. Microalgae increased leaf temperature differential in tomato leaves but hardly affected photosynthesis. Contrary to our expectations, RNA-seq data revealed remarkable differential expression of several genes participating in responses to abiotic stresses but only a few genes involved in flowering or pollen/ spore development. Late Embryogenesis Abundant (LEA) proteins (mostly dehydrins), oleosins, ethylene, and abscisic-related genes, and Nascent Polypeptide-Associated Complex (NAC)-domain-containing proteins were upregulated. Genes involved in carbohydrate metabolism were also differentially expressed; glycolysis-related genes were upregulated, while those involved in sugar transport were downregulated. The only upregulated gene implicated in the induction of flowering was Solyc07g006500.3.1 (encoding trehalose-6-phosphate synthase enzyme TPS1). Overall, microalgae treatment led to an empirical upregulation of genes involved in jasmonic acid, abscisic acid, and ethylene pathways which are all essential for abiotic stress response. This study shows that microalgae treatment primed plants by inducing the expression of genes involved in response to abiotic stress, especially cold and water stress, as well as pathogen attack.

Review and Opinions on the Research, Development and Application of Microalgae Culture Technologies for Resource Recovery from Wastewater

Wastewater is an abundant source of nutrients and energy. Under the circumstances of circular economy and carbon neutrality, resource recovery from wastewater has recently been motivated. The microalgal process is a promising alternative for resource recovery from wastewater, and it possesses potential for the cost reduction of wastewater treatment and fertilizer production, energy generation, and greenhouse gas emissions reduction. This paper reviews and discusses state-of-the-art microalgal process development, including microalgal species screening, configuration, biotic consortia construction, infection avoidance, nutrients balancing, operational parameter optimization, and biomass harvesting enhancement. Due to the lack of literature on practical applications, the microalgal process lacks economic and environmental feasibility assessments. Life cycle assessments from the perspective of circular economy and carbon neutrality on upscaled microalgal processes are required for various wastewater scenarios. To promote the upscaled application and successful implementation, efforts are also suggested to establish utilization guidelines, advanced recommendations, reliable standards, and proper safety evaluation criteria. This work could provide a reference and direct the follow-up research, development, and application of microalgae (MA)-based processes for resource recovery from wastewater.

Microalgal Feedstock for Biofuel Production: Recent Advances, Challenges, and Future Perspective

Globally, nations are trying to address environmental issues such as global warming and climate change, along with the burden of declining fossil fuel reserves. Furthermore, countries aim to reach zero carbon emissions within the existing and rising global energy crisis. Therefore, bio-based alternative sustainable feedstocks are being explored for producing bioenergy. One such renewable energy resource is microalgae; these are photosynthetic microorganisms that grow on non-arable land, in extreme climatic conditions, and have the ability to thrive even in sea and wastewater. Microalgae have high photosynthetic efficiencies and biomass productivity compared to other terrestrial plants. Whole microalgae biomass or their extracted metabolites can be converted to various biofuels such as bioethanol, biodiesel, biocrude oil, pyrolytic bio-oil, biomethane, biohydrogen, and bio jet fuel. However, several challenges still exist before faster and broader commercial application of microalgae as a sustainable bioenergy feedstock for biofuel production. Selection of appropriate microalgal strains, development of biomass pre-concentrating techniques, and utilization of wet microalgal biomass for biofuel production, coupled with an integrated biorefinery approach for producing value-added products, could improve the environmental sustainability and economic viability of microalgal biofuel. This article will review the current status of research on microalgal biofuels and their future perspective.

Efficient synergistic degradation of tetracycline hydrochloride by protonated g-C3N4 and Chlorella pyrenoidosa: Kinetics and mechanism

The combined application of microalgae and photocatalytic materials in degrading and detoxifying organic pollutants has shown good application prospects. However, the combined application of the two technologies had problems such as the difficult recovery of photocatalytic materials and poor biocompatibility. Therefore, this study combined the protonated graphitized carbon nitride (P-g-C3N4) with Chlorella pyrenoidosa through electrostatic adsorption to form a new photocatalytic microalgae composite degradation system. At the same time, Chlorella pyrenoidosa enhanced the photocatalytic activity of P-g-C3N4 through EOMs photosensitization and electron transfer, and there was a synergistic effect between P-g-C3N4 and Chlorella pyrenoidosa, which realized the efficient degradation and mineralization of tetracycline hydrochloride. Meanwhile, the new compound degradation system had a good solid–liquid separation effect and recycling efficiency. Electron paramagnetic resonance (EPR) and free radical capture experiments showed that superoxide radical was dominant in the reaction pathway. The research results can provide theoretical and practical support for the application of the combined technology of microalgae and photocatalytic materials.

Static supply of different simulated flue gases for native microalgae cultivation in diluted cow manure digestate

The application of microalgae to sequester CO2 from flue gases can be an interesting process since it can contribute to mitigate CO2 emission into the atmosphere. One obstacle of such application is the high CO2 concentration in the flue gases, which can lead to low pH in the cultivation medium and hence process failure. This study aims to investigate static CO2 gas supply for microalgae cultivation as a potential alternative that might allow applying different flue gases with different compositions and higher CO2 concentrations. Two sets of experiments were performed. First, the effect of increasing the amount of supplied carbon was tested. In the second experiment, the applicability of such system for different flue gases regarding their oxygen and carbon content was tested. In all experiments, 50 times diluted cow manure digestate was used as a culture medium. By increasing CO2 concentration up to 10% in the supplied air, microalgae growth productivity of 48.7 mg/L/d was achieved. A further improvement of microalgae growth was shown with increasing the gas/culture volume ratio. Microalgae productivity rate increased form 48.7 mg/L/d to 73.5 mg/L/d when the volume of gas increased from 47% to 81% of total volume. Applying CO2 in air (O2 content around 20%) or in N2 (O2 content less than 2%) didn't show any difference regarding inorganic carbon dissolution, pH, ammonium nitrogen removal, CO2 fixation or biomass productivity. Generally, it can be concluded that static gas supply for microalgae cultivation can allow the application of different flue gases from different industries with low or high O2 content and with CO2 concentration as high as 20%. According to our results, a microalgae cultivation system with continuous static gas supply was proposed.

Enhancing Urban Wastewater Treatment through Isolated Chlorella Strain-Based Phytoremediation in Centrate Stream: An Analysis of Algae Morpho-Physiology and Nutrients Removal Efficiency.

The release of inadequately treated urban wastewater is the main cause of environmental pollution of aquatic ecosystems. Among efficient and environmentally friendly technologies to improve the remediation process, those based on microalgae represent an attractive alternative due to the potential of microalgae to remove nitrogen (N) and phosphorus (P) from wastewaters. In this work, microalgae were isolated from the centrate stream of an urban wastewater treatment plant and a native Chlorella-like species was selected for studies on nutrient removal from centrate streams. Comparative experiments were set up using 100% centrate and BG11 synthetic medium, modified with the same N and P as the effluent. Since microalgal growth in 100% effluent was inhibited, cultivation of microalgae was performed by mixing tap-freshwater with centrate at increasing percentages (50%, 60%, 70%, and 80%). While algal biomass and nutrient removal was little affected by the differently diluted effluent, morpho-physiological parameters (FV/FM ratio, carotenoids, chloroplast ultrastructure) showed that cell stress increased with increasing amounts of centrate. However, the production of an algal biomass enriched in carotenoids and P, together with N and P abatement in the effluent, supports promising microalgae applications that combine centrate remediation with the production of compounds of biotechnological interest; for example, for organic agriculture.

The Diatom Cylindrotheca closterium and the Chlorophyll Breakdown Product Pheophorbide a for Photodynamic Therapy Applications

Microalgae, eukaryotic unicellular plants that are distributed worldwide, have been shown to exert anti-proliferative and anticancer activities on various human cancer cell lines. An example of a microalgal bioactive compound is a chlorophyll breakdown product named Pheophorbide a (Ppa), which has been reported to have anti-proliferative properties against various cell lines. This compound has also been tested with light exposure in photodynamic therapy for cancer treatment. In this paper, we screened eleven marine microalgae against a panel of cancer cells, and evaluated the synergistic anti-proliferative effect with Pheophorbide a, with and without photo-activation. The results showed significant anti-proliferative activity against melanoma cells when Ppa was combined with fraction E of the diatom Cylindrotheca closterium plus 1 h photo-activation. Its activity was also analyzed using gene expression and Western blot experiments. Altogether, these data give new insights into the possible application of microalgae for photodynamic therapy.

Correction: Youssef et al. Foliar Spray or Soil Drench: Microalgae Application Impacts on Soil Microbiology, Morpho-Physiological and Biochemical Responses, Oil and Fatty Acid Profiles of Chia Plants under Alkaline Stress. Biology 2022, 11, 1844

There were three errors in the original publication [...].

Biofuel Production Using Cultivated Algae: Technologies, Economics, and Its Environmental Impacts

The process of looking for alternative energy sources is driven by the increasing demand for energy and environmental contamination caused by using fossil fuels. Recent investigations reported the efficiency of microalgae for biofuel production due to its low cost of production, high speed of growth, and ability to grow in harsh environments. In addition, many microalgae are photosynthetic, consuming CO2 and solar light to grow in biomass and providing a promising bioenergy source. This review presents the recent advances in the application of microalgae for biofuel production. In addition, cultivation and harvesting systems and environmental factors that affect microalgae cultivation for biofuel production have also been discussed. Moreover, lipid extraction and conversion technologies to biofuel are presented. The mixotrophic cultivation strategy is promising as it combines the advantages of heterotrophy and autotrophy. Green harvesting methods such as using bio-coagulants and flocculants are promising technologies to reduce the cost of microalgal biomass production. In the future, more investigations into co-cultivation systems, new green harvesting methods, high lipids extraction methods, and the optimization of lipid extraction and converting processes should be implemented to increase the sustainability of microalgae application for biofuel production.

Improving the Quality of Reclaimed Water via Applying Spirulina platensis to Eliminate Residual Nitrate.

The application of reclaimed water has been recognized as the key approach for alleviating water scarcity, while its low quality, such as high nitrogen content, still makes people worry about the corresponding ecological risk. Herein, we investigated the feasibility of removing residual nitrate from reclaimed water by applying Spirulina platensis. It is found that 15 mg/L total nitrogen could be decreased to 1.8 mg/L in 5 days, equaling 88.1 % removal efficiency under the optimized conditions. The deficient phosphorus at 0.5-1.0 mg/L was rapidly eliminated but was already sufficient to support nitrate removal by S. platensis. The produced ammonia is generally below 0.2 mg/L, which is much lower than the standard limit of 5 mg/L. In such a nutrient deficiency condition, S. platensis could maintain biomass growth well via photosynthesis. The variation of pigments, including chlorophyll a and carotenoids, suggested a certain degree of influences of illumination intensity and phosphorus starvation on microalgae. The background cations Cu2+ and Zn2+ exhibited significant inhibition on biomass growth and nitrate removal; thus, more attention needs to be paid to the further application of microalgae in reclaimed water. Our results demonstrated that cultivation of S. platensis should be a very promising solution to improve the quality of reclaimed water by efficiently removing nitrate and producing biomass.

微藻在水产养殖尾水治理中的应用研究

微藻在水产养殖尾水治理中的应用研究

Applications of Microalgae in Five Areas of Biotechnology

Applications of Microalgae in Five Areas of Biotechnology

A novel peptide derived from Haematococcus pluvialis residue exhibits anti-aging activity in Caenorhabditis elegans via the insulin/IGF-1 signaling pathway.

To explore the value of Haematococcus pluvialis (H. pluvialis) residue remaining after astaxanthin extraction and being discarded uneconomically, in our previous study, we discovered a novel peptide (HPp) as a potential bioactive component. However, the possible anti-aging activity in vivo was not illuminated. In this study, the capacity of extending the lifespan and the mechanism based on Caenorhabditis elegans (C. elegans) were determined. The results showed that 100 μM HPp not only enhanced the lifespan of C. elegans in normal environments by 20.96% but also strengthened the lifespan in oxidative and thermal conditions effectively. Moreover, HPp succeeded in lessening the decline in physiological functions of aging worms. In terms of antioxidant efficacy, SOD and CAT enzyme activity were promoted, but the level of MDA was diminished significantly after HPp treatment. Subsequent analysis directly reflected the relationship between higher stress resistance and up-regulation of skn-1 and hsp-16.2, and between greater antioxidant ability and up-regulation of sod-3 and ctl-2. Further studies illustrated that HPp up-graded the mRNA transcription of the genes associated with the insulin/insulin-like growth factor signaling (IIS) pathway and some co-factors, including daf-16, daf-2, ins-18, and sir-2.1. Particularly, the activation of the IIS pathway required the regulation of subcellular localization of DAF-16/FOXO. Taken together, HPp could promote longevity with improved stress resistance and antioxidant properties in vivo through the IIS pathway. These data suggested that HPp might serve as a good source of anti-aging actives, and in particular, laid a foundation for the high value-added application of marine microalgae.