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25 pages, 3040 KiB

Open AccessArticle

Mixotrophy in a Local Strain of Nannochloropsis granulata for Renewable High-Value Biomass Production on the West Coast of Sweden

by Valeria Villanova, Christian Galasso, Giovanni Andrea Vitale, Gerardo Della Sala, Johan Engelbrektsson, Niklas Strömberg, Kashif Mohd Shaikh, Mats X. Andersson, Fortunato Palma Esposito, Susanne Ekendahl, Donatella De Pascale and Cornelia Spetea

Mar. Drugs 2022, 20(7), 424; https://doi.org/10.3390/md20070424 - 28 Jun 2022

Cited by 6 | Viewed by 2560

Abstract

A local strain of Nannochloropsis granulata (Ng) has been reported as the most productive microalgal strain in terms of both biomass yield and lipid content when cultivated in photobioreactors that simulate the light and temperature conditions during the summer on the [...] Read more.

A local strain of Nannochloropsis granulata (Ng) has been reported as the most productive microalgal strain in terms of both biomass yield and lipid content when cultivated in photobioreactors that simulate the light and temperature conditions during the summer on the west coast of Sweden. To further increase the biomass and the biotechnological potential of this strain in these conditions, mixotrophic growth (i.e., the simultaneous use of photosynthesis and respiration) with glycerol as an external carbon source was investigated in this study and compared with phototrophic growth that made use of air enriched with 1–2% CO₂. The addition of either glycerol or CO₂-enriched air stimulated the growth of Ng and theproduction of high-value long-chain polyunsaturated fatty acids (EPA) as well as the carotenoid canthaxanthin. Bioassays in human prostate cell lines indicated the highest antitumoral activity for Ng extracts and fractions from mixotrophic conditions. Metabolomics detected betaine lipids specifically in the bioactive fractions, suggesting their involvement in the observed antitumoral effect. Genes related to autophagy were found to be upregulated by the most bioactive fraction, suggesting a possible therapeutic target against prostate cancer progression. Taken together, our results suggest that the local Ng strain can be cultivated mixotrophically in summer conditions on the west coast of Sweden for the production of high-value biomass containing antiproliferative compounds, carotenoids, and EPA. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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16 pages, 3157 KiB

Open AccessArticle

Evaluation of Cellular Uptake and Removal of Chlorpropham in the Treatment of Dunaliella salina for Phytoene Production

by Laura Mazzucchi, Yanan Xu and Patricia J. Harvey

Mar. Drugs 2022, 20(6), 367; https://doi.org/10.3390/md20060367 - 30 May 2022

Cited by 1 | Viewed by 1834

Abstract

Chlorpropham is a carbamate herbicide that inhibits cell division and has been widely used as a potato sprout suppressant. Recently we showed that the microalga Dunaliella salina treated with chlorpropham massively accumulated the colourless carotenoids phytoene and phytofluene. Phytoene and phytofluene are valued [...] Read more.

Chlorpropham is a carbamate herbicide that inhibits cell division and has been widely used as a potato sprout suppressant. Recently we showed that the microalga Dunaliella salina treated with chlorpropham massively accumulated the colourless carotenoids phytoene and phytofluene. Phytoene and phytofluene are valued for their antioxidant, UV-absorption and skin protectant properties; however, they are present in very low quantities in nature. The low toxicity herbicide chlorpropham seems a promising catalyst to produce phytoene in large quantities from CO₂ and solar energy with D. salina. This study explored chlorpropham uptake by the algal cells, the formation of potential intermediate metabolites, and the removal of residual chlorpropham from harvested D. salina biomass. Algal biomass rapidly concentrated chlorpropham from culture media. However, washing the harvested biomass with fresh culture medium twice and five times removed ~83 and ~97% of the chlorpropham from the biomass, respectively, and retained algal cell integrity. Furthermore, chloroaniline, a common metabolite of chlorpropham degradation, was not detected in chlorpropham-treated cultures, which were monitored every two days for thirty days. Cells treated with chlorpropham for either 10 min or 24 h continued to over-accumulate phytoene after resuspension in an herbicide-free medium. These data imply that whilst Dunaliella cells do not possess the intracellular capacity to degrade chlorpropham to chloroaniline, the effect of chlorpropham is irreversible on cell nuclear division and hence on carotenoid metabolism. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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15 pages, 2287 KiB

Open AccessArticle

Evaluation of the Potential of Lipid-Extracted Chlorella vulgaris Residue for Yarrowia lipolytica Growth at Different pH Levels

by Guillaume Delfau-Bonnet, Nabila Imatoukene, Tiphaine Clément, Michel Lopez, Florent Allais and Anne-Lise Hantson

Mar. Drugs 2022, 20(4), 264; https://doi.org/10.3390/md20040264 - 13 Apr 2022

Cited by 1 | Viewed by 3010

Abstract

Projections show that the cultivation of microalgae will extend to the production of bio-based compounds, such as biofuels, cosmetics, and medicines. This will generate co-products or residues that will need to be valorized to reduce the environmental impact and the cost of the [...] Read more.

Projections show that the cultivation of microalgae will extend to the production of bio-based compounds, such as biofuels, cosmetics, and medicines. This will generate co-products or residues that will need to be valorized to reduce the environmental impact and the cost of the process. This study explored the ability of lipid-extracted Chlorella vulgaris residue as a sole carbon and nitrogen source for growing oleaginous yeasts without any pretreatment. Both wild-type Yarrowia lipolytica W29 and mutant JMY3501 (which was designed to accumulate more lipids without their remobilization or degradation) showed a similar growth rate of 0.28 h⁻¹ at different pH levels (3.5, 5.5, and 7.5). However, the W29 cell growth had the best cell number on microalgal residue at a pH of 7.5, while three times fewer cells were produced at all pH levels when JMY3501 was grown on microalgal residue. The JMY3501 growth curves were similar at pH 3.5, 5.5, and 7.5, while the fatty-acid composition differed significantly, with an accumulation of α-linolenic acid on microalgal residue at a pH of 7.5. Our results demonstrate the potential valorization of Chlorella vulgaris residue for Yarrowia lipolytica growth and the positive effect of a pH of 7.5 on the fatty acid profile. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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17 pages, 2179 KiB

Open AccessArticle

Total Phenolic Levels, In Vitro Antioxidant Properties, and Fatty Acid Profile of Two Microalgae, Tetraselmis marina Strain IMA043 and Naviculoid Diatom Strain IMA053, Isolated from the North Adriatic Sea

by Riccardo Trentin, Luísa Custódio, Maria João Rodrigues, Emanuela Moschin, Katia Sciuto, José Paulo da Silva and Isabella Moro

Mar. Drugs 2022, 20(3), 207; https://doi.org/10.3390/md20030207 - 12 Mar 2022

Cited by 11 | Viewed by 3494

Abstract

This work studied the potential biotechnological applications of a naviculoid diatom (IMA053) and a green microalga (Tetraselmis marina IMA043) isolated from the North Adriatic Sea. Water, methanol, and dichloromethane (DCM) extracts were prepared from microalgae biomass and evaluated for total phenolic content [...] Read more.

This work studied the potential biotechnological applications of a naviculoid diatom (IMA053) and a green microalga (Tetraselmis marina IMA043) isolated from the North Adriatic Sea. Water, methanol, and dichloromethane (DCM) extracts were prepared from microalgae biomass and evaluated for total phenolic content (TPC) and in vitro antioxidant properties. Biomass was profiled for fatty acid methyl esters (FAME) composition. The DCM extracts had the highest levels of total phenolics, with values of 40.58 and 86.14 mg GAE/g dry weight (DW in IMA053 and IMA043, respectively). The DCM extracts had a higher radical scavenging activity (RSA) than the water and methanol ones, especially those from IMA043, with RSAs of 99.65% toward 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) at 10 mg/mL, and of 103.43% against 2,2-diphenyl-1-picrylhydrazyl (DPPH) at 5 mg/mL. The DCM extract of IMA053 displayed relevant copper chelating properties (67.48% at 10 mg/mL), while the highest iron chelating activity was observed in the water extract of the same species (92.05% at 10 mg/mL). Both strains presented a high proportion of saturated (SFA) and monounsaturated (MUFA) fatty acids. The results suggested that these microalgae could be further explored as sources of natural antioxidants for the pharmaceutical and food industry and as feedstock for biofuel production. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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13 pages, 4162 KiB

Open AccessArticle

Developing a Chromochloris zofingiensis Mutant for Enhanced Production of Lutein under CO₂ Aeration

by Yuanyuan Ren, Jinquan Deng, Yan Lin, Junchao Huang and Feng Chen

Mar. Drugs 2022, 20(3), 194; https://doi.org/10.3390/md20030194 - 7 Mar 2022

Cited by 8 | Viewed by 2914

Abstract

Microalgae are competitive and commercial sources for health-benefit carotenoids. In this study, a Chromochloris zofingiensis mutant (Cz-pkg), which does not shut off its photosystem and stays green upon glucose treatment, was generated and characterized. Cz-pkg was developed by treating the algal [...] Read more.

Microalgae are competitive and commercial sources for health-benefit carotenoids. In this study, a Chromochloris zofingiensis mutant (Cz-pkg), which does not shut off its photosystem and stays green upon glucose treatment, was generated and characterized. Cz-pkg was developed by treating the algal cells with a chemical mutagen as N-methyl-N’-nitro-N-nitrosoguanidine and followed by a color-based colony screening approach. Cz-pkg was found to contain a dysfunctional cGMP-dependent protein kinase (PKG). By cultivated with CO₂ aeration under mixotrophy, the mutant accumulated lutein up to 31.93 ± 1.91 mg L⁻¹ with a productivity of 10.57 ± 0.73 mg L⁻¹ day⁻¹, which were about 2.5- and 8.5-fold of its mother strain. Besides, the lutein content of Cz-pkg could reach 7.73 ± 0.52 mg g⁻¹ of dry weight, which is much higher than that of marigold flower, the most common commercial source of lutein. Transcriptomic analysis revealed that in the mutant Cz-pkg, most of the genes involved in the biosynthesis of lutein and chlorophylls were not down-regulated upon glucose addition, suggesting that PKG may regulate the metabolisms of photosynthetic pigments. This study demonstrated that Cz-pkg could serve as a promising strain for both lutein production and glucose sensing study. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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16 pages, 1400 KiB

Open AccessArticle

Characterization of Novel Selected Microalgae for Antioxidant Activity and Polyphenols, Amino Acids, and Carbohydrates

by Paula Santiago-Díaz, Argimiro Rivero, Milagros Rico and Juan Luis Gómez-Pinchetti

Mar. Drugs 2022, 20(1), 40; https://doi.org/10.3390/md20010040 - 30 Dec 2021

Cited by 20 | Viewed by 3949

Abstract

The biochemical composition of three novel selected microalgae strains (Chlorophyta) was evaluated to confirm their potential possibilities as new sustainably produced biomass with nutritional, functional, and/or biomedical properties. Extracts from cultured Pseudopediastrum boryanum, Chloromonas cf. reticulata, and Chloroidium saccharophilum exhibited higher [...] Read more.

The biochemical composition of three novel selected microalgae strains (Chlorophyta) was evaluated to confirm their potential possibilities as new sustainably produced biomass with nutritional, functional, and/or biomedical properties. Extracts from cultured Pseudopediastrum boryanum, Chloromonas cf. reticulata, and Chloroidium saccharophilum exhibited higher radical scavenging activity of DPPH (1,1-diphenyl-2-picrylhydrazyl) when compared to butylated hydroxytoluene (BHT), but lower than butylated hydroxyanisole (BHA). Total phenolic compounds and amino acids were determined by newly developed RP-HPLC methods. Total phenolic contents, as µg g⁻¹ of dry biomass, reached 27.1 for C. cf. reticulata, 26.4 for P. boryanum, and 55.8 for C. saccharophilum. Percentages of total analysed amino acids were 24.3, 32.1, and 18.5% of dry biomass, respectively, presenting high values for essential amino acids reaching 54.1, 72.6, and 61.2%, respectively. Glutamic acid was the most abundant free amino acid in all microalgae samples, followed by proline and lysine in C. saccharophilum and P. boryanum, and methionine and lysine in C. reticulata. Soluble carbohydrates in aqueous extracts ranged from 39.6 for C. saccharophilum to 49.3% for C. reticulata, increasing values to 45.1 for C. saccharophilum and 52.7% for P. boryanum in acid hydrolysates of dried biomass. Results confirmed the potential possibilities of these microalgae strains. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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11 pages, 1418 KiB

Open AccessArticle

Comparative Study Highlights the Potential of Spectral Deconvolution for Fucoxanthin Screening in Live Phaeodactylum tricornutum Cultures

by Sean Macdonald Miller, Raffaela M. Abbriano, Anna Segecova, Andrei Herdean, Peter J. Ralph and Mathieu Pernice

Mar. Drugs 2022, 20(1), 19; https://doi.org/10.3390/md20010019 - 23 Dec 2021

Cited by 5 | Viewed by 2964

Abstract

Microalgal biotechnology shows considerable promise as a sustainable contributor to a broad range of industrial avenues. The field is however limited by processing methods that have commonly hindered the progress of high throughput screening, and consequently development of improved microalgal strains. We tested [...] Read more.

Microalgal biotechnology shows considerable promise as a sustainable contributor to a broad range of industrial avenues. The field is however limited by processing methods that have commonly hindered the progress of high throughput screening, and consequently development of improved microalgal strains. We tested various microplate reader and flow cytometer methods for monitoring the commercially relevant pigment fucoxanthin in the marine diatom Phaeodactylum tricornutum. Based on accuracy and flexibility, we chose one described previously to adapt to live culture samples using a microplate reader and achieved a high correlation to HPLC (R² = 0.849), effectively removing the need for solvent extraction. This was achieved by using new absorbance spectra inputs, reducing the detectable pigment library and changing pathlength values for the spectral deconvolution method in microplate reader format. Adaptation to 384-well microplates and removal of the need to equalize cultures by density further increased the screening rate. This work is of primary interest to projects requiring detection of biological pigments, and could theoretically be extended to other organisms and pigments of interest, improving the viability of microalgae biotechnology as a contributor to sustainable industry. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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25 pages, 2959 KiB

Open AccessArticle

Transcriptomic and Proteomic Characterizations of the Molecular Response to Blue Light and Salicylic Acid in Haematococcus pluvialis

by Xiaodong Wang, Chunxiao Meng, Hao Zhang, Wei Xing, Kai Cao, Bingkui Zhu, Chengsong Zhang, Fengjie Sun and Zhengquan Gao

Mar. Drugs 2022, 20(1), 1; https://doi.org/10.3390/md20010001 - 21 Dec 2021

Cited by 18 | Viewed by 3531

Abstract

Haematococcus pluvialis accumulates a large amount of astaxanthin under various stresses, e.g., blue light and salicylic acid (SA). However, the metabolic response of H. pluvialis to blue light and SA is still unclear. We investigate the effects of blue light and SA on [...] Read more.

Haematococcus pluvialis accumulates a large amount of astaxanthin under various stresses, e.g., blue light and salicylic acid (SA). However, the metabolic response of H. pluvialis to blue light and SA is still unclear. We investigate the effects of blue light and SA on the metabolic response in H. pluvialis using both transcriptomic and proteomic sequencing analyses. The largest numbers of differentially expressed proteins (DEPs; 324) and differentially expressed genes (DEGs; 13,555) were identified on day 2 and day 7 of the treatment with blue light irradiation (150 μmol photons m⁻²s⁻¹), respectively. With the addition of SA (2.5 mg/L), a total of 63 DEPs and 11,638 DEGs were revealed on day 2 and day 7, respectively. We further analyzed the molecular response in five metabolic pathways related to astaxanthin synthesis, including the astaxanthin synthesis pathway, the fatty acid synthesis pathway, the heme synthesis pathway, the reactive oxygen species (ROS) clearance pathway, and the cell wall biosynthesis pathway. Results show that blue light causes a significant down-regulation of the expression of key genes involved in astaxanthin synthesis and significantly increases the expression of heme oxygenase, which shows decreased expression by the treatment with SA. Our study provides novel insights into the production of astaxanthin by H. pluvialis treated with blue light and SA. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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20 pages, 1884 KiB

Open AccessArticle

Immune Status and Hepatic Antioxidant Capacity of Gilthead Seabream Sparus aurata Juveniles Fed Yeast and Microalga Derived β-glucans

by Bruno Reis, Ana Teresa Gonçalves, Paulo Santos, Manuel Sardinha, Luís E. C. Conceição, Renata Serradeiro, Jaume Pérez-Sánchez, Josep Calduch-Giner, Ulrike Schmid-Staiger, Konstantin Frick, Jorge Dias and Benjamín Costas

Mar. Drugs 2021, 19(12), 653; https://doi.org/10.3390/md19120653 - 23 Nov 2021

Cited by 20 | Viewed by 3768

Abstract

This work aimed to evaluate the effects of dietary supplementation with β-glucans extracted from yeast (Saccharomyces cerevisiae) and microalga (Phaeodactylum tricornutum) on gene expression, oxidative stress biomarkers and plasma immune parameters in gilthead seabream (Sparus aurata) juveniles. [...] Read more.

This work aimed to evaluate the effects of dietary supplementation with β-glucans extracted from yeast (Saccharomyces cerevisiae) and microalga (Phaeodactylum tricornutum) on gene expression, oxidative stress biomarkers and plasma immune parameters in gilthead seabream (Sparus aurata) juveniles. A practical commercial diet was used as the control (CTRL), and three others based on CTRL were further supplemented with different β-glucan extracts. One was derived from S. cerevisiae (diet MG) and two different extracts of 21% and 37% P. tricornutum-derived β-glucans (defined as Phaeo21 and Phaeo37), to give a final 0.06% β-glucan dietary concentration. Quadruplicate groups of 95 gilthead seabream (initial body weight: 4.1 ± 0.1 g) were fed to satiation three times a day for 8 weeks in a pulse-feeding regimen, with experimental diets intercalated with the CTRL dietary treatment every 2 weeks. After 8 weeks of feeding, all groups showed equal growth performance and no changes were found in plasma innate immune status. Nonetheless, fish groups fed β-glucans supplemented diets showed an improved anti-oxidant status compared to those fed CTRL at both sampling points (i.e., 2 and 8 weeks). The intestinal gene expression analysis highlighted the immunomodulatory role of Phaeo37 diet after 8 weeks, inducing an immune tolerance effect in gilthead seabream intestine, and a general down-regulation of immune-related gene expression. In conclusion, the results suggest that the dietary pulse administration of a P. tricornutum 37% enriched-β-glucans extract might be used as a counter-measure in a context of gut inflammation, due to its immune-tolerant and anti-oxidative effects. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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13 pages, 2379 KiB

Open AccessArticle

Exogenous Antioxidants Improve the Accumulation of Saturated and Polyunsaturated Fatty Acids in Schizochytrium sp. PKU#Mn4

by Sai Zhang, Xiaohong Chen, Biswarup Sen, Mohan Bai, Yaodong He and Guangyi Wang

Mar. Drugs 2021, 19(10), 559; https://doi.org/10.3390/md19100559 - 30 Sep 2021

Cited by 13 | Viewed by 2987

Abstract

Species of Schizochytrium are well known for their remarkable ability to produce lipids intracellularly. However, during their lipid accumulation, reactive oxygen species (ROS) are generated inevitably as byproducts, which if in excess results in lipid peroxidation. To alleviate such ROS-induced damage, seven different [...] Read more.

Species of Schizochytrium are well known for their remarkable ability to produce lipids intracellularly. However, during their lipid accumulation, reactive oxygen species (ROS) are generated inevitably as byproducts, which if in excess results in lipid peroxidation. To alleviate such ROS-induced damage, seven different natural antioxidants (ascorbic acid, α-tocopherol, tea extract, melatonin, mannitol, sesamol, and butylated hydroxytoluene) were evaluated for their effects on the lipid accumulation in Schizochytrium sp. PKU#Mn4 using a fractional factorial design. Among the tested antioxidants, mannitol showed the best increment (44.98%) in total fatty acids concentration. However, the interaction effects of mannitol (1 g/L) and ascorbic acid (1 g/L) resulted in 2.26 ± 0.27 g/L and 1.45 ± 0.04 g/L of saturated and polyunsaturated fatty acids (SFA and PUFA), respectively, in batch fermentation. These concentrations were further increased to 7.68 ± 0.37 g/L (SFA) and 5.86 ± 0.03 g/L (PUFA) through fed-batch fermentation. Notably, the interaction effects yielded 103.7% and 49.6% increment in SFA and PUFA concentrations in batch fermentation. The possible mechanisms underlining those increments were an increased maximum growth rate of strain PKU#Mn4, alleviated ROS level, and the differential expression of lipid biosynthetic genes andupregulated catalase gene. This study provides an applicable strategy for improving the accumulation of SFA and PUFA in thraustochytrids by exogenous antioxidants and the underlying mechanisms. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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16 pages, 2568 KiB

Open AccessArticle

Response to Static Magnetic Field-Induced Stress in Scenedesmus obliquus and Nannochloropsis gaditana

by Génesis Serrano, Carol Miranda-Ostojic, Pablo Ferrada, Cristian Wulff-Zotelle, Alejandro Maureira, Edward Fuentealba, Karem Gallardo, Manuel Zapata and Mariella Rivas

Mar. Drugs 2021, 19(9), 527; https://doi.org/10.3390/md19090527 - 21 Sep 2021

Cited by 12 | Viewed by 3482

Abstract

Magnetic fields in biological systems is a promising research field; however, their application for microalgae has not been fully exploited. This work aims to measure the enzymatic activity and non-enzymatic activity of two microalgae species in terms of superoxide dismutase (SOD), catalase (CAT), [...] Read more.

Magnetic fields in biological systems is a promising research field; however, their application for microalgae has not been fully exploited. This work aims to measure the enzymatic activity and non-enzymatic activity of two microalgae species in terms of superoxide dismutase (SOD), catalase (CAT), and carotenoids, respectively, in response to static magnetic fields-induced stress. Two magnet configurations (north and south) and two exposure modes (continuous and pulse) were applied. Two microalgae species were considered, the Scenedesmus obliquus and Nannochloropsis gaditana. The SOD activity increased by up to 60% in S. obliquus under continuous exposure. This trend was also found for CAT in the continuous mode. Conversely, under the pulse mode, its response was hampered as the SOD and CAT were reduced. For N. gaditana, SOD increased by up to 62% with the south configuration under continuous exposure. In terms of CAT, there was a higher activity of up to 19%. Under the pulsed exposure, SOD activity was up to 115%. The CAT in this microalga was increased by up to 29%. For N. gaditana, a significant increase of over 40% in violaxanthin production was obtained compared to the control, when the microalgae were exposed to SMF as a pulse. Depending on the exposure mode and species, this methodology can be used to produce oxidative stress and obtain an inhibitory or enhanced response in addition to the significant increase in the production of antioxidant pigments. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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Review

Jump to: Research

27 pages, 2931 KiB

Open AccessReview

Humic Substances as Microalgal Biostimulants—Implications for Microalgal Biotechnology

by Daria Gabriela Popa, Carmen Lupu, Diana Constantinescu-Aruxandei and Florin Oancea

Mar. Drugs 2022, 20(5), 327; https://doi.org/10.3390/md20050327 - 16 May 2022

Cited by 22 | Viewed by 4117

Abstract

Humic substances (HS) act as biostimulants for terrestrial photosynthetic organisms. Their effects on plants are related to specific HS features: pH and redox buffering activities, (pseudo)emulsifying and surfactant characteristics, capacity to bind metallic ions and to encapsulate labile hydrophobic molecules, ability to adsorb [...] Read more.

Humic substances (HS) act as biostimulants for terrestrial photosynthetic organisms. Their effects on plants are related to specific HS features: pH and redox buffering activities, (pseudo)emulsifying and surfactant characteristics, capacity to bind metallic ions and to encapsulate labile hydrophobic molecules, ability to adsorb to the wall structures of cells. The specific properties of HS result from the complexity of their supramolecular structure. This structure is more dynamic in aqueous solutions/suspensions than in soil, which enhances the specific characteristics of HS. Therefore, HS effects on microalgae are more pronounced than on terrestrial plants. The reported HS effects on microalgae include increased ionic nutrient availability, improved protection against abiotic stress, including against various chemical pollutants and ionic species of potentially toxic elements, higher accumulation of value-added ingredients, and enhanced bio-flocculation. These HS effects are similar to those on terrestrial plants and could be considered microalgal biostimulant effects. Such biostimulant effects are underutilized in current microalgal biotechnology. This review presents knowledge related to interactions between microalgae and humic substances and analyzes the potential of HS to enhance the productivity and profitability of microalgal biotechnology. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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27 pages, 1565 KiB

Open AccessReview

Wide Range Applications of Spirulina: From Earth to Space Missions

by Giacomo Fais, Alessia Manca, Federico Bolognesi, Massimiliano Borselli, Alessandro Concas, Marco Busutti, Giovanni Broggi, Pierdanilo Sanna, Yandy Marx Castillo-Aleman, René Antonio Rivero-Jiménez, Antonio Alfonso Bencomo-Hernandez, Yendry Ventura-Carmenate, Michela Altea, Antonella Pantaleo, Gilberto Gabrielli, Federico Biglioli, Giacomo Cao and Giuseppe Giannaccare

Mar. Drugs 2022, 20(5), 299; https://doi.org/10.3390/md20050299 - 28 Apr 2022

Cited by 40 | Viewed by 8823

Abstract

Spirulina is the most studied cyanobacterium species for both pharmacological applications and the food industry. The aim of the present review is to summarize the potential benefits of the use of Spirulina for improving healthcare both in space and on Earth. Regarding the [...] Read more.

Spirulina is the most studied cyanobacterium species for both pharmacological applications and the food industry. The aim of the present review is to summarize the potential benefits of the use of Spirulina for improving healthcare both in space and on Earth. Regarding the first field of application, Spirulina could represent a new technology for the sustainment of long-duration manned missions to planets beyond the Lower Earth Orbit (e.g., Mars); furthermore, it could help astronauts stay healthy while exposed to a variety of stress factors that can have negative consequences even after years. As far as the second field of application, Spirulina could have an active role in various aspects of medicine, such as metabolism, oncology, ophthalmology, central and peripheral nervous systems, and nephrology. The recent findings of the capacity of Spirulina to improve stem cells mobility and to increase immune response have opened new intriguing scenarios in oncological and infectious diseases, respectively. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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21 pages, 1279 KiB

Open AccessReview

Carotenoid Production from Microalgae: Biosynthesis, Salinity Responses and Novel Biotechnologies

by Yuanyuan Ren, Han Sun, Jinquan Deng, Junchao Huang and Feng Chen

Mar. Drugs 2021, 19(12), 713; https://doi.org/10.3390/md19120713 - 20 Dec 2021

Cited by 85 | Viewed by 7703

Abstract

Microalgae are excellent biological factories for high-value products and contain biofunctional carotenoids. Carotenoids are a group of natural pigments with high value in social production and human health. They have been widely used in food additives, pharmaceutics and cosmetics. Astaxanthin, β-carotene and lutein [...] Read more.

Microalgae are excellent biological factories for high-value products and contain biofunctional carotenoids. Carotenoids are a group of natural pigments with high value in social production and human health. They have been widely used in food additives, pharmaceutics and cosmetics. Astaxanthin, β-carotene and lutein are currently the three carotenoids with the largest market share. Meanwhile, other less studied pigments, such as fucoxanthin and zeaxanthin, also exist in microalgae and have great biofunctional potentials. Since carotenoid accumulation is related to environments and cultivation of microalgae in seawater is a difficult biotechnological problem, the contributions of salt stress on carotenoid accumulation in microalgae need to be revealed for large-scale production. This review comprehensively summarizes the carotenoid biosynthesis and salinity responses of microalgae. Applications of salt stress to induce carotenoid accumulation, potentials of the Internet of Things in microalgae cultivation and future aspects for seawater cultivation are also discussed. As the global market share of carotenoids is still ascending, large-scale, economical and intelligent biotechnologies for carotenoid production play vital roles in the future microalgal economy. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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24 pages, 4867 KiB

Open AccessReview

Microalgae as Sustainable Biofactories to Produce High-Value Lipids: Biodiversity, Exploitation, and Biotechnological Applications

by Tomásia Fernandes and Nereida Cordeiro

Mar. Drugs 2021, 19(10), 573; https://doi.org/10.3390/md19100573 - 14 Oct 2021

Cited by 38 | Viewed by 5937

Abstract

Microalgae are often called “sustainable biofactories” due to their dual potential to mitigate atmospheric carbon dioxide and produce a great diversity of high-value compounds. Nevertheless, the successful exploitation of microalgae as biofactories for industrial scale is dependent on choosing the right microalga and [...] Read more.

Microalgae are often called “sustainable biofactories” due to their dual potential to mitigate atmospheric carbon dioxide and produce a great diversity of high-value compounds. Nevertheless, the successful exploitation of microalgae as biofactories for industrial scale is dependent on choosing the right microalga and optimum growth conditions. Due to the rich biodiversity of microalgae, a screening pipeline should be developed to perform microalgal strain selection exploring their growth, robustness, and metabolite production. Current prospects in microalgal biotechnology are turning their focus to high-value lipids for pharmaceutic, nutraceutic, and cosmetic products. Within microalgal lipid fraction, polyunsaturated fatty acids and carotenoids are broadly recognized for their vital functions in human organisms. Microalgal-derived phytosterols are still an underexploited lipid resource despite presenting promising biological activities, including neuroprotective, anti-inflammatory, anti-cancer, neuromodulatory, immunomodulatory, and apoptosis inductive effects. To modulate microalgal biochemical composition, according to the intended field of application, it is important to know the contribution of each cultivation factor, or their combined effects, for the wanted product accumulation. Microalgae have a vital role to play in future low-carbon economy. Since microalgal biodiesel is still costly, it is desirable to explore the potential of oleaginous species for its high-value lipids which present great global market prospects. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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30 pages, 1255 KiB

Open AccessReview

Antioxidant Compounds from Microalgae: A Review

by Noémie Coulombier, Thierry Jauffrais and Nicolas Lebouvier

Mar. Drugs 2021, 19(10), 549; https://doi.org/10.3390/md19100549 - 28 Sep 2021

Cited by 124 | Viewed by 8812

Abstract

The demand for natural products isolated from microalgae has increased over the last decade and has drawn the attention from the food, cosmetic and nutraceutical industries. Among these natural products, the demand for natural antioxidants as an alternative to synthetic antioxidants has increased. [...] Read more.

The demand for natural products isolated from microalgae has increased over the last decade and has drawn the attention from the food, cosmetic and nutraceutical industries. Among these natural products, the demand for natural antioxidants as an alternative to synthetic antioxidants has increased. In addition, microalgae combine several advantages for the development of biotechnological applications: high biodiversity, photosynthetic yield, growth, productivity and a metabolic plasticity that can be orientated using culture conditions. Regarding the wide diversity of antioxidant compounds and mode of action combined with the diversity of reactive oxygen species (ROS), this review covers a brief presentation of antioxidant molecules with their role and mode of action, to summarize and evaluate common and recent assays used to assess antioxidant activity of microalgae. The aim is to improve our ability to choose the right assay to assess microalgae antioxidant activity regarding the antioxidant molecules studied. Full article

(This article belongs to the Special Issue Biotechnology Applications of Microalgae)

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