Growth Behavior, Biomass Composition and Fatty Acid Methyl Esters (FAMEs) Production Potential of Chlamydomonas reinhardtii, and Chlorella vulgaris Cultures.

The production of biomolecules by microalgae has a wide range of applications in the development of various materials and products, such as biodiesel, food supplements, and cosmetics. Microalgae biomass can be produced using waste and in a smaller space than other types of crops (e.g., soja, corn), which shows microalgae's great potential as a source of biomass. Among the produced biomolecules of greatest interest are carbohydrates, proteins, lipids, and fatty acids. In this study, the production of these biomolecules was determined in two strains of microalgae (Chlamydomonas reinhardtii and Chlorella vulgaris) when exposed to different concentrations of nitrogen, phosphorus, and sulfur. Results show a significant microalgal growth (3.69 g L-1) and carbohydrates (163 mg g-1) increase in C. reinhardtii under low nitrogen concentration. Also, higher lipids content was produced under low sulfur concentration (246 mg g-1). It was observed that sulfur variation could affect in a negative way proteins production in C. reinhardtii culture. In the case of C. vulgaris, a higher biomass production was obtained in the standard culture medium (1.37 g L-1), and under a low-phosphorus condition, C. vulgaris produced a higher lipids concentration (248 mg g-1). It was observed that a low concentration of nitrogen had a better effect on the accumulation of fatty acid methyl esters (FAMEs) (C16-C18) in both microalgae. These results lead us to visualize the effects that the variation in macronutrients can have on the growth of microalgae and their possible utility for the production of microalgae-based subproducts.

Revalorization of Microalgae Biomass for Synergistic Interaction and Sustainable Applications: Bioplastic Generation.

Microalgae and cyanobacteria are photosynthetic microorganisms' sources of renewable biomass that can be used for bioplastic production. These microorganisms have high growth rates, and contrary to other feedstocks, such as land crops, they do not require arable land. In addition, they can be used as feedstock for bioplastic production while not competing with food sources (e.g., corn, wheat, and soy protein). In this study, we review the macromolecules from microalgae and cyanobacteria that can serve for the production of bioplastics, including starch and glycogen, polyhydroxyalkanoates (PHAs), cellulose, polylactic acid (PLA), and triacylglycerols (TAGs). In addition, we focus on the cultivation of microalgae and cyanobacteria for wastewater treatment. This approach would allow reducing nutrient supply for biomass production while treating wastewater. Thus, the combination of wastewater treatment and the production of biomass that can serve as feedstock for bioplastic production is discussed. The comprehensive information provided in this communication would expand the scope of interdisciplinary and translational research.

Supercritical CO2-based tailor made valorization of Origanum vulgare L extracts: A green approach to extract high-value compounds with applied perspectives.

In this study, the supercritical CO2-based extraction approach was used from the green technologies to extract Oregano oil (Origanum vulgare L.). A Taguchi experimental design was applied to evaluate the effect of pressure, temperature and ethanol as co-solvent. High yield of oregano oil (13.40%) was obtained at 40 °C, 100 bar and 8 g min-1 of co-solvent flow. Fatty acids profile include α-linolenic, palmitic, oleic and linoleic that contribute to 70.9-76.8% of total fatty acids. Volatile compounds including carvacrol (29.99%), heneicosane (8.21%), nonacosane (11.78%), docosane (7.18%), borneol (4.35%) and thymol (4.51%) were the main compounds identified. Antimicrobial activity assays showed that extracts obtained at 40 °C were highly efficient against S. aureus, E. coli, and C. albicans. Highest antioxidant activities on DPPH and FRAP assays were reached under 8 g min-1 of co-solvent flow (6.08 and 6.89 µmol TE g-1 extract, respectively). On the other hand, antioxidant activity (35.76 µmol TE g-1) on ABTS assay was improved at 40 °C, 100 bar, and 4 g min-1 of co-solvent flow.

Effect of Supercritical Carbon Dioxide Extraction Parameters on the Biological Activities and Metabolites Present in Extracts from Arthrospira platensis.

Arthrospira platensis was used to obtain functional extracts through supercritical carbon dioxide extraction (SFE-CO2). Pressure (P), temperature (T), co-solvent (CX), static extraction (SX), dispersant (Di) and dynamic extraction (DX) were evaluated as process parameters through a Plackett-Burman design. The maximum extract yield obtained was 7.48 ± 0.15% w/w. The maximum contents of bioactive metabolites in extracts were 0.69 ± 0.09 µg/g of riboflavin, 5.49 ± 0.10 µg/g of α-tocopherol, 524.46 ± 0.10 µg/g of ß-carotene, 1.44 ± 0.10 µg/g of lutein and 32.11 ± 0.12 mg/g of fatty acids with 39.38% of palmitic acid, 20.63% of linoleic acid and 30.27% of γ-linolenic acid. A. platensis extracts had an antioxidant activity of 76.47 ± 0.71 µg GAE/g by Folin-Ciocalteu assay, 0.52 ± 0.02, 0.40 ± 0.01 and 1.47 ± 0.02 µmol TE/g by DPPH, FRAP and TEAC assays, respectively. These extracts showed antimicrobial activity against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231. Overall, co-solvent was the most significant factor for all measured effects (p < 0.05). Arthrospira platensis represents a sustainable source of bioactive compounds through SFE using the following extraction parameters P: 450 bar, CX: 11 g/min, SX: 15 min, DX: 25 min, T: 60 °C and Di: 35 g.

Deodorization of Arthrospira platensis biomass for further scale-up food applications.

BACKGROUND: Given the importance of A. platensis as a potential food protein source, we describe an affordable deodorization process that does not significantly affect the nutritional value of algae biomass. RESULTS: Ethanol, acetone or hexane were used to deodorize algae biomass and then to identify the profile of volatile compounds associated with its distinctive odor. Sensorial characteristics were improved in the biomass cake after the proposed solvent extraction. Panelists identified the ethanolic extract with the most pronounced algae-related odor. Gas chromatography-mass spectrometry analysis showed that a mixture of 20 different compounds derived from fatty acids and amino acids contributed to the characteristic smell of A. platensis biomass. The results of the present study show that the ethanol solvent-free A. platensis biomass contained > 600 g kg-1 protein, < 10 g kg-1 crude fat and > 65% in vitro protein digestibility, similar to the original biomass. The Fourier transform infrared spectroscopy secondary protein structure was comparable among samples, indicating that the only change after ethanol extraction was a reduction of the algae smell. CONCLUSION: The various extraction procedures investigated in the present study were effective in deodorizing the algae biomass. The most effective protocol was the removal of odoriferous compounds with ethanol. This particular procedure yielded an algae biomass with an improved sensorial traits. The results of the present study should help with the identification of odoriferous compounds derived from fatty acids, pigments and proteins associated with A. platensis. © 2017 Society of Chemical Industry.

Supercritical Carbon Dioxide and Microwave-Assisted Extraction of Functional Lipophilic Compounds from Arthrospira platensis.

Arthrospira platensis biomass was used in order to obtain functional lipophilic compounds through green extraction technologies such as supercritical carbon dioxide fluid extraction (SFE) and microwave-assisted extraction (MAE). The temperature (T) factor was evaluated for MAE, while for SFE, pressure (P), temperature (T), and co-solvent (ethanol) (CS) were evaluated. The maximum extraction yield of the obtained oleoresin was (4.07% ± 0.14%) and (4.27% ± 0.10%) for SFE and MAE, respectively. Extracts were characterized by gas chromatography mass spectrometry (GC-MS) and gas chromatography flame ionization detector (GC-FID). The maximum contents of functional lipophilic compounds in the SFE and MAE extracts were: for carotenoids 283 ± 0.10 µg/g and 629 ± 0.13 µg/g, respectively; for tocopherols 5.01 ± 0.05 µg/g and 2.46 ± 0.09 µg/g, respectively; and for fatty acids 34.76 ± 0.08 mg/g and 15.88 ± 0.06 mg/g, respectively. In conclusion, the SFE process at P 450 bar, T 60 °C and CS 53.33% of CO2 produced the highest yield of tocopherols, carotenoids and fatty acids. The MAE process at 400 W and 50 °C gives the best extracts in terms of tocopherols and carotenoids. For yield and fatty acids, the MAE process at 400 W and 70 °C produced the highest values. Both SFE and MAE showed to be suitable green extraction technologies for obtaining functional lipophilic compounds from Arthrospira platensis.

Identification of Bioactivity, Volatile and Fatty Acid Profile in Supercritical Fluid Extracts of Mexican arnica.

Supercritical fluid extraction (SFE) is a sustainable technique used for the extraction of lipophilic metabolites such as pigments and fatty acids. Arnica plant is considered a potential candidate material with high antioxidant and antimicrobial activities. Therefore, in this study, a locally available Heterotheca inuloides, also known as Mexican arnica, was analyzed for the extraction of high-value compounds. Based on different pressure (P), temperature (T), and co-solvent (CoS), four treatments (T) were prepared. A maximum 7.13% yield was recovered from T2 (T = 60 °C, P = 10 MPa, CoS = 8 g/min), followed by 6.69% from T4 (T = 60 °C, P = 30 MPa, CoS = 4 g/min). Some bioactive sesquiterpenoids such as 7-hydroxycadalene, caryophyllene and δ-cadinene were identified in the extracts by GC/MS. The fatty acid profile revealed that the main components were palmitic acid (C16:0), followed by linoleic acid (C18:2ω6c), α-linolenic acid (C18:3ω3) and stearic acid (C18:0) differing in percent yield per treatment. Antibacterial activities were determined by the agar diffusion method, indicating that all the treatments exerted strong antibacterial activity against S. aureus, C. albicans, and E. coli strains. The antioxidant capacity of the extracts was also measured by three in vitro assays, DPPH, TEAC and FRAP, using Trolox as a standard. Results showed high antioxidant capacity enabling pharmaceutical applications of Mexican arnica.

Combined simulation on pesticides fate, toxicities and ecological risk in rice paddies for Sustainable Development Goals achievements.

In order to assess the risk of pesticides to aquatic ecosystems, five single-dose pesticides including chlorpyrifos, pymetrozine, dinotefuran, azoxystrobin, and acetochlor that are frequently used in developing countries, were selected. Based on the principle of conservative risk assessment, application amounts for different dosage forms were recommended, the Top-Rice model and risk quotient method were used to evaluate the aquatic ecological risk of the aforementioned single-dose pesticide products. The results showed that predicted peak environmental concentration ranges after application on rice were 110.52-564.25 µg/L for chlorpyrifos, 20.79-114.6 µg/L for pymetrozine, 21.81-114.02 µg/L for dinotefuran, 16.52-56.94 µg/L for azoxystrobin, and 167.22-2184.01 µg/L for acetochlor in different seasons of Changsha, Hangzhou, Nanning in China, and Lahore and Faisalabad in Pakistan. Under the current conditions of registered administration, the acute and chronic risks posed by chlorpyrifos to fish and invertebrates were deemed alarming, and those by pymetrozine and dinotefuran were considered acceptable. The acute risk of exposure of azoxystrobin to vertebrates such as fish, and invertebrates such as daphnia and shrimp is alarming, whereas the chronic risk to vertebrates, invertebrates, and algae was acceptable. The acute exposure risk posed by acetochlor was deemed worrying, and in the case of chronic exposure, only 36 % of the simulation group exhibited a risk quotient below 1, indicating no risk. These findings imply that the ecological risks of using registered chlorpyrifos and acetochlor products on rice cannot be ignored. It should be noted that the analysis method and model employed in this study were intentionally conservative to ensure a comprehensive assessment of the potential risks associated with the use of registered pesticide products. However, the model failed to consider influential factors like photolysis of pesticides on the soil surface, thereby introducing a certain degree of conservativeness in the evaluation results.

Comparison of Alginate Mixtures as Wall Materials of Schizochytrium Oil Microcapsules Formed by Coaxial Electrospray.

This work evaluated maltodextrin/alginate and ß-glucan/alginate mixtures in the food industry as wall materials for the microencapsulation of Schizochytrium sp. oil, an important source of the omega-3 fatty acid DHA (docosahexaenoic acid). Results showed that both mixtures display a shear-thinning behavior, although the viscosity is higher in ß-glucan/alginate mixtures than in maltodextrin/alginate. Scanning electron microscopy was used to assess the morphology of the microcapsules, which appeared more homogeneous for maltodextrin/alginate. In addition, oil-encapsulation efficiency was higher in maltodextrin/alginate mixtures (90%) than in ß-glucan/alginate mixtures (80%). Finally, evaluating the microcapsules' stability by FTIR when exposed to high temperature (80 °C) showed that maltodextrin/alginate microcapsules were not degraded contrary to the ß-glucan/alginate microcapsules. Thus, although high oil-encapsulation efficiency was obtained with both mixtures, the microcapsules' morphology and prolonged stability suggest that maltodextrin/alginate is a suitable wall material for microencapsulation of Schizochytrium sp. oil.

New Perspective for Macroalgae-Based Animal Feeding in the Context of Challenging Sustainable Food Production.

Food production is facing challenging times due to the pandemic, and climate change. With production expected to double by 2050, there is a need for a new paradigm in sustainable animal feed supply. Seaweeds offer a highly valuable opportunity in this regard. Seaweeds are classified into three categories: brown (Phaeophyceae), red (Rhodophyceae), and green (Chlorophyceae). While they have traditionally been used in aquafeed, their demand in the feed market is growing, parallelly increasing according to the food demand. Additionally, seaweeds are being promoted for their nutritional benefits, which contribute to the health, growth, and performance of animals intended for human consumption. Moreover, seaweeds contain biologically active compounds such as polyunsaturated fatty acids, antioxidants (polyphenols), and pigments (chlorophylls and carotenoids), which possess beneficial properties, including antibacterial, antifungal, antiviral, antioxidant, and anti-inflammatory effects and act as prebiotics. This review offers a new perspective on the valorization of macroalgae biomass due to their nutritional profile and bioactive components, which have the potential to play a crucial role in animal growth and making possible new sources of healthy food ingredients.

Quantum yield alterations due to the static magnetic fields action on Arthrospira platensis SAG 21.99: Evaluation of photosystem activity.

Static magnetic fields (SMF) influence the metabolism of microorganisms, however, there is no knowledge explaining how SMF act in cells. This study aimed at evaluating the SMF (30 mT) effect on photosynthetic performance, growth and biomass composition of the cyanobacterium Arthrospira platensis SAG 21.99. A. platensis was cultivated under 30 mT applied for 1 h d-1 and 24 h for 10 d in glass bottles. SMF in both conditions increased cellular growth, achieving a 30% higher biomass concentration. SMF applied for 1 h d-1 increased the pigments and carbohydrate content. The quantum yield was used as an indicator of the photosystem II (PSII) activity and was shown to have been positively affected. SMF for 1 h d-1 had a significant effect on the OJIP curves. This is the first study that evaluated the photosynthetic activity in cyanobacteria cultures under SMF action.

Advancement of green process through microwave-assisted extraction of bioactive metabolites from Arthrospira Platensis and bioactivity evaluation.

Bioactivity and functional properties of cyanobacterial extract mostly depends on process of extraction, temperature and solvent used (polar or non-polar). To evaluate these parameters a design of experiment (DOE; using a 2k design) was performed with Arthrospira platensis. Extraction process was optimized through microwave-assisted extraction considering solvent ratio, temperature and time of extraction with polar (PS) and non-polar (NPS). Maximum extract yield obtained was 4.32±0.25% and 5.26±0.11% (w/w) respectively for PS and NPS. Maximum content of bioactive metabolites in PS extracts were thiamine (846.57±14.12µg/g), riboflavin (101.09±1.63µg/g), C-phycocyanin (2.28±0.10µg/g) and A-phycocyanin (4.11±0.03µg/g), while for NPS extracts were α-tocopherol (37.86±0.78µg/g), ß-carotene (123.64±1.45µg/g) and 19.44±0.21mg/g of fatty acids. A. platensis PS extracts showed high antimicrobial activity and PS extracts had antioxidant activity of 0.79±0.12µmolTE/g for FRAP assay, while for NPS extracts 1.03±0.08µmol α-TE/g for FRAP assay.

How to use Nile Red, a selective fluorescent stain for microalgal neutral lipids.

The use of Nile Red for rapid monitoring of the neutral lipid content in microalgae has gained interest over the last decade, since neutral lipids are feedstock for renewable transportation fuel. In this review, we discuss the main considerations needed to make an NR protocol reliable for staining neutral lipids in microalgae. Cell wall permeability must be enhanced by using stain carriers: DMSO (5% v/v to 25% v/v), glycerol (0.1 to 0.125mg/mL), or EDTA (3.0 to 3.8mg/mL). Temperatures between 30 and 40°C facilitate the diffusion of NR through the cell wall without incurring excess quenching. Good NR-lipid interaction requires using a low NR/cell ratio; the NR concentration must be between 0.25µg/mL and 2.0µg/mL, and the cell concentration >5×10(4)cells/mL. In order to have the maximum and stable NR fluorescence, it is necessary to scan the excitation/emission wavelengths for up to a 40-min of incubation time. We outline a five-step method to customize the Nile Red protocol to a specific strain: 1) Evaluate the strain's suitability by checking for the presence of neutral lipid, 2) Select of the best excitation/emission wavelength, 3) Optimization of incubation time, stain carrier, dye concentration, and temperature, 4) Prepare single-strain algal cultures with different lipid contents to calibrate NR fluorescence with neutral-lipid content, and 5) Correlate NR fluorescence intensity to neutral lipid content for the same strain. Once the protocol is customized, the NR method allows for rapid and reliable monitoring of neutral lipid content of a microalgae strain.

Extraction and purification of high-value metabolites from microalgae: essential lipids, astaxanthin and phycobiliproteins.

The marked trend and consumers growing interest in natural and healthy products have forced researches and industry to develop novel products with functional ingredients. Microalgae have been recognized as source of functional ingredients with positive health effects since these microorganisms produce polyunsaturated fatty acids, polysaccharides, natural pigments, essential minerals, vitamins, enzymes and bioactive peptides. For this reason, the manuscript reviews two of the main high-value metabolites which can be obtained from microalgae: pigments and essential lipids. Therefore, the extraction and purification methods for polyunsaturated fatty acids, astaxanthin, phycoerythrin and phycocyanin are described. Also, the effect that environmental growth conditions have in the production of these metabolites is described. This review summarizes the existing methods to extract and purify such metabolites in order to develop a feasible and sustainable algae industry.