Bioactive substances and potentiality of marine microalgae

The need for smart microalgal bioprospecting

Microalgae's adaptability and resilience to Earth's diverse environments have evolved these photosynthetic microorganisms into a biotechnological source of industrially relevant physiological functions and biometabolites. Despite this, microalgae-based industries only exploit a handful of species. This lack of biodiversity hinders the expansion of the microalgal industry. Microalgal bioprospecting, searching for novel biological algal resources with new properties, remains a low throughput and time-consuming endeavour due to inefficient workflows that rely on non-selective sampling, monoalgal culture status and outdated, non-standardized characterization techniques. This review will highlight the importance of microalgal bioprospecting and critically explore commonly employed methodologies. We will also explore current advances driving the next generation of smart algal bioprospecting focusing on novel workflows and transdisciplinary methodologies with the potential to enable high-throughput microalgal biodiscoveries. Images adapted from (Addicted04 in Wikipedia File: Australia on the globe (Australia centered).svg. 2014.; Jin et al. in ACS Appl Bio Mater 4:5080-5089, 2021; Kim et al. in Microchim Acta 189:88, 2022; Tony et al. in Lab on a Chip 15, 19:3810-3810; Thermo Fisher Scientific INC. in CTS Rotea Brochure).

Algal lipids: A review on current status and future prospects in food processing

The consumer demand for functional foods derived from natural sources has been enhanced due to health-promoting effects. Algae are widely available globally as a sustainable source of proteins, lipids, and carbohydrates. Algal lipids are underexplored natural sources that exhibit several nutraceutical effects and applications in fortification, cosmetics, and pharmaceuticals. Both macro- and microalgae are composed of high-quality lipids. These latter involve polar lipids, nonpolar lipids, and essential fatty acids. Therefore, this review aimed to bring out knowledge on the chemistry of various lipids isolated and identified from micro- and macroalgae. Further, their extraction using traditional thermal (solid-liquid, and liquid-liquid) and advanced nonthermal (supercritical fluid, microwave-, ultrasound-, and enzyme-assisted) techniques has been explored. Along with this, bioactivities of algal lipids have been discussed. This study explored algal lipids in advancing sustainable food processing technologies that contribute positively to environmental sustainability and global health, in line with United Nations Sustainable Development GroupUnited Nations Sustainable Development Group UNSDGs.

Efficient enhancement of the antimicrobial activity of Chlamydomonas reinhardtii extract by transgene expression and molecular modification using ionizing radiation

BACKGROUND

Ionizing radiation has been used for mutagenesis or material modification. The potential to use microalgae as a platform for antimicrobial production has been reported, but little work has been done to advance it beyond characterization to biotechnology. This study explored two different applications of ionizing radiation as a metabolic remodeler and a molecular modifier to enhance the antimicrobial activity of total protein and solvent extracts of Chlamydomonas reinhardtii cells.

RESULTS

First, highly efficient transgenic C. reinhardtii strains expressing the plant-derived antimicrobial peptides, AtPR1 or AtTHI2.1, were developed using the radiation-inducible promoter, CrRPA70Ap. Low transgene expression was significantly improved through X-irradiation (12-50 Gy), with peak activity observed within 2 h. Protein extracts from these strains after X-irradiation showed enhanced antimicrobial activity against the prokaryotic bacterium, Pseudomonas syringae, and the eukaryotic fungus, Cryptococcus neoformans. In addition, X-irradiation (12 Gy) increased the growth and biomass of the transgenic strains. Second, C. reinhardtii cell extracts in ethanol were γ-irradiated (5-20 kGy), leading to molecular modifications and increased antimicrobial activity against the phytopathogenic bacteria, P. syringae and Burkholderia glumae, in a dose-dependent manner. These changes were associated with alterations in fatty acid composition. When both transgenic expression of antimicrobial peptides and molecular modification of bioactive substances were applied, the antimicrobial activity of C. reinhardtii cell extracts was further enhanced to some extent.

CONCLUSION

Overall, these findings suggest that ionizing radiation can significantly enhance the antimicrobial potential of C. reinhardtii through efficient transgene expression and molecular modification of bioactive substances, making it a valuable source of natural antimicrobial agents. Ionizing radiation can act not only as a metabolic remodeler of transgene expression in microalgae but also as a molecular modifier of the bioactive substances.

Lipid extract of microalgae Chlorella vulgaris and Arthrospira platensis as a bioactive ingredient

A growing market for seaweed products has emerged in the last 20 years, with microalgae and their extracts representing a source of high-value chemicals. In this study, antioxidative and anti-inflammatory activities of lipid fraction extract from Chlorella vulgaris (Chlorella) and Arthrospira platensis (Spirulina) on Normal Human Dermal Fibroblasts (NHDF cells) were evaluated. Treatments with Chlorella and Spirulina lipid extracts in NHDF cells at 0.1, 0.5, and 1% significantly protect UVA-induced damage by decreasing oxidative stress in the form of reactive oxygen species (ROS) but do not display any significant protection from HEV-induced damage. Chlorella or Spirulina lipid extracts at 0.1 and 0.5% display significant anti-inflammatory effects by inhibiting the 2-propanol-induced IL-6 expression on NHDF cells in vitro but showed no decrease in TNF-α expression. Chlorella and Spirulina lipid extracts present antioxidant and anti-inflammatory activity on NHDF cells.

Effect of Spirulina Nigrita® Supplementation on Indices of Exercise-Induced Muscle Damage after Eccentric Protocol of Upper Limbs in Apparently Healthy Volunteers

Spirulina is a supplement with antioxidant and anti-inflammatory properties that may enhance performance and recovery after intense exercise. The present study aimed to investigate the effects of Spirulina Nigrita® on physical performance, and recovery markers after intense eccentric exercise in healthy moderately physically active volunteers. In a double-blind crossover design, participants were supplemented either with spirulina (42 mg Kg-1 BW per day) or a placebo for 15 days before conducting an eccentric exercise protocol using the non-dominant arm. A six-week washout period was required between conditions. Performance and mobility markers such as isometric peak torque (PTQ), ligament range of motion (ROM), and perceived muscle discomfort (VAS) were assessed and blood samples (CK, LDH) were obtained at 1, 24, 48, and 72 h post-exercise. No significant differences were noticed between the two conditions on any of the investigated markers, indicating that spirulina supplementation has no positive effect on isometric muscle performance or alleviation of exercise-induced muscle damage (EIMD) symptoms in the specific population.

Metabolomic Profile of Arthrospira platensis from a Bulgarian Bioreactor-A Potential Opportunity for Inclusion in Dietary Supplements

The present study aims to elucidate the metabolomic profile of Arthrospira platensis grown in a bioreactor in Bulgaria. The results show that Arthrospira platensis has a high content of mannose, 137.02 mg g-1, and vitamin A (retinol)-10.3 μg/100 g. High concentrations of calcium, sulfur, and zinc distinguish its elemental composition. The freeze-dried powder contained 15.81 ± 0.45% dietary fiber, 50.16 ± 0.25% total protein content, and 1.22 ± 0.11% total fat content. Among the unsaturated fatty acids with the highest content is α-linolenic acid (25.28%), while among the saturated fatty acids, palmitic acid prevails (22.55%). Of the sterols in the sample, β-sitosterol predominated. There is no presence of microcystins LR, RR, YR, and nodularin. Therefore, Arthrospira platensis grown in a Bulgarian bioreactor is safe for use in the pharmaceutical and food industries. Many of the organic compounds found have applications in medicine and pharmacology and play an important role in biochemical processes in the body. Therefore, Arthrospira platensis grown in Bulgaria has a high potential for use as an independent food supplement or in combination with other natural products.

Bioprospecting for new exopolysaccharide-producing microalgae of marine origin

Microalgae are photosynthetic organisms that can produce biomolecules with industrial interest, including exopolysaccharides (EPS). Due to their structural and compositional diversity, microalgae EPS present interesting properties that can be considered in cosmetic and/or therapeutic areas. Seven microalgae strains from three different lineages, namely Dinophyceae (phylum Miozoa), Haptophyta, and Chlorophyta, were investigated as EPS producers. All strains were found to be EPS producers, though the highest EPS yield was obtained for Tisochrysis lutea, followed by Heterocapsa sp. (126.8 and 75.8 mg L-1, respectively). Upon assessment of the polymers' chemical composition, significant contents of unusual sugars, including fucose, rhamnose, and ribose, were found. Heterocapsa sp. EPS stood out due to its high content of fucose (40.9 mol%), a sugar known to confer biological properties to polysaccharides. The presence of sulfate groups (10.6-33.5 wt%) was also noticed in the EPS produced by all microalgae strains, thus contributing to the possibility that these EPS might have biological activities worth exploring.

Oscillatoria sancta Cultivation Using Fruit and Vegetable Waste Formulated Media and Its Potential as a Functional Food: Assessment of Cultivation Optimization

The most cost-effective technique to cultivate microalgae is with low-cost resources, like fruit and vegetable peels. This study examined the viability of culturing microalgae (Oscillatoria sancta PCC 7515) isolated from a waterlogged region of Punjab, India, in a low-cost medium (fruit and vegetable waste peels) for pharmaceutical use. 16S rRNA sequencing discovered O. sancta PCC 7515. Fruit and vegetable peels were mineralized and chemically analyzed. At a 5% Bacillus flexus concentration, fruit and vegetable peels were liquefied at room temperature for 24 h. Response Surface Methodology (RSM) was used to assess and improve important cultural variables. The RSM predicted the best results at 10 pH, 30 days of incubation, 5% inoculum concentration, and 5% fruit and vegetable waste liquid leachate. The optimum conditions yielded more biomass than the basal conditions (0.8001 g/L). O. sancta PCC 7515 produced more lipids, proteins, Chl a, and Chl b in a formulated alternate medium than standard media. This study shows that O. sancta PCC 7515 may thrive on fruit and vegetable peel media. Fruit and vegetable waste (FVW) media assure low-cost microalgae-based functional foods.

Exploring Exogenous Indole-3-acetic Acid's Effect on the Growth and Biochemical Profiles of Synechocystis sp. PAK13 and Chlorella variabilis

Microalgae have garnered scientific interest for their potential to produce bioactive compounds. However, the large-scale industrial utilization of microalgae faces challenges related to production costs and achieving optimal growth conditions. Thus, this study aimed to investigate the potential role of exogenous indole-3-acetic acid (IAA) application in improving the growth and production of bioactive metabolites in microalgae. To this end, the study employed different concentrations of exogenously administered IAA ranging from 0.36 µM to 5.69 µM to assess its influence on the growth and biochemical composition of Synechocystis and Chlorella. IAA exposure significantly increased IAA levels in both strains. Consequentially, improved biomass accumulation in parallel with increased total pigment content by approximately eleven-fold in both strains was observed. Furthermore, the application of IAA stimulated the accumulation of primary metabolites. Sugar levels were augmented, providing a carbon source that facilitated amino acid and fatty acid biosynthesis. As a result, amino acid levels were enhanced as well, leading to a 1.55-fold increase in total amino acid content in Synechocystis and a 1.42-fold increase in Chlorella. Total fatty acids content increased by 1.92-fold in Synechocystis and by 2.16-fold in Chlorella. Overall, the study demonstrated the effectiveness of exogenously adding IAA as a strategy for enhancing the accumulation of microalgae biomass and biomolecules. These findings contribute to the advancement of microalgae-based technologies, opening new avenues to produce economically important compounds derived from microalgae.

Skeletonema marinoi Extracts and Associated Carotenoid Fucoxanthin Downregulate Pro-Angiogenic Mediators on Prostate Cancer and Endothelial Cells

The exploration of natural preventive molecules for nutraceutical and pharmaceutical use has recently increased. In this scenario, marine microorganisms represent an underestimated source of bioactive products endowed with beneficial effects on health that include anti-oxidant, anti-inflammatory, differentiating, anti-tumor, and anti-angiogenic activities. Here, we tested the potential chemopreventive and anti-angiogenic activities of an extract from the marine coastal diatom Skeletonema marinoi Sarno and Zingone (Sm) on prostate cancer (PCa) and endothelial cells. We also tested one of the main carotenoids of the diatom, the xanthophyll pigment fucoxanthin (Fuco). Fuco from the literature is a potential candidate compound involved in chemopreventive activities. Sm extract and Fuco were able to inhibit PCa cell growth and hinder vascular network formation of endothelial cells. The reduced number of cells was partially due to growth inhibition and apoptosis. We studied the molecular targets by qPCR and membrane antibody arrays. Angiogenesis and inflammation molecules were modulated. In particular, Fuco downregulated the expression of Angiopoietin 2, CXCL5, TGFβ, IL6, STAT3, MMP1, TIMP1 and TIMP2 in both prostate and endothelial cells. Our study confirmed microalgae-derived drugs as potentially relevant sources of novel nutraceuticals, providing candidates for potential dietary or dietary supplement intervention in cancer prevention approaches.

Advances in Genetic Engineering in Improving Photosynthesis and Microalgal Productivity

Even though sunlight energy far outweighs the energy required by human activities, its utilization is a key goal in the field of renewable energies. Microalgae have emerged as a promising new and sustainable feedstock for meeting rising food and feed demand. Because traditional methods of microalgal improvement are likely to have reached their limits, genetic engineering is expected to allow for further increases in the photosynthesis and productivity of microalgae. Understanding the mechanisms that control photosynthesis will enable researchers to identify targets for genetic engineering and, in the end, increase biomass yield, offsetting the costs of cultivation systems and downstream biomass processing. This review describes the molecular events that happen during photosynthesis and microalgal productivity through genetic engineering and discusses future strategies and the limitations of genetic engineering in microalgal productivity. We highlight the major achievements in manipulating the fundamental mechanisms of microalgal photosynthesis and biomass production, as well as promising approaches for making significant contributions to upcoming microalgal-based biotechnology.

Potential of Microalgae Extracts for Food and Feed Supplementation-A Promising Source of Antioxidant and Anti-Inflammatory Compounds

Microalgae are known producers of antioxidant and anti-inflammatory compounds, making them natural alternatives to be used as food and feed functional ingredients. This study aimed to valorise biomass and exploit new applications and commercial value for four commercially available microalgae: Isochrysis galbana, Nannochloropsis sp., Tetraselmis sp., and Phaeodactylum tricornutum. For that, five extracts were obtained: acetone (A), ethanol (E), water (W), ethanol:water (EW). The antioxidant capacity (ABTS^•+/DPPH^•/^•NO/O₂^•-/ORAC-FL) and anti-inflammatory capacity (HBRC/COX-2) of the extracts were screened. The general biochemical composition (carbohydrates, soluble proteins, and lipids) and the main groups of bioactive compounds (carotenoids, phenolic compounds, and peptides) of extracts were quantified. The results of antioxidant assays revealed the potential of some microalgae extracts: in ABTS^•+, Nannochloropsis sp. E and Tetraselmis sp. A, E, and P; in DPPH^•, Tetraselmis sp. A and E; in ^•NO, P. tricornutum E and EW; in O₂^•-, Tetraselmis sp. W; and in ORAC-FL, I. galbana EW and P. tricornutum EW. Concerning anti-inflammatory capacity, P. tricornutum EW and Tetraselmis sp. W showed a promising HBRC protective effect and COX-2 inhibition. Hence, Tetraselmis sp. and P. tricornutum extracts seem to have potential to be incorporated as feed and food functional ingredients and preservatives.

Microalgae Bioactive Compounds to Topical Applications Products-A Review

Microalgae are complex photosynthetic organisms found in marine and freshwater environments that produce valuable metabolites. Microalgae-derived metabolites have gained remarkable attention in different industrial biotechnological processes and pharmaceutical and cosmetic industries due to their multiple properties, including antioxidant, anti-aging, anti-cancer, phycoimmunomodulatory, anti-inflammatory, and antimicrobial activities. These properties are recognized as promising components for state-of-the-art cosmetics and cosmeceutical formulations. Efforts are being made to develop natural, non-toxic, and environmentally friendly products that replace synthetic products. This review summarizes some potential cosmeceutical applications of microalgae-derived biomolecules, their mechanisms of action, and extraction methods.

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

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.