Agnieszka Dmytryk

Biosorption of Microelements by Spirulina: Towards Technology of Mineral Feed Supplements

Surface characterization and metal ion adsorption properties of Spirulina sp. and Spirulina maxima were verified by various instrumental techniques. FTIR spectroscopy and potentiometric titration were used for qualitative and quantitative determination of metal ion-binding groups. Comparative FTIR spectra of natural and Cu(II)-treated biomass proved involvement of both phosphoryl and sulfone groups in metal ions sorption. The potentiometric titration data analysis provided the best fit with the model assuming the presence of three types of surface functional groups and the carboxyl group as the major binding site. The mechanism of metal ions biosorption was investigated by comparing the results from multielemental analyses by ICP-OES and SEM-EDX. Biosorption of Cu(II), Mn(II), Zn(II), and Co(II) ions by lyophilized Spirulina sp. was performed to determine the metal affinity relationships for single- and multicomponent systems. Obtained results showed the replacement of naturally bound ions: Na(I), K(I), or Ca(II) with sorbed metal ions in a descending order of Mn(II) > Cu(II) > Zn(II) > Co(II) for single- and Cu(II) > Mn(II) > Co(II) > Zn(II) for multicomponent systems, respectively. Surface elemental composition of natural and metal-loaded material was determined both by ICP-OES and SEM-EDX analysis, showing relatively high value of correlation coefficient between the concentration of Na(I) ions in algal biomass.

Evaluation of Supercritical Extracts of Algae as Biostimulants of Plant Growth in Field Trials

The aim of the field trials was to determine the influence of supercritical algal extracts on the growth and development of winter wheat (variety Akteur). As a raw material for the supercritical fluid extraction, the biomass of microalga Spirulina plantensis, brown seaweed – Ascophyllum nodosum and Baltic green macroalgae was used. Forthial and Asahi SL constituted the reference products. It was found that the tested biostimulants did not influence statistically significantly the plant height, length of ear, and shank length. The ear number per m2 was the highest in the group where the Baltic macroalgae extract was applied in the dose 1.0 L/ha (statistically significant differences). Number of grains in ear (statistically significant differences) and shank length was the highest in the group treated with Spirulina at the dose 1.5 L/ha. In the group with Ascophyllum at the dose 1.0 L/ha, the highest length of ear was observed. The yield was comparable in all the experimental groups (lack of statistically significant differences). Among the tested supercritical extracts, the best results were obtained for Spirulina (1.5 L/ha). The mass of 1000 grains was the highest for extract from Baltic macroalgae and was 3.5% higher than for Asahi, 4.0% higher than for Forthial and 18.5% higher than for the control group (statistically significant differences). Future work is needed to fully characterize the chemical composition of the applied algal extracts. A special attention should be paid to the extracts obtained from Baltic algae because they are inexpensive source of naturally occurring bioactive compounds, which can be used in sustainable agriculture and horticulture.

Supercritical Algal Extracts: A Source of Biologically Active Compounds from Nature

The paper discusses the potential applicability of the process of supercritical fluid extraction (SFE) in the production of algal extracts with the consideration of the process conditions and yields. State of the art in the research on solvent-free isolation of biologically active compounds from the biomass of algae was presented. Various aspects related with the properties of useful compounds found in cells of microalgae and macroalgae were discussed, including their potential applications as the natural components of plant protection products (biostimulants and bioregulators), dietary feed and food supplements, and pharmaceuticals. Analytical methods of determination of the natural compounds derived from algae were discussed. Algal extracts produced by SFE process enable obtaining a solvent-free concentrate of biologically active compounds; however, detailed economic analysis, as well as elaboration of products standardization procedures, is required in order to implement the products in the market.

Chemical Characterization of Enteromorpha prolifera Extract Obtained by Enzyme-Assisted Extraction and Its Influence on the Metabolic Activity of Caco-2

The green seaweed Enteromorpha prolifera was used as a feedstock for the production of enzymatic hydrolysate using cellulase. The selection of the conditions for enzymatic hydrolysis of the biomass was carried out for different enzyme doses and incubation periods. The obtained extract was examined in terms of its multielemental composition, content of polyphenols and antibacterial properties (tested against Escherichia coli and Staphylococcus aureus). Additionally, its influence on the metabolic activity of human colon epithelial cells (Caco-2) was analyzed. The tested concentrations of extract using an in vitro model were 62.5, 125, 250, 500, 1000 and 2000 µg/mL. The hydrolysis yield in the most suitable experimental conditions (8-h process and 50 and 100 µL of cellulase) was 36%. Micro- and macroelements were poorly extracted from the algal biomass. Total phenolic content was 55 mg of gallic acid equivalent per 100 g of dry mass of extract. The cytotoxic effect of extracts, related to the inhibition of the metabolic activity of Caco-2, was noted only after 24 h. In turn, cultures of Caco-2 propagated with extracts for 72 h were characterized by significantly elevated metabolism (the concentration of extracts ranged from 62.5 to 1000 µg/mL, p < 0.05). Obtained results indicated the high biological activity of the prepared extracts; however, the observed effects did not occur in a dose-dependent manner.

Algae as Source of Pharmaceuticals

Pharmaceuticals or pharmaceutical products are medicinal drugs—of proven safety, effectiveness and high quality, which are prescribed and intended to rational dosage. In general, most of the pharmacologically active compounds were isolated from microorganisms and plants, drug-resistance and identification of new disease entities have imposed to select both new sources and application areas of drug components. There is a broad range of health disorders—including cancer, allergy, diabetes, neurodegenerative diseases and inflammation, against which algae have been widely used. Medicinal application of algae depends on the biochemical diversity which is affected by a number of factors, including location, season, grazing pressure, salinity, water motion, temperature, light climate, biomass density and nutrient availability. Despite algae variability, main groups of compounds—such as polysaccharides, pigments, terpenoids, alkaloids, polyphenols, peptides and polyunsaturated fatty acids—showing pharmaceutical activity are indicated. Algae constitute an abundant source of bioactive compounds which have a great potential to be used as pharmaceuticals. Currently, the growing interest is put on the application of different algal compounds in the civilization diseases treatment and the market for pharmaceuticals based on compounds of natural origin is growing worldwide. The still untapped reservoir of chemically active compounds and potential in the field of pharmaceuticals imply a requirement of increased screening of algae for healthcare chemicals and the isolation methods development.

The Methods of Algal Biomass Extraction: Toward the Application

Increasing customer need for natural products of both high and well-defined activity has enhanced the use of biological materials, such as algal biomass. At the same time, algae transport and storage issues, concerning fresh seaweeds in particular, have led to the development of biomolecule isolation, including extraction. To the best of our knowledge, various approaches have been successfully applied in extracting biologically active compounds from algal biomass, among which solvent and temperature treatment are the most common. Considering novel methods, processing under high pressure (pressurized liquid and supercritical fluid extraction) and ultrasound-, microwave-, and enzyme-assisted extraction have been reported. The approaches differ in their efficacy and selectivity and extract purity, determining the usability of the final product in either bulk manufacturing or as a high-value material. Application of algae-based constituents in food and beverage products, dietary and feed supplements, cosmetics, and pharmaceuticals is being widely discussed. Recently, the usability of algae oil in the technology of biofuels has been extensively examined. In the current work, preparation of algal extracts and formulations for potential industrial use are discussed.

Algae As Fertilizers, Biostimulants, and Regulators of Plant Growth

Currently, legislation restricts the use of mineral fertilizers and pesticides and thus forces a new approach to reducing the use of chemical products through either parallel application or partial replacement with formulations capable of enhancing the efficiency of conventional treatment. Among the natural materials of such capability are algae, which contain a variety of biologically active compounds verified to have a beneficial influence on plants. Algal derivatives have been confirmed to provide crops with nutrients, increase biomass production, and activate the natural ability of plants to respond properly to stress agents. Depending on the formulation, algae-based products might show the functionality of organic fertilizers or components of organo-mineral fertilizers, soil amendments (improvers), (bio)stimulants, and pesticides. However, current European rules are not harmonized at the union level. Until a single market is established, algae’s potential for plant growth enhancement will not be sufficiently developed. There are, however, new strategies for elaborating EU-wide standards and regulations governing products obtained within value chains based on secondary feedstock.

Algae as Source of Food and Nutraceuticals

Increasing knowledge on nutrition and plant biotechnology has changed the concepts of agriculture, food, and its impact on health. The numerous scientific research and publications have shown that algae provide health benefits to the people. Seaweeds, due to the beneficial biochemical composition, have a great potential to be used as components of food aimed at increasing its nutritional value. Algal cells possess a wide diversity of biologically active metabolites, e.g., proteins, vitamins, minerals, polysaccharides, amino acids, fatty acids, lipids and could be used in the development of pharmaceuticals and also essential compounds for human nutrition. They could be used as an antioxidant, anti-inflammatory, anticoagulant, antimicrobial, antibacterial, antiviral, antifungal, anticancer, antiobesity, antidiabetic, hypercholesterolemic, and antihypertensive nutraceuticals. The nutritional algae value differs from various species, geographic areas, seasons, and water conditions are taken into account. Currently, the algal products have become familiar to people and the prevention of disease is better understood. The number of healthcare pharmaceuticals from algae is still in the development stage and new functions are being investigated.