Production of exopolymer substances from the thermophilic chlorophyte Graesiella: industrial and ecological applications

Microalgal extracellular polymeric substances (EPSs) are heteropolysaccharides that have characteristics suitable for industrial and biotechnological applications. Notably, they have strong anionic nature and high hydrophobicity. Nevertheless, systematic studies to demonstrate the viability of the production of EPSs on an industrial scale are still crucial. In this research, the chlorophyte Graesiella was grown on a raceway pond to view its EPS valorization. The biomass production achieved a maximum of 1.98 g L−1 and an EPS production of 1.6 g L−1 after six production days. The Graesiella EPSs with a molecular weight above 100 kDa are sulfated exopolymers containing mainly polysaccharide (70%) and protein (16%). The EPSs produced more stable emulsions with hydrocarbons and oils than Tween-20. The emulsification indices with n-hexane (88%) and maize oil (28%) indicate the EPSs’ strong emulsion-stabilizing capacity. The EPSs showed a peak flocculating percentage of 95% to kaolin suspension, with better flocculation performance than Al2(SO4)3 and alginate. Moreover, Graesiella EPSs had a significant effect on antimicrobial activity, significantly inhibiting fungal growth (71% for Botytis cinerea and 87% for Fusarium oxysporum), spore germination (100% of inhibition at a concentration of 1.8 g L−1), and mycelium growth (68% of inhibition). Also, Graesiella EPSs acted as a bactericide against Vibrio anguilaruim and Listonella anguilaruim (100% inhibition). EPSs were also found to have potent antioxidant activity compared with L-ascorbic acid. The obtained results open new perspectives to the further exploration of Graesiella sp. as a potential EPS producer, making it a promising candidate for numerous industrial applications.info:eu-repo/semantics/publishedVersio

Characterization of biodegradable films based on extracellular polymeric substances extracted from the thermophilic microalga Graesiella sp

In this research, a new type of biodegradable film based on the extracellular polymeric substances (EPS) and isolated from the thermophilic microalga Graesiella sp., was formulated and characterized. The EPS film was 0.221 mm thick. Atomic force microscopy and scanning electron microscopy images revealed a homogeneous character with a lamellar microstructure. The EPS film displayed yellowish color, high transparency, high ul traviolet barrier properties, and low oxygen (0.008 SI), and water-vapor permeability (0.037 SI). Film tensile strength (16.24 MPa) and elongation at break (4.76%) were in the range of common biofilms and the thermal analyses showed high transition temperature (126 ◦C) and high thermal stability (up to 800 ◦C). Compared to ascorbic acid, results indicated that the EPS film shows a higher antioxidant activity, mainly as β-carotene anti bleaching (84%), DPPH- free radical scavenging ability (80%), and ferrous iron-chelating (55%). Graesiella sp., EPS film effects on beef meat packaging were studied during nine days of cold storage. Compared to polyvinylchloride-packed meat, EPS-packed meat samples showed higher stability of color (redness = 13.6) and pH (5.85) during storage and low proliferation of total viable counts (4.04 CFU⋅g− 1 ) and Pseudomonas bacteria (4.09 CFU⋅g− 1 ). They also exhibit lower drip loss (9%) and less metmyoglobin (32%), heme iron (4.87 μg⋅g− 1 ) total volatile basic nitrogen (TVB-N = 22.96 mg⋅kg− 1 ), and lipid oxidation (MDA = 0.025 mg⋅kg− 1 ). The obtained results highlight the potential for use of microalgae EPS as a new film forming material that could be applied in beef meat preservation.info:eu-repo/semantics/publishedVersio

Natural pigments and biogas recovery from microalgae grown in wastewater

This study assessed the recovery of natural pigments (phycobiliproteins) and bioenergy (biogas) from microalgae grown in wastewater. A consortium of microalgae, mainly composed by Nostoc, Phormidium, and Geitlerinema, known to have high phycobiliproteins content, was grown in photobioreactors. The growth medium was composed by secondary effluent from a high rate algal pond (HRAP) along with the anaerobic digestion centrate, which aimed to enhance the N/P ratio, given the lack of nutrients in the secondary effluent. Additionally, the centrate is still a challenging anaerobic digestion residue since the high nitrogen concentrations have to be removed before disposal. Removal efficiencies up to 52% of COD, 86% of NH4+-N, and 100% of phosphorus were observed. The biomass composition was monitored over the experimental period in order to ensure stable cyanobacterial dominance in the mixed culture. Phycocyanin and phycoerythrin were extracted from harvested biomass, achieving maximum concentrations of 20.1 and 8.1 mg/g dry weight, respectively. The residual biomass from phycobiliproteins extraction was then used to produce biogas, with final methane yields ranging from 159 to 199 mL CH4/g VS. According to the results, by combining the extraction of pigments and the production of biogas from residual biomass, we would not only obtain high-value compounds, but also more energy (around 5-10% higher), as compared to the single recovery of biogas. The proposed process poses an example of resource recovery from biomass grown in wastewater, moving toward a circular bioeconomy

Identification of Marine Biotechnology Value Chains with High Potential in the Northern Mediterranean Region

© 2023. The authors. This document is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by /4.0/ This document is the Accepted version of a Published Work that appeared in final form in Marine Drugs. To access the final edited and published work see https://doi.org/10.3390/md21070416Marine (blue) biotechnology is an emerging field enabling the valorization of new products and processes with massive potential for innovation and economic growth. In the Mediterranean region, this innovation potential is not exploited as well as in other European regions due to a lack of a clear identification of the different value chains and the high fragmentation of business innovation initiatives. As a result, several opportunities to create an innovative society are being missed. To address this problem, eight Northern Mediterranean countries (Croatia, France, Greece, Mar. Drugs 2023, 21, 416. https://doi.org/10.3390/md21070416 https://www.mdpi.com/journal/marinedrugs Mar. Drugs 2023, 21, 416 2 of 26 Italy, Montenegro, Portugal, Slovenia and Spain) established five national blue biotechnology hubs to identify and address the bottlenecks that prevent the development of marine biotechnology in the region. Following a three-step approach (1. Analysis: setting the scene; 2. Transfer: identification of promising value chains; 3. Capitalization: community creation), we identified the three value chains that are most promising for the Northern Mediterranean region: algae production for added-value compounds, integrated multi-trophic aquaculture (IMTA) and valorization aquaculture/fisheries/processing by-products, unavoidable/unwanted catches and discards. The potential for the development and the technical and non-technical skills that are necessary to advance in this exciting field were identified through several stakeholder events which provided valuable insight and feedback that should be addressed for marine biotechnology in the Northern Mediterranean region to reach its full potential

Identification of Marine Biotechnology Value Chains with High Potential in the Northern Mediterranean Region

©2023. This manuscript version is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by/4.0/ This document is the Published, version of a Published Work that appeared in final form in Marine Drugs. To access the final edited and published work see https://doi.org/ 10.3390/md21070416Marine (blue) biotechnology is an emerging field enabling the valorization of new products and processes with massive potential for innovation and economic growth. In the Mediterranean region, this innovation potential is not exploited as well as in other European regions due to a lack of a clear identification of the different value chains and the high fragmentation of business innovation initiatives. As a result, several opportunities to create an innovative society are being missed. To address this problem, eight Northern Mediterranean countries (Croatia, France, Greece Italy, Montenegro, Portugal, Slovenia and Spain) established five national blue biotechnology hubs to identify and address the bottlenecks that prevent the development of marine biotechnology in the region. Following a three-step approach (1. Analysis: setting the scene; 2. Transfer: identifi cation of promising value chains; 3. Capitalization: community creation), we identified the three value chains that are most promising for the Northern Mediterranean region: algae production for added-value compounds, integrated multi-trophic aquaculture (IMTA) and valorization aquacul ture/fisheries/processing by-products, unavoidable/unwanted catches and discards. The potential for the development and the technical and non-technical skills that are necessary to advance in this exciting field were identified through several stakeholder events which provided valuable insight and feedback that should be addressed for marine biotechnology in the Northern Mediterranean region to reach its full potential

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

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

Comparison of Extraction Techniques and Surfactants for the Isolation of Total Polyphenols and Phlorotannins from the Brown Algae Lobophora variegata

Surfactant-mediated extraction (SME), pressurized liquid extraction (PLE), and enzyme-assisted extraction (EAE) have been compared to improve the isolation of phlorotannins from the brown algae Lobophora variegata. Enzymatic treatment with Alcalase 2.4 L FG, Carezyme 4500 L, protease from Streptomyces griseus, pectinase from Aspergillus niger, Celluclast 1.5 L, protease from Bacillus licheniformis; surfactant extraction with triacetin and guaiacol and PLE with ethanol:water as extracting solvent, have been studied in terms of total phenolic content by the Folin–Ciocalteu method and total phlorotannin content using the DMBA assay. The results showed that SME yields the highest amount of phenols and phlorotannins by using food grade guaiacol as the surfactant. An extraction protocol was developed to maximize the amount of extract obtained from L. variegata. The effects of various parameters such as the type of surfactant, efficacy of surfactant, and optimum pH, on the extraction efficiency of polyphenols were examined. The simultaneous use of the enzyme and surfactant was also investigated. However, a synergistic effect between the enzymes and the surfactant for the extraction of polyphenols has not been observed. Considering total phenols and total phlorotannins in the extract, the extraction yield were obtained for total phenols as SME > EAE > PLE and for total phlorotannins as SME > PLE > EAE

Antifungal activity of Ecklonia sp. and Jania sp. polysaccharides against Botrytis cinerea

Seaweeds are a source of macro and microelements, amino acids, vitamins, polysaccharides and hormones, such as auxins, auxin-like compounds and cytokinins (Craigie, 2011). Seaweeds extracts (SE) have long been used in agriculture as soil amendment for their beneficial properties on plants, because they stimulate both plant growth and production (Crouch & van Staden, 1992; Arthur et. al., 2003). They also increase fruit weight, fresh dry mass of root, leaf area, yield per plant, the chlorophyll content and minerals (Sivasankari et al., 2006; Rayorath et al., 2008; Roussos et al., 2009). It has also been shown that SE may help the plants to counteract abiotic and biotic stresses. Among abiotic stresses, Ashraf & Foolad (2007) demonstrated that SE are involved in overcoming plant stress conditions such as drought and salinaty. Several studies have shown antibiotic, antiviral and antifungal activities of SE against a number of plant pathogens such as Penicillium spp. and Fusarium oxysporum (Khallil et al., 2015) and Aspergillus sp. (Kosanić et al., 2015). Seaweeds extracts are also rich in several bioactive compounds, such as polysaccharides that are well known to be elicitors of plant defence responses. Simultaneously to the growing consumption of agricultural products, such as strawberry, there was an increase in the use of chemical fertilizers to improve plant yield, and of synthetic pesticides to control fungal plant pathogens. The continuous use of chemicals during the years has affected human and animal health and the ecosystem. Strawberry is one of the most consumed berries and its high nutritional value and composition have stimulated its consumption increase. A number of fungal pathogens can affect strawberry plants such as Colletotrichum spp., and several species of the soil borne pathogens, such as Rhizoctonia, Fusarium and Pythium causing the so-called black root rot complex (Manici et al., 2005). Among these pathogens, Botrytis cinerea, the agent of grey mold, cause several losses especially during shelf life. Alternative approaches to chemical treatments are necessary to preserve the quality of strawberries during the shelf life in order to protect health safety and limit the development of the fungus. In this study, the antifungal activity of cationic polysaccharides extracted from two macroalgae, Ecklonia sp. (Ochrophyta) and Jania sp. (Rhodophyta) was investigated against B. cinerea in vitro and in vivo on strawberry. Polysaccharides were extracted by selective precipitation with 2% (w/v) N-Cetylpyridinium bromide monohydrate (Cetavlon) (Diaz et al., 2011). In the in vitro assay, fungal colony portions were treated for 6 hours by immersion in three polysaccharides aqueous concentrations, 1.65, 0.82 and 0.41 mg/ml for Ecklonia sp. and 0.18, 0.09 and 0.045 mg/ml for Jania sp. The treated colony portions were inoculated in agarized medium and daily growth was measured for a week. Ecklonia sp. polysaccharides at 0.18 mg/ml and 0.09 mg/ml significantly inhibited B. cinerea growth by 21.0% and 22.8%, respectively, two days after treatment. Jania sp. polysaccharides did never inhibit fungal colony growth. For in vivo experiments, strawberry ripe fruits cv. Cristal were immerged before or after harvesting in polysaccharide aqueous solutions of Ecklonia sp. at the concentrations of 0.82 and 0.41 mg/ml, and of Jania sp., at 0.09 and 0.045 mg/ml. A spore suspension of B. cinerea (1 × 105 spores/ml) was inoculated by spraying fruits 24 hours after treatment. Disease symptoms over the total area inoculated of fruit were evaluated as percentage of infected area. The pre-harvest treatment with Jania sp. showed to reduce disease symptoms by 100% at 0.09 mg/ml and by 50% at 0.045 mg/ml and with Ecklonia sp. by 16.7% (0.82 mg/ml) and 11.11% (0.41 mg/ml). Post-harvest treatment did never inhibit disease symptoms. This study showed that SE could be considered for further investigation in control strategy against B. cinere

Natural Pigments and Biogas Recovery from Microalgae Grown in Wastewater

This study assessed the recovery of natural pigments (phycobiliproteins) and bioenergy (biogas) from microalgae grown in wastewater. A consortium of microalgae, mainly composed by Nostoc, Phormidium, and Geitlerinema, known to have high phycobiliproteins content, was grown in photobioreactors. The growth medium was composed by secondary effluent from a high rate algal pond (HRAP) along with the anaerobic digestion centrate, which aimed to enhance the N/P ratio, given the lack of nutrients in the secondary effluent. Additionally, the centrate is still a challenging anaerobic digestion residue since the high nitrogen concentrations have to be removed before disposal. Removal efficiencies up to 52% of COD, 86% of NH4+-N, and 100% of phosphorus were observed. The biomass composition was monitored over the experimental period in order to ensure stable cyanobacterial dominance in the mixed culture. Phycocyanin and phycoerythrin were extracted from harvested biomass, achieving maximum concentrations of 20.1 and 8.1 mg/g dry weight, respectively. The residual biomass from phycobiliproteins extraction was then used to produce biogas, with final methane yields ranging from 159 to 199 mL CH4/g VS. According to the results, by combining the extraction of pigments and the production of biogas from residual biomass, we would not only obtain high-value compounds, but also more energy (around 5-10% higher), as compared to the single recovery of biogas. The proposed process poses an example of resource recovery from biomass grown in wastewater, moving toward a circular bioeconomy