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Macroalgae are one of the most environmentally friendly resources, and their industrial by-products should also be sustainable. Algal polysaccharides represent valuable products, and the definition of new eco-sustainable extraction processes, ensuring a safe and high-quality product, is a new goal in the context of reducing the carbon footprint. The aim of the present work was to determine the influence of the extraction methodology on the properties and structure of the polysaccharides, comparing conventional and innovative microwave-assisted methods. We focused on extraction times, yield, chemical composition and, finally, biological activities of raw polymers from three macroalgal species of Chlorophyta, Rhodophyta and Phaeophyceae. The main objective was to design a sustainable process in terms of energy and time savings, with the aim of developing subsequent application at the industrial level. Extraction efficacy was likely dependent on the physico-chemical polysaccharide properties, while the use of the microwave did not affect their chemical structure. Obtained results indicate that the innovative method could be used as an alternative to the conventional one to achieve emulsifiers and bacterial antiadhesives for several applications. Natural populations of invasive algae were used rather than cultivated species in order to propose the valorization of unwanted biomasses, which are commonly treated as waste, converting them into a prized resource.

The use of seaweed as plant biostimulants is a solution for sustainable agriculture. The present study aims to quantify and compare the presence of plant growth regulators (PGRs) in four genetically labeled macroalgae growing in the Ionian Sea. Species were selected because they produce abundant biomass, disturbing ecological equilibrium and anthropic activities. We measured the content of gibberellic acid (GA3), kinetin (KN), indoleacetic acid (IAA), abscisic acid (ABA) and indole butyric acid (IBA). The method applied was modified from the literature to obtain simultaneously different PGRs from seaweed biomass in a shorter period of time. Among results, it is notable that Hypnea corona Huisman et Petrocelli (Rhodophyta) showed higher GA3 concentration, while in Spyridia filamentosa (Wulfen) Harvey (Rhodophyta), higher KN, IBA, IAA and ABA contents were recorded. The latter species displayed an interesting profile of PGRs, with an IAA value comparable with that reported in Ascophyllum nodosum (Linnaeus) Le Jolis (Ochrophyta), which is currently used as a source of plant biostimulants in agriculture. Macroalgae thrive abundantly in nutrient-rich environments, such as anthropized coastal areas affecting human economic activities. Consequently, environmental agencies are forced to dredge algal thalli and discard them as waste. Any use of unwanted biomass as an economic product is highly desirable in the perspective of ecosustainable development.

The exploitation of macroalgal biomass could provide novel environment-friendly molecules to prevent bacterial biofilm formation. Crude extracts, or polysaccharides, from the DNA-barcoded macroalgae Chaetomorpha aerea (Chlorophyta), and Agardhiella subulata and Hypnea cornuta (Rhodophyta) collected from the costal brackish Lake of Ganzirri (Italy) were evaluated for their effects on biofilm formation of Vibrio anguillarum, V. harveyi, Vibrio parahaemolyticus and Photobacterium damselae subsp. piscicida. All bacterial strains were able to produce biofilm on polystyrene surfaces at different extents. Without exerting antibacterial activity, the crude polysaccharides showed dose-dependent inhibitory activity on the biofilm formation. At the highest concentration (400 μg/ml), the strongest reduction of biofilm formation was observed in the presence of C. aerea and A. subulata extracts against V. harveyi (59 and 53%, respectively), followed by the H. cornuta extract against Photobacterium piscicida (52%) and V. parahaemolyticus (28%). The extract from A. subulata was also active against the biofilm formation of P. piscicida (48%) and Listonella anguillarum (33%). As resulted by the surface coating assay and the microbial adhesion onto hydrocarbons, the algal extracts were able to inhibit the adhesion of pathogens and modify their cell-surface properties and hydrophobicity. Moreover, all the extracts possessed high emulsifying activity (E24 up to 70%) and stabilizing capacity. Based on two different in vivo assays, using Artemia salina and Danio rerio, all the extracts showed no potential toxicity for aquaculture application. Our results suggest that the antibiofilm activity of algal extracts is related to the inhibition of the early bacterial adhesion. Consequently, these non-toxic and biodegradable polysaccharides, with surfactant and antiadhesive properties, could be proposed to prevent biofilms in aquaculture.

The exploitation of macroalgal biomass, as a source of antibacterial drugs, would result into the valuable transformation of waste into an economic resource. Ethanol and water extracts or polysaccharides, from nine DNA-barcoded macroalgae (2 Chlorophyta, 5 Ochrophyta and 2 Rhodophyta) collected from Italian coastal environments, were screened for antibacterial activity against ten bacterial pathogens with relevance for aquaculture and human health. All extracts have not cytotoxic effects on molluscan digestive gland cells and mammalian red blood cells. As resulted by agar diffusion assays, water extracts showed broader and higher inhibitory activity than ethanol extracts against the tested pathogens. Polysaccharides from Fucus virsoides (Ochrophyta) possessed the strongest inhibitory activity against Aeromonas salmonicida subsp. salmonicida and Photobacterium damselae subsp. damselae, an emergent pathogen for humans. Polysaccharides from Undaria pinnatifida (Ochrophyta) were the most active against V. harveyi, the major pathogen responsible for diseases in aquaculture, and also against a multiresistant, clinical strain of Pseudomonas aeruginosa. Our results suggest that these polysaccharides could represent a novel source of compounds active against bacterial pathogens relevant for eco-sustainable aquaculture and human health.

The simple and convergent morphologies of many red algae make these species difficult to identify using traditional morphological characters. Many cryptic species have been described in recent year...

The cosmopolitan genus Ulva Linnaeus includes species of green macroalgae found in marine, brackish and some freshwater environments. Although there is a wide literature for the determination of Ulva taxa in Europe, they are among the most problematic algae to accurately identify, because they have few distinctive features, as well as a high intraspecific variation. At present, the knowledge of both diversity and distribution of the genus Ulva in the Mediterranean Sea is almost entirely based on morphological studies and there is only a few published papers dealing with molecular data. Tunisia has a key position in the Mediterranean and constitutes a transition area with a rich habitat diversity between eastern and western basins. The latest inventory of marine macrophytes dates back to 1987, updated in 1995. The aim of the present paper is to provide a molecular-assisted alpha taxonomy survey of Ulva spp. along Tunisian coasts, in comparison with a few Italian sites, using the tufA marker. Nine genetic species groups were resolved, including the non indigenous species Ulva ohnoi, newly reported for Tunisia. The actual picture of the taxonomy of Ulva spp. in the Mediterranean as a whole is far to be clarified and the present data on Tunisian collections aim to be a step towards its clarification. This paper is the first DNA barcoding study on green macroalgae in Tunisia and it contributes to add records to the Barcode Of Life Data Systems which are publically available.

International audience; Tunisia is located at a key position in the Mediterranean Sea where it constitutes a transitional area between the eastern and western basins benefitting from rich habitat diversity. The most recent inventory of marine macrophytes dated back to 1987 with an update in 1995, however these inventories were performed with identification based on morphological observations, which can be misleading for many seaweed species. To the best of our knowledge, this is the first study of the Tunisian macroalgal flora using DNA barcoding methods. Our target was to carry out a survey of macroalgae, to reveal cryptic species and allochthonous introductions, and to identify taxa with problematic taxonomy. COI-5P sequence analysis resolved 26 genetic species, including two new reports and three alien species. Of the remaining taxa, several displayed cryptic diversity relative to species reported from the Mediterranean versus from other geographical regions with taxonomic and nomenclature updates provided where possible. The aim of the present paper was to provide a DNA barcode-assisted floristic list of florideophycean algae collected along the Tunisian coast.

Infections due to Cryptococcus neoformans/C. gattii complex have been reported to afflict, not only humans but also other mammals including seabirds and cetaceans, proving that the actual animal exposure to these fungi in nature could be underestimated. In this study, antifungal activity of ethanolic extracts obtained from red alga Asparagopsis taxiformis was evaluated against eight major genotypes of the C. neoformans/C. gattii complex, using both disk diffusion and microdilution broth methods. The algal extracts were active against all fungal strains tested and were not cytotoxic to human red blood cells. This study suggests that Asparagopsis taxiformis extracts possess attractive antifungal properties which should encourage the search for new drugs derived from marine algae.

The red algae Asparagopsis taxiformis collected from the Straits of Messina (Italy) were screened for antifungal activity against Aspergillus species. EUCAST methodology was applied and extracts showed antifungal activity against A. fumigatus, A. terreus and A. flavus. The lowest minimum inhibitory concentrations observed were0.15 mg ml(-1) and the highest were5 mg ml(-1) for Aspergillus spp. tested. Agar diffusion assays confirmed antifungal activity of A. taxiformis extracts in Aspergillus species.

Several compounds from marine organisms have been studied for their potential use in aquaculture. Among the red algae, Asparagopsis taxiformis is considered one of the most promising species for the production of bioactive metabolites with numerous proposed applications. Here, the in vitro antibacterial activity, the easy handling and the absence of adverse effects on marine fish species are reported. Depending on the seasonal period of sampling, ethanol extracts of A. taxiformis exhibited significantly different inhibitory activity against fish pathogenic bacteria. The extract obtained in late spring showed strong antibacterial activity against Aeromonas salmonicida subsp. salmonicida, Vibrio alginolyticus, and V. vulnificus, and moderate activity against Photobacterium damselae subsp. damselae, P. damselae subsp. piscicida, V. harveyi and V. parahaemolyticus. Sea bass and gilthead sea bream were fed with pellets supplied with the alga and algal extracts. The absence of undesired effects on fish was demonstrated. Hematological and biochemical investigations allowed to confirm that the whole alga and its extracts could be proposed for a future application in aquaculture.

Sulfated polysaccharides from marine macroalgae have been shown to possess a variety of biological activities against fungi, bacteria, viruses, and protozoa. In this study, the in vitro activity of algal polysaccharides against Leishmania infantum (Kinetoplastida: Trypanosomatidae) was investigated. The polysaccharides were extracted from different macroalgae of the Mediterranean Sea: Chaetomorpha linum, Agardhiella subulata, Gracilaria viridis, Gracilaria bursa-pastoris, Hypnea cornuta, Sargassum muticum, and Undaria pinnatifida. Preliminary results showed a good anti-leishmanial activity of the investigated species, encouraging the focus on their use as natural resources in order to match integrated management strategies for the employment of local macroalgae..

Ethanol extracts of Asparagopsis taxiformis collected from the Straits of Messina (Italy) were screened for antibacterial activity against pathogenic shellfish and fish bacteria previously isolated from local marine and brackish environments. Genetic labelling by DNA barcoding allowed us to identify the algal population as a biogeographical strain conspecific to A. taxiformis . The extract obtained in May showed the broadest antibacterial activity against all tested pathogenic bacteria, especially against Vibrio alginolyticus, Vibrio vulnificus and Aeromonas salmonicida subsp. salmonicida . Moderate activity was observed against Photobacterium damselae subsp. damselae and Photobacterium damselae subsp. piscicida , Salmonella sp., Vibrio cholerae , Vibrio harveyi and Vibrio parahaemolyticus . The absence of cytotoxic effects of active algal extracts was verified using trypan blue exclusion test on cells of digestive glands of Mytilus galloprovincialis . The results indicated that ethanol extracts of A. taxiformis could represent a source of antibacterial substances with potential use in aquaculture.

Crude extracts and column fractions from the red algae Asparagopsis taxiformis and A. armata from the Strait of Messina (Italy) were screened for the production of antimicrobial compounds. Extracts from both species revealed remarkable antiprotozoal activity against Leishmania, revealing such algae as a great source of natural antiprotozoal products.

Undaria pinnatifida (U. pinnatifida) is a highly invasive species and has caused concern all over the world because it has invaded coastal environments, has the potential to displace native species, significantly alters habitat for associated fauna, and disturbs navigation. Any attempt to eradicate it would be futile, owing to the elusive, microscopic gametophyte, and because the alga thrives in sites rich in anthropic activities. Venice Lagoon is the largest Mediterranean transitional environment and the spot of the highest introduction of non-indigenous species, including U. pinnatifida, which is removed as a waste. We demonstrated that polysaccharide extracts from U. pinnatifida have an anticoagulant effect on human blood in vitro and are not cytotoxic. The results obtained by PT (normal values 70-120%) and APTT (normal values 28-40s) assays were significantly prolonged by the polysaccharide extracts of U. pinnatifida, therefore algal extracts are ideal candidates as antithrombotic agents.

Leishmaniasis is a disease with a worldwide distribution affecting both humans and animals. There is a need to identify and develop new drugs for the treatment of leishmaniasis. This study showed that crude ethanolic extracts of the red alga Asparagopsis taxiformis have a powerful effect against L. infantum, the prevalent species of the genus Leishmania in the Mediterranean basin. L. infantum demonstrated decreased vitality with increasing concentration of the algal extracts. At a concentration of 40 μg/mL, the extracts achieved 100% mortality of the parasite and the LD50 value was 25 μg/mL for promastigotes and 9 μg/mL for amastigotes. Algal extracts caused morphological alterations and apoptosis in Leishmania cells. The potential cytotoxic action of crude extracts was investigated by a MTT viability assay on DH82 and Vero cell lines but there was no cytotoxic effect. The potential of red alga A. taxiformis metabolites as anti-leishmanial agents merits further pharmacological investigation.

Marine algae are important sources of phycocolloids like agar, carrageenans and alginates used in industrial applications. Algal polysaccharides have emerged as an important class of bioactive products showing interesting properties. The aim of our study was to evaluate the potential uses as anticoagulant drugs of algal sulphate polysaccharides extracted from Ulva fasciata (Chlorophyta) and Agardhiella subulata (Rhodophyta) collected in Ganzirri Lake (Cape Peloro Lagoon, north-eastern Sicily, Italy). Toxicity of algal extracts through trypan blue test and anticoagulant action measured by activated partial thromboplastin time (APTT), prothrombin time (PT) test has been evaluated. Algal extracts showed to prolong the PT and APTT during the coagulation cascade and to avoid the blood coagulation of samples. Furthermore, the algal extracts lack toxic effects towards cellular metabolism and their productions are relatively at low cost. This permits to consider the algae as the biological source of the future.

Objective: To study the activity of polysaccharides extracted from Undaria pinnatifida (U. pinnatifida) in vitro on red blood cell of Equus caballus, and compare it with heparin. Methods: Algal extracts was tested at two different concentrations 10 mg/mL and 20 mg/mL. In all studies, using horse red blood cells, control experiments were carried out without extract. We evaluated the toxicity of algal extracts through trypan blue test and haemolysis test and anticoagulant action measured by activated partial thromboplastin time, prothrombin time and fibrinogen test. Results: The polysaccharide extract of U. pinnatifida appeared to have no cytotoxic effect on the horse red blood cells. The values of prothrombin time, activated partial thromboplastin time and fibrinogen were significantly changed in the presence of the extract. Conclusions: This study suggests a possible exploitation of U. pinnatifida, thriving in the lagoon of Venice, as a source of anticoagulant drug, with the aim of transforming waste into a valuable biomass.

Chlorophylls based-dyes obtained from seaweeds represent attractive alternatives to the expensive and polluting pyridil based Ru complexes because of their abundance in nature. Another important characteristic is that the algae do not subtract either cropland or agricultural water, therefore do not conflict with agro-food sector. This pigment shows a typical intense absorption in the UV/blue (Soret band) and a less intense band in the red/near IR (Q band) spectral regions and for these reasons appear very promising as sensitizer dyes for DSSC. In the present study, we utilized chlorophylls from samples of the brown alga Undaria pinnatifida as sensitizer in DSSCs. The dye, extracted by frozen seaweeds and used without any chemical purification, showed a very good fill factor (0.69). Even the photelectrochemical parameters if compared with the existent literature are very interesting. © 2013 Elsevier B.V. All rights reserved.

Regeneration in macroalgae: an approach to studies of morphogenesis and correlation growth effects. - Seaweed regeneration is a rather spread survival strategy as a response to wounds which injure the plant integrity. In laboratory, the regeneration ability of algal segments provides suitable means for studying thallus growth and bud differentiation and for hypothesizing mechanisms of hormonal regulation of morphogenesis. Moreover, the most known correlation growth effects, i.e. polarity, apical dominance and apico-basal gradients, can be investigated. In this report the author describes and discuss some experimental results relating to these subjects.

Mediterranean reports of Gracilariaceae species, in particular those assigned to the G. verrucosa complex, were re-examined with the use of molecular tools, in order to verify their systematic position and better understand their distribution. Within this complex, we recognized four distinct taxa: Gracilariopsis longissima, Gracilaria gracilis, Gracilaria longa and a possible new species. The rbcL gene sequences, together with those of other terete Mediterranean entities, were included in a broad molecular phylogeny of the family. The reproductive characters of the studied taxa do not fit completely with published hypothesis on the generic and intrageneric relationships, suggesting that the anatomy of some subgroups should be better characterized.

The life history of Bangia atropurpurea (Bangiales, Rhodophyta) from the Alcantara River (Sicily, Italy) was studied in the field and laboratory. An alternation between a macroscopic phase and a microscopic filamentous conchocelis phase was found, and spermatia and carpogonia are described for the first time in a freshwater population of the species. Endosporangia have also been discovered on gametophytic plants in culture. In addition, the conchocelis phase produced either conchosporangia or monosporangia, and reproduction by fragmentation was common. Sexuality was indicated by chromosome counts of n = 3 and 2n =6 in gametophytes and sporophytes, respectively; resting cells were observed in both.