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Seaweeds are well recognized as a potential protein source. The edible green seaweed, Ulva sp., is abundant in the Brittany Coast, France. This study examined the extraction of proteins and glycoproteins from this seaweed. Four different extraction procedures (Procedure 1: deionized water, DW; Procedure 2: lysis solution 1 (LS1) containing 8 M urea, 2% Tween 20, 2% Triton X-100, 30 mM dithiothreitol, and 1% polyvinylpyrolidine; Procedure 3: lysis solution 2 (LS2) containing 50 mM Tris-HCl buffer pH 8, 10 mM EDTA, 2 mM Na2S2O5, and 1% Triton X-100; Procedure 4: 50 mM Tris-HCl buffer, pH 8) were applied to extract proteins from Ulva sp. in Brittany. The protein contents (%, dry basis) in the above extracts from Procedures 1–4 were 4.36 ± 0.21, 11.88 ± 0.23, 10.34 ± 0.35, and 3.58 ± 0.48, respectively. Moreover, electrophoresis (SDS-PAGE) revealed that the protein profile varies with season. Three glycoprotein-rich fractions, namely, GP-1 (from Procedure GP1), GP-2-DA, and GP-2-DS (from Procedure GP2), were extracted from Ulva sp. GP-1 and GP-2-DA fractions have a higher protein content than neutral sugars, while GP-2-DS contains a higher amount of neutral sugars than proteins. Matrix-assisted laser desorption ionization-time of flight/mass spectrometry (MALDI-TOF/MS) technique was applied to further proteomic analysis of each glycoprotein-rich fraction. GP-2-DS was hydrolyzed with protease enzyme to confirm the availability of proteins, and interestingly, the particular hydrolysate shows no original peaks in the MALDI-TOF/MS analysis. All three glycoprotein-rich fractions show no cytotoxicity in Vero cells at the tested concentration (500 mg dw mL−1). Collectively, these results revealed that the extractable protein content and protein profile of Ulva sp. differ according to the extraction liquid system and the season. The utilization and value addition of proliferative Ulva sp. in Brittany as a protein source is promising but needs to consider the seasonal change of the protein profile.

International audience; Seaweeds are potentially excellent sources of bio-active metabolites that could represent useful leads in the de-velopment of new functional ingredients in pharmaceuticaland cosmetic industries. In the last decade, new marinebioprocess technologies have allowed the isolation of sub-stances with biological properties. The brown algaSargassum muticum (Yendo) Fensholt (Ochrophyta) was en-zymatically hydrolyzed to prepare water-soluble extracts byusing six different commercially available carbohydrate-degrading enzymes and two proteases. Evaluation of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antiox-idant power (FRAP) antioxidant, tyrosinase, elastase, and bio-film inhibition, antibacterial and antiviral activities as well asevaluation of cytotoxicity were realized for each extract. Totalphenolic content was measured for extract characterization,and solid-phase extraction was useful to purify the enzymaticextract. Soluble total phenolic content of S. muticumViscozyme extract was highest with 6.4% of dry weight.Enzymatic Celluclast and Viscozyme extracts had the lowestvalue of DPPH IC50 indicating a strong antiradical activity,0.6 mg mL−1, in comparison with other enzymes. The ferricreducing antioxidant power ranged between 48.7 μM Fe 2+ Eq,digested with Viscozyme, and 60.8 μM Fe 2+ Eq, digested withAmyloglucosidase. Tyrosinase inhibition activity ofS. muticum Neutrase extract was 41.3% higher compared toother enzymes. Elastase inhibition activity of S. muticumShearzyme extract had highest activity (32.8%). All enzymat-ic extracts showed no cytotoxic effect towards the kidney Verocells. Meanwhile, only S. muticum Neutrase and Alcalase ex-tracts exhibited potential antiviral activity. In addition,S. muticum Viscozyme and Shearzyme extracts showed prom-ising activity in suppressing the biofilm formation againstPseudomonas aeruginosa and Escherichia coli, respectively. Purification of S. muticum Viscozyme extracts by solid-phaseextraction managed to concentrate the phenolic content andimprove the bioactivity. These results indicate the promisingpotential of enzyme-assisted followed by solid-phase extrac-tion in recovering phenolic content and in improving itsbioactivity.

International audience

International audience; This field study is intended to propose a global methodology to assess and monitor the water quality of the gulf of Morbihan, a littoral ecosystem under increasing anthropic pressure. To this end, the Locmariaquer site, where Crassostrea gigas is extensively cultivated, was selected to perform a one-year follow-up of tissular glutathione S-transferase and acetylcholinesterase specific activities in this filter feeder organism. Calculation of an integrated index, corresponding to the ratio of the two enzymes activities, allowed to discriminate from the environmental noise, several clusters which could be representative environmental stress, potentially latent pollution. Moreover, the estrogenic activity was assessed in water samples collected at Locmariaquer and other strategic sites of the gulf. The results evidenced a low estrogenic-disrupting compound contamination of waters. Overall, this methodology produced an accurate outlook of a basal state for the gulf and could be developed in the context of a chronic monitoring of this site.

Exopolysaccharides (EPS) were extracted from a sponge, Celtodoryx girardae recently discovered in the Golfe du Morbihan in 2000. Sponge samples were collected monthly from November 2007 to May 2008. SEC analysis of EPS samples showed that they exhibit a unique molecular weight of approximately 800 kDa. However, infrared analysis revealed that structural seasonal variations occur. EPS fractions also exhibit significant sulphate contents and were screened in vitro for a potential antiviral activity against Herpes simplex virus type 1 (HSV-1). The best result was obtained with a sample collected in January which exhibits an EC(50) of 5.9 microg/mL without cytotoxicity on the Vero cell line. Experiments carried out to elucidate the mechanism of the EPS showed that the sulphated groups of EPS interact with the glycoproteins on the surface of the virus' membrane.

The dynamics of bacterial colonies is complex in nature because it correlates the behavior of numerous individual cells in space and time and is characterized by emergent properties such as virulence or antibiotics resistance. Because there is no clear-cut evidence that periodic swarming of P. mirabilis colonies is ruled by chemical triggers responsible for cell-to-cell signaling in most of the biofilms, we propose that the observed periodicity relies on the colony's global properties. Hence, the biochemical and functional properties of the extracellular matrix (ECM) of P. mirabilis colonies were investigated. A binary exopolysaccharide mixture (1 and 300 kDa), glycinebetaine, and a phenoglycolipid were identified. Rheology, calorimetry, and water sorption experiments performed on purified EPS bring evidence that these exoproducts exhibit marked viscoelasticity, which likely relies on large scale H bond networks. Such behavior is discussed in terms of water activity because the mechanical ECM properties were found to depend on hydration.

One of the most promising alternatives to toxic heavy metal-based paints is offered by the development of antifouling coatings in which the active ingredients are compounds naturally occurring in marine organisms and operating as natural antisettlement agents. Sessile marine macroalgae are remarkably free from settlement by fouling organisms. They produce a wide variety of chemically active metabolites in their surroundings, potentially as an aid to protect themselves against other settling organisms. In this study, a dichloromethane extract from the brown seaweed Sargassum muticum was tested in situ and, after 2 months of immersion, showed less fouling organisms on paints in which the extract was included, compared to paints containing only copper after 2 months of immersion. No barnacles or mussels have been observed on the test rack. Identification by NMR and GC/MS of the effective compound revealed the abundance of palmitic acid, a commonly found fatty acid. Pure palmitic acid showed antibacterial activity at 44 A µg mL-1, and also inhibited the growth of the diatom Cylindrotheca closterium at low concentration (EC50 = 45.5 A µg mL-1), and the germination of Ulva lactuca spores at 3 A µg mL-1. No cytotoxicity was highlighted, which is promising in the aim of the development of an environmentally friendly antifouling paint.

The tributyltin-based products and organic biocides which are incorporated into antifouling paints have had a negative impact on the marine environment, and the ban on tributyltin-based antifouling products has urged the industry to find substitutes to prevent the development of fouling on ship hulls. Natural antifouling agents could be isolated from marine resources, providing an alternative option for the industry. The effects of different marine seaweed extracts from Sargassum muticum and Ceramium botryocarpum on the growth, pigment content and photosynthetic apparatus of the marine diatom Fragilaria pinnata were compared with those of Diuron, a biocide widely used in antifouling paints. The addition of the macroalgal extracts in the culture medium resulted in an inhibition of the growth of F. pinnata, but this inhibition was lower than that obtained with Diuron. After transfer to a biocide-free medium, F. pinnata cells previously exposed to the macroalgal extracts exhibited normal growth, in contrast to Diuron-treated cells, which died, demonstrating that the effects of the natural antifouling agents were reversible. Macroalgal extracts and Diuron-induced modifications in F. pinnata cellular pigment content. Chlorophyll a, fucoxanthin, and the xanthophyll pool, diadinoxanthin and diatoxanthin, were the most affected. Changes in the structure and function of the photosynthetic apparatus were studied by microspectrofluorimetry, and provided a comprehensive evaluation of the inhibition of the diatom Photosystem II (PSII) by the biocides. This study confirms that natural extracts from the macroalgae studied have the potential to be used as a substitute to commercial biocides in antifouling paints.