Biotechnological potential of the seaweed Cladophora rupestris (Chlorophyta, Cladophorales) lipidic extract.

Recently, with the advent of modern technologies, various marine organisms including algae are being studied as sources of natural substances effective on classical microorganisms and able to also combat the new trend of acquired resistance in microbes. In the present study the antimicrobial activity of the lipidic extract of the green seaweed Cladophora rupestris collected in a Mediterranean area, in two sampling periods (January and April), was assayed. The chemical characterization of the lipidic fractions was performed by gas-chromatography and multinuclear and multidimensional NMR spectroscopy. In the lipidic extract of C. rupestris collected in January an antibacterial activity against Enterococcus sp., Streptococcus agalactiae and Vibrio cholerae non-O1 was recorded; by contrast, bacterial inhibition was measured on several Vibrio species only in April. The fatty acid profile of C. rupestris lipidic extract, analyzed by gas chromatography, resulted mainly composed of palmitic, myristic, oleic, α linolenic, palmitoleic and linoleic acids. Moreover, since α-linolenic acid was the predominant ω3 fatty acid in April, we suggest its involvement in the antibacterial activity observed in this month, taking also into account that pure α-linolenic acid resulted effective towards some vibrios strains. C. rupestris fatty acid profile revealed also an interesting composition in polyunsaturated fatty acids in both the considered periods with the ω6/ω3 ratio lower than 1, leading to conclude that this macroalga may be employed as a natural source of ω3. Finally, the (1)H NMR spectrum in CDCl3 of algal lipid fractions showed the characteristic signals of saturated (SAFAs) and unsaturated fatty acids (UFAs) as well as other metabolites and a marked difference in free fatty acids (FFAs) content for the two examined algal lipid fractions. It is noteworthy that C. rupestris lipidic extracts show, by NMR spectroscopy, the signal pattern of polyhydroxybutyrate, a natural biocompatible and biodegradable polymer. In conclusion, on account of its antimicrobial activity, nutritional value and bioplastic content, C. rupestris lipidic extract can be considered a promising source for future biotechnological applications.

Mar Piccolo of Taranto: Vibrio biodiversity in ecotoxicology approach.

Microorganisms play an indispensable role in the ecological functioning of marine environment. Some species are sensitive while others are insensitive for a specific pollutant. The aim of this work is a preliminary study of the quantitative and qualitative distribution of cultivable vibrios in sediments and water samples characterized by different toxicity levels. For 1 year, in three suitably selected sampling stations of Mar Piccolo in Taranto (Ionian Sea, Italy), we have evaluated the toxicity level by Microtox® system, vibrios, total, and fecal coliform densities. The results of the Microtox® tests showed sediments characterized by an elevated level of toxicity, while the interstitial water of the same sites always showed biostimulatory phenomenon. The quantitative results show that vibrios and coliforms are more abundant in water than in sediment samples. The most often isolated strains were: Vibrio alginolyticus, Vibrio mediterranei, Vibrio metschinkovii, and Vibrio splendidus II. This work is the first example of study on the distribution of Vibrio species related to toxicity evaluation conducted by the Microtox® bioassay. The results show the different distribution of Vibrionaceae in two environmental matrices analyzed and characterized by different levels of toxicity.

The lipidic extract of the seaweed Gracilariopsis longissima (Rhodophyta, Gracilariales): a potential resource for biotechnological purposes?

In recent years seaweeds increasingly attracted interest in the search for new drugs and have been shown to be a primary source of bioactive natural products including antibiotics. In the present investigation the antimicrobial activity of Gracilariopsis longissima lipidic extract was assayed and its chemical characterization was carried out by means of advanced analytical techniques such as gas-chromatography and multinuclear and multidimensional NMR spectroscopy. G. longissima lipidic extract showed an antibacterial activity against several Vibrio species. These results are interesting considering both the resistance against antibiotics developed by vibrios and the need to control fish and shellfish diseases due to vibriosis. Analysis of fatty acid methyl esters performed by gas-chromatography showed that palmitic acid methyl ester (16:0) was the predominant saturated fatty acid (42%), while, among monounsaturated fatty acids, oleic acid methyl ester (18:1) prevailed (8.5%). Because the palmitic acid represents the main component of fatty acids we hypothesized its involvement in the antibacterial activity observed. However, a pure sample of palmitic acid did not show an antibacterial activity. The fatty acid profile of G. longissima revealed also an interesting composition in polyunsaturated fatty acids and in particular the ratio of ω-3 to ω-6 fatty acids was >1 thus suggesting that this macroalga may be used as a natural source of ω3. Moreover, the (1)H NMR spectrum in CDCl(3) of algal lipid fraction shows the characteristic signals of saturated and unsaturated fatty acids as well as other metabolites. Interestingly, in the lipid extract the presence of polyhydroxybutyrate, a linear biodegradable and biocompatible polyester, was clearly identified by NMR spectroscopy. In conclusion, the lipidic extract of G. longissima on account of its antimicrobial activity, nutritional value and content in biodegradable and biocompatible polyester represents an interesting potential biotechnological resource.

A test battery approach for ecotoxicological characterization of Mar Piccolo sediments in Taranto (Ionian Sea, Southern Italy).

The eco-toxicological approach is based on the determination of the toxic effects on organisms pertaining to various ecosystems and supplies information about the contaminants mixture bioavailability, in complex matrices as sediments. The use of a single species for a correct evaluation of the toxicity levels can be reductive, concerning the complexity of the ecosystem. In this work we have used species with various evolutionary levels and habitats; in particular, three different organisms: two amphipods species (Corophium insidiosum and Gammarus aequicauda) and one bacterium Vibrio fischeri. We have compared these organisms for the evaluation of sediments toxicity in four sites along the Ionian coast (Taranto, Italy); in particular, three sites in Mar Piccolo and one site in Mar Grande. The toxicity of sediments measured using Vibrio fischeri (Microtox Solid Phase Test protocol) has been compared with the mortality of the two amphipods. Both in polluted (Mar Piccolo sites) and in non-polluted environments (Mar Grande), the results of the three biological tests carried out converge into the evaluation of sediments quality monitored. In conclusion, these preliminary results show the potential use of Corophium insidiosum and Gammarus aequicauda as test species for a correct evaluation of sediments quality, together with Vibrio fischeri.