National Institute of Marine science and Technology

Monastir, Tunisia

National Institute of Marine science and Technology

Monastir, Tunisia
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Chentir I.,Blida University | Hamdi M.,University of Sfax | Doumandji A.,Blida University | HadjSadok A.,Blida University | And 3 more authors.
International Journal of Biological Macromolecules | Year: 2017

The interactive effects of light intensity and NaCl concentration were investigated for Spirulina two-step cultivation process using Full Factorial Design. In the experiment interval, light intensity had no effect while the NaCl concentration had significant effect on the enhancement of extracellular polymeric substances (EPS) production. Interestingly, results revealed a significant negative interaction between light and NaCl concentration indicating that high NaCl concentration (40gL-1) and low light intensity (10μmol photons m-2s-1) enhanced the EPS production. Under these conditions, EPS production reached a maximum of 1.02gg-1 of biomass (dry weight), which is 1.67-folds greater than EPS content under optimal growth conditions (10μmol photons m-2s-1, 1gL-1, 30°C). Desalting and deproteinezation steps of EPS were efficient to obtain polysaccharides (PS) with high carbohydrate (67.3±1.1%), low soluble proteins (5.14±0.32%), ash (5.85±0.71%) and sulfate (2.42±0.12%) contents. Rheological studies of PS at different concentrations (1%, 2.5% and 5%) revealed that the viscosity of the solution increased with the increase of PS concentration. In addition, PS exhibited a non Newtonian shear-thinning nature, a predominant gel-like behavior and a good resistance to consecutive heating-cooling cycles. The adopted process could be, then, a promising and economic strategy to enhance EPS production and extract polysaccharides with interesting rheological properties. © 2017 Elsevier B.V.


Trabelsi L.,National Institute of Marine science and Technology | Chaieb O.,National Institute of Marine science and Technology | Mnari A.,Research Laboratory in Nutrition Functional Food | Abid-Essafi S.,Laboratory of Research on Biologically Compatible Compounds | Aleya L.,University of Burgundy
BMC Complementary and Alternative Medicine | Year: 2016

Background: For thousands of years, Tunisian geothermal water has been used in bathing. Indeed, thermal baths "Hammam" were recommended in the treatment of different type of illnesses as, for instance, for relaxing joints and soothing. The ability of microalgae to sustain at the high temperature makes them potential producers of high value thermostable bio-products. This study aimed to explore the therapeutic potential of the aqueous extracellular polysaccharides (AEPS) of the Tunisian thermophilic microalgae Graesiella sp. and to evaluate its physico-chemical characteristics. Methods: Different parameters were used to characterize the AEPS. The dry weight, volatile dry weight, elemental analysis, monosaccharide composition and IR-spectroscopy analysis. Carbohydrate, uronic acid, ester sulfate and protein concentrations were also determined using colorimetric assay. AEPS was analyzed for its antioxidant propriety by means of total antioxidant capacity, DPPH radicals scavenging assay, ferrous chelating ability and hydroxyl and superoxide radical scavenging activity. The antiproliferative activity of AEPS was evaluated for HepG2 and Caco-2 cells using the MTT assay. Results: The Graesiella sp. AEPS is found to be a hetero-sulfated-anionic polysaccharides that contain carbohydrate (52 %), uronic acids (23 %), ester sulfate (11 %) and protein (12 %). The carbohydrate fraction was formed by eight neutral sugars glucose, galactose, mannose, fucose, rhamnose, xylose, arabinose and ribose. The FT-IR revealed the presence of carboxyl, hydroxyl, amine and sulfate groups. AEPS showed high activity as reducing agent, high ferrous chelating capacity and caused a significant decrease in a concentration-dependent manner of hydroxyl radical. A moderate DPPH scavenging activity and a poor superoxide radical scavenging ability were also observed. AEPS treatment (from 0.01 to 2.5 mg/ml) caused also a clear decrease of cell viabilities in a dose-dependent manner. The IC50 values obtained in HepG2 and Caco-2 cells were 1.06 mg/ml and 0.3 mg/ml respectively. Conclusions: This study evidenced that the Graesiella sp. AEPS exhibits antioxidant and antiproliferative activities. The biological activities of this extract depend on its fine structural features. Further work will identify and purify the active polysaccharides to enhance our understanding of their complete structure and relationships with its function. © 2016 The Author(s).


PubMed | Institute of Biotechnology, University of Sfax and National Institute of Marine science and Technology
Type: | Journal: Environmental science and pollution research international | Year: 2016

This study aims to investigate the effects of different concentrations of cadmium (Cd) (0-800M) on the growth, the photosynthetic performance, and the biochemical parameters of the Chlorophyta Picocystis sp. during 3 and 9days. Results showed that this exposure did not inhibit the Picocystis growth during the first 3days of treatment. Growth inhibition did not exceed 53%, which was recorded at high Cd concentrations (800M) after nine exposure days. Moreover, no inhibitory effect on the Picocystis sp. photosynthesis has been recorded during the three exposure days regardless the Cd concentrations. Lipid peroxidation was significantly increased at high Cd concentrations (500 and 800M) by 40 and 80%, respectively. Furthermore, the highest Cd concentration enhanced the thiol protein content, indicating no consequent protein oxidation. The exposure of Picocystis to Cd stimulated the antioxidant activities of catalase and ascorbate peroxidase. These results showed that Picocystis sp. has an impressive tolerance to Cd stress.


PubMed | Suez Canal University, Laboratory of Research on Biologically Compatible Compounds, National Institute of Marine science and Technology and University of Burgundy
Type: Journal Article | Journal: BMC complementary and alternative medicine | Year: 2016

In Tunisia, the use of hot spring waters for both health and recreation is a tradition dating back to Roman times. In fact, thermal baths, usually called Hammam are recommended as a therapeutic and prophylactic measure against many types of illness and toxicity. While the chemical concentration of thermal water is admittedly associated with its therapeutic effects, the inclusion in spa waters of efficient bioproduct additives produced by photosynthetic microorganisms and that act against oxidative stress may comprise a significant supplementary value for thermal centers. The aim of this study was to investigate the antioxidant potential of the Tunisian thermophilic cyanobacterium Leptolyngbya sp. and to determine its phytochemical constituents and phenolic profile.BME (Biomass Methanolic Extract), CME (Capsular polysaccharides Methanolic Extract) and RME (Releasing polysaccharides Methanolic Extract) of Leptolyngbya sp. were examined for their antioxidant activities by means of DPPH, hydroxyl radical scavenging and ferrous ion chelating assays. Their total phenols, flavonoids, carotenoids, Mycosporine-like amino acids (MAAs) and vitamin C contents, as well as their phenolic profiles were also determined.BME has the highest content of phenols (1391.2mg/g), flavonoids (34.90.32mg CEQ/g), carotenoids (2.030.56mg/g) and vitamin C (15.71.55mg/g), while the highest MAAs content (0.420.03mg/g) was observed in CME. BME presented both the highest DPPH and hydroxyl radical scavenging ability with an ICThe study demonstrated that the cyanobacterium Leptolyngbya sp. possesses abundant natural antioxidant products which may have prophylactic and therapeutic effects on many types of illness and toxicity. The present findings not only explain and reinforce the rationale behind traditional therapeutic practices in Tunisia in the exploitation of the countrys hot springs, but support the addition of Leptolyngbya to thermal waters as a means to enhance the value and reputation of the curative nature of Tunisian thermal waters.


PubMed | Laboratory of Research on Biologically Compatible Compounds, National Institute of Marine science and Technology and University of Burgundy
Type: | Journal: BMC complementary and alternative medicine | Year: 2016

For thousands of years, Tunisian geothermal water has been used in bathing. Indeed, thermal baths Hammam were recommended in the treatment of different type of illnesses as, for instance, for relaxing joints and soothing. The ability of microalgae to sustain at the high temperature makes them potential producers of high value thermostable bio-products. This study aimed to explore the therapeutic potential of the aqueous extracellular polysaccharides (AEPS) of the Tunisian thermophilic microalgae Graesiella sp. and to evaluate its physico-chemical characteristics.Different parameters were used to characterize the AEPS. The dry weight, volatile dry weight, elemental analysis, monosaccharide composition and IR-spectroscopy analysis. Carbohydrate, uronic acid, ester sulfate and protein concentrations were also determined using colorimetric assay. AEPS was analyzed for its antioxidant propriety by means of total antioxidant capacity, DPPH radicals scavenging assay, ferrous chelating ability and hydroxyl and superoxide radical scavenging activity. The antiproliferative activity of AEPS was evaluated for HepG2 and Caco-2 cells using the MTT assay.The Graesiella sp. AEPS is found to be a hetero-sulfated-anionic polysaccharides that contain carbohydrate (52%), uronic acids (23%), ester sulfate (11%) and protein (12%). The carbohydrate fraction was formed by eight neutral sugars glucose, galactose, mannose, fucose, rhamnose, xylose, arabinose and ribose. The FT-IR revealed the presence of carboxyl, hydroxyl, amine and sulfate groups. AEPS showed high activity as reducing agent, high ferrous chelating capacity and caused a significant decrease in a concentration-dependent manner of hydroxyl radical. A moderate DPPH scavenging activity and a poor superoxide radical scavenging ability were also observed. AEPS treatment (from 0.01 to 2.5mg/ml) caused also a clear decrease of cell viabilities in a dose-dependent manner. The IC50 values obtained in HepG2 and Caco-2 cells were 1.06mg/ml and 0.3mg/ml respectively.This study evidenced that the Graesiella sp. AEPS exhibits antioxidant and antiproliferative activities. The biological activities of this extract depend on its fine structural features. Further work will identify and purify the active polysaccharides to enhance our understanding of their complete structure and relationships with its function.


Jebali J.,Higher Institute of Agriculture | Chicano-Galvez E.,University of Cordoba, Spain | Banni M.,Higher Institute of Agriculture | Guerbej H.,National Institute of Marine science and Technology | And 3 more authors.
Ecotoxicology and Environmental Safety | Year: 2013

Gilthead seabream (Sparus aurata) specimens were caged in-field at the Téboulba harbour or exposed to benzo(a)pyrene [B(a)P] or to paraquat [PQ] plus B(a)P, and several biochemical biomarker responses were investigated. Antioxidant enzymes, such as glutathione peroxidase, catalase and glutathione reductase, significantly increased in the in-field and B(a)P+PQ exposures, but were only moderately affected by B(a)P alone. Glucose-6-phosphate and 6-phosphogluconate dehydrogenases significantly diminished after in-field exposure. Different responses with biotransformation enzymes were observed: the P4501A-associated EROD activity was highly induced in response to B(a)P and B(a)P+PQ exposures, while total activity of the glutathione S-transferase (GST) was similar to control. However, after purification of the GST proteins by affinity chromatograpy and analysis by two-dimensional electrophoresis, nineteen highly reproducible isoforms were resolved. In addition, some of reproducible isoforms showed different and specific expression patterns in response to contaminants.Thus, proteomic analysis of the purified GST subunits is a reliable tool for ecotoxicological research, useful in polluted marine ecosystem as an effective biomarker of contamination. © 2012 Elsevier Inc.


Mechri B.,University of Monastir | Mechri B.,National Institute of Marine science and Technology | Medhioub A.,National Institute of Marine science and Technology | Medhioub M.N.,National Institute of Marine science and Technology | Aouni M.,University of Monastir
Polish Journal of Microbiology | Year: 2016

In the current study, 65 Vibrio spp. were isolated from the Monastir lagoon water, were characterized phenotypically and genotypically. In addition, we looked for the presence of three Vibrio parahaemolyticus virulence genes (tlh, trh and tdh) and ten Vibrio cholerae virulence genes (ctxA, vpi, zot, ace, toxR, toxT, tosS, toxRS, tcpA and cpP). We also investigated the antibiotic susceptibilities and the adherence ability of the identified strains to abiotic material and to biotic surfaces. The cytotoxicity activity against HeLa and Vero cell lines were also carried out for all tested strains. All Vibrio isolates were identified to the species level and produced several hydrolytic exoenzymes. The results also revealed that all strains were expressing high rates of resistance to tested antibiotics. The minimum inhibitory concentration (MIC) values showed that tetracycline and chloramphenicol were the most effective antibiotics against the tested bacteria. Vibrio alginolyticus and V. cholerae species were the most adhesive strains to both biotic and abiotic surfaces. Besides, V. alginolyticus isolates has the high levels of recombination of genes encoding V. cholerae and V. parahaemolyticus virulence factors. In vitro cytotoxic activities of several Vibrio extracellular product were also observed among HeLa and Vero cells.


Zili F.,National Institute of Marine science and Technology | Mezhoud N.,National Institute of Marine science and Technology | Mezhoud N.,Masdar Institute of Science and Technology | Trabelsi L.,National Institute of Marine science and Technology | And 2 more authors.
Journal of Applied Phycology | Year: 2014

The combined effect of temperature, light intensity, and NaNO3 concentration on lipid biosynthesis and fatty acid composition was investigated for the thermophilic cyanobacterium Gloeocapsa gelatinosa (Kützing 1843) isolated from a thermal spring in Tunisia. Under optimal growth conditions, the lipid content was 7.3 % DW. Fatty acid analysis revealed the predominance of 16:0 and 18:0 (23.7 and 18.2 %, respectively) as main straight carbon chains of saturated fatty acids. Unsaturated fatty acids were also identified with 18:1n9c (18.8 %) and 16:1n7 (5 %) being the predominant components. The effect of environmental factors on fatty acid composition was monitored by using principal component analysis and central composite design. Variation of light intensity (20 to 150 μmol photons m-2 s-1), temperature (20 to 60 °C), and nitrogen concentration (0 to 3 g L-1) induced a significant variation in the amount of fatty acid proportions, whereas lipid content was only slightly modified. Results showed that light intensity had the strongest effect on the composition of fatty acids. Temperature had a synergic effect with light intensity while nitrogen concentration had a trivial effect. The combined effect of high light intensity (150 μmol photons m-2 s-1) and high temperature (60 °C) increased the proportion of saturated 16:0 and 18:0 fatty acids along with long-chain fatty acids to 82 % which was twofold higher than that in optimal growth conditions. This induced fatty acid profile makes G. gelatinosa-based biofuels adaptable for higher energetic efficiency and higher oxidative stability. © 2014 Springer Science+Business Media Dordrecht.


Fathallah S.,National Institute of Marine science and Technology | Medhioub M.N.,National Institute of Marine science and Technology | Kraiem M.M.,National Institute of Marine science and Technology
Environmental Engineering Science | Year: 2013

Individual and combined toxicities of lead (Pb) and cadmium (Cd) were investigated using sperm motility and embryo-larval bioassay of the clam Ruditapes decussatus. Fertilization and embryogenesis success and larval mortality were recorded after incubation of sperm (during 30 min before use for insemination), fertilized eggs (24 h) and D-shaped larvae (96 h) in seawater, both with single metals and combinations of the two tested metals. In spermiotoxicity bioassays, these metals, both individually and in combination, significantly (p<0.05) reduced the fertilization rate only at two higher concentrations that were studied. Median effective concentration (EC 50) values were 1033 μg/L (5 μM), 2098.5 μg/L (18.6 μM), and 1442 μg/L (10.8 μM), respectively for individual Pb, Cd, and the mixture (Pb+Cd). Embryogenesis success was also noticeably affected by the single metals and their mixture. Median effective concentrations (EC 50) values were 256.5 μg/L (1.24 μM), 570.9 μg/L (5.08 μM), and 355.4 μg/L (2.68 μM), respectively for individual Pb, Cd, and the mixture (Pb+Cd). Median lethal concentration (LC50) for 96 h larval mortality bioassay registered for individual Pb, Cd, and for the mixture were 453.6 μg/L (2.2 μM), 877.8 μg/L (7.8 μM), and 565.6 μg/L (4.3 μM), respectively. Marking-Dawson additive toxicity indices were 0.01, 0.08, and 0.18, respectively, for spermiotoxicity, embryotoxicity, and larval mortality tests, indicating additive effects with a slight trend toward synergism, which was statistically significant only for larval mortality. This work shows that both clam embryos and larvae bioassays are useful tools that can be used to evaluate toxicity of field samples of seawater, sediments, and effluents containing several toxicants. © Mary Ann Liebert, Inc.


PubMed | National Institute of Marine science and Technology
Type: Journal Article | Journal: Folia microbiologica | Year: 2012

The kinetic study of Arthrospira platensis extracellular polymeric substances (EPS) production under different trophic modes-photoautotrophy (100 mol photons m(-2) s(-1)), heterotrophy (1.5 g/L glucose), and mixotrophy (100 mol photons m(-2) s(-1) and 1.5 g/L glucose)-was investigated. Under photoautotrophic and heterotrophic conditions, the maximum EPS production 219.61 4.73 and 30.30 1.97 mg/L, respectively, occurred during the stationary phase. Under a mixotrophic condition, the maximum EPS production (290.50 2.21 mg/L) was observed during the early stationary phase. The highest specific EPS productivity (433.62 mg/g per day) was obtained under a photoautotrophic culture. The lowest specific EPS productivity (38.33 mg/g per day) was observed for the heterotrophic culture. The effects of glucose concentration, light intensity, and their interaction in mixotrophic culture on A. platensis EPS production were evaluated by means of 32 factorial design and response surface methodology. This design was carried out with a glucose concentration of 0.5, 1.5, and 2.5 g/L and at light levels of 50, 100, and 150 mol photons m(-2) s(-1). Statistical analysis of the model demonstrated that EPS concentration and EPS yield were mainly influenced by glucose concentration and that conditions optimizing EPS concentration were dissimilar from those optimizing EPS yield. The highest maximum predicted EPS concentration (369.3 mg/L) was found at 150 mol photons m(-2) s(-1) light intensity and 2.4 g/L glucose concentration, while the highest maximum predicted EPS yield (364.3 mg/g) was recorded at 115 mol photons m(-2) s(-1) light intensity and 1.8 g/L glucose concentration.

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