Dietary sulfated polysaccharides extracted from Caulerpa sp. and Padina sp. modulated physiological performance, antibacterial activity and ammonia challenge test in juvenile rainbow trout (Oncorhynchus mykiss).

Nowadays, the use of seaweed derivatives in aquaculture has drawn attention for their potential as an immunostimulant and growth promotor. The sulfated polysaccharide extracted (SPE ) from green (Caulerpa sp.; SPC) and brown (Padina sp.; SPP) seaweeds with two concentrations (0.05% and 0.1%); nominated in four groups: SPC0.05 , SPC0.1 , SPP0.05 , SPP0.1 and control group (free of SPE ) were used for juvenile rainbow trout (Oncorhynchus mykiss) diet. Fish (N: 150; 8.5 ± 0.2 g) were selected aleatory distributed in 15 circular tanks (triplicate for the group) and fed test diets for 56 days. The outcomes revealed that the supplementation of SPE up to 1 g kg-1 failed to show significant differences in the organosomatic indices as compared to the control group. The most inferior protein value of dress-out fish composition was observed in the fish fed the control diet, which was statistically lower than the SCP0.1 group (p < 0.05), while no significant difference was observed in other macronutrient composition among the treatments. Total monounsaturated fatty acid (MUFA) had lower trend in the carcass of fish fed SPE supplemented diets, so that lowest MUFA were observed in SPC0.05 group (p < 0.05; 25.22 ± 4.29%). The lowest value of docosahexaenoic acid was observed in the control diet compared to the SPE -supplemented diets (p < 0.05). The serum alternative complement pathway levels in all treatments tend to promote compared to the control treatment. A similar trend was observed for lysozyme activity. According to the results, the superoxide dismutase (SOD) value were highest in SPC0.05 and SPC0.1 compared to the other treatments (p < 0.05), while a further elevation of the SPE Padina sp. extracted level (SPP0.1 ) leads to a decrease in SOD value. Thiobarbituric acid reactive substances of plasma was indicated not to influence by sulfated polysaccharide extracts in the refrigerated storage. The lowest serum stress indicators were observed in fish fed SPP0.05 group postchallenge test. Taken together, our outcomes revealed that SPE of two species of seaweeds bestows benefits in some of the immunity and antioxidant system. Also, notable elevations in HUFA were observed in juvenile rainbow trout fed supplemented with SPE .

Sulfated Glucan from the Green Seaweed Caulerpa sertularioides Inhibits Adipogenesis through Suppression of Adipogenic and Lipogenic Key Factors.

Sulfated polysaccharides (SPS) from seaweeds have great biochemical and biotechnological potential. This study aimed to investigate the effect of SPS isolated from the seaweed Caulerpa sertularioides on adipogenic differentiation as a possible alternative treatment for obesity. The SPS-rich extract from the seaweed C. sertularioides was fractioned into three SPS-rich fractions (F0.5; F0.9; and F1.8) chemically characterized. Among these four samples, only F0.9 showed a significant inhibitory effect on adipogenesis of 3T3-L1 preadipocytes. Ten SPS-rich fractions were isolated from F0.9 through ion-exchange chromatography. However, only the fraction (CS0.2) containing a sulfated glucan was able to inhibit adipogenesis. CS0.2 reduces lipid accumulation and inhibits the expression of key adipogenic (PPARγ, C/EBPß, and C/EBPα) and lipogenic markers (SREBP-1c, Fabp4, and CD36). The data points to the potential of sulfated glucan from C. sertularioides for the development of functional approaches in obesity management.

Immunostimulatory Effect of Sulfated Galactans from the Green Seaweed Caulerpa cupressoides var. flabellata.

Sulfated polysaccharides (SPs) obtained from green seaweeds are structurally heterogeneous molecules with multifunctional bioactivities. In this work, two sulfated and pyruvated galactans were purified from Caulerpa cupressoides var. flabellata (named SP1 and SP2), and their immunostimulatory effect was evaluated using cultured murine macrophage cells. Both SPs equally increased the production of nitric oxide, reactive oxygen species, and the proinflammatory cytokines TNF-α and IL-6. NMR spectroscopy revealed that both galactans were composed primarily of 3)-ß-d-Galp-(1→3) units. Pyruvate groups were also found, forming five-membered cyclic ketals as 4,6-O-(1'carboxy)-ethylidene-ß-d-Galp residues. Some galactoses are sulfated at C-2. In addition, only SP2 showed some galactose units sulfated at C-4, indicating that sulfation at this position is not essential for the immunomodulatory activity of these galactans. Overall, the data showed that the galactans of C. cupressoides exhibited immunostimulating activity with potential therapeutic applications, which can be used in the development of new biomedical products.

Bioinformatic Characterization of Sulfotransferase Provides New Insights for the Exploitation of Sulfated Polysaccharides in Caulerpa.

Caulerpa is an unusual algal genus from Caulerpaceae (Chlorophyta, Bryopsidales). Species from this family produce a wide range of metabolites suitable for biotechnology applications. Among these, sulfated polysaccharides (SPs) are often highly desirable for pharmaceutical and nutraceutical applications. Here, we provide a classification of sulfotransferases from Caulerpa; these important enzymes catalyze the nodal step for the biosynthesis of SPs. For this, we performed phylogenetic, genomic, expression analyses and prediction of the protein structure on sulfotransferases from Caulerpa. Sequences, domains and structures of sulfotransferases generally shared common characteristics with other plants and algae. However, we found an extensive duplication of sulfotransferase gene family, which is unique among the green algae. Expression analysis revealed specific transcript abundance in the pinnae and rachis of the alga. The unique genomic features could be utilized for the production of complex SPs, which require multiple and specific sulfation reactions. The expansion of this gene family in Caulerpaceae would have resulted in a number of proteins characterizing the unique SPs found in these algae. We provide a putative biosynthetic pathway of SPs, indicating the unique characteristics of this pathway in Caulerpa species. These data may help in the future selection of Caulerpa species for both commercial applications and genetic studies to improve the synthesis of valuable products from Caulerpa.

Marine macroalga Caulerpa: role of its metabolites in modulating cancer signaling.

Cancer, the leading causes of death worldwide, causes multiple metabolic and physiological alterations, leading to an unregulated proliferation of cells. The existing anticancer therapies are usually nonspecific with side effects and or are extremely expensive, thus hunt for better therapeutics is still on, specially efforts are made to look for naturally occurring molecules. Sea harbors several organisms which are unexplored for their biological potentials. Green macroalga genus, Caulerpa, is one such invaluable repository of bioactive metabolites like alkaloids, terpenoids, flavonoids, steroids and tannins with reported bioactivities against many diseases including cancer. Anti-cancerous metabolites of Caulerpa like caulerpenyne (Cyn), caulerpin, caulersin, and racemosin C, possess unique structural moieties and are known to exhibit distinct effects on cancer cells. Theses metabolites are reported to affect microtubule dynamics, unfolded protein response, mitochondrial health, cell cycle progression, metabolic and stress pathways by their cross-talk with signalling proteins like AMPK, GRP78, GADD153, Bid, Bax, AIF, Bcl2, P21, cyclin D, cyclin E, caspase 9, and PTP1B. Targeting of multiple cancer hallmarks by Caulerpa metabolites, with concomitant modulations of multiple signalling cascades, displays its multifactorial approach against cancer. Evaluation of anti-cancer properties of this genus is particularly important as Caulerpa species are widely edible and utilized in several delicacies in the coastal countries. This is the first review article providing a consolidated information about the role of Caulerpa in cancer with major contributing metabolites and plausible modulations in cancer signaling and prospects.

Fishing for Targets of Alien Metabolites: A Novel Peroxisome Proliferator-Activated Receptor (PPAR) Agonist from a Marine Pest.

Although the chemical warfare between invasive and native species has become a central problem in invasion biology, the molecular mechanisms by which bioactive metabolites from invasive pests influence local communities remain poorly characterized. This study demonstrates that the alkaloid caulerpin (CAU)-a bioactive component of the green alga Caulerpa cylindracea that has invaded the entire Mediterranean basin-is an agonist of peroxisome proliferator-activated receptors (PPARs). Our interdisciplinary study started with the in silico prediction of the ligand-protein interaction, which was then validated by in vivo, ex vivo and in vitro assays. On the basis of these results, we candidate CAU as a causal factor of the metabolic and behavioural disorders observed in Diplodus sargus, a native edible fish of high ecological and commercial relevance, feeding on C. cylindracea. Moreover, given the considerable interest in PPAR activators for the treatment of relevant human diseases, our findings are also discussed in terms of a possible nutraceutical/pharmacological valorisation of the invasive algal biomasses, supporting an innovative strategy for conserving biodiversity as an alternative to unrealistic campaigns for the eradication of invasive pests.

The Bisindole Alkaloid Caulerpin, from Seaweeds of the Genus Caulerpa, Attenuated Colon Damage in Murine Colitis Model.

Caulerpin (CLP), an alkaloid from algae of the genus Caulerpa, has shown anti-inflammatory activity. Therefore, this study aimed to analyze the effect of CLP in the murine model of peritonitis and ulcerative colitis. Firstly, the mice were submitted to peritonitis to evaluate which dose of CLP (40, 4, or 0.4 mg/kg) could decrease the inflammatory infiltration in the peritoneum. The most effective doses were 40 and 4 mg/kg. Then, C57BL/6 mice were submitted to colitis development with 3% dextran sulfate sodium (DSS) and treated with CLP at doses of 40 and 4 mg/kg. The disease development was analyzed through the disease activity index (DAI); furthermore, colonic tissue samples were submitted to histological analysis, NFκB determination, and in vitro culture for cytokines assay. Therefore, CLP at 4 mg/kg presented the best results, triggering improvement of DAI and attenuating the colon shortening and damage. This dose was able to reduce the TNF-α, IFN-γ, IL-6, IL-17, and NFκB p65 levels, and increased the levels of IL-10 in the colon tissue. Thus, CLP mice treatment at a dose of 4 mg/kg showed promising results in ameliorating the damage observed in the ulcerative colitis.

Eco-friendly synthesis of silver nanoparticles using green algae (Caulerpa serrulata): reaction optimization, catalytic and antibacterial activities.

Stable colloidal silver nanoparticles (AgNPs) were synthesized using Caulerpa serrulata (green marine algae) aqueous extract as an efficient reducing and stabilizing agent. This method is considered to be a sustainable alternate to the more complicated chemical procedures. To achieve the optimization synthesis of AgNPs, several effects such as extract concentration, contact time, pH values, and temperature were examined. The synthesized AgNPs were characterized by UV-Vis spectroscopy, FT-IR, XRD, and HR-TEM. The synthesized AgNPs showed an intense surface plasmon resonance band at 412 nm at the optimal conditions (20% (v/v) extract and 95 °C). TEM reveal that higher extract concentration and higher temperature leading to the formation of spherical AgNPs with an average particle size of 10 ± 2 nm. The synthesized AgNPs showed excellent catalytic reduction activity of Congo red (CR) dye from aqueous solutions. The degradation percentage of CR with AgNPs accelerated by increasing either NaBH4 concentration or catalytic dosage. The AgNPs synthesized at higher temperature (e.g., 10Ag-95) exhibited the highest catalytic activity. The reaction kinetics was found to be pseudo first order with respect to the dye concentration. Moreover, the AgNPs displayed antibacterial activity at lower concentration against Staphylococcus aureus, Pseudomonas aeruginosa, Shigella sp., Salmonella typhi, and Escherichia coli and may be a good alternative therapeutic approach. The outcomes of the current study confirmed that the synthesized AgNPs had an awesome guarantee for application in catalysis and wastewater treatment.

Caulerpa racemosa: a marine green alga for eco-friendly synthesis of silver nanoparticles and its catalytic degradation of methylene blue.

In this study, a simple and green method has been demonstrated for the synthesis of highly stable silver nanoparticles (AgNPs) using aqueous extract of Caulerpa racemosa (C. racemosa) as a reducing and capping agent. The formation and stability of AgNPs were studied using visual observation and UV-Visible (UV-Vis) spectroscopy. The stable AgNPs were further characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and high resolution transmission electron microscopy (HR-TEM) with energy dispersive spectroscopic (EDS) methods. The biosynthesized AgNPs showed a sharp surface plasmon resonance peak at 441 nm in the visible region and they have extended stability which has been confirmed by the UV-Vis spectroscopic results. XRD result revealed the crystalline nature of synthesized AgNPs and they are mainly oriented in (111) plane. FT-IR studies proved that the phytoconstituents of C. racemosa protect the AgNPs from aggregation and also which are responsible for the high stability. The size of synthesized AgNPs was approximately 25 nm with distorted spherical shape, identified from the HR-TEM images. The synthesized AgNPs showed excellent catalytic activity towards degradation of methylene blue.

Extracellular synthesis of zinc oxide nanoparticle using seaweeds of gulf of Mannar, India.

BACKGROUND: The biosynthesis of metal nanoparticles by marine resources is thought to be clean, nontoxic, and environmentally acceptable "green procedures". Marine ecosystems are very important for the overall health of both marine and terrestrial environments. The use of natural sources like Marine biological resources essential for nanotechnology. Seaweeds constitute one of the commercially important marine living renewable resources. Seaweeds such as green Caulerpa peltata, red Hypnea Valencia and brown Sargassum myriocystum were used for synthesis of Zinc oxide nanoparticles. RESULT: The preliminary screening of physico-chemical parameters such as concentration of metals, concentration of seaweed extract, temperature, pH and reaction time revealed that one seaweed S. myriocystum were able to synthesize zinc oxide nanoparticles. It was confirmed through the, initial colour change of the reaction mixture and UV visible spectrophotometer. The extracellular biosynthesized clear zinc oxide nanoparticles size 36 nm through characterization technique such as DLS, AFM, SEM -EDX, TEM, XRD and FTIR. The biosynthesized ZnO nanoparticles are effective antibacterial agents against Gram-positive than the Gram-negative bacteria. CONCLUSION: Based on the FTIR results, fucoidan water soluble pigments present in S. myriocystum leaf extract is responsible for reduction and stabilization of zinc oxide nanoparticles. by this approach are quite stable and no visible changes were observed even after 6 months. These soluble elements could have acted as both reduction and stabilizing agents preventing the aggregation of nanoparticles in solution, extracellular biological synthesis of zinc oxide nanoparticles of size 36 nm.

Kombucha drink enriched with sea grapes (Caulerpa racemosa) as potential functional beverage to contrast obesity: An in vivo and in vitro approach.

BACKGROUND AND AIMS: Obesity is currently a global issue and is a major cause of the metabolic disorder, including dyslipidemia. However, currently approved treatments have various limitations including serious side effects, numerous contraindications, and lack of acceptance. Caulerpa racemosa, also referred as Sea grapes, is a seaweed known for its various benefits. C. racemosa extract has the potential to improve lipid profile and role as an anti-obese agent. In order to maximize its health benefits, C. racemosa was made using kombucha drink as a carrier medium. This study aims to assess the effect of Sea grapes kombucha drink on lipase activity in vitro and lipid profile in vivo. METHODS: A lipase inhibition test was carried out by incubating Sea grapes kombucha drink compared with orlistat as the control in porcine pancreatic lipase and p-nitrophenyl butyrate in reaction buffer. A total of four groups were made, each containing 10 male swiss webster albino mice; group A received standard dry pellet diet as control, group B received cholesterol and fat-enriched diets (CFED), group C and D received CFED and 150 and 300 mg/kgBW of kombucha drink from Sea grapes respectively for 4 weeks. RESULTS: Sea grapes kombucha drink improved lipid profiles in the way of reducing total cholesterol, triglyceride, LDL, and increasing HDL levels compared to CFED and normal groups. The effect was more robust following the incrementing dose of the Sea grapes excluding total cholesterol. The lipase inhibitory activity of Sea grapes kombucha drink was similar to orlistat at a dose of 250 µg/mL, otherwise, orlistat was superior in the lower doses. CONCLUSIONS: Sea grapes kombucha drink treatment also induced weight loss and increased level of liver SOD. Kombucha drink from C. racemosa has good potential as a functional beverage with anti-obese and lipid improving activity.

Production of biodiesel from Caulerpa racemosa oil using recombinant Pichia pastoris whole cell biocatalyst with double displayed over expression of Candida antartica lipase.

In this study, Caulerpa racemosa oil was used to produce biodiesel by recombinant Pichia pastoris displaying bound (rPp-BL) and secretory lipase (rPp-SL). Collected algae was pre-treated using ultrasonication, microwave and solvent extraction. Defatted C. racemosa was subjected to dilute acid treatment to obtain algal biomass hydrolysate. Both rPp-BL and rPp-SL were cultivated in algal biomass hydrolysate and glycerol. Surfactant treatment was performed on rPp-BL. Screening and optimization of variables were performed for biodiesel production using Plackett Burman design and central composite design, respectively. About 10.64 % (w/w) of algal oil was extracted from C. racemosa. Both rPp-BL and rPp-SL effectively utilized C. racemosa biomass hydrolysate and glycerol. rPp-SL combined with triton X (1.0 % w/v) treated rPp-BL for 3 min improved lipase activity. Methanol to oil ratio, combined whole cell biocatalyst and temperature were significant factors. Under optimum conditions, biodiesel yield reached about 93.64 % after 30 h using developed whole cell biocatalyst.

The effect of Caulerpa sertularioides extract on bull sperm freezablity and subsequent embryo development.

Artificial insemination is a valuable and essential tool in genetic improvement programs, and its success requires proper semen collection, freezing, and thawing procedures. Nowadays, despite applying of advanced protocols for semen cryopreservation, post-thawing sperm quantitative and qualitative parameters are not satisfactorily comparable to fresh sperm. The present study was designed to evaluate the effects of the supplementation of an alcoholic extract of Caulerpa sertolarioides alga into the tris-egg yolk-based Simmental bull sperm freezing media. The pooled semen samples were divided into five groups, of which four were supplemented with 500, 1000, 1500, and 2000 ppm alga extract and one allocated as a control. Total motility, progressive motility, plasma membrane integrity, DNA integrity, apoptosis, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, and total antioxidant capacity (TAC) of sperm were measured. The frozen sperm from each group were used for IVF on the slaughterhouse-derived oocytes. Fertilization, cleavage, and blastocyst rates were assessed for all groups. Total motility, progressive motility, and velocity curvilinear (VCL) parameters were higher (p ≤ 0.05) in group 1000 ppm than the control group. Velocity in a straight path (VSL) was higher (p ≤ 0.05) in all treatment groups except in 500 ppm compared to the control group. Average path velocity (VAP) was higher (p ≤ 0.05) in 1000 and 1500 ppm groups than in the control group. Straightness (STR) showed a higher value (p ≤ 0.05) in 1000 and 2000 ppm than the control group. Groups 500 and 1000 ppm showed more viable sperm than the control group (p ≤ 0.05). DNA damage was lower (p ≤ 0.05) in group 1000 ppm than in the control group. HOST was higher (p ≤ 0.05) in all groups than in the control group. SOD, GPx, and TAC were higher (p ≤ 0.05) in 1000 ppm than the control and all other groups. Apoptosis was not significantly different among the treatment and control groups. In conclusion, supplementation of alcoholic extract of Caulerpa sertularioides into the Simmental bull freezing extender ameliorated the sperm parameters after the freeze-thawing process. Moreover, the results of this study indicated that the best dose to achieve the antioxidant properties of the alga extract in Simmental bull sperm freezing media was 1000 ppm. It was also evident that 1000 ppm alga extract supplementation into the bull sperm improved fertilization, cleavage, and blastocyst rates.

Reciprocal effects of caulerpenyne and intense herbivorism on the antioxidant response of Bittium reticulatum and Caulerpa taxifolia.

We studied the antioxidant enzyme response of the gastropoda Bittium reticulatum feeding the toxic alga Caulerpa taxifolia, and also the effects of intense herbivorism on caulerpenyne production and on the antioxidant response of C. taxifolia. B. reticulatum were maintained in two separated aquariums containing Posidonia oceanica or C. taxifolia. Glutathione peroxidase, glutathione reductase and glutathione S-transferase activities were significantly higher in B. reticulatum living in presence of C. taxifolia with respect to animals living in P. oceanica aquarium. Malondialdehyde levels in B. reticulatum showed similar values in both environments. Caulerpenyne levels were significantly higher in C. taxifolia fronds after herbivore exposure. C. taxifolia activities of catalase and glutathione reductase significantly increased in presence of B. reticulatum. B. reticulatum exposed to caulerpenyne evidenced antioxidant enzyme adaptations to prevent oxidative damage. The presence of B. reticulatum in the aquarium induces a protective adaptation in C. taxifolia in order to reduce the herbivorism.

Removal of malachite green by using an invasive marine alga Caulerpa racemosa var. cylindracea.

The biosorption of a cationic dye, malachite green oxalate (MG) from aqueous solution onto an invasive marine alga Caulerpa racemosa var. cylindracea (CRC) was investigated at different temperatures (298, 308 and 318 K). The dye adsorption onto CRC was confirmed by FTIR analysis. Equilibrium data were analyzed using Freundlich, Langmuir and Dubinin-Radushkevich (DR) equations. All of the isotherm parameters were calculated. The Freundlich model gave a better conformity than Langmuir equation. The mean free energy values (E) from DR isotherm were also estimated. In order to clarify the sorption kinetic, the fit of pseudo-first-order kinetic model, second-order kinetic model and intraparticle diffusion model were investigated. It was obtained that the biosorption process followed the pseudo-second-order rate kinetics. From thermodynamic studies the free energy changes were found to be -7.078, -9.848 and -10.864 kJ mol(-1) for 298, 308 and 318 K, respectively. This implied the spontaneous nature of biosorption and the type of adsorption as physisorption. Activation energy value for MG sorption (E(a)) was found to be 37.14 kJ mol(-1). It could be also derived that this result supported physisorption as a type of adsorption.

Application of a chemically modified green macro alga as a biosorbent for phenol removal.

Phenol and substituted phenols are toxic organic pollutants present in tannery waste streams. Environmental legislation defines the maximum discharge limit to be 5-50 ppm of total phenols in sewers. Thus the efforts to develop new efficient methods to remove phenolic compounds from wastewater are of primary concern. The present work aims at the use of a modified green macro alga (Caulerpa scalpelliformis) as a biosorbent for the removal of phenolic compounds from the post-tanning sectional stream. The effects of initial phenol concentration, contact time, temperature and initial pH of the solution on the biosorption potential of macro algal biomass have been investigated. Biosorption of phenol by modified green macro algae is best described by the Langmuir adsorption isotherm model. Biosorption kinetics of phenol onto modified green macro algal biomass were best described by a pseudo second order model. The maximum uptake capacity was found to be 20 mg of phenol per gram of green macro algae. A Boyd plot confirmed the external mass transfer as the slowest step involved in the biosorption process. The average effective diffusion coefficient was found to be 1.44 x 10(-9) cm(2)/s. Thermodynamic studies confirmed the biosorption process to be exothermic.

Effects of irradiance and temperature on the photosynthesis and vegetative propagation of Caulerpa serrulata.

The photosynthetic oxygen evolution of Caulerpa serrulata was determined with oxygen electrodes. The effects of light and temperature on the growth and regeneration of fragmented C. serrulata thalli were analyzed. The regenerating rate and establishment of different sizes and portions of C. serrulata were studied. The results showed that the light saturation point of C. serrulata was 200 micromol photons/m(2) per s and the optimum growth temperature was 25-30 degrees C. Under these conditions, the maximum photosynthetic oxygen evolution rate was 15.1 +/- 0.29 mg O(2)/mg Chl a/h, the growth rate and elongation rate reached the highest values, 4.67 +/- 0.09 mg FW/d and 0.78 +/- 0.01 mm/d, respectively. The fragmented C. serrulata thalli was regenerated at 20-35 degrees C and survived at 15 degrees C and 200 micromol photons/m(2) per s. A different survival rate was detected according to fragment size. All of these results indicated that C. serrulata was a candidate to become an invasive species if introduced into a new place. Therefore, we should pay more attention to C. serrulata for its potential threat to marine ecosystem when it is sold for aquarium use.

Amendment of Caulerpa sertularioides marine alga with sulfur-containing materials to accelerate Cu removal from aqueous media.

This study reports a new approach of alga amendment in a live mode. The Caulerpa sertularioides alga was modified with sulfur-containing materials of methionine (C5H11NO2S) and sodium sulfate (Na2SO4) to more concentrate the sulfur content of the yielded biomass (adsorbent). The simple and amended C. sertularioides alga was fully characterized with FTIR, SEM, EDX, BET, BJH, and pHzpc techniques. The copper adsorption from aqueous media was done by three adsorbents of C. sertularioides-simple (CSS), C. sertularioides-Na2SO4 (CSN), and C. sertularioides-C5H11NO2S (CSC). The parameters of pH (2-6), adsorbent dosage (2-10 g/L), and contact time (3-80 min) were optimized at 5, 5 g/L, and 60 min, respectively. According to Langmuir isotherm (the best-fitted model), the maximum adsorption capacity of CSN (98.04 mg/g) was obtained 2.4 times higher than CSC (40.73 mg/g) and 9.5 times higher than CSS (10.29 mg/g). The Cu adsorption process by the adsorbents was best-fitted pseudo-second-order kinetic model. The CSN, CSC, and CSS biomasses were successfully reused 5, 4, and 4 times, respectively. The thermodynamic study revealed that the copper adsorption process by CSN is exothermic and non-spontaneous. Finally, the suitability of adsorbents prepared from algae was tested by cleaning a simulated wastewater.

Competition between the invasive macrophyte Caulerpa taxifolia and the seagrass Posidonia oceanica: contrasting strategies.

BACKGROUND: Plant defense strategy is usually a result of trade-offs between growth and differentiation (i.e. Optimal Defense Theory--ODT, Growth Differentiation Balance hypothesis--GDB, Plant Apparency Theory--PAT). Interaction between the introduced green alga Caulerpa taxifolia and the endemic seagrass Posidonia oceanica in the Mediterranean Sea offers the opportunity to investigate the plausibility of these theories. We have accordingly investigated defense metabolite content and growth year-round, on the basis of an interaction gradient. RESULTS: When in competition with P. oceanica, C. taxifolia exhibits increased frond length and decreased Caulerpenyne--CYN content (major terpene compound). In contrast, the length of P. oceanica leaves decreases when in competition with C. taxifolia. However, the turnover is faster, resulting in a reduction of leaf longevity and an increase on the number of leaves produced per year. The primary production is therefore enhanced by the presence of C. taxifolia. While the overall concentration of phenolic compounds does not decline, there is an increase in some phenolic compounds (including ferulic acid and a methyl 12-acetoxyricinoleate) and the density of tannin cells. CONCLUSION: Interference between these two species determines the reaction of both, confirming that they compete for space and/or resources. C. taxifolia invests in growth rather than in chemical defense, more or less matching the assumptions of the ODT and/or PAT theories. In contrast, P. oceanica apparently invests in defense rather than growth, as predicted by the GDB hypothesis. However, on the basis of closer scrutiny of our results, the possibility that P. oceanica is successful in finding a compromise between more growth and more defense cannot be ruled out.

Batch and column studies of biosorption of heavy metals by Caulerpa lentillifera.

The biosorption of Cu(II), Cd(II), and Pb(II) by a dried green macroalga Caulerpa lentillifera was investigated. The sorption kinetic data could be fitted to the pseudo second order kinetic model. The governing transport mechanisms in the sorption process were both external mass transfer and intra-particle diffusion. Isotherm data followed the Sips isotherm model with the exponent of approximately unity suggesting that these biosorption could be described reasonably well with the Langmuir isotherm. The maximum sorption capacities of the various metal components on C. lentillifera biomass could be prioritized in order from high to low as: Pb(II)>Cu(II)>Cd(II). The sorption energies obtained from the Dubinin-Radushkevich model for all sorption systems were in the range of 4-6 kJ mol(-1) indicating that a physical electrostatic force was potentially involved in the sorption process. Thomas model could well describe the breakthrough data from column experiments. Ca(II), Mg(II), and Mn(II) were the major ions released from the algal biomass during the sorption which revealed that ion exchange was one of the main sorption mechanisms.