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Laboratory experiments were conducted to investigate the effect of copper enrichment (0.6, 2, 4, 8, 18 and 36 μg L−1) and salinity (8.5, 17 and 24%) on growth, photosynthetic efficiency “PE” (expressed as chlorophyll fluorescence) and copper accumulation in germlings and adult brown alga Fucus ceranoides. The PE for the algae exposed to 17% salinity was markedly stable throughout the experiment, while it was significantly (0.01 ˂ p ˂ 0.05) reduced in algae exposed to 8.5% salinity in the presence of 36 μg L−1 Cu by 20% when compared to those exposed to 0.6 μg L−1 Cu. Moreover, the maximum electron transport rate (ETRmax) was decreased significantly with increasing concentrations of Cu (p ˂ 0.001) and level of salinity (p ˂ 0.01); moreover, there was a significant interaction between Cu and salinity. The combination of copper and reduced salinity gave synergistic effects, as a consequence, this could limit the population growth of seaweeds in coastal areas. More research is needed to understand the basic requirements and stress tolerance in seaweeds for reef restoration and other management actions to be successful for sustainable development.The results of the present study suggest that any change in the environment will directly and significantly affect algal physiology, and thus it could be used for biomonitoring in situ. Moreover, the assessment of the physiological status of algae in combination with the analysis of thallus metal content will improve the trustworthiness of the biomonitoring process.

ACTIVITIES of superoxide dismutase (SOD), catalase (CAT) and peroxidase (GR), lipid peroxidation (expressed as MDA), the accumulation of H2O2, and photosynthetic activities in Ulva lactuca (Ulvales, Chlorophyta) were determined in the present study in order to investigate their response to polyaromatic hydrocarbons (PAHs) at residential and industrial sites in Alexandria, Egypt.Increasing in PAHs concentrations caused significant (P˂ 0.01) inhibition in the activities of SOD and CAT by 32% each, while, the activity of GR was significantly increased by 1-fold (P≤ 0.001). MDA levels were increased with increasing concentrations of PAHs; however, their levels were inversely proportional to activities of antioxidant enzyme (especially CAT). Moreover, photosynthetic rates (Pn), chlorophyll fluorescence (Fv/Fm), and total chlorophyll were significantly reduced (P˂ 0.01) with increasing PAHs by 24, 25, and 19%, respectively. The apparent increase in GR activity could indicate that alga acclimatized to the oxidative stress of PAHs, although oxidation of membrane lipids was not totally prevented, as indicated by stimulated MDA levels.The results indicated that PAHs could exert oxidative damages, and the harmfulness occurred mainly in samples collected from the industrial site with higher concentrations of PAHs. To the best of our knowledge, this is the first study to investigate the novel and conventional effects of PAHs on the physiological and biochemical traits of alga.

Summary Using the total lipid contents and fatty acid profiles, the marine macro-algae Jania rubens (Rhodophyceae), Ulva linza (Chlorophyceae) and Padina pavonica (Phaeophyceae) were evaluated for biodiesel production during the spring, summer and autumn. Seawater parameters such as pH, salinity and temperature were measured. The total lipid content varied from 1.56% (J. rubens) to 4.14% (U. linza) of dry weight, with the highest values occurring in spring. The fatty acid methyl ester profiles were analysed using gas chromatography. The highest percentage of total fatty acids was recorded in P. pavonica, with 6.2% in autumn, whereas the lowest was in J. rubens, with 68.6% in summer. The relative amount of saturated to unsaturated fatty acids was significantly higher in P. pavonica than in the other macro-algae. Seasonal variations in pH, salinity and temperature had no significant effect on the total lipid and fatty acid contents. Principal component analysis grouped brown and green algae together, whereas red alga grouped out. Furthermore, methyl ester profiles indicate that brown and green seaweeds are preferred, followed by red seaweeds, which appears to have little potential for oil-based products. Therefore, these seaweeds are not targets for biodiesel production.

The uptake of fast orange dye by the red seaweed Laurencia papillosa has been demonstrated in order to explore its potential use as low-cost adsorbent. The adsorption kinetics of fast orange dye on the alga with respect to initial dye concentration, contact time, particle size and pH were investigated. The dye removal percentage increased from 25.92 to 67.08% and the equilibrium states were attained at almost 60 min within the experimental concentration range. The adsorption kinetic was analyzed using pseudo-first-order and pseudo-second-order models. The pseudo-second-order model was more appropriate to describe the sorption kinetics based on the relatively high values of the linear squared regression correlation coefficient. The nature of the possible adsorbent and fast orange interactions was examined by the Fourier transform infrared technique. This technique confirmed that hydroxyl, carboxyl, amine, sulfonyl, carbonyl and alkyl groups are responsible for the dye binding process. Significant increase in dye adsorption was observed with the decrease in sorbent particle size coupled with its large surface area. Maximum removal efficiency was determined to be 65.7% at a solution pH of 5. However, Laurencia papillosa proved to be a promising material for removing fast orange dye from aqueous solutions. Keywords: Dye adsorption, Macroalga, Laurencia papillosa , kinetics African Journal of Biotechnology Vol. 12(17), pp. 2215-2223

This study discusses the perspectives regarding the green alga Dunaliella salina Toed for biodiesel manufacturing purposes. The alga was cultivated under controlled lab conditions. Biomass concentration at early stationary grown microalga was 2.6 mg/L dry weight, while the algal oil was about 27.1% of the biomass. Algal oil was esterified and analyzed using GLC technique. Fourteen fatty acid methyl esters were identified. The amount of saturated and unsaturated fatty ester fractions was 35% and 65% respectively. The physicochemical properties of fatty acids comprising biodiesel were discussed. However, culture optimization coupled with genetic improvement will definitely represent contributions to bring about innovation in oil hyper-producing D. salina that will ultimately meet with success.

Background This batch study deals with the relation between lipid as well as triglyceride contents in Nannochloropsis salina and variation in culture conditions such as nitrogen concentration and temperature. Results The tested parameters caused reduction in growth expressed as cell count, optical density and dry weight, as well strongly involved in lipids and triglycerides accumulation and significantly affected the lipid productivity. At the beginning of the work, the concentration of nitrogen in the medium was reduced to three quarter, half and quarter of the original f2 medium while the temperature kept constant. After that, the optimal nitrogen concentration (quarter of the original media) giving high lipid yield was tested with different temperature degrees from 15 to 35°C with five degree intervals. Although the growth was insignificantly influenced, a considerable increase in lipid and triglyceride (56.1 and 15.1% of dry weight respectively) was observed when the concentration of nitrogen in the medium was reduced to the quarter. Moreover, 59.3% lipid and 17.1% triglyceride on the basis of dry weight were obtained by the combination of 25% nitrogen concentration and 30°C. Simple regressions recommended that the interaction effect of nitrogen limitation and temperature on lipid and triglyceride accumulation was not as fundamental as for nitrogen limitation stress. Conclusion The degree of nitrogen availability in the combination of temperature effect has been identified as the critical determinant for the maximal production of lipid in N. salina. Nevertheless, major advances in this field can be considered by studying more stresses techniques and genetic strategies. Electronic supplementary material The online version of this article (doi:10.1186/s40529-015-0085-7) contains supplementary material, which is available to authorized users.