An antimicrobial agent is produced by the cyanobacterium Synechococcus leopoliensis which was found to be active against the Gram-positive bacterium Staphylococcus aureus. The effects of temperature, pH, incubation period, some media and different nitrogen and carbon sources on both growth and antimicrobial activity were investigated. Temperature 35 degrees C and pH 8 were the best for growth and antimicrobial agent production and 14 and 15 days of incubation were found to be the best for maximum growth and antimicrobial activity, respectively, in the medium BG-11. No antimicrobial activity could be detected by the use of G medium, moderate activity was recorded with Chu 10 medium, while high activity was reported in BG-11 medium. Leucine was the best nitrogen source for antimicrobial activity, while maximum antimicrobial activity was introduced by using the carbon sources, citrate and acetate. Very high antimicrobial activity could be detected by using the carbon source galactose in combination with the nitrogen source alanine or by using arabinose with methionine.

The roles of pendimethalin and its nano-form to induce oxidative stress, osmolytes, biochemical alterations and cytotoxic effect in algal cells of Chlorella vulgaris after exposure to sub-lethal concentrations were carried out. The data indicated that, 96-h EC 50 values were 20 and 19 ppb for pendimethalin and its nano-form, respectively. Three concentration levels (0.1EC 50 , 0.025EC 50 and EC 50 ) of the examined herbicide decreased the algal pigments (Chlorophyll a and b), but increased carotenoid contents compared with the control group. Biomolecules such as protein, carbohydrates, proline and sucrose of the algal cells significantly increased for the all treatments compared with the control groups. Similarly, malondialdehyde (MDA), some enzymes such as catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) showed significant increases for the all treatments. On the other hand, ultrastructural investigation of the herbicide-treated algal cells showed significant changes in their organelles in comparing with the untreated cells through transmission electron microscope (TEM) images. From all findings, it was obtained that the nano-pendimethalin was more potential toxic than the traditional form to induce adverse effects on the freshwater alga. Thus, biosafety procedures must be followed on non-target species before decision for nano-herbicide practices.

A series of experiments were conducted to determine fatty acids, amino acids, protein contents and enzymes activities of the three algae (Ulva lactuca, Sargassum hornschuchii and Pterocladia capillacea), which were previously collected in the late of July 2009 from Abu Qir and subjected to UV-B radiation for 20, 40 & 60 minutes daily for five days. These parameters were estimated, when the UV-absorbing compounds contents recorded its maximum after the third day of irradiation of 60 minutes daily for the three algal species. This time was chosen as we expected a suitable response of the algal species to UV-B irradiation. Total saturated, mono unsaturated and polyunsaturated fatty acids of U. lactuca and S. hornschuchii were increased due to UV-B irradiation, the total fatty acids content in both irradiated algae increased also, while the contents of total saturated, mono and polyunsaturated fatty acids of Pterocladia capillacea decreased after exposure to UV-B radiation. The study shows that half of amino acids of Ulva lactuca increased after exposure to UV-B radiation for three days, while the other half of amino acids was decreased. S. hornschuchii showed the decreasing of all amino acids contents after exposure to UV-B radiation except the two basic amino acids histidine and lysine, and the aliphatic amino acid serine. All amino acids of P. capillacea increased after exposure to UV-B radiation for three days except the aliphatic amino acid serine and the aromatic amino acid tyrosine. The total protein content increased in U. lactuca and S. hornschuchii through out the irradiation experiment, while P. capillacea showed notable decreases of protein contents after UV-B irradiation. Exposure to UV-B radiation increased the activity of superoxide dismutase, ascorbate peroxidase and catalase of the three irradiated algal species. The findings also suggest that exposure to UV-B irradiance also affect the ultrastructure of all the irradiated algal species.

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Adsorption of hexavalent chromium using dried macro-alga Sargassum hornschuchii was studied under controlled laboratory conditions. Experimental parameters such as contact time, biomass dosage and pH were studied in a metal concentration of 25 mg L -1 . The adsorption of chromium was fast at the initial phase of study and gradually with time became slowly. The maximum removal percentage of chromium was statistically significant and it was found to be 99.36% at 36 hrs and pH 3 using 8 g L -1 algal dosage. Five consecutive adsorption / desorption cycles were operated on metal solution using 0.1 M NaOH and 0.1 M HCl. It was found that chromium adsorption decreased following each adsorption / desorption cycle. Results indicated the superiority of HCl for the recovery of chromium from algal biomass. The present investigation shows that the locally biosorbent Sargassum hornschuchii possesses high adsorption performance with regard to the removal of chromium from its aqueous solution.

HYTOREMEDIATION of waters by aquatic organisms such ……… as algae has been recently explored for the removal of organic pollutants possessing endocrine disrupting capacity. Two marines macro-algae Pterocladia capillacea and Ulva lactuca were tested for removal of chloramphenicol, clofibric acid, acetyl salicylic acid, nonylphenol and bisphenol in aqueous solutions at concentrations 5-60 mg/L under controlled laboratory conditions. The obtained results showed that chlorophyll "a" content of both algal biomasses reduced with increasing pharmaceuticals concentrations. Chlorophyll "a "content was diminished nearly to the half at concentration 45mg/L for both algal species. However, the nonylphenol and bisphenol were showed a strong inhibition of chlorophyll "a" biosynthesis at higher concentrations (50-60 mg/L). Both the Pterocladia capillacea and Ulva lactuca recorded the highest removal percentage of pharmaceuticals occurred at 12 hours of contact. Pterocladia capillacea had high capacity for bioremoval of pharmaceuticals and endocrine disruptor compounds than Ulva lactuca. The results also revealed that Pterocladia capillacea was recorded the maximum biosorption of pharmaceuticals and endocrine disruptor compounds in order nonylphenol > acetyl salicylic acid > clofibric acid > bisphenol > chloramphenicol, while the maximum biosorption exhibited by Ulva lactuca was recorded in order acetyl salicylic acid > clofibric acid > bisphenol > nonylphenol > chloramphenicol at contact time 12 hours. Both the tested algae suffered from oxidative stress as a result of pharmaceuticals and endocrine disruptor compounds exposure. Our results showed elevation in the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APO), catalase (CAT) levels in the tested algae after exposure to different pharmaceuticals when compared with their activities in the control.

The removal process of zinc from an aqueous solution illustrated a good biosorption of metal by both algal fresh materials. However, the highest removal percentage of zinc by P. capillacea was found to be greater than that by S. hornschuchii. The removal of zinc by P. capillacea and S. hornschuchii increased with increase in contact time up to 3 and 5 hours, respectively. It decreased by very slight rate within 4-12 hours for P. capillacea and within 6-12 hours for S. hornschuchii. This study evaluated the effect of zinc on growth, amino acids, fatty acids and protein contents of Pterocladia capillacea and Sargassum hornschuchii .In this investigation P. capillacea tolerates higher concentrations of heavy metals as compared to S.hornschuchii. Exposure of P. capillacea to zinc decreased all amino acids except tyrosine, phenylalanine and proline which increased. All amino acids of S.hornschuchii increased by exposure to zinc except glycine, alanine, valine, leucine, isoleucine, phenylalanine and methionine, which decreased. The protein content of P. capillacea was inhibited by zinc, while percentage of protein content of S.hornschuchii increased more than three times by exposure to zinc. All fatty acids of P. capillacea increased by exposure to zinc except C 16:1 , which decreased and C 11:0 , C 20:0 and C 17:1, which disappeared and C 18:3 and C 20:5 , which appeared. Exposure of S.hornschuchii to zinc causes the increase of the contents of all fatty acids except C 6:0, C 10:0, C 18:0 and C 18:2, which decreased, C 23:0 and C 20:3, which appeared. Concerning the ultrastructure of P. capillacea grown in zinc solution for hours, it showed destructive irregularity of cell wall, disordering of cell inclusions, appearance of vacuoles and aggregation of cell components in a dense black manner inside the cell, while examination of S. hornschuchii ultra-structure with zinc showed destructive change in thyllakoids arrangement and slightly deviation of protoplast from the cell wall.

This study evaluated the effect of different concentrations of vitamins, B 12 and C in the process of wastewater treatment by the bluegreen algae Synechocystis aquatilis and Chroococcus schizodermaticus. C. schizodermaticus was more efficient than S. aquatilis in removing phosphorus by using both vitamins at all concentrations, while maximum nitrate removal was attained after 20 days using vitamin C at concentration 25 mg/l in case of C. schizodermaticus reactor. Vitamin B 12 caused the accumulation of nitrate in both algal reactors after 6 days at concentration 50 mg/l, while that accumulation began after 8 days with the use of concentration 75 mg/l. Concentration 25 mg/l of vitamin B 12 caused accumulation after 6 days in C. schizodermaticus reactor and after 12 days at S. aquatilis reactor. Ammonia was completely disappeared from wastewater treated by C. schizodermaticus using vitamin B 12 (concentration 75 mg/l) and vitamin C at its three concentrations in C. schizodermaticus reactors and only at concentration 25 mg/l in case of S. aquatilis reactor.