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Background and Objectives: Microalgae have been widely used as a novel source of bioactive substances. These substanc- es exhibit various biological actions including, antioxidant and antitumor effects material. The present work is carried out to evaluate potential applications of cyanobacterium Oscillatoria simplicissima containing mainly polysaccharides. Materials and Methods: Crude polysaccharides from marine cyanobacteria Oscillatoria simplicissima and Oscillatoria acutissima were extracted and characterized according to their chemical content and cytotoxic activities. The isolated poly- saccharides characterized by the Fourier transmittance infrared spectrum (FT-IR). Results: These polysaccharides constituted 34.68 mg/g of sugar, 0.011 mg/g of protein, and 28.92 mg/g of sulfate contents. The antioxidant property of the methanol extracts of these green microalgae was evaluated by measuring the free radical scavenging activity by the DPPH assay method. The algal extracts were then evaluated for their suppressive effect on tumor cell growth (A-549, MDA-MB-231, PC-3, HT-29, HepG2, and HeLa) by using the SRB assay. At a concentration of 10 mg/ mL, Oscillatoria simplicissima exhibits an antioxidant activity of 45.97%. The cytotoxic activity revealed that Oscillatoria simplicissima polysaccharide shows potent cytotoxic activity against lung cancer (A-549) cell line 49.465 μg/mL. Conclusion: Microalgal polysaccharides have great therapeutically potential in drug development used as antitumor and antioxidant agents in near future.

Background and Objectives: Nanoparticles are widely used in various fields such as electronics, cosmetics, water purifica- tion, biomedical and biotechnology. Biosynthesis of nanoparticles using biological agents have gained much attention in the area of nanotechnology in the last few decades because of cost effective, non-toxic, and eco-friendly. Algae have been used to reduce metal ions and subsequently for the biosynthesis of nanoparticles. Materials and Methods: Silver nanoparticles (AgNPs) have been biosynthesized by Phormidium formosum isolated from Mediterranean Sea coast Egypt in an aqueous system. An aqueous solution of silver ions was treated with alive biomass of P. formousm for the formation of AgNPs. The physio-chemical properties of synthesized silver nanoparticles were studied using analytical techniques such as UV-Vis spectrophotometer, transmission electron microscopy (TEM), and Fourier Trans- form Infrared Spectroscopy (FTIR).  The antimicrobial effect of synthesized silver nanoparticles was also tested on several microorganisms by measuring the inhibition zone. Results: These nanoparticles showed an absorption peak at λmax 437 nm in the UV-visible spectrum, corresponding to the Surface Plasmon Resonance of AgNPs. The transmission electron micrographs of nanoparticles in an aqueous solution showed production of silver nanoparticles synthesized by P. formosum. The obtained AgNPs are spherical in shape with a size ranging from 1.83 nm to 26.15nm. The Fourier transmittance infrared spectrum (FTIR) confirms the presence of bio component in alive biomass of P. formosum which was responsible for the nanoparticles synthesis. The antimicrobial test revealed that AgNPs synthesized by P. formosum is capable to inhibit the growth of microorganisms. Conclusion: The results confirmed that AgNPs can act as a powerful antimicrobial agent against fish and human pathogens.

This study aimed at the amylase production using seawater instead of fresh water. Amylase is one of the most important enzymes and is very important for biotechnology. Versatile applications of amylase in many industries make optimization of the manufacturing process to achieve maximum yield is in need. Amylase is a widely used and sought-after industrial enzyme. The current research paper describes the production conditions of extracellular amylase from Oscillatoria acutissima. The marine cyanobacterium Oscillatoria acutissima culture was statistically optimized using Plackett-Burman and Box-Behnken designs, under submerged fermentation conditions, for optimum amylase production and activity conditions. The verified Plackett-Burman and Box-Behnken designs results showed that the starch degradation and incubation period improved significantly from 53% to 99% and from 18th to 12th days incubation period, respectively, with pH = 7 at temperature 35°C. SDS-PAGE resolved the molecular weight of partially purified amylase at 72 kilodalton. This research work suggested that marine cyanobacterium Oscillatoria acutissima could be a potential source of halophilic amylase enzyme needed for various industrial processes. To the best of our knowledge, this is one of a few studies on cyanobacteria since while and the first report on amylase production by marine cyanobacterium Oscillatoria acutissima.

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