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Lipases are enzymes that have the potential to hydrolyze triacylglycerol to free fatty acids and glycerol and have various applications. The aim of the present study was to isolate and screen marine bacteria for lipase production, optimize the production, and treat wastewater. A total of 20 marine bacterial isolates were obtained from the Mediterranean Sea and were screened for lipase production. All isolates were found to have lipolytic ability. The differences between the isolates were studied using RAPD-PCR. The most promising lipase producer (isolate 3) that exhibited the highest lipolytic hydrolysis (20 mm) was identified as Bacillus cereus HSS using 16S rDNA analysis and had the accession number MF581790. Optimization of lipase production was carried out using the Plackett–Burman experimental design with cotton seed oil as the inducer under shaking conditions at 10°C. The most significant factors that affected lipase production were FeSO4, KCl, and oil concentrations. By using the optimized culture conditions, the lipase activity increased by 1.8-fold compared with basal conditions. Immobilization by adsorption of cells on sponge and recycling raised lipase activity by 2.8-fold compared with free cells. The repeated reuse of the immobilized B. cereus HSS maintained reasonable lipase activity. A trial for the economic treatment of oily wastewater was carried out. Removal efficiencies of biological oxygen demand, total suspended solids, and oil and grease were 87.63, 90, and 94.7%, respectively, which is promising for future applications.

L-asparaginase (E.C.3.5.1.1) is an enzyme responsible for hydrolysis of L-asparagine into aspartic acid and ammonia, and has its significant applications in the therapeutics and food technology. It was produced by the marine Aspergillus terreus and precipitated by 65% ammonium sulphate, followed by purification using gel filtration on Sephadex G-100 and DEAE-cellulose ion exchange chromatography, which yielded 11.96 fold purification. The molecular weight of the purified L-asparaginase was approximately 85 kDa, determined by a sodium dodecyl sulphate polyacrylamide gel electrophoresis. L-asparaginase showed high affinity for L-asparagine with a Km of 31.5 mM and Vmax of 500 U/ml. The optimum pH and temperature of the purified enzyme were 5.8 and 40 o C, respectively. The L-asparaginase enzyme was stable from pH 4 to 5.8 and stable up to 70 o C. The effect of activators and inhibitors was studied providing that CdCl 2 , Pb Cl 2 , and Hg Cl 2 strongly inhibited the enzyme activity, while Na Cl highly enhanced activity. Anticancer activity of the purified L-asparaginase was detected against HCT-116, Hep-G2 and MCF-7 cell lines with IC 50 ranged from 3.79-12.6 µg/ml.

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Exopolysaccharides (EPSs) are high molecular weight polymers consisting of different sugar residues they are preferable for replacing synthetic polymers as they are degradable and nontoxic. Many microorganisms possess the ability to synthesize and excrete exopolysaccharides with novel chemical compositions, properties and structures to have potential applications in different fields. The present study attempt to optimize the production of EPS by marine Bacillus subtilis SH1 in addition to characterization and investigation of different valuable applications. Effect of medium type, incubation period and pH were studied using the one factor at a time experiments. It was shown that the highest productivity (24 gl-1) of exopolysaccharides was recorded by using yeast malt glucose medium with pH 9 at the fourth day of incubation. Experimental design using Response Surface Methodology (RSM) was applied to optimize various nutrients at different concentrations. The finalized optimized medium contained (gl-1) glucose (5), peptone (2.5), yeast extract (4.5) and malt extract (4.5) increased the production of EPS to 33.8 gl-1 with1.4 fold increase compared to the basal medium. Chemical characterization of the extracted EPS showed that, FTIR spectra exhibited bands at various regions. Moreover, HPLC chromatogram indicated that the EPS was a heteropolysaccharide consisting of maltose and rhamnose. The study was extended to evaluate the potentiality of the extracted polysaccharides in different medical applications. Results concluded that, EPS exhibited antibacterial activity against Aeromonas hydrophila, Pseudomonas aeruginosa and Streptococcus faecalis and the highest antibacterial activity (7.8, 9 and 10.4 AU/ml) was against S. faecalis at 50, 100 and 200 mg/ml respectively. The EPS exhibited various degree of antitumor effect toward the tested cell lines (MCF-7, HCT-116 and HepG2). In addition, EPS exhibited antiviral activity at 500 μg/ml. The antioxidant capacity increased with increasing the concentration of the sample. Scanning electron microscopic analysis showed that EPS had compact film-like structure, which could make it a useful in the future applications as in preparing plasticized film.

Tannase enzyme (EC 3.1.1.20) is an enzyme used in many biotechnological applications as in chemical, beverage, pharmaceutical and food industries. was isolated and purified from marine Aspergillus nomius GWA5 by 75% acetone fractional precipitation, followed by gel filtration in Sephadex G-100 and ion exchange chromatography on DEAE-Sephadex A-50 yielding 4.48-fold purification. Estimation of tannase molecular weight was carried out using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showing a molecular weight of 30 kDa. The highest activity (291 U/mg protein) were at pH 6.0 and 50 °C, respectively. Tannase stability was observed in acidic range (4-6) and was stable to heat treatment. In absence of its substrate it retained about 84.5% of its activity at 80 °C for 15 min. Effect of some metal ions and chelator on tannase activity was investigated. Mg 2+ activated as activator of the pure enzyme while EDTA, Cd 2+ , Pb 2+ and Hg 2+ inhibited its activity and retained about 40.78, 51.55, 30.24 and 24.55% of its activity, respectively. Promising activity of Tannase was shown in removing tannin stains of tea from clothes.

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