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The biodiversity of aquatic and terrestrial ecosystems in Egypt including seas, lakes, and soils with high salinity levels provides rich habitats for flourishing halophilic microorganisms. The present study aims to isolate halophilic bacteria from sixteen samples representing ecosystems with various geographic locations and surveying the mechanisms by which they can tolerate the osmotic stress. Results revealed the highest salinity levels; sodium, chloride, sulfate, magnesium, calcium, and potassium concentrations in water sample of Wadi El-Natroun Lake since the total number of halophilic bacteria was4.68/g and the largest number of halophilic genera was observed in the northern coast of Matrouh governorate. A total of 60 bacterial isolates selected during (June-October 2015) were screened using thin layer chromatography for osmolyte; ectoine. It has the ability to decrease the harmful effects of high salinity, heating, freezing, drying as well as oxygen radicals and other denaturing agents in halophiles. Quantitative estimation of ectoine by high-performance liquid chromatography showed its yield was ranged between 185 and 700 mg/l. Using biochemical tests and 16s rRNA technology, the most active ectoine-producers were identified as Vibrio sp. CS1 and Salinivibrio costicola SH3. The yielded ectoine was purified using cation exchange chromatography (Dowex 50 WX8 resin) and its physicochemical properties were investigated using standard methodology. Characterization of purified ectoine via nuclear magnetic resonance and fourier transform infrared spectroscopy showed the similarity between bacterial ectoine and the authentic was nearly 99%.

Numerous applications of compatible salts (osmolytes) as ectoine in food and pharmaceutical industries have been intensively increased nowadays. Decreasing the cost of industrial production of ectoine using low-cost cultivation media and improving the yield through modeling procedures are the main scopes of the present study. Three statistical design experiments have been successfully applied for screening the parameters affecting the production process, studying the relations among parameters and optimizing the production using response surface methodology. A novel semi-synthetic medium based on hydrolyzed corn gluten meal has been developed to cultivate moderate halophilic bacterial strains; Vibrio sp. CS1 and Salinivibrio costicola SH3, and support ectoine synthesis under salinity stress. Two regression equations describe the production process in the new medium have been formulated for each bacterial strain. Response surface optimizer of the central composite model predicts the maximum ectoine production is achieved at incubation time; 63.7 h, pH; 7.47 and salinity; 7.27% for Vibrio sp. CS1 whereas these variables should be adjusted at 56.95 h, 7.089 and 10.34%; on the same order regarding Salinivibrio costicola SH3. In application studies, 50 µg ectoine decreases RBCs hemolysis due to streptolysin O toxin by 21.7% within ten minutes. In addition, 2% ectoine succeeds to increase the viability of lactic acid bacteria in Yogurt as a classic example of functional food during the storage period (7 days). The present study emphasizes on modeling the process of ectoine production by halophilic bacteria as well as its activity as a cryoprotectant agent.

Sixty-three isolates belonging to the genus Pseudomonas were isolated from different environmental sources including; soil, water and clinical specimens. Twenty out of them were identified as Pseudomonas aeruginosa and individually screened for pyocyanin production. P. aeruginosa R 1; isolated from rice-cultivated soil and P. aeruginosa U 3 selected from clinical specimen (Urinary tract infection) were the highest pyocyanin producers; pyocyanin production reached 9.3 and 5.9 μg/ml, respectively on synthetic glucose supplemented nutrient medium (GSNB). The identification of both selected strains ( P. aeruginosa R 1 and P. aeruginosa U 3 ) was confirmed by 16S rRNA, the similarity with other strains available in database was 97% (with P. aeruginosa FPVC 14) and 94% (with P. aeruginosa 13.A), respectively. P. aeruginosa R 1 and P. aeruginosa U 3 are accessed at gene bank with accession numbers KM924432 and KM603511, in the same order. Pyocyanin was extracted by standard methods, purified by column chromatography and characterized by UV-Vis absorption, mass spectrometry and nuclear magnetic resonance. The antimicrobial activity of purified pyocyanin against multi-drug resistant microbes was investigated; the efficiency of pyocyanin was more obvious in Gram +ve bacteria than Gram−ve bacteria and yeast. To reduce the cost of pyocyanin production, a new conventional medium based on cotton seed meal supplemented with peptone was designed. The pyocyanin production of both selected strains P. aeruginosa R 1 and P. aeruginosa U 3 using the new medium is increased by 30.1% and 17.2%, respectively in comparison with synthetic GSNB medium, while the cost of production process is reduced by 56.7%.