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Two types of yoghurt with Rosmarinus officinalis oil was prepared and stored up to 21 days. The extract plant was added at the rate of 0.14, 0.21, 0.29, and 0.36 g/L. Yoghurt samples were analyzed for some physical, chemical, microbiological and sensory some characteristics. The total and fecal coliform count, Staphylococcus aureus count, Salmonella count, yeast and mold counts were determined in yoghurt samples at two, seven and 21 days of storage period. There were significantly differences between the control and enriched yogurts in the dry matter, lactose, ash and protein contents. No germ detected in all samples during the storage period. Sensory analysis indicated that the highest flavour, taste and texture, of the two yoghurt types added was with 0.14g/L of essential oil among the yoghurts samples.

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Six isolates (Ps1, Ps2, Ps3, Ps4, Ps5 and Ps6) producing lipase were screened from wastewater on a selective medium agar containing Tween 80 or olive oil as the only source of carbon. Isolate Ps 5 showed the highest lipase activity which was later identified as Pseudomonas aeruginosa. The effect of media composition was analysed to maximize the production of lipase. The maximum extracellular lipase present in the broth was purified 4 folds with an overall yield of 19.4% through the purification procedure of ammonium sulphate precipitation and diethyl aminoethyl (DEAE) cellulose chromatography. The purified lipase had the maximal activity within the pH range of 6 to 8, with an optimum pH of 7, and within the temperature range of 20 to 35°C, with an optimum temperature for the hydrolysis of olive oil at 30°C. The enzyme activity of P. aeruginosa lipase was enhanced by Ca 2+ and Mg 2+ but strongly inhibited by heavy metals such as Zn 2+ , Cu 2+ and Mn 2+ .

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