الفهرس 
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Abstract
A survey of 17 different fungal isolates was carried out for the production of lipases. Among these tested fungi, Aspergillus niger and Aspergillus rubber (550.0 & 525.0 U/mL) were found to be the most potent microorganisms for lipase production followed by Fusarium solani, Penicillium racemosis and Penicillium crystium, (475, 475, 375.0 U/mL). Experimentations aiming to the optimization of the cultivation conditions. The optimum inoculum size was 4.325x106 spores /ml; optimum incubation periods 4 days for fungi using shaking technique, 200 rpm; optimum temperature 30°C; optimum pH, 7.0 using 0.2 M phosphate buffer .
Optimization of the enzyme production was carried out using a sequential optimization strategy, based on a statistical experimental design, This strategy led to an overall increase in lipase activity about 2.1folds than that of the basal medium.
The crude Aspergillus niger NRRL599 lipase was partially purified by fractional precipitation with different techniques including ethanol, acetone and ammonium sulphate. Ammonium sulphate at 40 – 60 % saturation proved to be the best method for partial purification of Aspergillus niger NRRL 599 lipase (3.2 purification folds).
This partially purified lipase was used for immobilization by physical adsorption; on gelatin coated titanium dioxide which showed the highest immobilization yield (123.3%). Comparison between the properties of the free and the nano immobilized Aspergillus niger NRRL 599 lipase was carried out. The free and immobilized enzymes were optimally active at pH 7.6. The later was more stable at acidic pHs (3.0, 4.0, 5.0) and alkaline pH (8.0, 9.0, 10). The nano immobilized and free enzymes were optimally active at temperature 40°C. The activation energy for nano immobilized enzyme (0.4 Kcal/mole) was lower than that of free one (0.5 Kcal/mole). The calculated half life values at 50, 55 and 60°C for the nano immobilized enzyme were (23.1, 34.6 & 23.1.min. respectively) higher than those for the free enzyme (17.3, 23.1 & 17.3 min., respectively) indicating that the enzyme immobilization process by adsorbtion on nanoparticles increased the enzyme stability.
The immobilized and free enzymes were deactivated by different metals. ZnSO4 exhibited low inhibitory effect (67.6 %) on immobilized lipase activity, while, Na2CO3 and CaCO3 exhibited high inhibitory effects on the activity of both the immobilized enzyme and the free one (0& 3.03, 0& 4.4 respectively). The calculated values of Km and Vmax using olive oil as a substrate were found to be (12.5` mM & 296.3 U/mg protein) for free enzyme and (11.11 mM & 416.6 U/mg protein) for immobilized enzyme.
The partially purified Aspergillus niger NRRL 599 lipase and nano immobilized lipase were used in the textile to improve color strength. The pretreatment using 1.5% concentration of nano enzyme showed the highest value of color strength (K/S) for wool fibers dyed with saffron natural dye by microwave.