الفهرس 
Filamentous fungiOnly 14 pages are availabe for public view
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Abstract
The economic production of effective and stable fungal catalase [H2O2 oxidoreductase, (EC 1.11.1.6)] was investigated. Penicillium chrysogenum was selected out of molds belonging to ten different fungal species as the most potent producer of catalase. Czapek’s Dox medium (1% sucrose, 0.3% NaNO3, 0.1% KH2PO4, 0.05% KCl, 0.05% MgSO4, 0.001% FeSO4), 28◦C and initial pH 5 were the optimum culture conditions for catalase production by P. chrysogenum at flask level.
The produced enzyme (concentrated by acetone precipitation) was active over a wide range of pH (5.5-8.5) and stable at 50◦C for 3h, the specifications required for some industrial applications such as textile industry. It also showed higher stability toward temperature and different concentrations of H2O2 than commercial bovine liver catalase.
Batch fermentations of P. chrysogenum were grown in 7.5 L bench top bioreactor under the optimum culture conditions previously established at flask level and new different parameters like aeration (1v/v/m) and agitation (300 rpm). Maximum intracellular catalase activity (44491 U/l) was obtained after 7 days of growth. pH control (pH 6) enhanced the production of catalase by more than 300 %. Agitation at 300
rpm appeared to be the optimum to ensure good growth and best catalase production; above which, production was reduced.
The proposed kinetic equations (linear and logistic equations for growth and Luedeking-Piret equation for catalase production) were in good agreement with the experimental data and therefore can be used in the modeling of the fermentation process which is eventually useful in the fermenter design, optimization and scale–up.
The evaluation of the produced enzyme revealed that just low concentrations (> 0.03 U/l) of the enzyme were sufficient to completely degrade the residual H2O2 in the bleaching liquor of textile industry after 10 min.