Bulgarian Journal of Agricultural Science
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D. Nikolova, L. Mushekova, M. Badalova, V. Savov, Ts. Licheva, Y. Evstatieva
Abstract: The cellulase produced by Trichoderma strains is regarded as the most suitable agent for hydrolysis of cellulose materials. Trichoderma viride is one of the best known producers of cellulolytic enzymes, synthesizing technologically significant quantities of the complete set of extracellular cellulases for the Stryama degradation of crystalline cellulose. The meaning of the concept of “modification” of mineral systems is that important minerals (bentonites, natural zeolites, vermiculite, kaolinite) acquire new and useful practical properties after defi nitive treatment (chemical, tribochemical, thermal, ion exchange). Immobilization of microbial cells and enzymes is defined as the physical closing or localizing of intact cells or enzymes in a specific region of space, while the desired catalytic activity is retained. Characteristic for the immobilized bioobjects is that they can be used repeatedly and continuously. Many microorganisms have the ability to attach to different types of natural surfaces to ensure greater proximity with their substrate. Natural zeolites are a group of minerals formed by deformation of volcanic ash in an alkaline environment. They have porous crystalline structure formed by interconnected channels in three different directions. The presence of free molecules of the alkali metals and water determine their unique properties – ion exchange capacity with a high selectivity and high ability for adsorption of liquids and gases. For the purpose of this experiment natural and modified zeolites are used. Four variants of immobilization of the studied strain are constructed by the method of adsorption with the using of natural and modified zeolites. A comparison is made between the classical medium of Mandels and a modified medium. Due to the inclusion of microelements in the matrix (modified zeolite) a correction of the salt composition of the classical medium is made.
Keywords: cellulase activity; immobilization; Trichoderma; zeolite
Date published: 2017-10-20
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