Natural and Modified Zeolites as Matrices for the Immobilization of Trichoderma viride SL-45

M. BADALOVA, Y. EVSTATIEVA, L. MUSHEKOVA, Ts. LICHEVA, D. NIKOLOVA and V. SAVOV
Sofia University “St. Kliment Ohridski”, Faculty of Biology, BG – 1164 Sofi a, Bulgaria

Abstract

BADALOVA, M., Y. EVSTATIEVA, L. MUSHEKOVA, Ts. LICHEVA, D. NIKOLOVA and V. SAVOV, 2014. Natural and modifi ed zeolites as matrices for the immobilization of Trichoderma viride SL-45. Bulg. J. Agric. Sci., Supplement 1: 93–96

 

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 signifi cant quantities of the complete set of extracellular cellulases for the degradation of crystalline cellulose. The meaning of the concept of “modifi cation” 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 defi ned as the physical closing or localizing of intact cells or enzymes in a specifi c 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 modifi ed zeolites are used. Four variants of immobilization of the studied strain are constructed by the method of adsorption with the using of natural and modifi ed zeolites. A comparison is made between the classical medium of Mandels and a modifi ed medium. Due to the inclusion of microelements in the matrix (modifi ed zeolite) a correction of the salt composition of the classical medium is made.

Key words: Trichoderma; cellulase activity; immobilization; zeolite

 

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