ZEOLITES AS POTENTIAL MATRICES FOR IMMOBILIZATION OF ASPEGILLUS ORYZAE PP
MARIYA ABAEVA*, YANA EVSTATIEVA, VALENTIN SAVOV, SVETLA ILIEVA, DILYANA NIKOLOVA
Department of Biotechnology, Faculty of Biology, Sofia University
“St. Kliment Ohridski”, Sofia, Bulgaria
*Corresponding author: maria_jord@mail.bg
Keywords: immobilization; Aspergillus oryzae; zeolites, α-amylase activity
Abstract: Aspergillus oryzae was used predominantly for commercial production of the enzyme α-amylase by batch fermentation technique. The use of this enzyme in many industrial fields determines the development of new methods for enhancement of the productivity of the fungal species.
Adsorption on a solid support material is the most general, easiest to perform and oldest protocol of physical immobilization methods, used to increase cell viability.
The present investigation describes the use of different types of zeolites for immobilization of fungal cells of the fungal strain Aspergillus oryzae PP and the production of the enzyme a-amylase. Spore suspension was immobilized in situ by natural adsorption, i.e. through direct contact between cells and three types of zeolites: natural and modified with Cu2+ and Fe2+ at the beginning of the cultivation processes. α-amylase production of immobilized cultures was investigated up to 744th h during batch fermentation and compared with enzyme activity of free cell culture. Immobilized cultures demonstrated a successful adsorption onto all types of zeolites tested in the present study. α-amylase production of 1050,72 SKB U/ml at 216th h of the fermentation process by immobilized cultures on zeolite modified with Cu2+ was detected. Immobilized cultures of all the types of zeolites are able to retain their biosynthetic capabilities up to 744th h due to the solidity and the porosity of the investigated zeolite particles.