Immobilized cells Md. Assaduzzaman Khan Md.Mahmudul Hasan Arifin Islam

The term "immobilized" means unable to move or stationary. And that is exactly what an immobilized enzyme is. Enzyme immobilization can be defined as the attachment of free or soluble enzymes to different types of supports resulting in reduction or loss of mobility of the enzyme. What is an immobilized enzyme?

Why immobilize enzymes? Protection from degradation and deactivation Re-use the enzymes for many reaction cycles Lowering the total production cost Enhanced stability Easy separation of the enzyme from the product Enzyme is not contaminated with the product

Methods for enzyme immobilization Adsorption on glass, alginate beads or matrix: Attached to the outside of inert material, slowest. No chemical reaction Entrapment: The enzyme is trapped in insoluble beads or microspheres, such as calcium alginate beads. Cross-linkage: Enzyme molecules are covalently bonded to each other to create a matrix consisting of almost only enzyme. Covalent bond: The enzyme is bound covalently to an insoluble support Encapsulation: This type of immobilization is done by enclosing the enzymes in a membrane capsule.

Advantages Simple and economical Limited loss of activity Can be recycled, regenerated and reused Less labor input in the processes Minimum reaction time Less chance of contamination in products More stability of products

Disadvantages Relatively low surface area for binding High cost for the isolation, purification Industrial applications are limited and only very few industries are using immobilized enzymes or immobilized whole cells. Catalytic properties of some enzymes are reduced or completely lost after their immobilization on support Some enzymes become unstable after immobilization. Enzymes are inactivated by the heat generated in the system

Applications of enzyme immobilization Industrial production Biomedical applications Food industry Research Production of bio-diesel Waste water management Textile industry Detergent industry

Two examples L-aspertate B-galactocidase Some applications

L-aspertase Using Escherichia coli First used immobilized cell The initial process made use of polyacrylamide entrapment which was later substituted with the carragenan treated with glutaraldehyde and hexamethylenediamine.

. Kyowa Hakko Kogyo Co. uses Duolite A7, a phenolformaldehyde resin, for adsorbing aspartase used in their continuous process. Others including Mitsubishi Petrochemical Co. and Purification Engineering Inc. in Japan companies like Tanabe Seiyaku and Kyowa Hakko, have used the immobilized fumarase for the production of malic acid.

Malic acid is becoming of greater market interest as food acidulant in competition with citric acid. Studies from our laboratory have shown the possibility of using immobilized mitochondria as a source of fumarase.

B-galactosidase dairy industry, preparation of lactose-hydrolysed milk and whey. Lactose hydrolysis also enhances the sweetness and solubility of the sugars. Lactose-hydrolysed whey may be used as a component of whey-based beverages, leavening agents, feed stuffs, or may be fermented to produce ethanol and yeast, thus converting an inexpensive byproduct into a highly nutritious, good quality food ingredient.

The first company to commercially hydrolyse lactose in milk by immobilized lactase was Centrale del Latte of Milan, Italy, utilizing the Snamprogetti technology. The process makes use of a neutral lactase from yeast entrapped in synthetic fibers.

comtamination A co-immobilizate obtained by binding of glucose oxidase on the microbial cell wall using Con A has been used to minimize the bacterial contamination.

Penicillium chrysogenum Scientific classification Kingdom:Fungi Division:Ascomycota Classr:Eurotiomycetes Orde:Eurotiales Family:Trichocomaceae Genus:Penicillium Species:P. chrysogenum

 It is common in temperate and subtropical regions and can be found on salted food product.  Mostly found in indoor environment especially in damp or water damaged buildings.  Previously known as penicilliun notatum.  Reproduce by forming dry chain of spores.

Conidia of Penicillium chrysogenum were immobilized in K-carrageenan beads and then incubated in a growth-supporting medium to yield a penicillin producing immobilized cell mass. These in situ grown immobilized cells were used for the semicontinuous and continuous production of penicillin-G. When periodically replaced into a minimal production medium, immobilized cells exhibited a half-life for penicillin production which was ninefold greater than that exhibited by free cells. The half-life of penicillin production and the yield of penicillin from glucose in such a replacement culture were greatly affected by the frequency of replacement and by the production medium's pH and concentration of glucose, phosphate, and trace metal nutrients. semicontinuous and continuous production of penicillin g production from penicillium chrysogenum:

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