Researcher 2017;9(12) http://www.sciencepub.net/researcher 1 An Overview of Enzyme Immobilization *Ajayi, A. A., Onibokun, E. A. Department of Biological Sciences, Covenant University, Ota *Corresponding author: adesola.ajayi@covenantuniversity.edu.ng Orcid ID：0000-0001-7771-4130 Abstract: The use of enzymes as biological catalysts has gained increasing importance in industries. Although enzymes can be obtained from plant and animal origin, microbial enzymes have several advantages over enzymes derived from other sources. Due to the high cost of separation of enzymes from product, the instability of enzymes and reduced enzyme activity, several strategies are now been explored to develop immobilized enzymes. Immobilized enzymes have been produced by cell immobilization techniques. Immobilized enzymes have found several industrial applications where they provide the advantages of easy separation of the enzyme from the product, reuse of the enzyme, convenient handling, high stability under extreme physical and chemical conditions, being applicable for all types of reactors with varied interior design, and provides easier process control. However, despite these advantages, enzyme immobilization techniques continue to pose some challenges. These challenges notwithstanding, the development of industrial by-products based on immobilization techniques is very promising. [Ajayi, A. A., Onibokun, E. A. An Overview of Enzyme Immobilization. Researcher 2017;9(12):1-7]. ISSN 1553- 9865 (print); ISSN 2163-8950 (online). http://www.sciencepub.net/researcher . 1. doi:10.7537/marsrsj091217.01 . Keywords: Enzymes; Immobilization; Adsorption; Entrapment, Covalent binding, Crosslinking Introduction Enzymes are biological macromolecules that are produced by living organisms which act as catalysts to bring about specific biochemical reactions (Gurung et al., 2013). With the exception of a small group of catalytic RNA molecules, all enzymes are proteins (Agarwal, 2006). Enzymes are classified as either simple or complex. Simple enzymes are composed only of proteins while complex enzymes are composed of proteins and a relatively small group of organic molecule known as the prosthetic group (Ajayi et al., 2014). Enzymes are central to every biochemical process where they act in organized sequences to catalyze a hundred of stepwise reactions that degrade nutrient molecules, and make biological macromolecules from simple precursors (Ajayi et al., 2014). Microbial enzymes, due to the numerous advantages they offer are more readily applied in several industries such as food, for the clarification of fruit juices, extraction of lycopene (Ajayi et al., 2015; Ajayi et al., 2013) beverage, textile, pulp and paper, pharmaceutical, agriculture, petroleum, medical industries and in waste management. The current demands of sustainable green methodologies have increased the use of enzymatic technology in industrial processes (Mohamad, 2015). Due to the high cost of separating enzymes from product, the instability of enzymes and reduced enzyme activity (Fernandez-Lafuente, 2017), immobilization have now become an acceptable technique in the production of many useful metabolites including industrial enzymes. Immobilization is a process by which an enzyme is fixed to or within solid supports, creating a heterogeneous immobilized enzyme system (Homaei et al., 2013). It also refers to enzymes physically confined or localized in a certain defined region of space with retention of their catalytic activities, and which can be used repeatedly and continuously (Hassan et al., 2016). History of Immobilized Enzymes The technique of enzyme immobilization arose after the discovery of biofilms by Anthony van Leeuwenhoek which he initially described as aggregated microorganisms in the ‘scurf of his teeth’ and ‘particles scraped off his tongue’ (Hoiby, 2014). Scientists soon observed that microorganisms were capable of normal physiological activities when growing attached to surfaces as with their free-living forms. However, it was not until 1978 that the term ‘Biofilms’ was coined by Bill Costerton (Chandki, 2011). Biofilms are surface attached microbial communities consisting of multiple layers of cells embedded in hydrated matrices (Kierk-Pearson and Karatan, 2005). They are microbially derived sessile communities characterized by the cells that are irreversibly attached to a substratum or to each other (Hassan et al., 2011). Biofilms have been found growing on various naturally occurring supports like rock immersed in a stream, an implant in the human body, a tooth, a water pipe or conduit etc. (Mahmoud and Helmy, 2009). However, it was not until 1916 that the first immobilized enzyme was reported by Nelson and Griffin. They reported that invertase extracted from brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Covenant University Repository