Hassan et al., J. Mater. Environ. Sci., 2018, 9 (9), pp. 2483-2492 2483 J. Mater. Environ. Sci., 2018, Volume 9, Issue 9, Page 2483-2492 http://www.jmaterenvironsci.com Journal of Materials and Environmental Sciences ISSN : 2028;2508 CODEN : JMESCN Copyright © 2018, University of Mohammed Premier Oujda Morocco Covalent Immobilization of β-Galactosidase Enzyme onto Modified Alginate Gel Beads Mohamed E. Hassan 1, 2# , Ahmed Galal Ibrahim 3 , H. Abd El-Wahab 3 , Farag Abdel Hai 3 , Hamza Mahmoud 3 , Ghada E. A. Awad 1, 2 1 Chemistry of Natural and Microbial Products Department, National Research Center, El Behouth Street, Cairo 12622, Egypt 2 Center of Excellence, Encapsulation & Nano-biotechnology Group, National Research Center, El-Behouth Street, Cairo 12622, Egypt. 3 Chemistry Department, Faculty of Science, Al Azhar University, Cairo 11884, Egypt. 1. Introduction There are of paramount importance for natural polymers, where it found in nature as a result of all organisms growth cycle. In recent years, there is an attraction goes to utilize biodegradable polymers which produced from renewable resources. Production and development as well as research on biodegradable biopolymers have been fasted in recent years. These natural biodegradable polymers called biopolymers. Polysaccharides, as alginate, starch, chitosan and cellulose, represent the most characteristic family of these natural polymers [1]. Alginate, a non-branched binary copolymer, is a biopolymer found in brown algae. It is composed of β- D-mannuronic acid monomer linked to α-L-guluronic acid monomer, through a 1,4-glycoside linkage. Alginate is able to form gels in the presence of counter ions, as divalent cations, such as Ca 2+ [2]. This gelling property makes it important biopolymer [3]. Copolymers of acrylamide with ionic comonomers are of high interest for a multitude of industrial applications, and have been studied by academics [4]. It presents an interesting and useful model for academic copolymerization studies. On the other hand, both the homopolymers and copolymers are of practical interest with productions in the thousands of tons scale. Both homo and copolymers were also subject of characterization studies [5, 6]. The combination between alginate and acrylamide copolymers has many advantages in immobilization procedure. As the carrier should have great attention by choosing the one that has good mechanical strength, resistant for microorganisms, cheap and has available function groups in its large surface area [7]. There are many methods of immobilization such as adsorption, crosslinking, entrapment, encapsulation and covalent binding method [8]. One-variable-at-a-time considered as the classical optimization method does not allow determination of the interactive effects of the parameters in the investigated process [9, 10]. Due to these drawbacks, response surface methodology (RSM) considered as an excellent alternatives currently used. Box and Wilson (1951), was firstly used RSM as a statistical tool that enables to evaluate the effect of the independent variables, Abstract Alginate / H0 (acrylamide-co-acrylic acid) gel beads was generated and modified by sequential soaking with polyethyleneimine (PEI) and glutaraldehyde (GA) as a functional carrier suitable for enzymes immobilization. The modification was carried out by using response surface methodology. Maximum immobilization yield (78.2%) of β- galactosidase was obtained by soaking the gel beads with 3.5% of (PEI) for 5hrs. followed by soaking the treated gel beads with 4 % of (GA) for 6hrs. Analysis of variance (ANOVA) showed a high coefficient of determination value (R 2 ) of 0.90, ensuring a satisfactory adjustment of the quadratic model with the experimental data. Thermo gravimetric analysis (TGA) of gel beads during different improvement steps showed a remarkable increase in their thermal stability from 190, 200 and 210 °C for Alginate-H0, Alginate-H0 / PEI and Alginate-H0 / PEI / GA respectively. The reusability test proved the durability of the modified Alginate / H0 (acrylamide-co-acrylic acid) gel beads for 7 cycles with retention of 100% of the immobilized enzyme activity losing only 10% of its activity after 17 cycles. To be more convenient for industrial uses , considerable stability and reusability of bound enzyme maybe advantageous for its industrial application. Received 11 Oct 2017, Revised 25 Nov 2017, Accepted 30 Nov 2017 Keywords ! Alginate, ! Acrylamide, ! Immobilization, ! Modification, ! Response surface methodology. mohassan81@gmail.com ; Phone: +201117887429