Environmental Engineering and Management Journal March 2015, Vol.14, No. 3, 631-638 http://omicron.ch.tuiasi.ro/EEMJ/ “Gheorghe Asachi” Technical University of Iasi, Romania SIMPLE ECO-FRIENDLY -GALACTOSIDASE IMMOBILIZATION ON FUNCTIONALIZED MAGNETIC PARTICLES FOR LACTOSE HYDROLYSIS Kalim Belhacene 1 , Elena Florentina Grosu 2 , Alexandra Cristina Blaga 2 , Pascal Dhulster 1 , Mariana Pinteala 3 , Renato Froidevaux 1 1 Charles VIOLLETTE Institute– Equipe Laboratoire des Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM) – EA 1026, Université Lille 1 – Sciences et Technologies, Villeneuve d’Ascq, France 2 ”Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Department of Organic, Biochemical and Food Engineering, 73 Prof. Dr. docent Dimitrie Mangeron Str., 700050 Iasi, Romania 3 “Petru Poni” Institute of Macromolecular Chemistry of Romanian Academy, Center of Advanced Research in Bionanoconjugates and Biopolymers, 41A Aleea Grigore Ghica Voda, 700487 Iasi, Romania Abstract β-galactosidase from Aspergillus oryzae was strongly immobilized on magnetic particles functionalized with amino groups. By simple incubation without any activating agents, electrostatic interactions between amino groups and enzymes allowed obtaining a strong linkage. The immobilization efficiency was studied with the quantification of amino groups of the particles and of immobilized β-galactosidase. Kinetic parameters, especially the maximal velocity Vmax and the affinity Km, were determined with two substrates, o-NPG and lactose, and compared with free enzyme values in order to evaluate the influence of our immobilization methodology on the kinetic behavior of the enzyme. Therefore, magnetic capacity of the functionalized particles allows recovering and reusing the support. Results show efficient immobilization of β-galactosidase (58 µg/mg of support), able to hydrolyze substrates during multiple cycles of use. Thus, magnetic particles functionalized with amino groups represent an attractive support for simple and efficient β-galactosidase immobilization process. Key words: ȕ-galactosidase, immobilization, lactose, magnetic, particles Received: November, 2014; Revised final: March, 2015; Accepted: March, 2015  Author to whom all correspondence should be addressed: e-mail: renato.froidevaux@univ-lille1.fr; Phone: +33(0)320417566; Fax: +33(0)328767356 1. Introduction β-galactosidase is an important enzyme biocatalyst used in food industry for the hydrolysis of lactose (Kim et al., 2001) necessary for lactose- intolerant people (Carpio et al., 2000). In addition, this enzyme catalyzes the formation of galacto- oligosaccharides, which are prebiotic additives for the so-called “healthy foods” (Matsumoto et al., 1989). However, since the price of β-galactosidase is quite high, the direct addition of the enzymes to the substrate is economically unacceptable (Mahoney, 1997). Immobilised β-galactosidase biocatalyst can be reused several times, which decrease the costs of the process (Genari et al., 2003). Several studies have been carried out to immobilize this enzyme to enhance the biotechnological conversion of food lactose in bioreactors (Roy and Gupta, 2003). The performance of an immobilized enzyme is mainly governed by the properties of supporting materials, the technique used to immobilize the enzyme, and the nature of reactor used (packed bed, fluidized bed or membrane reactor) (Marangoni, 2005; Roy and Gupta, 2003).