Gum Tragacanth Gels as a New Supporting Matrix for Immobilization of Whole-Cell

Document Type : Research Article


1 Department of Biotechnology and Chemical Engineering, College of Science and Research, Islamic Azad University, Tehran, I.R. IRAN

2 Department of Chemical Engineering, Sharif University of Technology, Tehran, I.R. IRAN


We introduce a new smooth, non-toxic, biocompatible method for cross-linking of gum tragacanth (GT), a polysaccharide of natural origin, in order to serve as a new supporting matrix for immobilization systems.  The modified gum is used as a matrix for the catalysis of the conversion of benzyl penicillin to 6-aminopenicillanic acid (6-APA) by means of Escherichia coli ATCC11105 with penicillin G acylase (PGA) activity.  The results show that GT beads can not only serve as a proper matrix for immobilization, but show enhanced hydrolysis rate and stability compared to other immobilization systems used for this reaction.  This signifies the potential of GT as a biocompatible matrix for immobilization and its positive prospects for use in more demanding immobilization applications where traditional matrices such as alginate may fall short. The effect of environmental factors, such as temperature, pH, and substrate concentration, have also been studied on the hydrolysis rate and compared with the other immobilizing systems used for the same reaction, such as calcium alginate.  Under the optimal conditions, penicillin G conversion reached 91.5% after 6 h and remained over 80% after 45 repeated cycles of 6 h each. 


Main Subjects

[1] “SBP Handbook of Industrial Gums and Resins”, by SBP Board of Consultants and Engineers, Delhi, India (1998).
[2] Bielecki, S., Bolech, R., Immobilization of Recom-binant E.coli Cells with Phenollyase Activity”, Elsevier Science B.V., Immobilized cells: Basics and  Applications, (1996).
[3] Dobos, P., Use of Gum Tragacanth Overlay, Applied at Room Temperature, in the Plaque Assay of Fish and Other Animal Viruses, J. Clinical Microb., 3(3), 373 (1976).
[4] Kedmi, S., Katazenelson, E., A Rapid Quantitative Fluorescent Antibody Assay of Poliviruses Using Tragacanth Gum, Archives of Virology, 56, 337 (1978).
[5] Kheirolomoom, A.,  Arjmand,  M., Fazelinia, H., Zakeri, A., Clarification of Penicillin G Acylase Reaction Mechanism, Process Biochemistry, 36, 1095 (2001).
[6] Erarslan, A., Guray, A., Kinetic  Investigation of Penicillin G Acylase from a Mutant Strain of Escherichia coli ATCC 11105 Immobilized on Oxiran-Acrylic Beads, J. Chem. Tech. Biotechnol., 51, 181 (1991).
[7] Hegde, M.M., Thadani, S.B., Singh, U., Naik, S. R., Isolation and Purification of  Penicillin G  Acylase  Obtained  from Escherichia Coli (NCIM-2400) and Immobilisation on Eupergit C for the Production of 6 Amino Penicillanic Acid,  Hind. Antibiot. Bull., 39, 1 (1997).
[8] Thu, B.,  Smidsrod, O.,  Skjak-Braek, G.;  Alginate  Gels – Some  Structure – Function Corrections Relevant to Their Use as Immobilization Matrix for Cells, Department of Biotechnology, University of Trondheim, Norway, Immobilized Cells: Basics and Applications, 19 (1996).
[9] Chandy, T., Mooradian, D. L, Rao, G. H. R., Evalu-ation of Modified Alginate-Chitosan-Polyethylene Glycol Microcapsules for Cell Encapsulation, Artif. Organs., 23(10), 894, (1999).
[10] Kheirolomoom,  A.,  Arjmand,  M., Fazelinia,  H., Zakeri, A., Isolation of Penicillin G Acylase from Escherichia coli ATCC 11105 by Physical and Chemical treatments, Biochem. Eng. J., 8, 223 (2001).
[11] Imeson, A., “Thickening and Gelling Agents for food”, Blackie Academic & Professional, an imprint of Chapman & Hall, London, Chapter 4, PP.  66-97, (1992).
[12] Lagerolf, E., Nthorst-Westfelt,  L., Ekstrom,  B., “Production of 6-Aminopenicillinic acid with Immobilized Escherichia coli acylase”, In Mosbach, K.(ed.), Methods in  Enzynology, 44, 759-768, Academic Press, New york.
[13] Blanco, R. M., Alvaro, G., Fernandez-Lafuente, R., Guisan, J. M., Immobilization-Stabilization of Penicillin G Acylase from E. coli, Applied  Biochem. Biotech., 181 (1990).
[14] Balasingham, K., Warburton, D., Dunnill, P., Lilly, D., The Isolation and Kinetics of Penicillin amidase from Escherchia Coli, Biochem. Biophys. Acta, 276, 250 (1972).
[15] Eraeslan,  A., Ertan,  H., “Thermostabilization  of  Penicillin  G  Acylase  Obtained from  a  Mutant  of  Escherichia  coli  ATCC 11105 by Bismidoesters as Homobifunctional Cross-Linking Agents”, Enzyme Microb. Technol., 17, 629 (1995).
[16] Hsiau, L.T., Lee, W.C., Wang, F.S., Immobilization of Whole Cell Penicillin G Acylase by Entrapping within Polymethacrylamide Beads, App. Biochem. Biotech., 62, 303 (1997).
[17] Bickerstaff, G. F., “ Immobilization of Enzyme and Cells ”, University of Paisley