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PublicationCatalysis today

Immobilization and stabilization of an endoxylanase from Bacillus subtillis (XynA) for xylooligosaccharides (XOs) production

Authors:PUBLICACIONES, Roberto Fernandez-Lafuente
Groups of research:Enzymatic Engineering, Optimization of biocatalysts and bioprocesses
Thais S. S. Milessia, Willian Koppa, Mayerlenis J. Rojasa, Anny Manricha,1, Alvaro Baptista-Netob, Paulo W. Tardiolic, Roberto C. Giordanoc, Roberto Fernandez-Lafuented, Jose M. Guisane, Raquel L. C. Giordanoc*
a Graduate Program in Chemical Engineering - Federal University of São Carlos, PO Box 676, São Carlos, São Paulo, Brazil
b Bioproc.Bioeng. Department - FCF- Rod.Araraquara-Jau, Km 01, Araraquara, São Paulo, Brazil
c Chemical Engineering Department - Federal University of São Carlos, PO Box 676, ZC 13565-905, São Carlos, São Paulo, Brazil- *
d Biocatalysis Department, ICP – CSIC, CampusUAM-CSIC,Cantoblanco, ZC 28049 Madrid, Spain
e  Catalysis Department, ICP – CSIC, Campus UAM-CSIC, Cantoblanco, ZC 28049 Madrid, Spain
One important market for xylanases is the industrial production of xylooligosaccharides (XOs), small oligomers constituted by 2-10 units of xylan monomers. They can be produced through the enzymatic hydrolysis of xylan catalyzed by an endoxylanase, avoiding the co-production of xylose. The high cost of the enzymatic process may be decreased by using immobilized and stabilized enzymes. In this study, XynA, a recombinant enzyme from B. subtillis, was immobilized in three different supports: agarose and chitosan activated with glyoxyl groups and chitosan activated with glutaraldehyde. High immobilization yields were obtained, 100% for agarose-glyoxyl and chitosan-glutaraldehyde, 82% for chitosan-glyoxyl, with recovered activities of 42.7% (±1.3), 10.7 ± 0.8 %. and 53.6 % (± 1.7), respectively. A great increase in the thermal stability of the enzyme (at 56°C, pH 5.5) was achieved for the glyoxyl derivatives: 75-fold for chitosan and 8600-fold for agarose. The great thermal stability obtained to the derivative agarose-glyoxyl can be explained by the enzyme immobilization through lysine residues located in unstable sites of the protein structure. The agarose-glyoxyl derivative was tested in the production of XOs (X2, X3 and X4) from soluble and conventional birchwood xylan, reaching app. 20% of conversion in three hours and 23% in 24 hours, without xylose production. After 10 cycles of hydrolysis, the conversion remained almost unchanged.
Keywords:Immobilization, B. subtillis endoxylanase, XynA, stabilization, xylooligosaccharides
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