Effect of Bacillus circulans D1 thermostable xylanase on biobleaching of eucalyptus kraft pulp.
The alkalophilic Bacillus circulans D1 was isolated from decayed wood. It produced high levels of extracellular cellulase-free xylanase. The enzyme was thermally stable up to 60 degrees C, with an optimal hydrolysis temperature of 70 degrees C. It was stable over a wide pH range (5.5-10.5), with an optimum pH at 5.5 and 80% of its activity at pH 9.0. This cellulase-free xylanase preparation was used to biobleach kraft pulp. Enzymatic treatment of kraft pulp decreased chlorine dioxide use by 23 and 37% to obtain the same kappa number (kappa number) and brightness, respectively. Separation on Sephadex G-50 isolated three fractions with xylanase activity with distinct molecular weights.
Departmento de Quimica de Geociencias, Laboratório de Bioquímica dos Processos e Microbiologia Aplicada, IBILCE-UNESP, Rua Cristovão Colombo 2265, São José do Rio Preto, SP, CEP 15054-000, Brazil.
Daniela A
DA
Bocchini
Valquiria B
VB
Damiano
Eleni
E
Gomes
Roberto
R
Da Silva
D001407:Bacillus / Q000201:enzymology*; D001709:Biotechnology / Q000379:methods; D002480:Cellulase / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases; D004795:Enzyme Stability; D005052:Eucalyptus; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D013816:Thermodynamics; D014990:Xylans / Q000378:metabolism; D014995:Xylosidases / Q000378:metabolism*
D014990:Xylans; D014995:Xylosidases; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases