Production of extracellular xylanases by Penicillium janthinellum. Effect of selected growth conditions.
Xylanase production by Penicillium janthinellum using 10-100 mM of 2,2-dimethylsuccinate (DMS) buffer, in a range of pH 4.5-6.0 was studied. The enzyme activity was enhanced using oat xylan as the carbon source. Under these conditions a culture produced 1.14 mumol/min (11.4 U/mL or 84.4 U/mg) of beta-xylanase after 5 d of growth in a 10-mM buffer solution at pH 4.5. Protease was absent in the DMS buffer except when 100 mM phosphate buffer at pH 6.0 was used (4 U/mL). beta-Xylosidase was only found at a pH of 4.5 in all the buffer concentrations. At a 50 mM DMS buffer concentration at pH 4.5 beta-xylanases were induced by both oat and birch xylans, having a greater effect with oat spelt xylans. Electrophoretic analyses showed that the birchwood xylan induction exhibited different proteins profiles. No beta-xylosidase or beta-glucosidase was induced until d 5. The beta-xylanases were rapidly inactivated at 50 degrees C, however, birch xylanase appeared to be more stable than oat xylanase. Using oat xylan as an inductor, the beta-xylosidase and beta-glucosidase were 85 and 91 U/L, respectively, on d 7. The xylanase produced by induction from sugar cane bagasse hydrolyzate was used for pulp biobleaching. A 20% decrease on the Kappa value in Kraft pulp using the culture extract was obtained. These selective growth conditions led us to modulate the xylanase production for pulp delignification.
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Instituto de Quimica, Universidad Católica de Valparaiso, Chile.
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D018554:Avena; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010407:Penicillium / Q000201:enzymology*; D043325:Xylan Endo-1,3-beta-Xylosidase; D014990:Xylans / Q000378:metabolism; D014995:Xylosidases / Q000096:biosynthesis* / Q000378:metabolism; D001617:beta-Glucosidase / Q000096:biosynthesis
D014990:Xylans; D006026:Glycoside Hydrolases; D014995:Xylosidases; D001617:beta-Glucosidase; D043325:Xylan Endo-1,3-beta-Xylosidase; C026579:exo-1,4-beta-D-xylosidase