title: Xylanolytic enzyme production by an Aspergillus niger isolate.
abstract: Production of xylanolytic enzymes by an Aspergillus niger CCMI 850 isolate was investigated in batch cultures. The effect of the composition of a fermentation medium that did not include chemical inducers, on beta-xylanase, beta-xylosidase, alpha-L-arabinofuranosidase, and total cellulase activity was studied. With 4% xylan as the carbon source, about 65 U/mL of beta-xylanase was obtained, whereas the total cellulase activity was undetectable, under the specified conditions. This beta-xylanase activity represents the highest reported for a wild-type strain of A. niger. The effect of pH and temperature on the activity of beta-xylanase was studied. Partial characterization of the beta-xylanase showed that with insoluble birchwood as substrate the Km and Vmax were 0.3 mM and 19 mumol/min, respectively. Aspects of using the crude beta-xylanase preparation for applications in the pulp and paper industry were discussed.
authors.affiliation: Biotechnology Unit, National Institute for Industrial Engineering and Technology, INETI/DTIQ, Est. das Palmeiras, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Costa-Ferreira
authors.forename: A
authors.initials: A
authors.lastname: Dias
authors.forename: C
authors.initials: C
authors.lastname: Máximo
authors.forename: M J
authors.initials: MJ
authors.lastname: Morgado
authors.forename: G
authors.initials: G
authors.lastname: Sena-Martins
authors.forename: J C
authors.initials: JC
authors.lastname: Duarte
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology* / Q000302:isolation & purification; D002480:Cellulase; D003470:Culture Media; D002523:Edible Grain; D043364:Endo-1,4-beta Xylanases; D004795:Enzyme Stability; D005285:Fermentation; D006026:Glycoside Hydrolases / Q000032:analysis / Q000096:biosynthesis*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D043325:Xylan Endo-1,3-beta-Xylosidase; D014990:Xylans
chemical_list: D003470:Culture Media; D014990:Xylans; D006026:Glycoside Hydrolases; D043325:Xylan Endo-1,3-beta-Xylosidase; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases