title: Optimization of xylanase production from Aspergillus niger for biobleaching of eucalyptus pulp.
abstract: A crude endo-xylanase produced by Aspergillus niger BCC14405 was investigated for its potential in pre-bleaching of chemical pulp from eucalyptus. The optimal fermentation conditions on the basis of optimization using response surface methodology included cultivation in a complex medium comprising wheat bran, rice bran, and soybean meal supplemented with yeast extract, glucose, peptone, and lactose with a starting pH of 6.0 for 7 d. This resulted in production of 89.5 IU/mL of xylanase with minor cellulase activity. Proteomic analysis using LC/MS/MS revealed that the crude enzyme was a composite of hemicellulolytic enzymes, including endo-β-1,4-xylanase and other hemicellulolytic enzymes attacking arabinoxylan and mannan. Pretreatment of the pulp at a xylanase dosage of 10 IU/g increased the brightness ceiling after the C-Eop-H bleaching step up to 3.0% using a chlorine charge with a C-factor of 0.16-0.20. Xylanase treatment also led to reduction in chlorine charge of at least 20%, with an acceptable brightness level. The enzyme pretreatment resulted in a slight increase in pulp viscosity, suggesting an increase in relative cellulose content. The crude enzyme was potent in the enzyme-aided bleaching of chemical pulp in an environmentally friendly pulping process.
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Klong Luang, Pathumthani, Thailand.
authors.forename: Parichart
authors.initials: P
authors.lastname: Khonzue
authors.forename: Thanaporn
authors.initials: T
authors.lastname: Laothanachareon
authors.forename: Nakul
authors.initials: N
authors.lastname: Rattanaphan
authors.forename: Phungjai
authors.initials: P
authors.lastname: Tinnasulanon
authors.forename: Saowanee
authors.initials: S
authors.lastname: Apawasin
authors.forename: Atchara
authors.initials: A
authors.lastname: Paemanee
authors.forename: Vasimon
authors.initials: V
authors.lastname: Ruanglek
authors.forename: Sutipa
authors.initials: S
authors.lastname: Tanapongpipat
authors.forename: Verawat
authors.initials: V
authors.lastname: Champreda
authors.forename: Lily
authors.initials: L
authors.lastname: Eurwilaichitr
mesh_terms: D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology*; D057886:Bleaching Agents / Q000737:chemistry* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D004043:Dietary Fiber / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis / Q000302:isolation & purification; D005052:Eucalyptus / Q000737:chemistry* / Q000378:metabolism; D005285:Fermentation; D005936:Glucans / Q000378:metabolism; D055772:Green Chemistry Technology / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000378:metabolism; D008351:Mannans / Q000378:metabolism; D010461:Peptones / Q000378:metabolism; D013025:Glycine max / Q000378:metabolism; D013696:Temperature; D014783:Viscosity; D043325:Xylan Endo-1,3-beta-Xylosidase / Q000096:biosynthesis / Q000302:isolation & purification; D014990:Xylans / Q000378:metabolism
chemical_list: D057886:Bleaching Agents; D004043:Dietary Fiber; D005936:Glucans; D008351:Mannans; D010461:Peptones; D014990:Xylans; C065495:rice bran saccharide; D002482:Cellulose; C085118:arabinoxylan; D043325:Xylan Endo-1,3-beta-Xylosidase; D043364:Endo-1,4-beta Xylanases; D007785:Lactose