Optimization of Xylanase Production fromAspergillus nigerfor 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.

Microbial xylanases and their industrial application in pulp and paper biobleaching: a review

“…It has been demonstrated from a few studies that xylanase prebleaching is an environment friendly, economically cheap innovation and can diminish the amount of bleached chemicals required to achieve a given brightness in the resulting chemical bleaching stage. Pretreatment with xylanases enhances the effectiveness of chemical extraction of lignin from pulp and minimizes the necessity of chlorine dioxide (ClO 2 ) (Khonzue et al 2011). The innovation likewise enhances paper quality, mass thickness and breaking length and it could lessen the release of volatile organic compounds.…”

“…The main advantages of this process are: Reduced electrical energy consumption and increased mill throughput for mechanical pulping. The process also improved strength properties of paper, and reduced environmental impact (Khonzue et al 2011). The use of biopulping as a pretreatment for the Kraft process is still an open research issue.…”

Biobleaching Effects of Crude Xylanase from Streptomyces griseorubens LH-3 on Eucalyptus Kraft Pulp

“…This facilitates pulp bleaching and lowers chemical consumption, thereby reducing the discharge of toxic organo-chlorine compounds into the environment. Using xylanase from Aspergillus niger in the biobleaching of eucalyptus pulp, Khonzue et al (2011) reduced chemical consumption by 20% to achieve the same final pulp brightness compared with the control. Using xylanase from Bacillus sp.…”

Isolation and characterization of a novel GH67 α-glucuronidase from a mixed culture

“…DEG75-AG can potentially be utilized in industrial processes that occur under alkaline conditions. For instance, DEG75-AG could be combined with alkaline-active endoxylanases in biobleaching of pulp to dramatically decrease the use of harsh chemicals [2,4,13].…”