title: Bioprocess and biotecnology: effect of xylanase from Aspergillus niger and Aspergillus flavus on pulp biobleaching and enzyme production using agroindustrial residues as substract.
abstract: This study compares two xylanases produced by filamentous fungi such as A. niger and A. flavus using agroindustrial residues as substract and evaluated the effect of these enzymes on cellulose pulp biobleaching process. Wheat bran was the best carbon source for xylanase production by A. niger and A. flavus. The production of xylanase was 18 and 21% higher on wheat bran when we compare the xylanase production with xylan. At 50°C, the xylanase of A. niger retained over 85% activity with 2 h of incubation, and A. flavus had a half-life of more than 75 minutes. At 55°C, the xylanase produced by A. niger showed more stable than from A. flavus showing a half-life of more than 45 minutes. The xylanase activity of A. niger and A. flavus were somehow protected in the presence of glycerol 5% when compared to the control (without additives). On the biobleaching assay it was observed that the xylanase from A. flavus was more effective in comparison to A. niger. The kappa efficiency corresponded to 36.32 and 25.93, respectively. That is important to emphasize that the cellulase activity was either analyzed and significant levels were not detected, which explain why the viscosity was not significantly modified.
authors.affiliation: Laboratory of Biochemistry, CCBS - Universidade Federal de Mato Grosso do Sul/UFMS, Av Costa e Silva s/n°, Campo Grande, MS 79070-900 Brazil.
authors.forename: Nelciele Cavalieri
authors.initials: NC
authors.lastname: de Alencar Guimaraes
authors.forename: Michele
authors.initials: M
authors.lastname: Sorgatto
authors.forename: Simone de Carvalho
authors.initials: Sde C
authors.lastname: Peixoto-Nogueira
authors.forename: Jorge Henrique Almeida
authors.initials: JH
authors.lastname: Betini
authors.forename: Fabiana Fonseca
authors.initials: FF
authors.lastname: Zanoelo
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Marques
authors.forename: Maria de Lourdes Teixeira
authors.initials: Mde L
authors.lastname: de Moraes Polizeli
authors.forename: Giovana C
authors.initials: GC
authors.lastname: Giannesi
keywords: Agroindustrial residues; Aspergillus flavus; Aspergillus niger; Biobleaching; Wheat bran