Xylanases from Aspergillus niger, Aspergillus niveus and Aspergillus ochraceus produced under solid-state fermentation and their application in cellulose pulp bleaching

Abstract

This study describes the production of xylanases from Aspergillus niveus, A. niger, and A. ochraceus under solid-state fermentation using agro-industrial residues as substrates. Enzyme production was improved using a mixture of wheat bran and yeast extract or peptone. When a mixture of corncob and wheat bran was used, xylanase production from A. niger and A. ochraceus increased by 18%. All cultures were incubated at 30 degrees C at 70-80% relative humidity for 96 h. For biobleaching assays, 10 or 35 U of xylanase/g dry cellulose pulp were incubated at pH 5.5 for 1 or 2 h, at 55 degrees C. The delignification efficiency was 20%, the brightness (percentage of ISO) increased two to three points and the viscosity was maintained confirming the absence of cellulolytic activity. These results indicated that the use of xylanases could help to reduce the amount of chlorine compounds used in cellulose pulp treatment.

Experimental design of response surface methodology used for utilisation of palm kernel cake as solid substrate for optimised production of fungal mannanase

“…It is clearly evident from Figure 2(b) that urea adversely affected β-mannanase production. These results are well supported by the earlier reports on hemicellulase production where organic nitrogen sources, particularly, yeast extract has been found to enhance enzyme production (Gaffney et al 2009) while urea supplementation repressed β-mannanase production (Betini et al 2009). …”

Xylanase and β-Xylosidase from Penicillium janczewskii: Production, Physico-chemical Properties, and Application of the Crude Extract to Pulp Biobleaching

“…This is crucial for a further application of this enzymatic extract, since the presence of cellulases could damage the fibers, resulting in loss of strength and performance. As verified in this work (especially in 2 h treatments) and in other studies (Medeiros et al 2002;Betini et al 2009), maintenance of pulp viscosity or even its increase can be attributed to the selective removal of the pulp hemicellulose, which could be interfering with the overall pulp viscosity (Suurnäkki et al 1997). …”

Purification and characterisation of a cellulase obtained from cocoa (Theobroma cacao) pod-degrading Bacillus coagulans Co4

“…In principle, all lignocellulosics can be converted into simple sugars which can serve as useful raw materials in the production of fuel, animal feedstock and feedstock for chemical synthesis [4]. Against this backdrop, there has been several studies on the use of different agricultural wastes which include bagasse [1,3], corn cob [3,5], sawdust [6,7], wheat bran [5] and wheat straw [8] as lignocellulosic substrate for cellulase hydrolysis. Relatively high temperatures are often necessary in some industrial processes involving hydrolytic enzymes.…”