Influence of mechanical agitation on the pH profile of total, soluble and insoluble filter paper activity of Hypocrea jecorina cellulase preparations

Abstract

The characterization of cellulases is complex and has gained increasing importance due to the application of cellulases in finishing of textile fibres and the conversion of lignocellulose into second generation ethanol. Usually two or three different substrates such as filter paper Whatman No. 1, carboxymethylcellulose and avicel are used to characterize total, endo (EG) and exoglucanase (ExG) activity, respectively, and assays are carried out without any mechanical agitation. Unfortunately, the different activities obtained are not directly comparable and do not reflect cellulase behaviour in industrial applications, mainly due to physic-chemical differences between the substrates and the adopted procedures. In this study the pH profiles of three different cellulase preparations from Hypocrea jecorina (former Trichoderma reesei) have been characterized with modified filter paper assays which permitted the distinction between EG and ExG activities using a single insoluble substrate. Furthermore, the influence of mechanical agitation was studied. With the modified procedures, it could be shown that the contribution of EG and ExG activity to total cellulase activity and the endo/exo activity ratio depends on the cellulase preparation and varies with pH. When the assay was carried out under orbital agitation, EG activity increased significantly and the endo/exo-activity ratio increased.

Keywords::

• cellulase
• endoglucanase
• exoglucanase
• filter paper activity
• mechanical agitation
• Hypocrea jecorina (Trichoderma reesei)

Acknowledgements

This work was supported by the Brazilian National Council of Scientific and Technological Development (CNPq), FURB (Universidade Regional de Blumenau) and FINEP (Research and Projects Financing, Brazil). The authors would also like to thank the grant of Marcos H.L. Silveira from FINEP (Brazil) and the grant of Martinho Rau from Capes (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), Brazil.

Declaration of interests: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.