Mechanistic investigation of the effect of endoglucanases related to pulp refining

Martin Nagl*, Oskar Haske-Cornelius, Lukas Skopek, Florian Bausch, Alessandro Pellis, Wolfgang Bauer, Gibson S. Nyanhongo, Georg M. Guebitz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Endoglucanases are increasingly being touted as the ultimate solution for reducing energy consumption during the refining process in the pulp and paper industry. However, due to the high variety of endoglucanases in different enzyme formulations, these perform heterogeneously when applied to different pulps. In this study, the effect of four endoglucanases on softwood and hardwood pulp was studied using confocal laser scanning microscopy (CLSM) after addition of fluorescently labelled carbohydrate binding modules (CBMs). Nuclear magnetic resonance (NMR) analysis and high-performance liquid chromatography quantification of released oligo- and monosaccharides was performed for in-depth mechanistical investigation. Changes in the crystallinity levels caused by enzymatic degradation of amorphous regions were monitored by incubation with two different CBMs from Caldicellulosiruptor bescii and from Thermobifida fusca with high preference to either amorphous or crystalline regions of cellulose, respectively. When dosed at identical activity on the endoglucanase specific CellG5 substrate, CLSM analysis indicated the highest decrease of amorphous regions for those endoglucanases which were also most active in laboratory refining trials and which released highest amounts of cellooligomers from pulp. Using 13C-NMR analysis, an increase in para-crystalline cellulose caused by enzyme application was observed. Release of reducing sugars was determined at identical CellG5 dosage, indicating a high variance between the enzymes, especially when complex enzyme formulations were used. Scanning electron microscopy images were obtained for visualization of the endoglucanase activity. The results of mechanistical studies indicate that reduction of amorphous moieties of pulp by endoglucanases is especially beneficial for the refining process.
Original languageEnglish
Pages (from-to)2579-2598
Number of pages20
Issue number4
Early online date4 Feb 2022
Publication statusPublished - Mar 2022


  • Carbohydrate binding module
  • CellG5
  • CLSM
  • Endoglucanase
  • HPLC
  • NMR

ASJC Scopus subject areas

  • Polymers and Plastics

Fields of Expertise

  • Advanced Materials Science


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