Use of Endoglucanase and Accessory Enzymes to Facilitate Mechanical Pulp Nanofibrillation

Abstract

Although selective enzyme treatments have been used to successfully fibrillate chemical pulps, high lignin-containing mechanical pulps have proven to be more recalcitrant. When a bleached chemi-thermomechanical pulp (BCTMP) was sulfonated prior to enzymatic treatment, relatively good fibrillation was achieved, although some pulp hydrolysis occurred after 6 h hydrolysis when using a commercial cellulase enzyme preparation (Cellic CTec 3). To try to minimize pulp losses, various enzyme cocktails, including endoglucanase (EG), xylanase, mannanase, and lytic polysaccharide monooxygenase (LPMO), were assessed for their ability to enhance fibrillation while minimizing cellulose hydrolysis. It was apparent that the yield as well as the zeta potential of the lignin-containing cellulose nanofibrils increased with enzyme treatment. This was likely due to an increase in surface charge and a decrease in particle size after LPMO and hemicellulase treatments, respectively. When carbohydrate-binding modules (CBMs) were used to quantify fiber changes, it was apparent that sulfonation had increased the accessibility of enzymes, while the combined action of the hemicellulases and LPMO increased EG accessibility to the less-ordered regions of the mechanical pulp, resulting in enhanced fibrillation. This work described, for the first time, the synergistic action of EG and various accessory enzymes enhancing mechanical pulp nanofibrillation.

Micro/nanostructured lignonanocellulose obtained from steam-exploded sugarcane bagasse

“…The presence of relatively low lignin contents in biomass, although requiring higher mechanical energy for grinding, produced nanofibers with narrower diameter distributions. Another detrimental effect of lignin is enzyme adsorption when endoglucanases are used to facilitate mechanical refining by weakening fiber strength and fiber-to-fiber bonding (Han et al 2021;Lu et al 2018). In addition, Pereira and Arantes (2020) carried out the enzymatic hydrolysis of bleached steam-exploded sugarcane bagasse (SEB) to obtain a soluble fraction with high sugar concentration (> 120 g L -1 glucose) and an insoluble fraction with CNCs with 20 nm in diameter.…”

A Comparative Investigation on Structural and Chemical Differences between the Pith and Rind of Sunflower Stalk and Their Influences on Nanofibrillation Efficiency

“…In contrast, stalk rind appeared to be more recalcitrant towards ultrasonication fibrillation as numerous micron-sized fiber and fragments with diameters of 2~4 μm are prevalent both in the R-1-U and R-4-U samples ( Figure 10 c,d). In addition, the occurrence of spherical lignin particles could be observed, likely due to lignin aggregation resulting from its aromatic structure and amphiphilic nature [ 34 ]. Therefore, only alkali treatment and ultrasound are insufficient to fibrillate rind.…”

Enzymes – Key Elements of the Future Biorefineries

“…It attacks amorphous regions of cellulose fiber, where the crystalline structure was distorted by refining. These brakes make fibers more "hairy" and improve fibrillation (incorporation of the fibers into paper webbing), which eventually translates into improved strength properties of the paper [38,39]. This enzymatic activity can also be used to even further cleave the amorphous region and help to create nano-cellulose [40], which is widely used in various applications from packaging to electronics and health.…”