Nanocellulose isolation using a thermostable endoglucanase-rich cocktail from Myceliophthora thermophila cultivated in a multilayer packed-bed bioreactor

• Published in: Biomass conversion and biorefinery Vol. 14; no. 8; pp. 9121 - 9136
• Main Authors: Katayama, Eric, Rodrigues, Natalia A., Bilatto, Stanley, Casciatori, Fernanda P., Farinas, Cristiane S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2024; Springer Nature B.V
• Subjects: Bioreactors; Biotechnology; Cellulose; Cellulose pulp; Cultivation; Design of experiments; Endoglucanase; Energy; Eucalyptus; Glucose; Glucosidase; Hydrolysis; Moisture content; Multilayers; Nanomaterials; Original Article; Renewable and Green Energy; Solid state; Substrates; Thermal stability; Endoglucanase; Solid-state cultivation; Packed-bed bioreactor; Nanocellulose; Enzymatic hydrolysis
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-022-02977-1

The isolation of nanocellulose materials by means of enzymatic hydrolysis offers advantages in terms of their properties and operational conditions, but there is still a lack of enzymatic cocktails specifically designed for this application. The present work investigates the use of a thermostable endoglucanase-rich enzymatic cocktail from
Myceliophthora thermophila
for nanocellulose production. An initial set of experiments was conducted to determine the optimal conditions for enzyme production under solid-state cultivation in small-scale polypropylene plastic bags. A full factorial experimental design was used as a statistical tool to evaluate the effects of the solid substrate and moisture content on the production of endoglucanase and β-glucosidase. Solid-state cultivations in a multilayer packed-bed bioreactor were then carried out under the selected conditions to obtain a larger volume of an enzymatic extract with high endoglucanase selectivity, given by the ratio of endoglucanase (203 ± 6 U/g-substrate) to β-glucosidase activity (1.6 ± 0.1 U/g-substrate). The enzymatic hydrolysis of eucalyptus cellulose pulp at different temperatures, with this endoglucanase-rich cocktail at a loading of 10 mg-protein/g-pulp, resulted in higher glucose release (11 ± 2 g-glucose/L) at 60 °C, with 61 ± 9% cellulose conversion and 16.2% nanocellulose yield. The isolated nanomaterial with average diameter of 36.65 nm and length of 156.63 nm, presented a crystallinity index of 77.4% and thermal stability temperature of 316 °C. These results show the potential to isolate nanocellulose using a thermostable endoglucanase-rich enzymatic cocktail produced locally by solid-state cultivation in a packed-bed bioreactor, in accordance to the biorefinery concept.