Decreasing the Crystallinity and Degree of Polymerization of Cellulose Increases Its Susceptibility to Enzymatic Hydrolysis and Fermentation by Colon Microbiota

Karel Thielemans; Yamina De Bondt; Luke Comer; Jeroen Raes; Nadia Everaert; Bert F Sels; Christophe M Courtin

doi:10.3390/foods12051100

Decreasing the Crystallinity and Degree of Polymerization of Cellulose Increases Its Susceptibility to Enzymatic Hydrolysis and Fermentation by Colon Microbiota

Foods. 2023 Mar 4;12(5):1100. doi: 10.3390/foods12051100.

Authors

Karel Thielemans^{1

2}, Yamina De Bondt¹, Luke Comer³, Jeroen Raes⁴, Nadia Everaert³, Bert F Sels², Christophe M Courtin¹

Affiliations

¹ Laboratory of Food Chemistry and Biochemistry, Department of Microbial and Molecular Systems (M2S), KU Leuven, Kasteelpark Arenberg 20, 3001 Leuven, Belgium.
² Center for Sustainable Catalysis and Engineering, Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
³ Divison Animal and Human Health Engineering, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium.
⁴ Department of Microbiology and Immunology, KU Leuven, Herestraat 49-Bus 1028, 3000 Leuven, Belgium.

Abstract

Cellulose can be isolated from various raw materials and agricultural side streams and might help to reduce the dietary fiber gap in our diets. However, the physiological benefits of cellulose upon ingestion are limited beyond providing fecal bulk. It is barely fermented by the microbiota in the human colon due to its crystalline character and high degree of polymerization. These properties make cellulose inaccessible to microbial cellulolytic enzymes in the colon. In this study, amorphized and depolymerized cellulose samples with an average degree of polymerization of less than 100 anhydroglucose units and a crystallinity index below 30% were made from microcrystalline cellulose using mechanical treatment and acid hydrolysis. This amorphized and depolymerized cellulose showed enhanced digestibility by a cellulase enzyme blend. Furthermore, the samples were fermented more extensively in batch fermentations using pooled human fecal microbiota, with minimal fermentation degrees up to 45% and a more than eight-fold increase in short-chain fatty acid production. While this enhanced fermentation turned out to be highly dependent on the microbial composition of the fecal pool, the potential of engineering cellulose properties to increased physiological benefit was demonstrated.

Keywords: amorphization; cellulose; colonic fermentation; depolymerization; dietary fiber; prebiotic; short chain fatty acids.

Grants and funding

This work was supported by KU Leuven internal grants, and the FWO-SBO project BioWood (Grant number: S003518N). Yamina De Bondt acknowledges Internal Funds KU Leuven for PDM funding (PDMT1/21/022) and the Research Foundation–Flanders (FWO-Vlaanderen, Brussels, Belgium) for a position as postdoctoral research fellow (Grant number: 12B3723N). The Raes lab is funded by VIB, KU Leuven and the Rega institute.