By: Richard D. Cummings
While plant cellulose is very famous, many commercial products containing cellulose actually use bacterial cellulose. It is often a part of bacterial biofilms, typically of Gram negative (1). This form of cellulose can be highly purified compared to preparations of plant cellulose, and lacks contaminating components. Bacterial cellulose, derived by fermentation, is used in all types of products, from acoustic membranes in hi-fidelity loudspeakers and headphones, to cosmetics, and medical applications, such as bone grafts (2). There is much research on the biological effects of consuming bacterial cellulose, but in general it appears that oral consumption of this form of cellulose is well tolerated by animals (3), but its uptake and metabolism in cells is still under study.
Bacterial cellulose differs from plant cellulose in the degree of polymerization - bacterial cellulose is 2,000–6,000 glucose units whereas plant cellulose is 13,000–14,000 (4). However, bacterial cellulose, like plant cellulose, has parallel stacking of polymers due to intra- and intermolecular forces (van der Waals forces and H-bonds) that lead to crystalline nanofibers. Industrial scale production exploits the Gram-negative bacterium Gluconacetobacter xylinus (also known as Acetobacter xylinum), where bacterial cellulose was first discovered (5).
The biosynthesis of cellulose in bacteria is remarkable. The cellulose synthase from Rhodobacter sphaeroides has a large transmembrane region within which is a polysaccharide channel created by a complex of the multi-spanning catalytic BcsA subunit and the membrane-anchored, periplasmic BcsB protein (6). Within the channel it is proposed that the cellulose polysaccharide within and emerging from that channel and extending from the cell grows by addition of a single glucose from UDP-Glc to the non-reducing end of the growing polysaccharide on the cytoplasmic side. In addition, some modified forms of cellulose can also be produced by bacteria, such as the cellulose modified with phosphoethanolamine (pEtN), by a pEtN transferase that appears to closely associated with the catalytic channel; this pEtN-modified cellulose is produced by several Enterobacteriaceae (7).
References
- Morgan, J. L., McNamara, J. T., and Zimmer, J. (2014) Mechanism of activation of bacterial cellulose synthase by cyclic di-GMP. Nat Struct Mol Biol 21, 489-496
- Czaja, W. K., Young, D. J., Kawecki, M., and Brown, R. M., Jr. (2007) The future prospects of microbial cellulose in biomedical applications. Biomacromolecules 8, 1-12
- Silva-Carvalho, R., Rodrigues, P. M., Martins, D., Rodrigues, A. C., Sampaio, P., Dourado, F., Goncalves, C., and Gama, M. (2024) Bacterial Cellulose In Vitro Uptake by Macrophages, Epithelial Cells, and a Triculture Model of the Gastrointestinal Tract. Biomacromolecules
- Lahiri, D., Nag, M., Dutta, B., Dey, A., Sarkar, T., Pati, S., Edinur, H. A., Abdul Kari, Z., Mohd Noor, N. H., and Ray, R. R. (2021) Bacterial Cellulose: Production, Characterization, and Application as Antimicrobial Agent. Int J Mol Sci 22
- Zhong, C. (2020) Industrial-Scale Production and Applications of Bacterial Cellulose. Front Bioeng Biotechnol 8, 605374
- Morgan, J. L., Strumillo, J., and Zimmer, J. (2013) Crystallographic snapshot of cellulose synthesis and membrane translocation. Nature 493, 181-186
- Verma, P., Ho, R., Chambers, S. A., Cegelski, L., and Zimmer, J. (2024) Insights into phosphoethanolamine cellulose synthesis and secretion across the Gram-negative cell envelope. Nat Commun 15, 7798