Properties of Cellulose:
A bacterially synthesized cellulose fiber shows exceptional material properties such as high chemical and thermal stability, biocompatibility and bioinertness and high mechanical stability. The diameter of a bacterial cellulose fiber is about 40-60 nm, which corresponds to one- hundredth of the diameter of a plant fiber. The modulus of elasticity is about 134 GPa, which can be compared with the one of cast iron (grey cast iron: E = 90 - 140 GPa). A single fiber shows the tensile strength of 2 GPa, this is comparable with some stainless steel types like AK steel (AK Steel 17-7 PH: Rm = 1,3 - 1,5 GPa).[6],[7],[8],[9]
The study of the iGEM Team of the Imperial College London (2014) advises a maximum working shear stress of 7.5 MPa.[10]
The nano structured system shows a large specific surface (60-100 m2/g), this is responsible for the possibility of intense interactions.[6]
One example is the link of cellulose binding domains (CBDs) to the cellulose matrix by hydropbobic interactions. Genetic engineering is our solution for the attachment of the Flagellas on our surface material. This means an effective immobilization of CBD-flagellin fusion proteins on the cellulose matrix without the need for covalent cross linking. The results of Kauffmann et al. (2000) show that the CBD causes no activity loss of the attached protein. In addition immobilization often results in a higher stability of the protein.[11]
Life-time of the product:
The estimated half-life of cellulose itself at 25° C is about 5-8 million years. It can be degraded aerobically and anaerobically. The degradation is catalyzed by a range of enzymes in cellulolytic microorganisms. Three types of enzymes are involved in the degradation process: endoglucanases, cellobiohydrolases, and β-glucosidases.
The known enzymes responsible for cellulose degradation, as well as the cleavage sites, are shown in table 1.



Currently, we are still researching some other properties. We are focusing on following questions:
How good are the links between the flagella and cellulose, and the flagella and enzymes?
How does this fact affect the life time of our product?
Synthetic biology is of high interest for maker and do-it-yourself biology community. DIYbio spaces and groups are being formed continuously all over the globe (diybio.org). Often people that are involved in diybio are able to come up with clever solutions to manufacture biomaterials as well as bio lab equipment improvising. The production of cellulose in a diybio setting has been demonstrated in various projects like in art projects such as “Xylinum Cones” from Berlin based designer Jannis Huelsen or a speculative approach by iGEM Berlin member and designer Valerian Blos in his works about “Restriction as design and design as restriction” . This indicates that, first, there is a communal interest in cellulose as a biomaterial and second that cellulose production does not have to occur in a laboratory setting. For this, the Flagellulose may be further developed outside of the academic setting. Especially so, as the Biobricks produced will be openly accessible through the iGEM registry.

[6] F. Wesarg: Herstellung funktioneller Hybride auf Basis von bakteriell synthetisierter Nanocellulose (Doctoral dissertation, Jena, Friedrich-Schiller-Universität Jena, Diss., 2013).
[7] D. Klemm, B. Heublein, H.-P. Fink and A. Bohn: Cellulose: Fascinating Biopolymer and Sustainable Raw Material, Angew. Chem. Int. Ed. 44 [22] (2005), 3358-3393.
[8] G. Guhados, W. Wan and J.L. Hutter: Measurement of the elastic modulus of single bacterial cellulose fibers using atomic force microscopy, Langmuir 21 [14] (2005), 6642-6646.
[9] H. Yano, J. Sugiyama, A.N. Nakagaito, M. Nogi, T. Matsuura, M. Hikita and K. Handa: Optically Transparent Composites Reinforced with Networks of Bacterial Nanofibers, Adv. Mater. 17 [2] (2005), 153-155.
[10] iGEM Team of the Imperial College London (2014). https://2014.igem.org/Team:Imperial/Mechanical_Testing
[11] C. Kauffmann, O. Shoseyov, E. Shpigel, E. A. Bayer, R. Lamed, Y. Shoham and R. T. Mandelbaum: Novel methodology for enzymatic removal of atrazine from water by CBD-fusion protein immobilized on cellulose. Environmental science & technology 34.7 (2000): 1292-1296.