Shear-induced unidirectional deposition of bacterial cellulose microfibrils using rising bubble stream cultivation

In crystalline cellulose I, all glucan chains are ordered from reducing ends to non-reducing ends. Thus, the polarity of individual chains is added forming a large dipole within the crystal. If one can engineer unidirectional alignment (parallel packing) of cellulose crystals, then it might be possible to utilize the material properties originating from polar crystalline structures. However, most post-synthesis manipulation methods reported so far can only achieve the uniaxial alignment with bi-directionality (antiparallel packing). Here, we report a method to induce the parallel packing of bacterial cellulose microfibrils by applying unidirectional shear stress during the synthesis and deposition through the rising bubble stream in a culture medium. Driving force for the alignment is explained with mathematical estimation of the shear stress. Evidences of the parallel alignment of crystalline cellulose I alpha domains were obtained using nonlinear optical spectroscopy techniques.

Automated summary

A method is reported to induce the parallel packing of bacterial cellulose microfibrils by applying unidirectional shear stress during synthesis and deposition. The driving force for alignment is explained with mathematical estimation of the shear stress. Evidence of the parallel alignment of crystalline cellulose I alpha domains was obtained using nonlinear optical spectroscopy techniques.