Turbulence-assisted formation of bacterial cellulose

Bacterial cellulose is an important class of biomaterials which can be grown in well-controlled laboratory and industrial conditions. The cellulose structure is affected by several biological, chemical and environmental factors, including hydrodynamic flows in bacterial suspensions. Turbulent flows leading to random motion of fluid elements may affect the structure of the extracellular polymeric matrix produced by bacteria. Here we show that two-dimensional turbulence at the air-liquid interface generates chaotic rotation at a well-defined scale and random persistent stretching of the fluid elements. This leads to a remarkable change in the structure of the bacterial cellulose morphology and to the formation of spherical cellulose beads whose size is controlled by the turbulence forcing scale. In addition, turbulence affects the cellulose microstructure, including the porosity of the material, by random but persistent stretching of the fluid elements. The results offer new approaches to engineering of the bacterial cellulose structure by controlling turbulence parameters.