3D bacterial cellulose biofilms formed by foam templating.

Bacterial cellulose is a remarkable fibrous structural component of biofilms, as it forms a mechanically strong hydrogel with high water adsorption capabilities. Additionally, bacterial cellulose is biocompatible and therefore of potential interest for skin regeneration and wound healing applications. However, bacterial cellulose produced through conventional production processes at water-air interfaces lack macroporosity control, which is crucial for regenerative tissue applications. Here we demonstrate a straightforward and efficient approach to form a macroporous bacterial cellulose foam by foaming a mannitol-based media with a bacterial suspension of Gluconoacetobacter xylinus . The bacterial suspension foam is stabilized with Cremodan as a surfactant and viscosified with Xanthan preventing water drainage. Further foam stabilization occurs through cellulose formation across the foam network. As bacterial cellulose formation is influenced by the viscosity of the growth media, we fine-tuned the concentration of Xanthan to allow for bacterial cellulose formation while avoiding water drainage caused by gravity. With this simple approach, we were able to design 3D bacterial cellulose foams without any additional processing steps. We argue that this templating approach can further be used to design foamy biofilms for biotechnological approaches, increasing the surface area and therefore the yield by improving the exchange of nutrients and metabolic products.