Engineering bacterial cellulose-based materials for advanced functional applications

Growing environmental concerns related to petroleum-based plastics, including waste accumulation and greenhouse gas emissions, have intensified the search for sustainable, biodegradable alternatives. Among bio-based materials, cellulose represents a versatile platform for advanced applications, and bacterial cellulose (BC) is particularly attractive due to its high purity, crystallinity, hydrophilicity, water-holding capacity, and mechanical strength. BC can be produced from renewable substrates, including agro-food by-products, supporting circular economy principles. This doctoral work, conducted in collaboration with an industrial partner, investigated BC produced via kombucha fermentation, where a symbiotic culture of bacteria and yeasts (SCOBY) generates a cellulose biofilm at the air–liquid interface. Although inherently purer than plant cellulose, BC still requires purification to remove fermentation residues, especially for applications in biomedical, cosmetic, or food sectors. Therefore, the first part of the study focused on optimizing alkaline purification conditions, balancing cleaning efficiency with preservation of film integrity. The optimized protocol was successfully transferred to a pre-industrial environment, demonstrating scalability and operational feasibility. Subsequently, glycerol plasticization was explored to improve flexibility and reduce brittleness of BC films, allowing mechanical properties to be tuned for applications such as packaging, biomedical patches, and textiles. To address BC’s intrinsic hydrophilicity and prevent plasticizer leaching, several surface coating strategies were developed to enhance water resistance and durability. Structural, thermal, surface, and mechanical characterizations confirmed that different formulations enable tailored performance under diverse environmental conditions. The final phase investigated nanostructuring through combined enzymatic hydrolysis and mechanical disintegration, yielding stable BC nanomaterials processed into transparent nanopapers with enhanced mechanical properties. The protocol was also successfully adapted to industrial equipment, supporting process scalability. Taken together, the results highlight how bacterial cellulose can be effectively processed and functionally tailored through scalable methods, providing practical routes toward the development of sustainable materials suitable for diverse technological and industrial applications.