In situ functionalized bacterial cellulose for functional and smart nanomaterials: an expanded biochemical, biophysical, and industrial biotechnology review

In situ functionalization of bacterial cellulose (BC) enables the incorporation of compatible functional components during biosynthesis, in contrast to post-synthetic and hybrid modification approaches. BC is produced extracellularly by Komagataeibacter species and has high purity, water-holding capacity, and crystallinity, while its mechanical and biological properties are influenced by production and processing conditions. This narrative review evaluates 78 primary and review articles published between 2005 and 2025. Building on earlier reviews of BC modification, it provides an integrative biochemical, biophysical, and industrial biotechnology perspective on in situ functionalization strategies linking bacterial metabolism and cellulose synthase activity to the incorporation of carbon nanomaterials, conductive polymers, and nanoparticles within the BC matrix. These functionalized nanocomposites often exhibit improved mechanical, thermal, electrical, antimicrobial, and bioactive properties, although additive incorporation may reduce crystallinity depending on concentration, dispersion, and interaction mechanisms. The roles of c-di-GMP signaling, carbon flux regulation, cellulose synthase-directed extrusion, and enzyme-assisted co-assembly in governing material architecture and structure-property relationships are discussed. Key limitations include additive dispersion, bacterial viability, protocol reproducibility, product biocompatibility, and process scale-up. Functionalized BC offers exciting potential as a customizable biofabrication platform for advanced nanomaterials useful in bioelectronics, tissue engineering, wound healing, packaging, and sustainable industrial applications.