Bacterial biofilms as platforms engineered for diverse applications

Historically, biofilms have been perceived as problematic or detrimental. However, biofilms possess favorable traits such as self-regeneration, sustainability, scalability, and tunability, which make them candidates for diverse applications. Traditional applications of biofilms, such as environmental remediation, bioleaching, microbial fuel cells, and corrosion protection, are often built on the basis of wild-type or metabolically engineered strains. In this review, we further comment on the design strategies for multiple innovative applications of living functional biofilms. With the integration of signaling pathways, engineering of metabolic pathways and modification of extracellular polymeric substances, living functional biofilms have been constructed by researchers through various strategies. Functional biofilms for diverse applications, including catalysis, electric conduction, bioremediation, and medical therapy have been demonstrated in the literature. The mechanical properties of biofilms can be tuned through genetic editing, metal ion curing and synthetic gene circuits, etc. In addition, the improvement of 3D printing to use bioinks has also achieved significant progresses in fabricating living functional biofilms with specific structures. In the future, the combination of synthetic biology and techniques from other disciplines will lead to practical large-scale applications of biofilms.