Reprogramming <i>Shewanella</i> Biofilms as Adsorptive Materials for Efficient and Selective Arsenic Removal via Matrix-Integrated Binding Proteins

The health risks associated with exposure to arsenic (As)-contaminated water have spurred initiatives focused on As remediation through membrane filtration or chemical precipitation. Microbial approaches to sequestering As with biofilms present a promising alternative to these costly and chemical-intensive processes. In this study, we engineered the biofilm of <i>Shewanella oneidensis</i> to incorporate As-binding sites (ArsR) into the biofilm matrix through a matrix-associated protein, BpfA, for effective removal of As from water. Specifically, we constructed a chromosome-modified strain with constitutive expression of a genetically fused protein, BpfA-ArsR, along with two mutant strains harboring inducible plasmid constructs that link ArsR to truncated versions of BpfA for tunable expression. All three engineered strains produced biofilms comparable to that of the wild-type (WT). In comparison to the WT, the engineered strains demonstrated a significantly improved As sorption capability, achieving approximately 2.4-3.8 times the performance of the WT. Remarkably, the modified biofilm matrix continued to exhibit a strong preference for As sorption even in the presence of its chemical analog, phosphate. While bioremediation serves as an application example, the broader significance lies in establishing the biofilm matrix as a programmable and modular engineering space. The engineered biofilms developed here represent a generalizable platform for constructing matrix-integrated functional materials, enabling future applications in biosensing, resource recovery, extracellular catalysis, and adaptive living materials.