Biofilm response in potential difference-enhanced membrane-aerated biofilm systems for accelerated antibiotic removal...

A membrane-aerated bio-cathode configuration was engineered, leveraging counter-diffusion biofilm architecture to physically segregate oxygen from cathode reactions. This design minimized electron diversion to oxygen (a competing terminal electron acceptor), thereby optimizing electron allocation for antibiotic co-metabolism. Further, the biofilms self-regulation and the molecular dynamics (MD) mechanism of antibiotic/antibiotic resistance genes (ARGs) reduction were simultaneously investigated. At 80 V/m potential difference, anode biofilms exhibited enhanced protein secretion (2.31-fold increase versus controls), which mitigated SMX-induced static quenching of tyrosine-like fluorophores by shifting to dynamic quenching mechanisms. Concurrent cathode analyses revealed substantial ARG suppression, with sul1 (-1.25 log₂) and sul2 (-1.22 log₂) reductions attributed to host genus inactivation (Nitrateductor, Pseudomonas, Methylobacterium abundance undetectable). MD simulations elucidated critical interaction mechanism: Reduced polar solvation energy (ΔG_PB=-31.363 kJ/mol) promoting Sul1-encoded protein and SMX interactions strengthened, enhancing resistance sustainability under ARGs reduction. Besides, Flavin mononucleotide activation promoted SMX degradation via Cytochrome P450, likely driving rapid SMX removal under electric fields, with a 1.5-fold SMX removal rate enhancement versus conventional MABR.