(161p) Modulating the Single-Bacterium Adhesion Behavior Via Regulation of Extracellular Electron Transfer

Electrochemically active bacteria (EAB) can exchange electrons with external environment through metabolism (i.e. extracellular electron transfer, EET) and have been widely used in wastewater treatment, power generation, biosensors and chemical synthesis, etc., which demonstrates bright development prospects in the fields of energy, environment, material protection and biological testing, etc. Biofilm formation on the substrate surface is a key step for EAB to come to function and the initial bacterial adhesion to the substrate surfaces is the first and the most critical step in biofilm formation. Excellent researches about the influences of material surface properties and external environmental conditions on the initial bacterial adhesion have been performed and great progresses have been made. However, qualitative study of bacterial community and external environment from macroscopic perspective makes bacterial adhesion mechanism unclear, which hinders the effective utilization and prevention of EAB. Therefore, quantitative study of influence of EET on bacterial adhesion behavior under in-situ conditions at single-cell level can improve the understanding of bacterial adhesion mechanism and realize effective control of bacterial adhesion, which has important research value.

In this work, we integrated a three-electrode electrochemical cell and an inverted optical microscope into AFM to construct an in-situ electrochemical single-cell force spectroscopy measurement system that was used to detect the nN scale adhesion force between single bacterium and golden film electrode in bacterial medium under in-situ EET conditions. Influences of electrode potential and EET pathway on bacterial adhesion force were investigated. SERS and numerical simulation of Worm-like chain model reveals the dynamic effect of EET on the folding and unfolding process of cytochrome C. We found that the adhesion force between S. Oneidensis and golden film electrode mainly come from electrostatic force and EET pathway have significant effect on bacterial adhesion and conformation of cytochrome C.