A quantitative electrodiffusion model of antibacterial heavy metals: Ion influx through hydrophilic pores

Abstract

Excessive heavy-metal ions in the cytoplasm, being toxic ions, can inactivate bacteria, which has been widely used as an effective antibacterial method. Nevertheless, how such toxic ions can be transported into bacteria is poorly understood. Here, we discovered a new mechanism showing that toxic ions electro-diffuse into the cytoplasm through the inherent hydrophilic pores in the cell membrane of living bacteria. Transmembrane potential induces recoverable defects by enhancing the thermal fluctuation of phospholipid molecules. By integrating electroporation, surface potential, and cell osmotic pressure, we develop a simple model for the influx rate of heavy metal ions into living bacteria. Our modeling results agree well with the experimental ones on the survival rates of Gram-negative and Gram-positive bacteria.