Bacterial and fungal cytoplasmic membrane and associated cellular water

The bacterial and fungal cytoplasmic membrane and associated cellular water represent a fundamental structural and functional unit of microbial cells, serving as the primary barrier between the cytoplasm and the external environment (Madigan et al., Brock Biology of Microorganisms, 2020). The membrane is a phospholipid bilayer embedded with proteins that facilitate essential processes such as nutrient transport, signal transduction, and energy generation through the maintenance of a proton motive force. Associated cellular water refers to the hydration shell and osmotic environment necessary for the structural integrity of these membrane components and the solubility of intracellular molecules. This target is primarily exploited by broad-spectrum antiseptics like povidone-iodine, which releases free iodine to oxidize membrane lipids and proteins, and by membrane-active antibiotics like polymyxins and daptomycin (Bigliardi et al., 2017, 'Povidone-iodine in wound healing'; Nature Reviews Microbiology, 2019). Disruption of this target leads to rapid cell death via the leakage of ions and metabolites, collapse of the electrochemical gradient, and physical lysis of the cell. Due to the lack of high specificity compared to protein-specific targets, many agents acting here are restricted to topical use to avoid systemic toxicity in humans.

Other names

Microbial cytoplasmic membranePlasma membraneInner membraneBacterial cell membraneFungal cell membrane

Antimicrobial agents target this site through the oxidation of membrane components (e.g., iodine), pore formation (e.g., polymyxins, polyenes), or general disruption of the lipid bilayer, leading to the leakage of intracellular contents and loss of osmotic control (Bigliardi et al., 2017; MIMS, 2023).