Microbial cell membrane and associated cellular components

The microbial cell membrane is a complex lipid bilayer that acts as a semi-permeable barrier, essential for maintaining cellular homeostasis and protecting the internal environment of bacteria and fungi (Silhavy et al., 2010). It serves as the primary site for vital biological processes, including energy production via the electron transport chain, active transport of nutrients, and the coordination of cell wall biosynthesis. In Gram-negative bacteria, the membrane system includes both an inner cytoplasmic membrane and an outer membrane containing lipopolysaccharides, while fungal membranes are distinguished by the presence of ergosterol (Landman et al., 2008; Mesa-Arango et al., 2012). Antimicrobial agents target these structures by inducing physical disruption, forming transmembrane pores, or causing rapid depolarization, which leads to the leakage of vital ions and cellular death (Humphries et al., 2013). Despite its effectiveness as a target, the structural similarity between certain microbial and host membrane components can lead to significant clinical toxicities, such as nephrotoxicity.

Other names

Bacterial cytoplasmic membraneFungal plasma membraneMicrobial plasma membraneProkaryotic cell membraneBacterial cell envelope (membrane component)

Antimicrobial agents targeting the microbial cell membrane primarily function through physical disruption of the lipid bilayer or the formation of transmembrane pores. For instance, polymyxins bind to lipopolysaccharides in Gram-negative bacteria to disrupt the outer and inner membranes, while daptomycin inserts into the Gram-positive cytoplasmic membrane in a calcium-dependent manner, causing rapid depolarization and ion leakage (Landman et al., 2008; Humphries et al., 2013). Polyene antifungals like amphotericin B bind to ergosterol, creating pores that allow the efflux of potassium and other intracellular molecules (Mesa-Arango et al., 2012).