Optimal membrane fluidity modulates biofilm formation in Escherichia coli

Changes in membrane composition govern the fitness and survival of bacteria in response to environmental stresses. One critical parameter is membrane fluidity, which dictates overall membrane integrity, adaptability to environmental fluctuations (e.g., temperature changes), and the functionality and interactions between integral and peripheral membrane proteins. In recent years, substantial evidence has shown that membrane fluidity is finely tuned for biofilm formation. While high membrane fluidity promotes robust biofilm formation in Klebsiella pneumoniae, this is challenged by reports from multiple species indicating that biofilms are enriched in saturated fatty acids (i.e., reduced fluidity). We hypothesize that this paradox arises from the complex relationship between lipid composition and biofilm formation. Our findings demonstrate that an optimal balance of lipid fluidity is required for biofilm formation. We propose that the precise fluidity required for biofilm growth, relative to that required for planktonic growth, may differ between species, and is readily adjusted during lifestyle transitions.