Not too rigid nor too wobbly: Defining an optimal membrane fluidity range essential for biofilm formation in .

Membrane fluidity plays a crucial role in bacterial fitness and adaptation to cope with rapid environmental changes. While high membrane fluidity promotes robust biofilm formation in , studies in several other species, including , suggest that biofilm formation is associated with reduced fluidity. This paradox may reflect the complex relationship between lipid composition and biofilm formation. Our findings demonstrated that both low and high extremes of lipid fluidity restrict biofilm formation. We propose that the required fluidity for biofilm growth, relative to that required for planktonic growth, may differ between species and is readily adjusted to fall within a "Goldilocks" range during lifestyle transitions.