The highly tolerant acetic acid bacterium Gluconacetobacter europaeus adapts to the presence of acetic acid by changes in lipid composition, morphological properties and PQQ-dependent ADH expression

E. coli incorporates increasing proportions of saturated and long-chain fatty acids into phospholipids as growth temperature is increased. It was found that this compositional variation results in the biosynthesis of phospholipids that have identical viscosities at the temperature of growth of the cells. This "homeoviscous adaptation" can also be observed in E. coli membrane preparations. Viscosities were determined by use of the electron spin resonance spin-label technique.

Membranes lipids are one of the most adaptable molecules in response to perturbations. Even subtle changes of the composition of acyl chains or head groups can alter the packing arrangements of lipids within the bilayer. This changes the balance between bilayer and nonbilayer lipids, serving to affect bilayer stability and fluidity, as well as altering lipid-protein interactions. External factors can also change membrane fluidity and lipid composition; including temperature, chemicals, ions, pressure, nutrients and the growth phase of the microbial culture. Various biophysical techniques have been used to monitor fluidity changes within the bacterial membrane. In this review, bacterial cytoplasmic membrane changes and related functional effects will be examined as well as the use of fluorescence polarization methods and examples of data obtained from research with bacteria. Copyright 2003 Elsevier Science B.V.