Electron Spin Resonance Analysis of the Effect of Butanol on the Membrane Fluidity of Intact Cells of Clostridium acetobutylicum.

Analysis of electron spin resonance spectra of 5-doxyl stearic acid in aqueous suspensions of Clostridium acetobutylicum ATCC 824 and the butanol-tolerant SA-2 derivative during a small-scale fermentation at three different butanol challenge levels indicated that the SA-2 strain is able to respond to the physical fluidizing effect of high (1.5%) butanol challenge by reducing its membrane fluidity at 12 and 30 h. The wild-type 824 strain was unable to so respond when challenged at the 1.5% level.