Abstract
in the general framework of studies on thermal adaptation of bacteria, isotherms of monolayers made of lipids isolated from Bacillus subtilis plasma membranes grown at 20degreesC and 40degreesC (these lipids will be referred to as L20 and L40 preparation, respectively) are investigated. The mean molecular area was found to be higher for L20 preparations than for L40 ones.
When the temperature of L40 preparation increases, we observe a decrease of the mean molecular area at constant pressure. With the L20 preparation, an enhancement of the mean molecular area occurs first due to an increase of the fluidity of the molecules.
This is followed by a decrease of the mean molecular area due to desorption of the molecules. This difference in behaviour between L20 and L40 lipids and its relationship with the thermal adaptation phenomenon are discussed.