When E. coli cells enter the stationary phase, a depletion of nutrients or starvation conditions are encountered, and a number of morphological and physiological changes occur. Stationary- phase cells became smaller and rounder, the cells accumulated storage compounds such as glycogen and polyphosphate, and the DNA condensed (Nystrom 1995, Huisman and others 1996) There were a number of changes in the fatty acid composition of the inner membrane and in. the protein composition of both inner and outer membranes in E. coli (Huisman and others 1996 DiRusso and Nystrom 1998). RpoS is the major regulator of the stationary phase general stress response in E. coli and other en- teric bacteria. This alternative sigma factor has been recognized as a key factor in producing greater resistance of stationary phase and stressed cells.