Two pH dependent systems were described in all E. coli. One was induced in log phase, and the other was induced in stationary phase (Small and others 1994). The log phase acid survival stem in E. coli was referred to as acid habituation, which produced them with increased resistance to subsequent exposures to low pH. Many compounds such as glucose, glutamate, aspartate, FeCl3, KCI, and L-proline can induce acid habituation in log phase cells grown at pH 7 in nutrient broth in E. coli (Goodson and Rowbury 1989; Rowbury and Goodson 1998; Foster. 2000) Phosphate and CAMP also influence induction of acid tolerance in enterobacteriaceae (Rowbury and Goodson 1993, 1998) and proteins secreted during a pH 5 adaptation induced acid habitulog phase grown at neutral pH in E. coli (Rowbury and others 1998, 1999).