Acid adaptation of Escherichia coli: a genetic study

Abstract

E. coli log-phase cells are capable of inducing of log-phase acid tolerance response (ATR), but stationary-phase cells do not exhibit this adaptive ability. To study the genetic systems responsible for the induction of log-phase ATR, we investigated E. coli mutants deficient in the known acid resistance systems. Our results show that RpoS-dependent oxidative and arginine decarboxylase systems are not induced during acid adaptation of log-phase cells. Glutamate decarboxylases were found to be induced during adaptation and result in a more efficient acid-protection. However, our study shows that other highly efficient protection mechanisms are induced, operate and play the main role in log-phase ATR. Keywords: E. coli acid tolerance response (ATR), acid resistance systems (AR), RpoS-dependent oxidative system, glutamate and arginine decarboxylase systems