+44 1223 790975
Enteroaggregative Escherichia coli (EAEC) is emerging as a significant diarrheal pathogen in multiple population groups. Like any other enteropathogen, EAEC may encounter life-threatening levels of inorganic acids (H+) during their natural route of infection. In this study, we showed that EAEC orchestrates acid tolerance by modulating the levels of acid-induced outer membrane proteins (OMP). EAEC (T8) was grown in vitro by mimicking in vivo pH conditions of both in stomach and intestine. The lowest pH where EAEC showed growth was 4.0 in Luria Bertani (LB) media, and surprisingly during log phase two de novo OMP of sizes 41 kDa and 48 kDa were exclusively observed at this pH. Further, acid-induced proteins at pH 4.0 were identified by 2D gel electrophoresis and Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF). The role of the most notable acid/pH response regulator rpoS in ASP expression was determined by gene knockout in the clinical strain EAEC (T8). Mutation of rpoS gene suppressed growth and downregulated the expression of ASP in EAEC (T8) at pH 4.0 confirming probable role of rpoS in EAEC.