Contribution of urease to acid tolerance in Yersinia enterocolitica

Abstract

The stomach serves as a barrier to enteric infection because of the antibacterial effect of the hydrochloric acid in gastric juice. In this study, we tested the ability of the enteric pathogen Yersinia enterocolitica to tolerate a pH range of 2.0 to 6.0 and found that under the conditions of a normal human fasting stomach (pH < 3 and a gastric emptying time of 2 h), E enterocolitica is highly acid resistant, showing approximately 85% survival. The resistance of Y. enterocolitica to acid in vitro depended on the bacterial growth phase and the concentration of urea in the medium, being maximal during stationary phase in the presence of at least 0.3 mM urea. Urease-negative mutants of Y. entero..