Acid adaptation induces cross-protection against some environmental stresses in Vibrio parahaemolyticus

The relationship of acid adaptation to the resistance of other environmental stresses was examined in Vibrio parahaemolyticus. Acid-adapted cells were found to have increased resistance to various stresses, including heat, crystal violet, bile, and deoxy cholic acid. However, heat-adapted cells showed no increased resistance against acid stress. Adaptation required protein synthesis, since treatment with chloramphenicol during adaptation to pH 5.3 prevented the development of acid resistance. Acid-adapted cells showed an increased amount of outer membrane protein with an apparent molecular weight of 27,000. These results show that acid-induced cross-protection involved changes in outer membrane protein composition and the known enhancement of intracellular pH homeostasis.