Many bacteria, including human and animal pathogens can acquire a high-resistance state as a consequence of exposure to stress. Since in their natural environments, bacteria seldom encounter conditions that allow exponential growth, understanding the mechanism/s behind stress-induced cross-resistance is of uttermost importance for the control of bacterial populations. In particular, the epidemiology and virulence of many human, animal, and plant pathogens appears to be related to stress-induced cross-resistance and phenomena such as biofilm formation appear to be the direct consequence of exposure to environmental stress. Therefore, understanding these bacterial survival strategies has important medical and economical implications. The research proposed here aims at the characterization of the molecular details behind the strategies used by two different Gram negatives, Escherichia coli and Vibrio anguillarum, for the development of stress-induced cross-resistance.E. coli is the organism for which the most detailed picture of cellular physiology exists and has been commonly used as a model for the study of the bacterial protein synthesis and the response to stress. My previous research with this organism has uncovered an important link between the ribosome and the process of stress-induced cross-resistance. The molecular details of this phenomenon will be explored in Specific Aim I.V. anguillarum is the fish pathogen which causes vibriosis, a devastating disease affecting aquaculture. Therefore, there exists high economic interest in developing methods for the control of this bacterium. Increased virulence in V. anguillarum appears to be related to iron deficiency, a common type of environmental stress. The goal of Specific Aim II is to study the cellular response to iron deficiency as well as the molecular details of iron uptake in V. anguillarum, so that strategies for its containment can be designed.