['Resistance to acidic stress contributes to bacterial persistence in the host and is thought to promote their passage through the human gastric barrier. The aim of this study was to examine whether nucleosides have a role in the survival under acidic conditions in Escherichia coli.', 'We found that adenosine has a function to survive against extremely acidic stress. The deletion of add encoding adenosine deaminase that converts adenosine into inosine and NH(3) attenuated the survival in the presence of adenosine. The addition of adenosine increased intracellular pH of E. coli cells in pH 2·5 medium. Addition of inosine or adenine did not increase the resistance to acidic conditions.'] Does adenosine deamination increase the survival under acidic conditions in Escherichia coli?