One intrinsic characteristic of low-moisture foods that is frequently overlooked is pH. Although pH affects the survival of microorganisms in high-moisture foods, its influence in low-moisture foods with less available moisture has not been examined. Escherichia coliO157:H7, E. coliO121, Salmonella entericaAnatum, and S. entericaAgona were grown on solid media with and without added glucose, harvested, and then suspended in buffer at pH 4, 5, and 7 for 10 min. All cultures were spotted individually onto cellulose filters and dried in a biohazard cabinet (23 ± 2°C) overnight (24 ± 2 h) and then stored in a 25°C incubator at 33% relative humidity. Populations were examined at regular intervals up to 26 (E. coli) or 29 (Salmonella) days. Additional controls for pH consisted of cultures held in buffer at pH 4, 5, and 7 at 25°C for the same time periods as the desiccated cells. For all strains tested, pH had an effect on survival whether stored dried or in liquid buffer (P< 0.05). However, when grown on solid media, acid adaptation (grown with glucose) before acid treatment did not appear beneficial to Salmonelladuring desiccation. Instead, both acid-adapted Salmonellaserovars appeared less resistant during drying than did non–acid-adapted cells. Once dried, the rates of decline for Salmonellawere not significantly different for acid-adapted and nonadapted cells (P> 0.05), indicating similar persistence following desiccation. A reverse trend was observed for E. coliO121; acid adaptation on solid media improved survival during desiccation and subsequent storage at low pH (P< 0.05). E. coliO157:H7 survival was significantly lower than that of either Salmonellaor E. coliO121 under all conditions tested. Results indicate that the response to desiccation and pH stress differs between the microorganisms and under different growth conditions.