Summer Research Description: Helicobacter pylori is a Gram negative curved bacillus found in the gastric mucosa of approximately half the world’s population. H. pylori infection and a high salt diet are each risk factors for noncardia gastric adenocarcinoma and gastric lymphoma. H. pylori is a non-invasive bacterium, and the pathogenesis of H. pylori-associated diseases is thought to be dependent on the actions of secreted proteins. The goal of this project was to analyze H. pylori growth and protein secretion under multiple conditions relevant for understanding gastric carcinogenesis. To examine how the secreted proteome of H. pylori changes in response to different salt concentrations, H. pylori was cultured in medium containing either 0.5% NaCl or 1.25% NaCl. Cultures were centrifuged to yield bacterial pellets and supernatants, and bacteria were fractionated to yield preparations enriched in soluble and membrane proteins. Preliminary results indicate that H. pylori grows more slowly and to lower optical densities in the high salt medium. The protein content of samples is being analyzed by SDS-PAGE and mass spectrometry. Further studies will examine the effects of additional variations in medium composition or environmental conditions on bacterial growth and protein secretion.