The express pattern of Salmonella enterica´s secreted protein SipA changed in five vegetable extracts

Foodborne pathogens such as Salmonella can cause gastrointestinal illness if they are ingested with uncooked foods such as salad. Foods such as salad pose a greater risk because they are consumed raw and have been the source of major outbreaks of disease from fresh produce. SipA, one of Salmonella ´s effectors, is an actin-binding protein that is required for its efficient entry into host cells. We report here that the expression pattern of SipA is changed when Salmonella are grown in the extracts of five commonly consumed fresh vegetable products: lettuce, Roma tomatoes, spinach, red peppers and alfalfa sprouts. We describe that the growth of Salmonella is inhibited by high osmolarity and low pH. The yield of SipA is negatively correlated to pH and osmolarity.