Salmonella enteritidis hilA gene fusion response after incubation in spent media from either S. enteritidis or a poultry Lactobacillus strain.

ABSTRACT

The purpose of this study was to determine if growth of a poultry probiotic lactobacilli strain can influence S. enteritidis virulence expression by measuring the response of a hilA-lacZY transcriptional fusion. beta-galactosidase activity was not detected when S. enteritidis was incubated in Lactobacillus-spent medium (24 h growth, pH 4.1, 50.4 mM lactate) but was detectable in spent medium from 4 h growth cultures of Lactobacillus sp. (final OD of 0.213, pH 5.7, 12 mM lactate) when pH and lactate were adjusted to that of the 24 h-pH 4 spent media levels. Adjusting the pH of the 24 h spent medium from 4 to 6, resulted in a measurable beta-galactosidase activity that was significantly higher than expression in LB broth. When S. enteritidis was grown in Salmonella-spent media (24 h growth, pH 4.2, 78 mM acetate), hilA expression was increased 4-fold over expression in the LB broth.