Influence of the norepinephrine and medium acidification in the growth and adhesion of Salmonella Heidelberg isolated from poultry.

Salmonella spp. are among the leading pathogens responsible for foodborne illnesses worldwide. Bacterial communities use a quorum sensing (QS) system to control biofilm formation. QS is a cell-to-cell signaling mechanism involving compounds called auto-inducers (AI). Norepinephrine utilizes the same bacterial signaling of AI-3 and serves as a signal of QS. Acid stress is a challenge encountered by microorganisms in food processing environments and in the gastrointestinal tracts of hosts. Thus, adaptation to acidic environments may increase the pathogenicity of the strain. The aim of this study was to evaluate the influence of two concentrations of norepinephrine (100 μM and 250 μM) and acidification (pH 3.0) of the medium on the growth and adhesion of Salmonella Heidelberg strains isolated from poultry sources at 12 °C and 25 °C. Furthermore, three genes associated with the biofilm formation process were detected (adrA, csgD, and sidA). Norepinephrine stimulation did not influence the growth or adhesion of Salmonella Heidelberg strains, regardless of the catecholamine concentration and temperature. On the other hand, the use of acidified medium (pH 3.0) resulted in a significant reduction of growth and a significant increase of S. Heidelberg adhesion at both temperatures, indicating that the acidified medium favors the biofilm formation process. The adrA and sidA genes showed higher detection frequencies than csgD. Experiments analyzing the biofilm production process by S. Heidelberg strains are not common, and further studies are necessary to understand this complex process.