The global regulator SpoVG is involved in biofilm formation and stress response in foodborne Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a primary culprit of food poisoning. As a highly adaptable pathogen, S. aureus demonstrates formidable biofilm-forming and stress tolerance capabilities, inducing significant challenges to eradicate food contamination caused by this organism. SpoVG, a regulatory protein in S. aureus, controls the expression of numerous genes. However, its role in biofilm formation and stress response in foodborne S. aureus remains to be elucidated. In this study, we investigated the functions of SpoVG involved in food-related stress responses and biofilm formation in S. aureus RMSA50. The results demonstrated that SpoVG deletion enhanced biofilm formation and resistance to heat and desiccation, while decreased tolerance to oxidative stress. Further analysis revealed that cell aggregation and the accumulation of extracellular DNA (eDNA) may contribute to the enhanced biofilm formation. Real-time quantitative reverse transcription-PCR (RT-qPCR) revealed that the expression levels of nuc and sasC, which are related to cell aggregation and eDNA concentration, were significantly altered in the spoVG mutant. Electrophoretic mobility shift assays (EMSA) confirmed that SpoVG directly binds to the promoter region of nuc and sasC to regulate their expression. These findings suggest that SpoVG may serve as a target to decrease biofilm formation and control S. aureus contamination in the food industry.