Inhibition and metabolic toxicity regulation of niacin on Staphylococcus aureus and its application in meat product preservation.

Niacin, an essential vitamin, inhibits Staphylococcus aureus (S. aureus) growth by disrupting its cell wall and membrane integrity. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of niacin against S. aureus ATCC 29213 were both 4 mg/mL. Alkaline phosphatase (AKP) levels indicate cell wall damage. Niacin depolarizes the bacterial membrane, alters cell morphology, and reduces intracellular adenosine-triphosphate (ATP) while increasing reactive oxygen species (ROS) and causing nucleic acid and protein leakage. Agarose gel electrophoresis and Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that high concentrations of niacin significantly degrade genomic DNA and proteins in S. aureus, with notable differences observed. RT-qPCR results indicate that niacin at sub-inhibitory concentrations modulates S. aureus quorum sensing, virulence gene expression, adhesion capacity, and overall regulatory gene expression (P < 0.05). The experimental results indicate that niacin can reduce the toxicity of S. aureus metabolites, with MIC niacin decreasing the hemolytic activity of the metabolites to 31.83%. In beef, niacin effectively reduces bacterial counts, decreasing them by 0.80 CFU/g, 1.30 CFU/g, and 1.00 CFU/g at 4 °C, 25 °C, and 37 °C, respectively. Niacin helps maintain pH and preserve color, thereby improving storage quality. These findings highlight the potential of niacin in preventing S. aureus contamination in meat products.