Abstract:The effects of acetaldehyde on cell membrane integrity, membrane potential, total protein content, Na+K+-ATPase changes, and bacterial biofilm of Pseudomonas fluorescens were analyzed to investigate the bacteriostatic activity of acetaldehyde against P. fluorescens and its mechanism of action. Results showed that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of acetaldehyde against P. fluorescens were 0.5 μL/mL and 1 μL/mL, respectively. Conductivity and fluorescein diacetate (FDA) staining experiments revealed that acetaldehyde treatment could cause cell membrane rupture in P. fluorescens. When P. fluorescens was cultured with acetaldehyde at 1×MIC, 2×MIC and 4×MIC, reduction in bacterial membrane potentials was observed after 3 h; the mean fluorescence intensity decreased from 72.10 AU to 35.57, 15.31, and 7.46 AU, respectively, indicating that the metabolic activity of the bacteria was affected. Intracellular protein content of P. fluorescens treated with acetaldehyde at different concentrations decreased to 0.40, 0.35, and 0.34 mg/mL within 3 h of treatment and exhibited a slight, gradual decrease between 3 h to 12 h, which demonstrated the destruction of cell membrane integrity. Acetaldehyde reduced the activity of Na+K+-ATPase, leading to abnormal intracellular ATP metabolism and the inability to provide a normal supply of energy for cellular activities, which ultimately promoted the apoptosis of P. fluorescens. The rate at which 0.25 μL/mL acetaldehyde inhibited biofilm formation was 30.11%, indicating a significant reduction in the biofilm formation of P. fluorescens. It can be inferred that the bacteriostatic activity of acetaldehyde against P. fluorescens is possibly exerted through the alteration of bacterial cell membrane integrity. Our results may provide a novel approach for the preservation and freshness retention of aquatic products.
