该研究通过分析乙醛对荧光假单胞菌（Pseudomonas fluorescens）菌体细胞膜完整性、膜电位、总蛋白含量、Na+K+-ATP酶变化以及细菌生物被膜的影响，探究乙醛对P. fluorescens的抑菌活性及其抑菌机理。结果表明：乙醛对P. fluorescens的最小抑菌浓度MIC值为0.5 μL/mL，最小杀菌浓度MBC值为1 μL/mL；电导率和二乙酸荧光素染色实验发现乙醛处理可引起P. fluorescens细胞膜出现破裂；添加1×MIC、2×MIC、4×MIC乙醛3 h后降低菌体膜电位，平均荧光强度从72.10 AU分别下降至35.57、15.31和7.46 AU，影响细菌的代谢活力；不同浓度乙醛处理后胞内蛋白质的含量3 h内分别下降至0.40、0.35和0.34 mg/mL，3~12 h期间呈现平缓、略有下降，表示细胞膜的完整性遭到破坏；乙醛降低了Na+K+-ATP 酶活性，导致胞内ATP代谢异常，不能正常为细胞活动供给能量，促使荧光假单胞菌的凋亡；0.25 μL/mL的乙醛对生物被膜形成抑制率为30.11%，显著降低P. fluorescens生物被膜形成。由此可见，乙醛对P. fluorescens可能的抑菌机理是改变菌体细胞膜完整性,为拓展水产品的防腐保鲜提供新思路。

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.

广西重点研发计划项目（AB18221117）；国家自然科学基金资助项目（NSFC 31960484）