基于代谢活性的ε-聚赖氨酸杀菌动力学

Bactericidal Kinetics of ε-Poly-L-Lysine Based on Metabolic Activity

摘要:

ε-聚赖氨酸是一种高安全性天然食品防腐剂，具有抑菌谱广、抑菌活性强的特点。该研究以大肠杆菌（Escherichia coli）和枯草芽孢杆菌（Bacillus subtilis）为指标菌，利用荧光探针5-氰基-2,3-二甲苯基氯化四唑检测菌体细胞在ε-聚赖氨酸处理前后的代谢活性，计算相对活性，考察ε-聚赖氨酸的杀菌效果，利用Linear和Weibull模型拟合杀菌动力学过程。结果表明：液体体系条件下低质量分数（0.005%）ε-聚赖氨酸与大肠杆菌作用15 min，活性下降至起始活性的86.33%，120 min时为73.44%；ε-聚赖氨酸作用质量分数为0.025%时，处理15 min时活性为起始活性的21.06%，120 min时仅为3.61%。ε-聚赖氨酸杀灭枯草芽孢杆菌的效果与大肠杆菌相近。动力学分析显示ε-聚赖氨酸杀菌效果的Linear模型拟合度低，R2值低于0.70，Weibull模型在测试质量分数范围可精确拟合杀菌动力学过程，R2值大于0.97。该研究表明基于细胞代谢活性指标，Weibull模型可准确拟合ε-聚赖氨酸杀菌动力学过程。

Abstract:

ε-Poly-L-lysine (ε-PL) is a natural and safe food preservative with a broad-spectrum and strong antimicrobial activity. In the present study, Escherichia coli and Bacillus subtilis were used to investigate their metabolic activity before and after treatment with the fluorescent probe, 5-cyano-2,3-ditolyl tetrazolium chloride. The relative activity was calculated to investigate the bactericidal effect of ε-PL. Both the Linear and Weibull models were used to describe the bactericidal dynamics of ε-PL. For E. coli in liquid culture, a low-concentration of ε-PL (0.005%) applied for 15 and 120 min decreased metabolic activity of E. coli to 86.33% and 73.44% of its original activity, respectively. When a relative higher concentration of 0.025% was used, E. coli metabolic activity was only 21.06% after 15 min treatment and 3.61% at 120 min treatment. The bactericidal effect of ε-PL on B. subtilis was similar to that on E. coli. The kinetic analysis revealed that the fit of the Linear model was low, with an R2 value <0.70. By contrast, the Weibull model showed a better fit in all test concentrations of ε-PL against E. coli and B. subtilis, with an R2 value >0.97. The findings indicate that using metabolic activity as an index, the Weibull model can accurately fit the bactericidal kinetics of ε-PL.