NaCl对嗜热脂肪芽孢杆菌耐热性影响的研究

Effect of Sodium Chloride on the Thermal Resistance of Geobacillus stearothermophilus

摘要:

为了确定在100 ℃以下NaCl对嗜热脂肪芽孢杆菌耐热性的影响，本研究以体积个数为107 CFU/mL的嗜热脂肪芽孢杆菌菌悬液为热处理时的初始菌液,在菌悬液的中心温度在约150 s达到70 ℃、80 ℃、90 ℃条件下，研究不同浓度的NaCl制备的菌悬液经热处理后，嗜热脂肪芽胞杆菌的残存体积个数和热致死率,并对嗜热脂肪芽孢杆菌的残存体积个数初步建立各温度和各NaCl浓度条件下的热失活模型。研究结果表明，嗜热脂肪芽孢杆菌菌悬液在各条件下的失活曲线均可用Origin 8.0软件中DoseResp模型拟合，且判定系数R2均可达到0.96以上。对嗜热脂肪芽孢杆菌在不同温度、不同时间点和不同浓度NaCl下的热致死率进行单因素方差分析，空白在不同热处理温度前40 s致死率均达到95%以上，而不同浓度氯化钠在70 ℃下前120 s均达到95%以上，在80 ℃下前60 s均达到93%以上，在90 ℃下前60 s均达到98以上，可见不同浓度的NaCl对嗜热芽孢杆菌具有保护作用，其中2% NaCl的保护作用显著大于其它浓度的NaCl。

Abstract:

To determine the effect of sodium chloride on the thermal resistance of Geobacillus stearothermophilus at temperatures below 100℃, G. stearothermophilus bacterial suspensions of 107 CFU/mL were used as the initial cultures for heat treatment. After the center temperature of the suspension reached 70 ℃, 80 ℃, and 90 ℃, respectively, the corresponding death rates and residual concentrations of G. stearothermophilus in the suspensions, prepared using different concentrations of sodium chloride, were studied, and the inactivation models of each temperature and concentration of sodium chloride were preliminarily established based on the residual concentrations. The results indicated that the inactivation curves of G. stearothermophilus suspensions under all conditions could be fitted with the DoseResp model in Origin 8.0, and all coefficients of determination (R2) were above 0.96. Single factor analysis of variance was performed on the thermal death rate of G. stearothermophilus at different temperatures, different time points, and different concentrations of sodium chloride. The death rate in the control during the first 40 s reached 95% or more at different temperatures, and the death rate with different concentrations of sodium chloride at temperatures below 70 ℃ reached more than 95% during the first 120 s, more than 93% at 80 ℃ during the first 60 s, and 98% or more at 90 ℃ during the first 60 s. Therefore, different concentrations of sodium chloride had a protective effect on G. stearothermophilus, and the protective effect of 2% sodium chloride was more significant than that of the other concentrations of sodium chloride tested.