防腐剂复配对苏云金芽孢杆菌抑菌效果研究

Inhibitive effect of mixed preservatives on Bacillus thuringiensis

目的获得最佳的复配防腐剂抑制苏云金芽孢杆菌效果。方法选择不同的防腐剂,通过药敏纸片法、最小抑菌浓度(MIC)法测定苏云金芽孢杆菌对其敏感性,利用正交设计筛选最佳防腐剂组合,并对获得的最佳防腐剂组合抑菌效果进行验证。结果苏云金芽孢杆菌对乳酸链球菌素、聚赖氨酸、尼泊金乙酯较为敏感,其MIC分别为0.01、0.078和0.039 mg/ml,但是对乳酸钠、山梨酸钾不敏感。正交试验结果表明,当乳酸链球菌素、聚赖氨酸和尼泊金乙酯浓度分别为0.313、0.039和0.25 mg/ml时效果最佳,可使基质中苏云金芽孢杆菌降低2.35个数量级。结论选择这一最佳组合在室温(25℃)条件下,猕猴桃汁、里脊肉糜、牛乳中细菌数在4 d时分别增长1.61、2.95、2.16个数量级;在0～4℃贮藏5 d时分别增长1.24、0.94、0.14个数量级。

Objective To acquire the optimum preservatives compounding to inhibit Bacillus thuringiensis.Methods The inhibitive effect of preservatives on Bacillus thuringiensis was examined by susceptibility test paper and minimum inhibitory concentration（MIC） methods;the optimized combination of preservatives was screened by orthogonal design,and the inhibitive effect of the best combination of preservatives was also checked.Results The results showed that Bacillus thuringiensis were not sensitive to sodium lactate and potassium sorbate,but are sensitive to nisin,polylysine and ethylparaben with a MIC of 0.01,0.078 and 0.039 mg/ml respectively.The inhibitive effect of a mixture of preservatives on Bacillus thuringiensis examined by orthogonal design showed that the best combination was nisin,polylysine and ethylparaben at 0.313,0.039 and 0.25 mg/ml respectively.The bacteriostatic effect was better under combining use of preservatives,and the number of Bacillus thuringiensis in food medium could be depressed 2.35 orders of magnitude.Conclusion The growth of Bacillus thuringiensis in fruit juice,meat and milk stored under room temperature（25 ℃）for 4 days was increased 1.61,2.95 and 2.16 orders of magnitude,those stored at 0-4℃ for 5 days was increased only 1.24,0.94 and 0.14 orders of magnitude.