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目的评估ε-聚赖氨酸(ε-PL)对尿样中金黄色葡萄球菌、粪肠球菌、铜绿假单胞菌和大肠杆菌4种常见腐败菌的抑菌效果及其对尿铅测定结果的影响。方法采用肉汤稀释法测定ε-PL对4种常见腐败菌的最小抑菌浓度(MIC);观察终质量浓度为40.000 mg/L的ε-PL对尿样的抑菌效果;用石墨炉原子吸收光谱法测定质量浓度为40.000 mg/L的ε-PL溶液中的铅本底水平和正常健康人群尿样的尿铅水平;比较ε-PL和硝酸对尿样的抑菌效果。结果ε-PL对金黄色葡萄球菌、粪肠球菌、铜绿假单胞菌和大肠杆菌同时具有抑菌效果的MIC为40.000 mg/L。含终质量浓度为40.000 mg/L的ε-PL的尿样在常温下保存24 h~15 d均无细菌生长。质量浓度为40.000 mg/L的ε-PL溶液中铅水平<2.0μg/L。分别以质量浓度为40.000 mg/L的ε-PL和体积分数为1.0%硝酸作为防腐剂时,尿样中铅水平的下降率相近,且尿样保存15 d后尿铅水平的下降率均小于10.0%。结论ε-PL可替代硝酸作为尿铅测定样品保存的新型天然防腐剂。
Objective To evaluate the antibacterial effect of ε-polylysine (ε-PL) on four kinds of common spoilage bacteria in urine, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli, Impact. Methods The minimum inhibitory concentration (MIC) of ε-PL against four kinds of common spoilage bacteria was determined by broth dilution method. The antibacterial effect of ε-PL on the urine samples was observed at a final concentration of 40.000 mg / L. Absorbance spectrophotometry was used to determine the level of lead in ε-PL solution with mass concentration of 40.000 mg / L and urine lead level in normal healthy people. The inhibitory effect of ε-PL and nitric acid on urine samples was also compared. Results The MIC of ε-PL against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli was 40.000 mg / L. Urine samples containing ε-PL at a final concentration of 40.000 mg / L had no bacterial growth for 24 h to 15 d at room temperature. The lead level in the ε-PL solution at a concentration of 40.000 mg / L was <2.0 μg / L. When the concentration of ε-PL was 40.000 mg / L and the volume fraction of 1.0% nitric acid was used as preservative respectively, the drop rates of lead levels in urine samples were similar, and the drop rates of urine lead levels after 15 days of urine samples storage were all less than 10.0%. Conclusion ε-PL can replace nitric acid as a new natural preservative for the determination of urine lead.