ε-聚赖氨酸抑菌效果及对尿铅测定影响研究

Bacteriostatic effect of ε-polylysine and its effect on urine lead level

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 bacteriostatic effect of ε-polylysine（ ε-PL） on four common putrefactive bacteria including Staphylococcus aureus,Enterococcus faecalis,Pseudomonas aeruginosa,and E. coli and its effect on urine lead level. Methods Broth dilution method was used for the determination of the minimum inhibitory concentration（ MIC） ofε-PL on the four kinds of putrefactive bacteria; the inhibitory effects of ε-PL with final mass concentration of 40. 000 mg / L on the urine sample were observed; graphite furnace atomic absorption spectrometry was used for determining the lead level in the 40. 000 mg / L（ mass concentration） ε-PL solution and the urine lead level in normal healthy groups; the bacteriostatic effects of ε-PL and nitric acid were compared. Results The MIC of ε-PL on Staphylococcus aureus,Enterococcus faecalis,Pseudomonas aeruginosa,and E. coli was 40. 000 mg / L. There was no bacterial growth in the urine sample with40. 000 mg / L（ mass concentration） ε-PL when urine was kept at room temperature for 24 hours to 15 days. The lead level was 〈2. 0 μg / L in the 40. 000 mg / L（ mass concentration） ε-PL solution. When the ε-PL with final mass concentration of 40. 000 mg / L and the nitric acid with a volume fraction of 1. 0% were respectively used as the antiseptics,the descending rates of the lead levels in the urine samples were similar,and after the urine sample was preserved for 15 days,the descending rates of the urine lead were both smaller than 10. 0% after be stored for 15 days. Conclusion ε-PL can substitute nitric acid as a new natural preservative for preservation of samples for urine lead determination.