ABSTRACT
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.