Isolation, purification and bioactivity of a novel lipopeptide

Objective: To isolate and purify crude lipopeptide from the fermentation liquid of Staphylococcus epidermidis and analyze its bioactivity. Methods: The crude extracts of lipopeptide were obtained from the fermentation liquid of Staphylococcus epidermidis by acid precipitation and organic solvent extraction, and analyzed for properties by oil-drain test, thin layer chromatography (TLC) and HPLC. Mice were percutaneously infected with Staphylococcus aureus then injected s.c. with the crude extracts to observe the effect on leukocytes in vivo as well as anti-bacterial activity. The effect of the lipopeptide on expression of β-defensin14 (mBD14) in mice were determined by real-time quantitative PCR. Results: The activity of crude extract F2 of lipopeptide in oil-drain was higher than that of extract F1. TLC showed homologue of lipopeptide, with a purity of more than 60%, in extract F2. The extracts relieved the acute inflammation and leucocytosis of mice caused by infection with Staphylococcus aureus, and inhibited the proliferation of bacteria in skin by up-regulating the expression of mBD14. Conclusion: The crude extract of a novel lipopeptide with bioactivity was successfully obtained from the fermentation liquid of Staphylococcus epidermidis.