Purification and Antimicrobial Activity of Lipopeptide Produced by Bacillus natto TK-1 and Its Surfactant Property
Bacillus natto TK-1产脂肽的纯化、抑菌活性及其表面活性剂特性

Lipopeptide biosurfactant from Bacillus natto TK-1 was purified via acidic precipitation, methanol extract and thin-layer chromatography (TLC) system. The surface-active substance migrated at the position of Rf 0.58-0.65 as a single line on the TLC. The critical micelle concentration (CMC) was estimated to be around 115 mg/L and the minimum surface tension of lipopeptide was 30.1 mN/m at a concentration of 512 mg/L. Meanwhile, the anti-adhesion activity of lipopeptide was investigated in vitro. The results indicated that lipopeptide was found to significantly inhibit the adhesion of Salmonella typhimurium, Escherichia coli and Staphylococcus aureaus to 96- well microtiter plates at various concentrations. The highest anti-adhesion activity was exhibited against Salmonella typhimurium with inhibition percentage till 51.9% at 12.8 g/L. The antimicrobial activity of lipopeptide was evaluated against ten microorganisms using disc diffusion method and the lipopeptide showed a broad spectrum of antimicrobial activity. The strongest inhibitory effect was found against Botrytis cinerea and Fusarium moniliforme.