Efficient Purification of the Biosurfactant Viscosin from Pseudomonas libanensis Strain M9-3 and Its Physicochemical and Biological Properties

Viscosin (1), an effective surface-active cyclic lipopeptide, was efficiently recovered from Pseudomonas libanensis M9-3 with a simple purification protocol. A major pigment also obtained during this process was identified as phenazine-1-carboxylic acid. The critical micelle concentration (cmc) of viscosin was determined to be 54 mg L−1, and the minimum surface tension between air and water at the cmc was 28 mN m−1. Viscosin forms stable emulsions even at low concentrations (7.5 mg L−1), and the conditional stability constant for a cadmium−viscosin complex was determined to be 5.87. The physicochemical properties measured for viscosin are similar to other well-studied biosurfactants such as rhamnolipid and surfactin. Viscosin inhibited migration of the metastatic prostate cancer cell line, PC-3M, without visible toxicity. These properties suggest the potential of viscosin in environmental and biomedical applications.