Alasan, an extracellular bioemulsifier protein by Acinetobacter radioresistens S13: prospectives in cosmetics.

Acinetobacter radioresistens S13 is a non-pathogenic bacterium selected for its ability to degrade phenol (Pessione et al. 1997) and can potentially be used in bioremediation processes. This strain synthesize a macromolecular biosurfactant glycoprotein referred to as Alasan, made-up by three subunits (45, 31 and 16 kDa); the heaviest shows high homology to an OmpA-like protein from Acinetobacter spp. (Toren et al. 2001). The present study deals with the comparison of the bacterial bioemulsifier with an industrial synthesized detergent , usually employed in cosmetic products (40 OE Ethoxylated Hydrogenated Ricin Oil). Generic emulsifying activity of these two detergents (absorbance at 600nm) has been measured first using a hexadecane/2-metylnaphthalene mixture (Navon-Venezia, S. et al. 1995) and then on three different hydrophobic compounds used in cosmetic formulation, like vitamin E, mint essential oil and Hedione. It turns out demonstrate that Alasan is more and more effective of the Ethoxylated Ricin Oil already at the concentration of 2 mg/ml. Results on specific emulsifying activity (abs 600nm / mg of emulsifier) moreover demonstrate that Alasan has a high solubilizing power also at the level of single molecule. Purified proteins are active emulsifiers and toxicological test (EpiOcular) will be performed. A more efficient stategy of production of these proteins is in development.