CHARACTERIZATION OF A NEW LIPOPEPTIDE SURFACTANT PRODUCED BY THERMOTOLERANT AND HALOTOLERANT SUBSURFACE BACILLUS-LICHENIFORMIS BAS50

Strain BAS50, isolated from a petroleum reservoir at a depth of 1,500 m and identified as Bacillus licheniformis, grew and produced a lipope ptide surfactant when cultured on a variety of substrates at salinitie s of up to 13% NaCl. Surfactant production occurred both aerobically a nd anaerobically and was optimal at 5% NaCl and temperatures between 3 5 and 45 degrees C. The biosurfactant, termed lichenysin A, was purifi ed and chemically characterized, A tentative structure and composition for the surfactant are described, Lichenysin A is a mixture of lipope ptides, with the major components ranging in size from 1,006 to 1,034 Da. The lipid moiety contains a mixture of 14 linear and branched beta -hydroxy fatty acids ranging in size from C-12 to C-17. There are seve n amino acids per molecule, The peptide moiety is composed of the foll owing amino acids: glutamic acid as the N-terminal amino acid, asparag ine, valine, leucine, and isoleucine as the C-terminal amino acid, at a ratio of 1.1:1.1:1.0:2.8:1.0, respectively. Purified lichenysin A de creases the surface tension of water from 72 mN/m to 28 mN/m and achie ves the critical micelle concentration with as little as 12 mg/liter, characterizing the product as a powerful surface-active agent that com pares favorably to others surfactants, The antibacterial activity of l ichenysin A has been demonstrated.