Surfactin is a very powerful surfactant commonly used as an antibiotic. It is a bacterial cyclic lipopeptide, largely prominent for its exceptional surfactant power. Its amphiphilic properties help this substance to survive in both hydrophilic and hydrophobic environments. It is an antibiotic produced by the Gram-positive endospore-forming bacteria Bacillus subtilis. Surfactin's structure consists of a peptide loop of seven amino acids (L-asparagine, L-leucine, glutamic acid, L-leucine, L-valine and two D-leucines), and a hydrophobic fatty acid chain thirteen to fifteen carbons long which allows it to penetrate cellular membranes. Glutamic acid and aspartic acid residues at positions 1 and 5 respectively, constituting a minor polar domain. On the opposite side, valine residue at position 4 extends down facing the fatty acid chain, making up a major hydrophobic domain.
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