Lichenysin: A More Efficient Cation Chelator Than Surfactin

Abstract

The lipopeptide lichenysin (cyclo-[L-Gln1-->D-Leu2-->L-Leu3-->L-Val4--> L-Asp5-->D-Leu6-->L-Ile7-beta-OH fatty acid]) produced by Bacillus licheniformis structurally resembles surfactin from Bacillus subtilis. The main difference is the presence of a glutaminyl residue in position 1 of the peptide sequence in place of glutamic acid in surfactin. This local variation causes significant changes in the properties of the molecule compared to surfactin. Lichenysin has a higher surfactant power, the critical micellar concentration (c.m.c.) being strongly reduced from 220 to 22 microM and a much higher hemolytic activity because 100% hemolysis was observed with only 15 microM instead of 200 microM. Lichenysin is also a better chelating agent because its association constants with Ca2+ and Mg2+ are increased by a factor of 4 and 16, respectively. This effect is assigned to an increase in the accessibility of the carboxyl group to cations owing to a change in the side chain topology induced by the Glu/Gln exchange. Additionally, the propensity of the lipopeptide for extensive hydrophobic interactions, as illustrated by its low c.m.c., contributes to further stabilization of the cation and an increase in the partitioning of lichenysin into the erythrocyte membrane. Our data support the formation of a lichensyin-Ca2+ complex in a molar ratio of 2:1 instead of 1:1 with surfactin, suggesting an intermolecular salt bridge between two lichenysin molecules. Therefore, when Ca2+ ions are present in the solution, micellization occurs via a dimer assembly, with a possible long-range effect on the spatial arrangement of the micelles or other supramolecular structures. Finally, among all the surfactin peptidic variants so far known, lichenysin is the one for which the three tested activities are the most substantially improved.

Biosurfactants and Bioemulsifiers Biomedical and Related Applications – Present Status and Future Potentials

“…Huang et al, (2007) reported that a lipopeptide antimicrobial substance produced by B. subtilis fmbj strain, which is mainly composed of surfactin and fengycin, was able to inactivate endospores of B. cereus through damaging the surface structure of the spores as seen by Transmission Electron Microscopy. Lichenysin, pumilacidin and polymyxin B (Grangemard et al, 2001;Landman et al, 2008;Naruse et al, 1990;Yakimov et al, 1995) are other antimicrobial lipopeptides produced by Bacillus licheniformis, Bacillus pumilus and Bacillus polymyxa, respectively. Polymyxin B, in particular, due to its high affinity for the lipid moieties of lipopolysaccharide, has shown antibacterial activities against a wide variety of Gram-negative pathogens.…”

Genetic and functional characterization of the gene cluster directing the biosynthesis of putisolvin I and II in Pseudomonas putida strain PCL1445

“…Putisolvins I and II were shown (i) to reduce the surface tension of the medium, (ii) to increase the formation of an emulsion with toluene, (iii) to stimulate were reported to permeabilize membranes, resulting in pore formation and haemolysis (Grangemard et al, 2001) and to play a role in bacterial attachment to surfaces (Neu, 1996). Lipopeptides produced by Serratia (Lindum et al, 1998) and Burkholderia (Huber et al, 2002) were shown to be essential for the stimulation of swarming motility and thus could contribute to the regulation of biofilm formation (Huber et al, 2002).…”

Biosurfactants Produced From Agriculture Process Waste Streams To Improve Oil Recovery in Fractured Carbonate Reservoirs

“…22;23 Surfactin is also an effective antimicrobial and antiviral agent, able to induce formation of ionic pores in phospholipid bilayers, 24 and transport cations across membranes. 25 Its cation-complexing property, due to two negative charges on the aspartyl and glutamyl residues, is probably fully utilized in systems containing ubiquitous amounts of Ca ++ and Na + ions.…”

“…Figure 11 shows porosity and permeability values for all the cores characterized to date, overlaid on similar data from Watney (1994). 25 Watney characterized Bethany Falls and Mound Valley oolites and found a wide range of porosity and permeability. Dubois et al 24 noted that the LKC was very similar to modern Caribbean oolites and our experimental data for moldic LKC outcrop and reservoir cores, as well as Miami and Joulters Cay oolite agree well with the published values for similar material.…”