LC/ESI‐MS/MS characterisation of lipopeptide biosurfactants produced by the Bacillus licheniformis V9T14 strain

Abstract

Lipopeptide biosurfactants produced by the Bacillus licheniformis V9T14 strain showed an interesting anti-adhesion activity against biofilm formation of human pathogenic bacterial strains. The chemical characterisation of the crude extract of V9T14 strain was first developed through electrospray ionisation mass spectrometry (ESI-MS) and ESI-MS/MS direct infusions: two sets of molecular ion species belonging to the fengycin and surfactin families were revealed and their structures defined, interpreting their product ion spectra. The LC/ESI-MS analysis of the crude extract allowed to separate in different chromatogram ranges the homologues and the isoforms of the two lipopeptide families. The extract was then fractionated by silica gel chromatography in two main fractions, I and II. The purified biosurfactants were analysed through a new, rapid and suitable LC/ESI-MS/MS method, which allowed characterising the composition and the structures of the produced lipopeptides. LC/ESI-MS/MS analysis of fraction I showed the presence of C(13), C(14) and C(15) surfactin homologues, whose structures were confirmed by the product ion spectra of the sodiated molecules [M + Na](+) at m/z 1030, 1044 and 1058. LC/ESI-MS/MS analysis of fraction II confirmed the presence of two main fengycin isoforms, with the protonated molecules [M + H](+) at m/z 1478 and 1506 corresponding to C(17) fengycin A and C(17) fengycin B, respectively. Other homologues (C(14) to C(16)) were revealed and confirmed as belonging to fengycin A or B according to the retention times and the product ions generated, although with the same nominal mass. Finally, a relative percentage content of each homologue for both lipopeptides families in the whole extract was proposed.

Screening concepts, characterization and structural analysis of microbial-derived bioactive lipopeptides: a review

“…[56,57] Indirect methods can provide preliminary information on BS production kinetics and yield. Although these methods may result in false positive or false negative qualitative data as well as underor overestimating BS yields.…”

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

“…These effect were observed either by coating the polystyrene surface with these compounds or by adding the biosurfactant to the inoculum. The chemical characterization of V9T14 lipopeptide biosurfactant carried out by LC/ESI-MS/MS revealed that it was composed of 77% of surfactin and of 23% of fengycin (Pecci et al, 2010). The activity of AgNO 3 combined with the lipopeptide biosurfactant V9T14 has also been studied against a preformed E. coli biofilm on the Calgary Biofilm device .…”

Identification of lipopeptides produced by Bacillus subtilis Czk1 isolated from the aerial roots of rubber trees

“…Iturins are also classified on the basis of the variation of amino acids in their corresponding peptide moieties: iturin A, iturin C, iturin D, iturin E, bacillomycin D, bacillomycin F, bacillomycin L, bacillomycin Lc, and mycosubtilin (Winkelmann et al, 1983;Gong et al, 2006;Romero et al, 2007;Pecci et al, 2010). Iturin A is the most promising antifungal lipopeptide because it is secreted by most Bacillus strains and is characterized by strong and broad-spectrum antifungal activity (Romero et al, 2007;Pecci et al, 2010). Surfactin contains a β-hydroxy fatty acid with 13 to 15 carbon atoms (Koumoutsi et al, 2004).…”

“…The lipopeptides belonging to the surfactin family are β-hydroxy heptacyclic depsipeptides with Ala, Val, Leu, or Ile variations at positions 2, 4, and 7 in the cyclic depsipeptide moieties, and C13 to C16 variations in the β-hydroxy fatty acid chains (Peypoux et al, 1994;Kowall et al, 1998;Hue et al, 2001). Different Bacillus strains also exhibit diversity in the production of cyclic lipopeptides; for example, most Bacillus strains produce lipopeptides belonging to only one family, whereas a few strains co-produce lipopeptides belonging to two or three families (Vater et al, 2002;Nagórska et al, 2007;Romero et al, 2007;Pecci et al, 2010).…”