Characterization, Production, and Applications of Lipopeptides - Biosurfactants: Research Trends and Applications - page 156

Biosurfactant proteins produced by Lactobacillus fermentum RC-14 have also
been identified by a ProteinChip-interfaced mass spectrometer (Reid et al., 2002).
Five tryptic peptide sequences by collision-induced dissociation tandem mass spec-
trometry were identified following on-chip digestion of collagen-binding proteins.
This may lead to the determination of the factors that are responsible for antistaphy-
lococcal activity.
1 H-NMR was used by Bonmatin et al. (1994) to show that surfactin can have two
conformations depending on the pH. The saddle-like structure is bidentate with the
two charged amino acids as sites for cation binding.
SANS studies were performed to study the characteristics of surfactin (Shen
et al., 2009). At pH 7.5, the aggregation number was only 20, and the diameter of the
micelles was 50 Å with a hydrophobic core of 22 Å radius. It is postulated that the
leucines are in the hydrophobic core, which is consistent with its foaming character-
istics. Further work (Shen et al., 2010) showed the solubilization of diphenylcarba-
myl chloride.
Pecci et al. (2010) characterized the biosurfactants produced by B. licheniformis
V9T14 strain. This strain exhibited antimicrobial activity that inhibited biofilm for-
mation of human pathogens. LC-ESI-MS/MS analyses were used, and fengycin and
surfactin homologues were determined. Fractionation was further performed by
silica gel chromatography. C13, C14, and C15 surfactin homologues were found plus
C17 fengycins A and B. Other C14-C16 fengycin homologues were also confirmed.
Most of the surfactin (61.3%) was in the C15 form with an MW of 1035. The two
most common forms of fengycin A and B, respectively, were the C17 of MW 1477
(25.1%) and 1505 (55.1%). The LC-ESI-MS/MS proved useful for the characteriza-
tion of the lipopeptides.
An oil emulsification test was used to screen for biosurfactants and bioemulsi-
fiers for strains from a sea mud (Liu et al., 2010). A B. velezensis H3 strain was
isolated and could produce biosurfactants on starch and ammonium sulfate. C14 and
C15 surfactins were discovered, which could lower the surface tension to 25.7 and
27.0 mN/m, respectively, from pH 4 to 10. CMCs were in the order of 10 −5 mol/L.
Antimicrobial properties were shown. The yield however was only 0.49 g/L. Highest
yields of up to 50 g/L have been previously found by a strain on maltose and soybean
flour (Yoneda et al., 2006).
GENETICS OF LIPOPEPTIDE PRODUCTION
Ultraviolet radiation mutation between argC4 and hisA1 on the genetic map led
to a strain that produced 3.5 times surfactin (Mulligan et al., 1989). Another tech-
nique included random mutagenesis by N-methyl-N′ nitro-N-nitrosoguanidine of
B. licheniformis, where an increase in surfactin production of 12-fold was obtained
(Lin et al., 1998). Tsuge et al. (2001) not only found that the yerP gene is involved in
surfactin resistance in the strain but also evaluated if this gene was involved in sur-
factin production. Although the sfp gene was inserted into the strain, production was
low. Therefore, it did not appear that the yerP gene was linked to surfactin production.
Washio et al. (2010) analyzed the genetics of arthrofactin production by
Pseudomonas sp. MIS38. Arthrofactin are cyclic lipopeptides that function as