Microbial enhanced oil recovery research. Annex 5, Summary annual report, 1991--1992 Page: 6 of 16
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additional low field signal at S 5.3 confirmed the presence of lactone as indicated in the
IR spectrum.
Attempts to obtain the sequence of the amino acids using 2-D NOE (ROESY)
(Figure 3) in combination with 2-D TOCSY were only moderately successful because of
signal overlap in both CDCl2CDCl2 and 90%H20/10%D20. The following partial
sequences were obtained (not in particular order):
fatty acid-Glu-Leu, Asp-Leu, Leu-Leu
Carbon-13 NMR (90% H20/10% D20) confirmed all the above proton NMR
assignments (data not shown). Peak multiplicity was determined using the DEPT
sequence and inverse CH correlation gave direct relationships between peaks in the
proton and carbon spectra, aiding the assignment of both. The fatty acid component of the
lipopeptide consisA of a mixture of normal, anteiso, and iso branched forms (CH3 at S
13.4, 10.7 and 18.7 and ca. 22, respectively), with the latter predominating as seen in the
proton NMR spectra. Furthermore, the presence of only one major molecular ion species
in the MS spectra indicated that the compound consists of a C15 chain with little if any
size heterogeneity. The chemical structure of biosurfactant produced by B. licheniformis
JF-2 is shown in Figure 4. The presence of a family of lipopeptides with the same
peptide domains but different chain lengths of lipid tails, which has been frequently
observed for lipopeptides produced by other microorganisms (6, 9), was not observed in
the B. licheniformis JF-2 compound.
The partial amino acid sequences in the B. licheniformis JF-2 lipopeptide are the
same as those found in surfactin (10) and other related lipopeptides from Bacillus sp.
such as esperin from Bacillus mesentericus (15) and BL-86 from Bacillus licheniformis
strain 86 (6). Recent studies have indicated that Bacillus lipopeptides exhibit some
heterogeneity in the composition of the peptide, particularly at the ultimate position
(6,14). For example, Peypoux and Michel (14) reported that surfactin, the best studied
biosurfactant, consists of two groups of homologous lipopeptides differing by the
presence of valine instead of leucine at the seventh amino acid position. The relative
ratio of Val7 to Leu7 was found to depend on the strain of B. subtilis and the growth
conditions. However, in contrast to the results with surfactin no heterogeneity in the
amino acid composition of the peptide could be detected in the compound from B.
licheniformis JF-2.
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Sharma, M. M. & Georgiou, G. Microbial enhanced oil recovery research. Annex 5, Summary annual report, 1991--1992, report, December 31, 1992; Austin, Texas. (https://digital.library.unt.edu/ark:/67531/metadc1314592/m1/6/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.