Some iturin A-producing strains of Bacillus subtilis will elaborate the novel fluorinated analogue when incubated with 3-fluoro-L-tyrosine. The activity of iturin A is dependent on the D-tyrosine residue and the presence of fluorotyrosine may result in an improvement of the biological properties of this lipopeptide. The fluorinated iturin might also be used as a probe for studying its interaction with biological membranes.

Bacillus sp. strain CS93, which was previously isolated from Pozol, was previously shown to produce iturin A, bacilysin and chlorotetaine. To investigate the biosynthetic mechanism of chlorotetaine production, the bac genes were amplified from genomic DNA of Bacillus sp. CS93 by PCR and sequenced. The genes bacABCDE were determined, but no gene that might code for a halogenating enzyme was detected either within the gene cluster or in the flanking sequences. Following further analysis of culture supernatants that were active against bacteria by liquid chromatography-MS, it was not possible to detect bacilysin/chlorotetaine. However, in methanolic fractions containing antibacterial activity, molecular ions characteristic of surfactins and fengycin were detectable by electrospray MS. Using primers complementary for conserved regions of nonribosomal peptide synthase, it was possible to amplify gene fragments that had a high degree of homology with known surfactin and fengycin biosynthetic genes. Thus, in addition to the known antimicrobial compounds, we have shown that this strain produces other bioactive lipopeptides, which might account for some of the medicinal properties of Pozol.

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