Fengycin or plipastatin? A confusing question in Bacilli

According to most of the related literature published since their discovery in 1986, fengycin and plipastatin are very related molecules. These are lipodecapeptides encoded by operons of five synthetase genes. The most important difference between these two molecules lies in the peptide moiety at the position of the D-tyrosine, which is encoded by the second gene fenB of fengycin operon and by the fourth gene ppsD of plipastatin operon. Here, we aimed to differentiate between fengycin and plipastatin molecules. We designed degenerate primers using the consensus sequence of the epimerization domain responsible for the transformation of L-tyrosine to D-tyrosine from Bacillus subtilis 168, Bacillus amyloliquefaciens FZB42, and Bacillus atrophaeus 1942. These degenerate primers were then used to amplify fragments from B. amyloliquefaciens S499, B. subtilis ATCC 21332, and Bacillus cereus. Alignment of the sequences of the amplified fragments with the sequences from the mentioned strains deposited in GenBank database showed high similarity with 64 B. subtilis strains, 24 B. amyloliquefaciens strains, seven B. atrophaeus strains, one B. cereus strain, one Bacillus sonorensis strain, two Bacillus methylotrophicus strains, and 45 Bacillus velezensis strains. The results confirmed that these Bacillus strains harbor the tyrosine epimerization domain located on the fourth gene of their fengycin or plipastatin operons, which indicated that these strains synthesize plipastatin rather than fengycin.