Figure 6.

Multi-omic characterization of Paenibacillus polymyxa P4 strain selected by ultrahigh-throughput screening of anti-Gram-negative antibiotic activity using the developed live biosensor. (A) Polymyxin E (colistin) was identified as a major secondary metabolite of P. polymyxa P4 active against Gram-negative bacteria. The chemical structures of polymyxin E and related polymyxins A, B, and D-Dab₃ B produced by distinct Paenibacillus are presented. PMX—colistin peptide backbone. (B) LC-MS chromatogram of active fraction of P. polymyxa P4 metabolites. Specific peaks of polymyxin E₁ and polymyxin E₂ are presented with their experimental and calculated [M+H]⁺ molecular ion masses. (C) BGC of polymyxin E identified in the genome of P. polymyxa P4. Core NRPSs (PmxA, PmxB, and PmxE) and ABC transporters are colored with orange and aquamarine, respectively. Predicted amino acid specificity of NRPS modules are presented. Related BGCs of polymyxin A [21], D-Dab₃-polymyxin B [22], and polymyxin E [23] are presented with their predicted modular specificities. Distinct modular specificities are highlighted with red.