Two Bactericidal Cyclic Lipopeptides from Pseudomonas wayambapalatensis and Pseudomonas cyanflava sp. nov. Are Critical for Biocontrol of the Bacterial Wilt Caused by Ralstonia solanacearum

Bacterial wilt is a devastating disease caused by Ralstonia solanacearum worldwide. This study identified two highly antagonistic soil isolates as Pseudomonas wayambapalatensis L7 and a novel species, P. cyanflava sp. nov. SC11, by genome sequencing analyses. Using an “antagonism-genome-transcriptome” approach, secondary metabolite (SM) biosynthesis gene clusters (BGCs) were prioritized. Deletion of the BGCs revealed that the antibacterial activity of strain SC11 depends on the combined effects of wlp and tox BGCs, while strain L7 acts solely through the wlp BGC. High-resolution mass spectrometry (HRMS) and X-ray crystallography identified White Line-Inducing Principles (WLIP and WLIPβ) as active compounds, with WLIP inhibiting R. solanacearum in a minimum inhibitory concentration (MIC) of 1 μg/mL. WLIP-defective mutants of both strains were greatly attenuated in their biocontrol efficacy, highlighting the critical roles of WLIPs in biocontrol. This work reports a novel Pseudomonas species with promising biocontrol potentials, presents an effective strategy for linking BGCs to bioactive metabolites, and establishes WLIP cyclic lipopeptides as highly potent anti-R. solanacearum agents.