Phenazines contribute to microbiome dynamics by targeting topoisomerase IV.

Phenazines are highly prevalent, natural bioactive substances secreted by microbes. However, their mode of action and potential involvement in shaping microbiomes remain elusive. Here we performed a comprehensive analysis of over 1.35 million bacterial genomes to identify phenazine-producing bacteria distributed across 193 species in 34 families. Analysis of rhizosphere microbiome and public rhizosphere metagenomic datasets revealed that phenazines could shape the microbial community by inhibiting Gram-positive bacteria, which was verified by pairwise interaction assays using Phenazine-1-carboxamide (PCN)-producing Pseudomonas chlororaphis. PCN induced DNA damage in Bacillus subtilis, a model Gram-positive target, where it directly bound to the bacterial topoisomerase IV, inhibiting its decatenation activity and leading to cell death. A two-species consortium of phenazine-producing Pseudomonas and resistant B. subtilis exhibited superior synergistic activity in preventing Fusarium crown rot in wheat plants. This work advances our understanding of a prevalent microbial interaction and its potential for biocontrol.