Interspecies signaling modulates the biosynthesis of antimicrobial secondary metabolites related to biological control activities of <i>Pseudomonas fluorescens</i> 2P24

Rhizosphere microorganisms release vital signals that shape microbial communities, with antibiotics at low concentrations acting as intra- and interspecies signals. However, the mechanisms of these signals in coordinating gene expression are unclear. In non-pyoluteorin-producing <i>Pseudomonas fluorescens</i> 2P24, pyoluteorin was identified as an interspecies signal that regulates the <i>phl</i> biosynthesis gene cluster for 2,4-DAPG production. TetR family repressors PhlH and PhlF were found to positively regulate 2,4-DAPG hydrolysis and negatively regulate its synthesis in response to pyoluteorin. Structural modeling and docking analyses revealed the interactions between pyoluteorin and both PhlH and PhlF, modulating gene expression. Phylogenetic analyses showed a wide distribution of PhlH and PhlF across <i>Pseudomonas</i> spp. with conserved ligand-binding domains. These findings deepen our understanding of interspecies signaling mechanisms and highlight the potential for designing co-inhabiting <i>Pseudomonas</i> spp. as effective biocontrol agents.