Role of secondary metabolites in the interaction betweenPseudomonas fluorescensand soil microorganisms under iron-limited conditions

Abstract

Microorganisms can be versatile in their interactions with each other, being variously beneficial, neutral or antagonistic in their effect. Although this versatility has been observed among many microorganisms and in many environments, little is known regarding the mechanisms leading to these changes in behavior. In the present work, we analyzed the mechanism by which the soil bacterium Pseudomonas fluorescens BBc6R8 shifts from stimulating the growth of the ectomycorrhizal fungus Laccaria bicolor S238N to killing the fungus. We show that among the three secondary metabolites produced by the bacterial strain-the siderophores enantio-pyochelin and pyoverdine, and the biosurfactant viscosin-the siderophores are mainly responsible for the antagonistic activity of the bacterium under iron-limited conditions. While the bacterial strain continues to produce beneficial factors, their effects are overridden by the action of their siderophores. This antagonistic activity of the strain P. fluorescens BBC6R8 in iron-depleted environments is not restricted to its influence on L. bicolor, since it was also seen to inhibit the growth of the actinomycete Streptomyces ambofaciens ATCC23877. We show that the strain P. fluorescens BBc6R8 uses different strategies to acquire iron, depending on certain biotic and abiotic factors.

Importance of Endophytic Strains Pantoea agglomerans in the Biological Control of Rhizoctonia solani

“…When developing new biological preparations, antagonistic interactions between different microorganisms are adopted as well as antagonistic reactions between produced metabolites and the phytopathogens. The antagonistic bacteria are among others: Pseudomonas fluorescens, P. putida, P. malophilia, Agrobacterium radiobacter, Bacillus subtilis, B. cereus, B. amyloliquefaciens, B. mycoides, B. brevis, Serratia odorifera, Pantoea agglomerans [6][7][8][9][10]. Their mode of plant's health improvement is mainly based on the pathogen's growth inhibition and an induction of plant's resistance.…”

“…Their mode of plant's health improvement is mainly based on the pathogen's growth inhibition and an induction of plant's resistance. However, there are a few mechanisms employed in their antagonistic activity against pathogens, which include: a competition for living space and nutrients, mycoparasite, production of antifungal compounds including antibiotics and toxins, induction of plant's resistance ISR (Induced Systemic Resistance), production of volatile compounds inhibiting pathogens' growth which may play an important role in a biocontrol process [7,8].…”

High‐throughput analysis of genes involved in biocontrol performance ofPseudomonas fluorescensNBC275 against Gray mold

“…Siderophores modulate the availability of iron, which indirectly stimulates the biosynthesis of other antimicrobial compounds (Duffy and Défago ). Maldonado‐González et al () reported that pyoverdine was not a key factor for biocontrol ability of P. fluorescens PICF7, whereas Deveau et al () showed that pyoverdine was responsible for antagonism against fungus Laccaria bicolor S238N and actinomycete Streptomyces ambofaciens ATCC 23877 under iron‐limited conditions. Several pyoverdine‐related genes contributed to the swarming motility of Pseudomonas aerudinosa PA14 (Strehmel et al ).…”

A decade of understanding secondary metabolism in Pseudomonas spp. for sustainable agriculture and pharmaceutical applications

“…Similarly, MALDI mass spectrometry of P. aeruginosa treated with macrolide antibiotic azithromycin demonstrated the inability of azithromycin to inhibit cell-to-cell signaling in pathogenic strains of P. aeruginosa (Phelan et al 2015). Also, using MALDI-IMS, a significant study determined the siderophore pyochelin as the main antagonizing metabolite of P. fluorescens BBc6R8 against ectomycorrhizal fungus Laccaria bicolor S238N (Deveau et al 2016). The integration of MALDI-IMS with LC-MS/MS techniques has successfully unveiled the potential adaptability of pseudomonads in response to challenging environmental conditions.…”