Genomic analysis of antifungal metabolite production by Pseudomonas fluorescens Pf-5

2007 ◽  
pp. 265-278 ◽  
Author(s):  
Joyce E. Loper ◽  
Harald Gross
Keyword(s):  
Pseudomonas Fluorescens ◽  
Genomic Analysis ◽  
Antifungal Metabolite ◽  
Metabolite Production

scholarly journals An Interspecies Signaling System Mediated by Fusaric Acid Has Parallel Effects on Antifungal Metabolite Production by Pseudomonas protegens Strain Pf-5 and Antibiosis of Fusarium spp.

2015 ◽  
Vol 82 (5) ◽  
pp. 1372-1382 ◽  
Author(s):  
Maria Carolina Quecine ◽  
Teresa A. Kidarsa ◽  
Neal C. Goebel ◽  
Brenda T. Shaffer ◽  
Marcella D. Henkels ◽  
...  
Keyword(s):  
Culture Media ◽  
Antibiotic Production ◽  
Fusaric Acid ◽  
Plant Diseases ◽  
Transcriptional Level ◽  
Signaling System ◽  
Content Type ◽  
Antifungal Metabolite ◽  
Metabolite Production ◽  
Antifungal Metabolites

ABSTRACTPseudomonas protegensstrain Pf-5 is a rhizosphere bacterium that suppresses soilborne plant diseases and produces at least seven different secondary metabolites with antifungal properties. We derived mutants of Pf-5 with single and multiple mutations in biosynthesis genes for seven antifungal metabolites: 2,4-diacetylphoroglucinol (DAPG), pyrrolnitrin, pyoluteorin, hydrogen cyanide, rhizoxin, orfamide A, and toxoflavin. These mutants were tested for inhibition of the pathogensFusarium verticillioidesandFusarium oxysporumf. sp.pisi. Rhizoxin, pyrrolnitrin, and DAPG were found to be primarily responsible for fungal antagonism by Pf-5. Previously, other workers showed that the mycotoxin fusaric acid, which is produced by manyFusariumspecies, includingF. verticillioides, inhibited the production of DAPG byPseudomonasspp. In this study, amendment of culture media with fusaric acid decreased DAPG production, increased pyoluteorin production, and had no consistent influence on pyrrolnitrin or orfamide A production by Pf-5. Fusaric acid also altered the transcription of biosynthetic genes, indicating that the mycotoxin influenced antibiotic production by Pf-5 at the transcriptional level. Addition of fusaric acid to the culture medium reduced antibiosis ofF. verticillioidesby Pf-5 and derivative strains that produce DAPG but had no effect on antibiosis by Pf-5 derivatives that suppressedF. verticillioidesdue to pyrrolnitrin or rhizoxin production. Our results demonstrated the importance of three compounds, rhizoxin, pyrrolnitrin, and DAPG, in suppression ofFusariumspp. by Pf-5 and confirmed that an interspecies signaling system mediated by fusaric acid had parallel effects on antifungal metabolite production and antibiosis by the bacterial biological control organism.

scholarly journals Cyclic-di-GMP Regulates the Quorum-Sensing System and Biocontrol Activity of Pseudomonas fluorescens 2P24 through the RsmA and RsmE Proteins

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Fei Liang ◽  
Bo Zhang ◽  
Qingqing Yang ◽  
Yang Zhang ◽  
Dehong Zheng ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Pseudomonas Fluorescens ◽  
Genomic Analysis ◽  
Fine Tuning ◽  
Content Type ◽  
Rhizosphere Bacterium ◽  
Wide Range ◽  
Biocontrol Activity ◽  
Biocontrol Potential ◽  
Polyketide Antibiotic

ABSTRACT Pseudomonas fluorescens 2P24 is a rhizosphere bacterium that protects many crop plants against soilborne diseases caused by phytopathogens. The PcoI/PcoR quorum-sensing (QS) system and polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are particularly relevant to the strain’s biocontrol potential. In this study, we investigated the effects of c-di-GMP on the biocontrol activity of strain 2P24. The expression of the Escherichia coli diguanylate cyclase (YedQ) and phosphodiesterase (YhjH) in P. fluorescens 2P24 significantly increased and decreased the cellular concentration of c-di-GMP, respectively. The production of the QS signals N-acyl homoserine lactones (AHLs) and 2,4-DAPG was negatively regulated by c-di-GMP in 2P24. The regulatory proteins RsmA and RsmE were positively regulated by c-di-GMP. Genomic analysis revealed that 2P24 has 23 predicted proteins that contain c-di-GMP-synthesizing or -degrading domains. Among these proteins, C0J56_12915, C0J56_13325, and C0J56_27925 contributed to the production of c-di-GMP and were also involved in the regulation of the QS signal and antibiotic 2,4-DAPG production in P. fluorescens. Overexpression of C0J56_12915, C0J56_13325, and C0J56_27925 in 2P24 impaired its root colonization and biocontrol activities. Taken together, these results demonstrated that c-di-GMP played an important role in fine-tuning the biocontrol traits of P. fluorescens. IMPORTANCE In various bacteria, the bacterial second messenger c-di-GMP influences a wide range of cellular processes. However, the function of c-di-GMP on biocontrol traits in the plant-beneficial rhizobacteria remains largely unclear. The present work shows that the QS system and polyketide antibiotic 2,4-DAPG production are regulated by c-di-GMP through RsmA and RsmE proteins in P. fluorescens 2P24. The diguanylate cyclases (DGCs) C0J56_12915, C0J56_13325, and C0J56_27925 are especially involved in regulating the biocontrol traits of 2P24. Our work also demonstrated a connection between the Gac/Rsm cascade and the c-di-GMP signaling pathway in P. fluorescens.

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