title: A ptsP deficiency in PGPR Pseudomonas fluorescens SF39a affects bacteriocin production and bacterial fitness in the wheat rhizosphere.
abstract: Pseudomonas fluorescens SF39a is a plant-growth-promoting bacterium isolated from wheat rhizosphere. In this report, we demonstrate that this native strain secretes bacteriocins that inhibit growth of phytopathogenic strains of the genera Pseudomonas and Xanthomonas. An S-type pyocin gene was detected in the genome of strain SF39a and named pys. A non-polar pys::Km mutant was constructed. The bacteriocin production was impaired in this mutant. To identify genes involved in bacteriocin regulation, random transposon mutagenesis was carried out. A miniTn5Km1 mutant, called P. fluorescens SF39a-451, showed strongly reduced bacteriocin production. This phenotype was caused by inactivation of the ptsP gene which encodes a phosphoenolpyruvate phosphotransferase (EI(Ntr)) of the nitrogen-related phosphotransferase system (PTS(Ntr)). In addition, this mutant showed a decrease in biofilm formation and protease production, and an increase in surface motility and pyoverdine production compared with the wild-type strain. Moreover, we investigated the ability of strain SF39a-451 to colonize the wheat rhizosphere under greenhouse conditions. Interestingly, the mutant was less competitive than the wild-type strain in the rhizosphere. To our knowledge, this study provides the first evidence of both the relevance of the ptsP gene in bacteriocin production and functional characterization of a pyocin S in P. fluorescens.
authors.affiliation: Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36-Km 601-5800, Río Cuarto, Córdoba, Argentina. Electronic address: agodino@exa.unrc.edu.ar.
authors.forename: Agustina
authors.initials: A
authors.lastname: Godino
authors.affiliation: Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36-Km 601-5800, Río Cuarto, Córdoba, Argentina. Electronic address: aprincipe@exa.unrc.edu.ar.
authors.forename: Analía
authors.initials: A
authors.lastname: Príncipe
authors.affiliation: Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36-Km 601-5800, Río Cuarto, Córdoba, Argentina. Electronic address: sfischer@exa.unrc.edu.ar.
authors.forename: Sonia
authors.initials: S
authors.lastname: Fischer
mesh_terms: D004251:DNA Transposable Elements; D017353:Gene Deletion; D016254:Mutagenesis, Insertional; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D011551:Pseudomonas fluorescens / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D011709:Pyocins / Q000378:metabolism*; D058441:Rhizosphere; D012988:Soil Microbiology; D014908:Triticum / Q000382:microbiology*; D014974:Xanthomonas
chemical_list: D004251:DNA Transposable Elements; D011709:Pyocins; D010770:Phosphotransferases
keywords: Bacteriocin; Competitiveness; Phosphotransferase system; Plant growth-promoting rhizobacterium; Pseudomonas; Regulation