A ptsP deficiency in the PGPR Pseudomonas fluorescens SF39a affects bacteriocin production and bacterial fitness in the wheat rhizosphere

AGUSTINA GODINO; ANALÍA PRÍNCIPE; SONIA FISCHER

RESEARCH IN MICROBIOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 167 p. 178 - 189

0923-2508

Pseudomonas fluorescens SF39a is a plant-growth-promoting bacterium isolated from wheat rhizosphere. In this report, we demonstrate thatthis native strain secretes bacteriocins that inhibit growth of phytopathogenic strains of the genera Pseudomonas and Xanthomonas. An S-typepyocin gene was detected in the genome of strain SF39a and named pys. A non-polar pys::Km mutant was constructed. The bacteriocin productionwas 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 whichencodes a phosphoenolpyruvate phosphotransferase (EINtr) of the nitrogen-related phosphotransferase system (PTSNtr). In addition, this mutantshowed a decrease in biofilm formation and protease production, and an increase in surface motility and pyoverdine production compared withthe 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 firstevidence of both the relevance of the ptsP gene in bacteriocin production and functional characterization of a pyocin S in P. fluorescens.