Godino Agustina, Príncipe Analía, Fischer Sonia
Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36-Km 601-5800, Río Cuarto, Córdoba, Argentina.
Res Microbiol. 2016 Apr;167(3):178-89. doi: 10.1016/j.resmic.2015.12.003. Epub 2015 Dec 18.
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.
荧光假单胞菌SF39a是一种从小麦根际分离得到的促进植物生长的细菌。在本报告中，我们证明了这种天然菌株能分泌抑制假单胞菌属和黄单胞菌属植物致病菌株生长的细菌素。在菌株SF39a的基因组中检测到一个S型绿脓菌素基因，并将其命名为pys。构建了一个非极性的pys::Km突变体。该突变体的细菌素产生受到损害。为了鉴定参与细菌素调控的基因，进行了随机转座子诱变。一个名为荧光假单胞菌SF39a - 451的miniTn5Km1突变体，其细菌素产生显著减少。这种表型是由ptsP基因失活引起的，该基因编码氮相关磷酸转移酶系统（PTS(Ntr)）的磷酸烯醇丙酮酸磷酸转移酶（EI(Ntr)）。此外，与野生型菌株相比，该突变体的生物膜形成和蛋白酶产生减少，表面运动性和绿脓菌素产生增加。此外，我们研究了菌株SF39a - 451在温室条件下在小麦根际定殖的能力。有趣的是，该突变体在根际的竞争力不如野生型菌株。据我们所知，本研究首次提供了ptsP基因在细菌素产生中的相关性以及荧光假单胞菌中绿脓菌素S功能特性的证据。
