Summary We report the identification of an ATP‐binding cassette (ABC) transporter and associated large cell‐surface protein that are required for biofilm formation by Pseudomonas fluorescens WCS365. The genes coding these proteins designated lap l arge a dhesion p rotein. LapA protein, with predicted molecular weight ∼900 kDa, is found to be loosely cell surface present in culture supernatant. LapB, LapC LapE cytoplasmic membrane‐localized ATPase, membrane fusion outer component,...

ABSTRACT Many agricultural uses of bacteria require the establishment efficient bacterial populations in rhizosphere, for which colonization plant seeds often constitutes a critical first step. Pseudomonas putida KT2440 is strain that colonizes rhizosphere number agronomically important plants at high population densities. To identify functions involved initial seed by P. KT2440, we subjected this to transposon mutagenesis and screened mutants defective attachment corn seeds. Eight different...

Abstract Background Mutualistic interactions less well known than those between rhizobia and legumes are commonly found plants bacteria, frequently pseudomonads, which colonize roots adjacent soil areas (the rhizosphere). Results A global analysis of Pseudomonas putida genes expressed during their interaction with maize revealed how a bacterial population adjusts its genetic program to this lifestyle. Differentially were identified by comparing rhizosphere-colonizing populations three...

Many of the changes in gene expression observed when Escherichia coli cells enter stationary phase are regulated at level transcription initiation. A group stationary-phase-inducible promoters, known as "gearbox" promoter, display a characteristic sequence -10 region which differs greatly from consensus for sigma 70-dependent promoters. Here we describe our studies on gearbox promoters bolAp1 and mcbAp, responsible temporally bolA genes involved synthesis peptide antibiotic microcin B17,...

We have investigated the role of LapF, one two largest proteins encoded in genome Pseudomonas putida KT2440, bacterial colonization solid surfaces. LapF is 6310 amino acids long, and localized on cell surface. The C-terminal region protein essential for its secretion, which presumably requires ABC transporter by an operon (lapHIJ) adjacent to lapF gene. Although initial attachment stages are not different between wild type a mutant, microcolony formation subsequent development mature biofilm...

Quorum sensing is a bacterial communication mechanism that controls genes, enabling bacteria to live as communities, such biofilms. Homoserine lactone (HSL) molecules function quorum-sensing signals for Gram-negative bacteria. Plants also produce previously unidentified compounds affect quorum sensing. We identified rosmarinic acid plant-derived compound functioned an HSL mimic. In vitro assays showed bound the regulator RhlR of Pseudomonas aeruginosa PAO1 and competed with ligand...

ABSTRACT l -Lysine catabolism in Pseudomonas putida KT2440 was generally thought to occur via the aminovalerate pathway. In this study we demonstrate operation of alternative aminoadipate pathway with intermediates d -lysine, -pipecolate, and aminoadipate. The simultaneous both pathways for use -lysine as sole carbon nitrogen source confirmed genetically. Mutants mutations either failed source, although they still used albeit at reduced growth rates. New genes were identified pathways,...

Mechanisms governing biofilm formation have generated considerable interest in recent years, yet comparative analyses of processes for bacterial establishment on abiotic and biotic surfaces are still limited. In this report we expanded previous information the genetic determinants required colonization plant by Pseudomonas putida populations analyzed their correlation with surfaces. Insertional mutations affecting flagellar genes or synthesis transport large adhesin LapA lead to decreased...

ABSTRACT LapA and LapF are large extracellular proteins that play a relevant role in biofilm formation by Pseudomonas putida . Current evidence favors sequential model which is first required for the initial adhesion of individual bacteria to surface, while participates later stages development. In agreement with this model, lapF transcription was previously shown take place at late times growth respond stationary-phase sigma factor RpoS. We have now analyzed pattern lapA other regulatory...

Although it is well established that one- and two-component regulatory systems participate in regulating biofilm formation, there also exists evidence suggesting chemosensory pathways are involved. However, little information about which chemoreceptors signals modulate this process. Here we report the generation of complete set chemoreceptor mutants Pseudomonas putida KT2440 identification four with significantly altered phenotypes. These receptors a WspA homologue aeruginosa, previously...

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Motility is a key trait for rhizosphere colonization by Pseudomonas fluorescens. Mutants with reduced motility are poor competitors, and hypermotile, more competitive phenotypic variants selected in the rhizosphere. Flagellar feature associated to planktonic, free-living single cells, although it necessary initial steps of biofilm formation, bacteria lack flagella. To test correlation between formation colonization, we have used P. fluorescens F113 hypermotile derivatives mutants affected...

Summary Pseudomonas putida KT2440 is unable to swarm at its common temperature of growth in the laboratory (30°C) but exhibits surface motility similar swarming patterns other between 18°C and 28°C. These motile cells show differentiation, consisting on elongation presence appendages. Analysis a collection mutants define molecular determinants this type movement shows that while IV pili lipopolysaccharide O‐antigen are requisites flagella not. Although flagellar was macroscopically...

Summary We used a combination of in silico and large‐scale mutagenesis approaches to expand our current knowledge the genetic determinants by Pseudomonas putida KT2440 attach surfaces. first identified orthologues that have been annotated aeruginosa as potentially involved attachment. In this search 67 paired‐related genes P. were associated adhesion. To test potential role corresponding gene products adhesion, 37 knockout mutants KT2440, available Reference Culture Collection, analysed with...

The aim of this study was to find and use rhizobacteria able confer plants advantages deal with saline conditions.We isolated 24 different bacterial species from the rhizosphere halophyte growing in Santiago del Estero, Argentina salt flat. Four strains were selected upon their ability grow salinity biochemical traits associated plant growth promotion. Next, we tested adhesion on soybean seeds surface root colonization four isolates. Isolate 19 stood out rest for further experiments. This...

ABSTRACT We have characterized the expression pattern of a gene, ddcA , involved in initial colonization corn seeds by Pseudomonas putida KT2440. The gene codes for putative membrane polypeptide belonging to family conserved proteins unknown function. Members this are widespread among prokaryotes and include products Salmonella enterica serovar Typhimurium expressed during invasion macrophages psiE an Escherichia coli phosphate starvation-inducible gene. Although its specific role is...

Summary We describe the first two‐partner secretion system known to play a role in mutualistic plant–bacterial interactions, identified soil and rhizosphere‐colonizing bacterium Pseudomonas putida KT2440. The genes coding for two components of are organized an operon, which we have named hlpBA . HlpA is secreted protein that has similarities with iron‐regulated haemolysins, while HlpB would be responsible activation transport across outer membrane. Mutations this novel result reduced...

LapF is a large secreted protein involved in microcolony formation and biofilm maturation Pseudomonas putida. Its C-terminal domain shows the characteristics of proteins through type I secretion system includes predicted calcium binding motif. We provide experimental evidence specific Ca(2+) to purified (CLapF). Calcium promotes aggregates, which disappear presence chelator EGTA. Immunolocalization also tendency this accumulate vivo certain extracellular regions. These findings, along with...