A directed genome evolution method to enhance hydrogen production in .

Nitrogenase-dependent H production by photosynthetic bacteria, such as , has been extensively investigated. An important limitation to increase H production using genetic manipulation is the scarcity of high-throughput screening methods to detect possible overproducing mutants. Previously, we engineered strains that emitted fluorescence in response to H and used them to identify mutations in the nitrogenase Fe protein leading to H overproduction.

Functional Nitrogenase Cofactor Maturase NifB in Mitochondria and Chloroplasts of .

Engineering plants to synthesize nitrogenase and assimilate atmospheric N will reduce crop dependency on industrial N fertilizers. This technology can be achieved by expressing prokaryotic nitrogen fixation gene products for the assembly of a functional nitrogenase in plants. NifB is a critical nitrogenase component since it catalyzes the first committed step in the biosynthesis of all types of nitrogenase active-site cofactors.

Hydrogen overproducing nitrogenases obtained by random mutagenesis and high-throughput screening.

When produced biologically, especially by photosynthetic organisms, hydrogen gas (H) is arguably the cleanest fuel available. An important limitation to the discovery or synthesis of better H-producing enzymes is the absence of methods for the high-throughput screening of H production in biological systems. Here, we re-engineered the natural H sensing system of Rhodobacter capsulatus to direct the emission of LacZ-dependent fluorescence in response to nitrogenase-produced H.

F113 Can Produce a Second Flagellar Apparatus, Which Is Important for Plant Root Colonization.

The genomic sequence of F113 has shown the presence of a 41 kb cluster of genes that encode the production of a second flagellar apparatus. Among 2,535 pseudomonads strains with sequenced genomes, these genes are only present in the genomes of F113 and other six strains, all but one belonging to the cluster of species, in the form of a genetic island. The genes are homologous to the flagellar genes of the soil bacterium .

Identification of flgZ as a flagellar gene encoding a PilZ domain protein that regulates swimming motility and biofilm formation in Pseudomonas.

Diguanylate cyclase and phosphodiesterase enzymatic activities control c-di-GMP levels modulating planktonic versus sessile lifestyle behavior in bacteria. The PilZ domain is described as a sensor of c-di-GMP intracellular levels and the proteins containing a PilZ domain represent the best studied class of c-di-GMP receptors forming part of the c-di-GMP signaling cascade. In P.

Genome sequence reveals that Pseudomonas fluorescens F113 possesses a large and diverse array of systems for rhizosphere function and host interaction.

Background: Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) isolated from the sugar-beet rhizosphere. This bacterium has been extensively studied as a model strain for genetic regulation of secondary metabolite production in P. fluorescens, as a candidate biocontrol agent against phytopathogens, and as a heterologous host for expression of genes with biotechnological application.

The Gac-Rsm and SadB signal transduction pathways converge on AlgU to downregulate motility in Pseudomonas fluorescens.

Flagella mediated motility in Pseudomonas fluorescens F113 is tightly regulated. We have previously shown that motility is repressed by the GacA/GacS system and by SadB through downregulation of the fleQ gene, encoding the master regulator of the synthesis of flagellar components, including the flagellin FliC. Here we show that both regulatory pathways converge in the regulation of transcription and possibly translation of the algU gene, which encodes a sigma factor.

Genome sequence of the biocontrol strain Pseudomonas fluorescens F113.

Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) that has biocontrol activity against fungal plant pathogens and is a model for rhizosphere colonization. Here, we present its complete genome sequence, which shows that besides a core genome very similar to those of other strains sequenced within this species, F113 possesses a wide array of genes encoding specialized functions for thriving in the rhizosphere and interacting with eukaryotic organisms.

Pseudomonas fluorescens F113 mutant with enhanced competitive colonization ability and improved biocontrol activity against fungal root pathogens.

Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system.

Efficient rhizosphere colonization by Pseudomonas fluorescens f113 mutants unable to form biofilms on abiotic surfaces.

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

Three independent signalling pathways repress motility in Pseudomonas fluorescens F113.

Motility is one of the most important traits for rhizosphere colonization by pseudomonads. Despite this importance, motility is severely repressed in the rhizosphere-colonizing strain Pseudomonas fluorescens F113. This bacterium is unable to swarm under laboratory conditions and produce relatively small swimming haloes.

Transcriptional organization of the region encoding the synthesis of the flagellar filament in Pseudomonas fluorescens.

Pseudomonas fluorescens F113 is motile by means of type b flagella. Analysis of the region encoding the synthesis of the flagellar filament has shown a transcriptional organization different from that of type a flagella. Additionally to the promoters driving fliC, fliD, and fleQ expression, we have found promoters upstream of the flaG gene and the fliST operon.