Commensal Pseudomonas fluorescens Strains Protect from Closely Related Pseudomonas Pathogens in a Colonization-Dependent Manner.

Plants form commensal associations with soil microorganisms, creating a root microbiome that provides benefits, including protection against pathogens. While bacteria can inhibit pathogens through the production of antimicrobial compounds , it is largely unknown how microbiota contribute to pathogen protection . We developed a gnotobiotic model consisting of Arabidopsis thaliana and the opportunistic pathogen Pseudomonas sp.

Putrescine and Its Metabolic Precursor Arginine Promote Biofilm and c-di-GMP Synthesis in Pseudomonas aeruginosa.

Pseudomonas aeruginosa, an opportunistic bacterial pathogen, can synthesize and catabolize several small cationic molecules known as polyamines. In several clades of bacteria, polyamines regulate biofilm formation, a lifestyle-switching process that confers resistance to environmental stress. The polyamine putrescine and its biosynthetic precursors, l-arginine and agmatine, promote biofilm formation in Pseudomonas spp.

Convergent gain and loss of genomic islands drive lifestyle changes in plant-associated Pseudomonas.

Host-associated bacteria can have both beneficial and detrimental effects on host health. While some of the molecular mechanisms that determine these outcomes are known, little is known about the evolutionary histories of pathogenic or mutualistic lifestyles. Using the model plant Arabidopsis, we found that closely related strains within the Pseudomonas fluorescens species complex promote plant growth and occasionally cause disease.

A Genome-Wide Screen Identifies Genes in Rhizosphere-Associated Required to Evade Plant Defenses.

and related plant root ("rhizosphere")-associated species contribute to plant health by modulating defenses and facilitating nutrient uptake. To identify bacterial fitness determinants in the rhizosphere of the model plant , we performed a high-throughput transposon sequencing (Tn-Seq) screen using the biocontrol and growth-promoting strain sp. WCS365.