REGULATION OF ANTIBIOTIC PRODUCTION IN ROOT-COLONIZING PSEUDOMONAS SPP. AND RELEVANCE FOR BIOLOGICAL CONTROL OF PLANT DISEASE

Abstract

Certain strains of fluorescent pseudomonads are important biological components of agricultural soils that are suppressive to diseases caused by pathogenic fungi on crop plants. The biocontrol abilities of such strains depend essentially on aggressive root colonization, induction of systemic resistance in the plant, and the production of diffusible or volatile antifungal antibiotics. Evidence that these compounds are produced in situ is based on their chemical extraction from the rhizosphere and on the expression of antibiotic biosynthetic genes in the producer strains colonizing plant roots. Well-characterized antibiotics with biocontrol properties include phenazines, 2,4-diacetylphloroglucinol, pyoluteorin, pyrrolnitrin, lipopeptides, and hydrogen cyanide. In vitro, optimal production of these compounds occurs at high cell densities and during conditions of restricted growth, involving (i) a number of transcriptional regulators, which are mostly pathway-specific, and (ii) the GacS/GacA two-component system, which globally exerts a positive effect on the production of extracellular metabolites at a posttranscriptional level. Small untranslated RNAs have important roles in the GacS/GacA signal transduction pathway. One challenge in future biocontrol research involves development of new strategies to overcome the broad toxicity and lack of antifungal specificity displayed by most biocontrol antibiotics studied so far.

Insect pathogenicity in plant-beneficial pseudomonads: phylogenetic distribution and comparative genomics

“…Many strains of fluorescent pseudomonads isolated from the rhizosphere have been studied for their ability to suppress root diseases, to promote plant growth and to induce systemic resistance (Haas and Défago, 2005;Bakker et al, 2007). They harbor strain-specific arsenals of antifungal metabolites, which enable them to inhibit pathogen growth through direct antibiosis (Haas and Keel, 2003;Raaijmakers et al, 2010). All these features make fluorescent pseudomonads interesting organisms for use as biofertilizers and biopesticides in sustainable agriculture and several products have been commercialized .…”

Comparative genomic, proteomic and exoproteomic analyses of three Pseudomonas strains reveals novel insights into the phosphorus scavenging capabilities of soil bacteria

“…Various Pseudomonas strains can also degrade organic P compounds, such as phytate, phosphonates and phosphites (Ternan and Quinn, 1998; White and Metcalf, 2004, 2007). Three Pseudomonas strains , Pseudomonas putida BIRD‐1, Pseudomonas fluorescens SBW25 and Pseudomonas stutzeri DSM4166 (hereafter, BIRD‐1, SBW25 and DSM4166 respectively) are three examples of PGPR (Naseby et al ., 2001; Hass and Keel, 2003; Preston, 2004; Yu et al ., 2011; Roca et al ., 2013). SBW25 inhabits the rhizosphere of Pea plants and is antagonistic towards the pathogen Pythium ultimum (Naseby et al ., 2001), whereas DSM4166, an ‘unusual’ nitrogen‐fixing bacterium, was isolated from a cultivar of Sorghum nutans (Yu et al ., 2011).…”

Sepsis por Pseudomonas aeruginosa en un lactante previamente sano

“…Un dato interesante asociado al cuadro del paciente fue el uso de una "calita de cardenal" para el manejo del cuadro febril, considerando que Pseudomonas spp habita normalmente en plantas y vegetales como colonizador; actualmente se estudia su probable rol como agente patógeno o regulador biológico 14,15 . Presumimos que esta bacteria pudo estar colonizando el vegetal utilizado lo cual facilitó su adquisición por el paciente.…”