Jimena Alicia Ruiz

Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. CONICET · CONICET

Fusaric acid (FA) is a mycotoxin produced by several Fusarium species. Burkholderia ambifaria T16 is a rhizosphere bacterium, able to use FA as sole nitrogen, carbon, and energy source. By screening a transposon insertional library, combined with proteomic analysis, genes and enzymes involved in the microbial degradation of FA were identified for t...

Burkholderia ambifaria T16 is a bacterium isolated from the rhizosphere of barley plants that showed a remarkable antifungal activity. This strain was also able to degrade fusaric acid (5-Butylpyridine-2-carboxylic acid) and detoxify this mycotoxin in inoculated barley seedlings. Genes and enzymes responsible for fusaric acid degradation have an im...

Burkholderia ambifaria T16 is a bacterial strain isolated from the rhizosphere of barley plants, which showed a potent antifungal activity against several Fusarium species. In this work, the construction of a mini-Tn5 insertional library in this strain allowed us the identification of several genes involved in the antifungal activity. In particular...

Thermoanaerobacterium thermosaccharolyticum GSU5 was isolated from animal dung collected in a pasture plain in Buenos Aires, Argentina. This thermophilic and anaerobic microorganism was able to produce butanol and ethanol, but not acetone, using sugars such as xylose, arabinose, glucose, galactose, fructose, sucrose, and cellobiose. Key metabolic e...

Pseudomonas protegens synthesizes two major iron-chelating metabolites (siderophores): pyoverdine (Pvd) and enantio-pyochelin (E-Pch). Although iron sequestration and uptake seem to be the main biological role of these siderophores, other functions including metal homeostasis and antibiotic activity have been proposed. The aim of this study was to...

Fusaric acid (FA) is a fungal metabolite produced by several Fusarium species responsible for wilts and root rot diseases of a great variety of plants. Bacillus spp. and Pseudomonas spp. have been considered as promising biocontrol agents against phytopathogenic Fusarium spp., however it has been demonstrated that FA negatively affects growth and p...

Fusaric acid is produced by pathogenic fungi of the genus Fusarium, and is toxic to plants and rhizobacteria. Many fluorescent pseudomonads can prevent wilt diseases caused by these fungi. This study was undertaken to evaluate the effect of fusaric acid on P. protegens Pf-5 and elucidate the mechanisms that enable the bacterium to survive in the pr...

Pseudomonas extremaustralis produces mainly polyhydroxybutyrate (PHB), a short chain length polyhydroxyalkanoate (sclPHA) infrequently found in Pseudomonas species. Previous studies with this strain demonstrated that PHB genes are located in a genomic island. In this work, the analysis of the genome of P. extremaustralis revealed the presence of an...

Bioprocesses conducted under conditions with restricted O2 supply are increasingly exploited for the synthesis of reduced biochemicals using different biocatalysts. The model facultative anaerobe Escherichia coli has elaborate sensing and signal transduction mechanisms for redox control in response to the availability of O2 and other electron accep...

Bioprocesses conducted under conditions with restricted O2 supply are increasingly exploited for the synthesis of reduced biochemicals using different biocatalysts. The model facultative aerobe Escherichia coli, the microbial cell factory par excellence, has elaborate sensing and signal transduction mechanisms that respond to the availability of el...

Expression of lysP, which encodes the lysine-specific transporter LysP in Escherichia coli, is regulated by the concentration of exogenous available lysine. In this study, the LysR-type transcriptional regulator ArgP was identified as the activator of lysP expression. At lysine concentrations higher than 25 μM, lysP expression was shut off and phen...

To determine whether the stationary sigma factor, sigma(S), influences polyhydroxyalkanoate metabolism in Pseudomonas putida KT2440, an rpoS-negative mutant was constructed to evaluate polyhydroxyalkanoate accumulation and expression of a translational fusion to the promoter region of the genes that code for polyhydroxyalkanoate synthase 1 (phaC1)...

Escherichia coli and other facultative anaerobes can adapt their metabolism according to oxygen availability by means of aerobic and anaerobic respiration and fermentation. ArcAB is a two-component signal transduction system that controls, at the transcriptional level, the choice of energy generation pathway according to the intracellular redox sta...

arcA codes for a central regulator in Escherichia coli that responds to redox conditions of growth. Mutations in this gene, originally named dye, confer sensitivity to toluidine blue and other redox dyes. However, the molecular basis for the dye-sensitive phenotype has not been elucidated. In this work, we show that toluidine blue redirects electro...

Pseudomonas sp. 14-3, a strain that accumulates large quantities of polyhydroxybutyrate (PHB) when grown on octanoate, was isolated from Antarctic environments. This isolate was characterized on the basis of phenotypic features and partial sequencing of its 16S ribosomal RNA gene. Pseudomonas sp. 14-3 showed increased tolerance to both thermal and...

The expression of the rpoS gene during PHA depolymerization was monitored in Pseudomonas oleovorans GPo1 and its mutant defective in PHA degradation by analyzing the tolerance to oxidative and thermal stresses and the RpoS intracellular content. An increase in the tolerance to H2O2 and heat shock was observed coincidentally with PHA degradation. We...

Los polihidroxialcanoatos (PHA) son sintetizados por muchas especies de distintos géneros bacterianos en condiciones de crecimiento caracterizadas por exceso en la fuente carbonada y limitación de otros nutrientes como nitrógeno o fósforo. Estos polímeros se acumulan en gránulos intracitoplasmáticos y son utilizados como fuente de carbono y energía...

Pseudomonas oleovorans GPo1 and its polyhydroxyalkanoic acid (PHA) depolymerization-minus mutant, GPo500 phaZ, residing in natural water microcosms, were utilized to asses the effect of PHA availability on survival and resistance to stress agents. The wild-type strain showed increased survival compared to the PHA depolymerase-minus strain. The appe...

Bacterial survival in natural environments involves the ability of scavenging nutrients and energy sources. Polyhydroxyalkanoates (PHAs) are intracellular polymers that endow bacteria with enhanced survival capabilities in adverse environmental conditions. In this paper we compared survival of Pseudomonas oleovorans wild type and PHA depolymerase m...

Bacillus megaterium is a potential bioremediation and biocontrol agent. The accumulation of reserve polymers, such as poly-3-hydroxybutyrate (PHB), increases survival of B. megaterium in water. We used wild-type strains of this species and mutant strains deficient in PHB synthesis in soil microcosms for testing the hypothesis that differences in su...