Papers by Hilda Rodriguez
Plant growth-promoting bacteria (PGPB) are soil and rhizosphere bacteria that can benefit plant g... more Plant growth-promoting bacteria (PGPB) are soil and rhizosphere bacteria that can benefit plant growth by different mechanisms. The ability of some microorganisms to convert insoluble phosphorus (P) to an accessible form, like orthophosphate, is an important trait in a PGPB for increasing plant yields. In this mini-review, the isolation and characterization of genes involved in mineralization of organic P sources (by the action of enzymes acid phosphatases and phytases), as well as mineral phosphate solubilization, is reviewed. Preliminary results achieved in the engineering of bacterial strains for improving capacity for phosphate solubilization are presented, and application of this knowledge to improving agricultural inoculants is discussed.
FEMS Microbiology Ecology, 2000
Azospirillum brasilense 8-I was chromosomally labeled with green fluorescent protein (gfp) genes,... more Azospirillum brasilense 8-I was chromosomally labeled with green fluorescent protein (gfp) genes, using either the native promoterless gfp gene or the mutant gfpmut2 gene under the transcriptional control of the neomycin phosphate transferase (npt2) promoter inserted into Tn5 suicide plasmid vectors. One A. brasilense exconjugant, showing a steady and strong fluorescence following irradiation with 365-nm UV light was characterized in detail. This strain, A. brasilense 8-I-gfp showed increased N 2 -fixation of approximately threefold, up to a twofold increase in exopolysaccharide production, and a significant decrease in indole-3-acetic acid and poly-b-hydroxybutyrate production over the parental strain. Sequence analysis showed that the Tn5 carrying the gfp gene was inserted in the clpX gene encoding a heat-shock protein. This data is consistent with a model in which the observed physiological changes are a consequence of pleiotropic changes that occur as a consequence of impaired heat shock (stress) protein synthesis. In summary, (i) chromosomally labelled Azospirillum brasilense was obtained carrying either native or mutant gfp genes, (ii) Pleiotropic physiological effects were caused by disruption of the clpX gene as the consequence of the insertion, (iii) a new indole-3-acetic acid-attenuated mutant of A. brasilense producing only 0.25% of the indole-3-acetic acid produced by the wild-type is presented.
Acta Biotechnologica, 1992
Developments in Plant and Soil Sciences, 2007
ABSTRACT This work describes the subcloning of the gene encoding the PhoC acid phosphatase from M... more ABSTRACT This work describes the subcloning of the gene encoding the PhoC acid phosphatase from Morganella morganii (phoC gene) in a vector that permits stable chromosomal integration of this gene in plant growth-promoting bacteria (PGPB). A plasmid was constructed using the suicide delivery vector pJMT6 (a pUT/mini Tn5 derivative vector) and the plasmid pLR1, the latter harboring the phoC gene. The recombinant construction pLF17, which contains a non-antibiotic resistance selection marker, was transformed and expressed in Escherichia coli CC118λpir. A transformant clone, E. coli CC118λpir F17 was selected and further characterized, showing phoC gene expression through an histochemical assay and zymograms developed to detect phosphatase activity. With this technique, it was possible to detect, in the whole cell extract, the 25-kDa polypeptidic component responsible for acid phosphatase activity. Acid phosphatase activity was quantified in the whole cell and in the supernatant of the culture as being higher in the transformant E. coli CC118λpir F17 than in E. coli CC118λpir without plasmids along the cultivation time.
Page 1. CARACTERIZACION DE LA ACTIVIDAD FOSFATASA EN UNA CEPA DE BURKHOLDERIA cepacia Hilda Rodrí... more Page 1. CARACTERIZACION DE LA ACTIVIDAD FOSFATASA EN UNA CEPA DE BURKHOLDERIA cepacia Hilda Rodríguez, Onaydis Torres, Tania Gonzalez, Gloria Bueno Instituto Cubano de Investigaciones de la Caña de Azúcar, Apdo. ...
ABSTRACT Microorganisms play an important role in processes that affect phosphorus (P) transforma... more ABSTRACT Microorganisms play an important role in processes that affect phosphorus (P) transformation in soil and its availability to plants. In particular, microorganisms can solubilize and mineralize P from organic and inorganic sources through different mechanics as the liberation of organic acids and hydrolytic enzymes which improve the mobilization and availability of P for plants nutrition. Given that most soils are deficient in P, the use of chemical fertilizers represents a significant cost for agriculture in the world. There is interest in the use of soil microorganisms as inoculants to mobilize P from poorly available sources in soil. This would be a promising alternative to reduce environmental pollution and to improve crops productivity.
Several mutants of Xanthomonas campestris showing increased viscosity and/or gum production wer... more Several mutants of Xanthomonas campestris showing increased viscosity and/or gum production were detected after UV treatment. Xanthan solutions of the different mutants showed different intrinsic viscosity values, and no relationship was found between pyruvate or acetate contents and viscosifying ability of the xanthan. The best performance mutant (M-11) was obtained using halo size around colonies in starch-agar plates as the
Acta Biotechnologica, 1993
Revista Peruana de Biología, 2011
Las fitasas son una clase especial de fosfatasas que catalizan la hidrólisis secuencial del fitat... more Las fitasas son una clase especial de fosfatasas que catalizan la hidrólisis secuencial del fitato. La incapacidad de las plantas para utilizar el fósforo a partir de los fitatos del suelo es debido a la baja actividad de fitasas en sus raíces. Los microorganismos del suelo juegan un importante papel en los procesos que afectan la transformación de los compuestos fosforados. Muchos de ellos pueden solubilizar el fósforo a partir de los fitatos, mediante la liberación de fitasas. Este proceso permite la movilización del fósforo hacia las plantas y un mejor aprovechamiento de este nutriente. Sin embargo, muchas bacterias carecen de los genes que codifican para estas enzimas, lo que disminuye la disponibilidad de este elemento en el suelo. Una alternativa es mejorar las rizobacterias en cuanto a su capacidad de solubilizar los fitatos del suelo, mediante la transformación genética. En este trabajo el gen phyL de Bacillus licheniformis fue clonado en el vector de liberación suicida pJMT6 (vector derivado del sistema pUT/mini Tn5). La construcción recombinante que contiene un marcador de selección no antibiótico, fue transformada en Escherichia coli CC118λpir. Un clon transformante (F16) fue seleccionado y posteriormente caracterizado. Estos resultados constituyen un primer paso para desarrollar rizobacterias promotoras del crecimiento mejoradas en cuanto a la producción de actividad fitasa recombinante, como alternativa para reducir la contaminación ambiental y mejorar la productividad de los cultivos.
Azospirillum brasilense 8-I was chromosomally labeled with green fluorescent protein (gfp) genes,... more Azospirillum brasilense 8-I was chromosomally labeled with green fluorescent protein (gfp) genes, using either the native promoterless gfp gene or the mutant gfpmut2 gene under the transcriptional control of the neomycin phosphate transferase (npt2) promoter inserted into Tn5 suicide plasmid vectors. One A. brasilense exconjugant, showing a steady and strong fluorescence following irradiation with 365-nm UV light was characterized in
Acta Biotechnologica, 2001
A composite plasmid was constructed using the broad-host-range vector pRK293 and the plasmid pPM9... more A composite plasmid was constructed using the broad-host-range vector pRK293 and the plasmid pPM9, the latter one harbouring a gene encoding the Nap A acid phosphatase from M. morganii. The recombinant construction was transformed and expressed in E. coli MC1061. Transformant clones were selected and characterized, showing that the relative orientation of both original plasmids with respect to each other affected the expression of the gene, with one of the plasmids (pT4) expressing significantly lower values of activity than the opposite orientation construction (pT5). Zymograms developed to detect acid phosphatase activity also corroborated the gene expression in the E. coli host. The genetic constructions (pT4 and pT5) were transferred to B. cepacia IS-16 by conjugation. The same effect of the original plasmid orientation in the construction was corroborated in the B. cepacia IS-16 strain. Compared with the strain lacking the recombinant plasmid, no significant improvement of cell-bound enzymatic activity was achieved by the exconjugant harbouring pT5. However, a significant increase in the extracellular enzyme activity was detected in the recombinant strains. No metabolic load due to the presence of the recombinant plasmid was detected in both E. coli and Burkholderia hosts.
ICIDCA. Sobre los …, 2006
World Journal of Microbiology and Biotechnology, 1993
of Cehdomonas was optimal with 1% (w/v) bagasse pith pre-treated with either 0.2 M NaOH for 1 h a... more of Cehdomonas was optimal with 1% (w/v) bagasse pith pre-treated with either 0.2 M NaOH for 1 h at 80°C or 0.4 M NaOH for 40 h at 28 to 30°C. Growth was similar to that obtained with a more severe treatment used as control and compared well with other reports for cellulolytic bacteria cultivated on pre-treated bagasse pith.
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Papers by Hilda Rodriguez