Standardization of a complex culture media for multiplication of C50 Rhizobium sp. strain

El uso indiscriminado de fertilizantes químicos y su proceso de obtención y aplicación ha incrementado los costos de producción agrícola y los problemas ambientales debido a la contaminación del aire, el suelo y las aguas. Se ha planteado como alternativa la aplicación de fertilizantes biológicos como una herramienta económica y limpia para el manejo sostenible de los ecosistemas. Sin embargo, en los procesos de escalamiento de un biofertilizante pueden incrementarse los costos de producción debido al tipo de formulación y a los medios de cultivo empleados para la multiplicación de las bacterias. Esta investigación, con base en el uso secuencial de diseños estadísticos, presenta la estandarización de un medio de cultivo económico para la multiplicación de la cepa C50 de Rhizobium sp. De ocho fuentes nutricionales se seleccionaron cinco, teniendo como criterios los menores costos económicos y la disponibilidad de dichas fuentes, de estas cinco, tres influyeron significativamente sobre el desarrollo de la cepa. La composición optimizada del medio alterno incluyó glicerol, melaza, glutamato, extracto de levadura y sales. No se presentaron diferencias significativas en el crecimiento de la cepa C50 en el medio alterno comparado con el tradicional (levadura-manitol), ni en la viabilidad de la cepa crecida en el medio tradicional respecto al alterno, cuando se inoculó sobre turba. El inoculante conservó su calidad en refrigeración durante 30 días. Las cepas J01, T14 y C2 mostraron buen índice de crecimiento sobre el medio alterno, no se presentaron diferencias significativas en los recuentos entre las cepas J01 y T14, mientras que la cepa C2 creció mejor en el medio alterno.;The indiscriminate use of chemical fertilizers, its process of production and its application had increased the costs of agricultural production and the environmental problems because of the pollution of air, soil and water sources. The alternative is the use of biological fertilizers as an economical and clean tool in order to sustainable management of ecosystems. However, in the escalation processes of a biofertilizer the costs of production could increase due to the type of formulation and the culture media used for the multiplication of the bacteria. This research, by using statistical designs sequentially, presents the standardization of an economical culture media used to multiply the strain C50 of Rhizobium sp. From eight nutritional sources, five were selected taking as criteria the low economical costs and the availability of above mentioned nutritional sources, from these five sources, three of them influenced the development of the strain significantly. The optimized composition of the alternative culture media included glycerol, molasses, glutamate, yeast extract and salts. There were no significantly differences in the growth of the strain C50 in the alternative culture media compared with the traditional one (yeast extract mannitol), nor in viability of the strain growth on traditional media culture compared with the alternative one, when it was inoculated on peat. The inoculants conserved its quality in refrigeration during 30 days. The strains J01, T14 and C2 showed a better rate of growth on the alternative culture media, it was not show significant differences in the counts between the strains J01 and T14, whereas, the strain C2 growth better in the alternative culture media

Specific pattern of flea antigen recognition by IgG subclass and IgE during the progression of papular urticaria caused by flea bite

Q4Q2Artículo original197-202Background: Papular urticaria caused by flea bite presents clinical symptoms of a hypersensitivity reaction accompanied by skin lesions. However, the pattern of recognition by different antibody isotypes during the progression of the disease is unknown. This study evaluated variations in immunoglobulin E and immunoglobulin G subclass antibody responses to flea antigens during the progression of papular urticaria caused by flea bite Methods: Twenty-five patients clinically diagnosed with papular urticaria due to flea bite were included. Ten healthy children were included as controls. Recognition of antigens from complete flea body extract by patients and healthy controls was determined using immunoblot assays. Results: The results revealed that patients with 2–5 years of papular urticaria evidenced more IgE bands than those with shorter or longer durations of symptoms. In contrast, healthy children showed a predominance of immunoglobulin G1 and immunoglobulin G3. The majority of the recognised antigens were low molecular weight proteins (o90 kDa). Proteins with molecular weights between 16–20, 21–25, and 31–35 kDa showed different patterns of recognition between patients and healthy children. Conclusion: The predominant specific antibody isotypes vary according to the time elapsed since the onset of symptoms in papular urticaria caused by flea bite

Differential Th1/Th2 balance in peripheral blood lymphocytes from patients suffering from flea bite-induced papular urticaria

Q4Q2Artículo original7-10Background: The Th1/Th2 balance has not been characterized in patients suffering from flea bite-induced papular urticaria (FBPU). Our aim was to improve understanding of the immunopathogenesis of CD4+ and CD8+ T-cells in humans suffering from flea bite-induced papular urticaria. Methods: Peripheral blood mononuclear cells were obtained from 18 pediatric patients and 10 age-matched healthy controls. Cellular phenotypes, intracellular production of interferon gamma (IFN) and interleukin-4 (IL-4) in T-cells stimulated with polyclonal stimuli was determined by fl ow cytometry following short-term in vitro stimulation. Results: The results revealed lower frequencies of IFN-secreting (p = 0.02) and higher frequencies of IL-4-secreting (p = 0.03) CD4+ T-cells in patient lymphocyte cultures compared to healthy control cultures in the presence of polyclonal stimuli. This is the first description of differential cytokine patterns in papular urticaria patients. Conclusion: Patients suffering from papular urticaria have an atopic status compared to healthy children

Role of plant growth-promoting bacteria on Phytoextraction process of Cu(II) and Cr(VI) by Helianthus annuus and Zea mays

As a result of inappropriate deposition of organic residues, toxic anthropogenic compounds have become ubiquitous components in soil and waters. Several alternatives have been developed, however, one of the most important is bioremediation. It is a low-cost, effective and environmentally friendly alternative to remediate contaminated soil. In particular, the phytoremediation of heavy metals has become an important tool to alleviate the impact occasioned by inorganic contamination with arsenic, lead, cadmium, copper or chromium, for example. We decided to evaluate the process of phytoextraction of copper by its implications in agricultural productivity and chromium by its negative effects on both human and animal health. Additionally, selected two vegetable species: maize and sunflower. With regard to maize, it is plant specie of fast-growth and high biomass, characteristics desired in a phytoremediation process. While sunflower has been widely reported and characterized by its qualities to extract several heavy metals from soil. Plant growth-promoting bacteria (PGPB) defined as microorganisms with beneficial effect on plant development, have elucidated to be a relevant strategy to improve phytoremediation process. In this study, we exhibited the role of PGPB on improvement of this biotechnological strategy. We evaluated eight bacteria and characterized them by its capacity as PGPR. Also, identified this molecularly. We demonstrated that bacterial inoculation with bacteria Pseudomonas putida GN4 and Acinetobacter sp. CC30 enhanced plant growth and the content of chlorophyll a, chlorophyll b and carotenoids in both maize and sunflower plants under copper (II) and chromium (VI) contamination. With respect to extraction process, bacterial inoculation exerted an important effect on ions mobility in soil. Furthermore, increased the availability of copper extractable from soil. Several bacterial strategies are though to influence the efficiency of phytoremediation process. Bacterial capacities to synthesize indole or siderophores, solubilize phosphate or mineralize ammonia have evidenced to influence significantly on remediation of heavy metals by plants. Hence, in summary, utilization of PGPR to improve phytoremediation process is an important alternative to reduce cost and increased remediation efficiency. Further, it is a sustainable strategy to preserve the quality of environment.Magíster en Ciencias BiológicasMaestrí

Novel pathways of regulation of the transcription factor Spx in Bacillus subtilis

Spx is a transcription factor present in low G+C Gram-positive bacteria, including Bacillus subtilis and several human pathogens. By direct binding to the αCTD domain of the RNA polymerase, Spx modulates the expression of a large set of genes in B. subtilis. The Spx regulon is active in growing cells, and its expression is further induced in response to some stresses. Spx activation has been typically studied using diamide to generate disulfide stress. By using molecular biology, genetic, and biochemistry techniques, I show that the Spx regulon is also induced in response to cell wall stress, and that Spx is critical for survival of B. subtilis upon treatment with cell wall antibiotics. I further show the molecular mechanisms that lead to activation of Spx. Unlike disulfide stress, induction of the Spx regulon in response to cell wall stress requires transcriptional induction of the spx gene. This induction is mediated by the alternative extracytoplasmic sigma factor σM, and occurs at a promoter upstream of the yjbC-spx operon (i.e. PM1). Interestingly, activation of the Spx regulon in response to cell wall stress also requires stabilization; however, unlike disulfide stress, this process is mediated by a small protein called YirB. YirB is an anti-adaptor protein that binds with high affinity to YjbH, the adaptor protein required for ClpXP-mediated proteolysis, and therefore reduces the rate of Spx degradation. Transcriptional induction and post-translational stabilization are thus required for activation of the Spx regulon in response to antibiotics that inhibit peptidoglycan biosynthesis. Then, I show that yirB is also induced in response to cell wall stress, and that its activation requires the coordinated action of the YuxN repressor and the CssRS two-component system. Finally, I show that Spx is not only degraded through ClpXP, but also by ClpCP. The adaptor that mediates this degradation in unstressed cells appears to be MecA, and the evidence comes from the Spx-dependent synthetic lethality of ClpX and MecA. The McsB arginine kinase, which also acts as a ClpCP adaptor, as well as the YwlE arginine phosphatase are also shown to play an important role in Spx regulation. Overall, this work expands the regulatory mechanisms that control the activity of a pleiotropic transcription factor in B. subtilis

Estandarización de un medio de cultivo complejo para la multiplicación de la cepa C50 rhizobium sp

Microbiólogo (a) IndustrialPregrad

Entrapment of Rhizobium sp. by fluidized bed technique using polymers as coating materials

The spray-drying technique was applied for the development of three solid formulations of Rhizobium. Sodium alginate and hydroxypropyl methylcellulose (HPMC) with concentrations of 0.5 % were used as polymers. Results showed that none of the solid formulations had negative effects in vitro on the growth-promoting capacities of Rhizobium sp. G58 (p < 0.05). PCA´s first three components explained 84.5 % of the total variance. This analysis concluded that the solid formulation had not negative effects on the biological nitrogen fixation activity in vitro or on the process of nodulation in greenhouse experiments. Symbiosis between Rhizobium and the plant was effective, which suggested that, under controlled conditions, the coating process with the polymers had allowed a controlled release of the bacteria and a proper transfer of Rhizobium sp. from the microparticles to the root of the plant

Entrapment of Rhizobium sp. by fluidized bed technique using polymers as coating materials

The spray-drying technique was applied for the development of three solid formulations of Rhizobium. Sodium alginate and hydroxypropyl methylcellulose (HPMC) with concentrations of 0.5 % were used as polymers. Results showed that none of the solid formulations had negative effects in vitro on the growth-promoting capacities of Rhizobium sp. G58 (p < 0.05). PCA´s first three components explained 84.5 % of the total variance. This analysis concluded that the solid formulation had not negative effects on the biological nitrogen fixation activity in vitro or on the process of nodulation in greenhouse experiments. Symbiosis between Rhizobium and the plant was effective, which suggested that, under controlled conditions, the coating process with the polymers had allowed a controlled release of the bacteria and a proper transfer of Rhizobium sp. from the microparticles to the root of the plant

Entrapment of Rhizobium sp. by fluidized bed technique using polymers as coating materials

The spray-drying technique was applied for the development of three solid formulations of Rhizobium. Sodium alginate and hydroxypropyl methylcellulose (HPMC) with concentrations of 0.5 % were used as polymers. Results showed that none of the solid formulations had negative effects in vitro on the growth-promoting capacities of Rhizobium sp. G58 (p &lt; 0.05). PCA´s first three components explained 84.5 % of the total variance. This analysis concluded that the solid formulation had not negative effects on the biological nitrogen fixation activity in vitro or on the process of nodulation in greenhouse experiments. Symbiosis between Rhizobium and the plant was effective, which suggested that, under controlled conditions, the coating process with the polymers had allowed a controlled release of the bacteria and a proper transfer of Rhizobium sp. from the microparticles to the root of the plant