ABSTRACT
In the original article, last name and first names of all the authors are inverted. The correct names should appears as "Romina Molina, Gastón López, Belén Rodríguez, Susana Rosas, Verónica Mora, Fabricio Cassán".
ABSTRACT
Resumen Azospirillum brasilense Az39 es utilizada por empresas productoras de inoculantespara la formulación de bioinsumos en América del Sur desde hace más de 30 a˜nos. Esta cepapuede promover el crecimiento, desarrollo, así como la capacidad de tolerar diferentes tiposde estrés en las plantas inoculadas, lo que determina un aumento de la productividad de culti-vos de interés agronómico. En la actualidad, no existen protocolos en Argentina que permitanconfirmar la identidad de Az39 en productos comerciales a nivel de laboratorios de control decalidad de inoculantes. Por ello, el objetivo de este trabajo fue desarrollar una metodología enbase molecular que permita la identificación certera de A. brasilense Az39. Con la secuenciacompleta del genoma y mediante herramientas bioinformáticas, se pudieron reconocer frag-mentos de ADN presentes únicamente en el genoma de Az39. Se dise˜naron cebadores dirigidosa amplificar por PCR dichas secuencias. Como resultado se observaron los productos específicosúnicamente en la presencia de la cepa de interés. La reacción pudo detectar un título mínimode 105UFC/ml (4,5 ng/l ADN) o de 102UFC/ml (0,88 ng/l ADN) o una concentración mínimade 0,098 ng/l ADN, dependiendo del método de extracción utilizado. Los cebadores fueronevaluados en el análisis de productos comerciales obtenidos del mercado nacional, arrojandoresultados positivos, tanto en muestras directas como así también en pruebas confirmatoriasa partir de colonias aisladas de tales productos. La metodología desarrollada en este trabajo,permite la detección certera de A. brasilense Az39 en cultivos puros o mezclas complejas demicroorganismos.
Abstract Azospirillum brasilense Az39 has been used since more than 30 years by several companies in South America for biofertilizers production. This strain may promote plants growth and development, as well as the ability of inoculated plants to tolerate environmental stresses, which determines an increase in the productivity under field conditions. At present, there are no protocols in Argentina to confirm the identity of Az39 in commercial products; however, such biofertilizers are formulated almost exclusively with this strain. Therefore, the objective of this paper was to develop a molecular methodology that allows the accurate identification of A. brasilense Az39. Using the complete genome sequence and several bioinformatics tools, fragments of DNA present only in the Az39 genome were recognized. A set of PCR primers to amplify these sequences were designed, and the specific products were observed only in the strain of our interest. The sensitivity of the methodology was evaluated, where the strain could be detected up to a titer of 105 CFU/ml (4.5 ng/pl ADN) or 102 CFU/ml (0.88 ng/pl DNA) or in a minimal concentration of 0.098 ng/pl DNA, depending on the DNA extraction methodology used. Primers were tested against direct samples of commercial inoculants and cultures, in both cases there were specifics products, both in direct samples and in confirmatory tests from isolated colonies from those products. The procedure presented in this paper allows the accurate identification of A. brasilense Az39 in pure cultures, mixtures of microorganisms, and commercial biofertilizers.
Subject(s)
Azospirillum brasilense/isolation & purification , Azospirillum brasilense/genetics , Argentina , DNA, Bacterial/analysis , Bacteriological Techniques/methods , Nucleic Acid Amplification TechniquesABSTRACT
Azospirillum brasilense Az39 has been used since more than 30 years by several companies in South America for biofertilizers production. This strain may promote plants growth and development, as well as the ability of inoculated plants to tolerate environmental stresses, which determines an increase in the productivity under field conditions. At present, there are no protocols in Argentina to confirm the identity of Az39 in commercial products; however, such biofertilizers are formulated almost exclusively with this strain. Therefore, the objective of this paper was to develop a molecular methodology that allows the accurate identification of A. brasilense Az39. Using the complete genome sequence and several bioinformatics tools, fragments of DNA present only in the Az39 genome were recognized. A set of PCR primers to amplify these sequences were designed, and the specific products were observed only in the strain of our interest. The sensitivity of the methodology was evaluated, where the strain could be detected up to a titer of 105 CFU/ml (4.5 ng/µl ADN) or 102 CFU/ml (0.88 ng/µl DNA) or in a minimal concentration of 0.098 ng/µl DNA, depending on the DNA extraction methodology used. Primers were tested against direct samples of commercial inoculants and cultures, in both cases there were specifics products, both in direct samples and in confirmatory tests from isolated colonies from those products. The procedure presented in this paper allows the accurate identification of A. brasilense Az39 in pure cultures, mixtures of microorganisms, and commercial biofertilizers.
Subject(s)
Azospirillum brasilense/genetics , Azospirillum brasilense/isolation & purification , Argentina , Bacteriological Techniques/methods , DNA, Bacterial/analysis , Nucleic Acid Amplification TechniquesABSTRACT
Indole-3-acetic acid (IAA) is one of the most important molecules produced by Azospirillum sp., given that it affects plant growth and development. Azospirillum brasilense strains Sp245 and Az39 (pFAJ64) were pre-incubated in MMAB medium plus 100 mg/mL L-tryptophan and treated with or exposed to the following (a) abiotic and (b) biotic stress effectors: (a) 100 mM NaCl or Na2SO4, 4.0% (w/v) PEG6000, 0.5 mM H2O2, 0.1 mM abscisic acid, 0.1 mM 1-aminocyclopropane 1-carboxylic acid, 45 °C or daylight, and (b) 4.0% (v/v) filtered supernatant of Pseudomonas savastanoi (Ps) or Fusarium oxysporum (Fo), 0.1 mM salicylic acid (SA), 0.1 mM methyl jasmonic acid (MeJA), and 0.01% (w/v) chitosan (CH). After 30 and 120 min of incubation, biomass production, cell viability, IAA concentration (µg/mL), and ipdC gene expression were measured. Our results show that IAA production increases with daylight or in the presence of PEG6000, ABA, SA, CH, and Fo. On the contrary, exposure to 45 °C or treatment with H2O2, NaCl, Na2SO4, ACC, MeJA, and Ps decrease IAA biosynthesis. In this report, growth and IAA biosynthesis in A. brasilense under biotic and abiotic stress conditions are discussed from the point of view of their role in bacterial lifestyle and their potential application as bioproducts.
Subject(s)
Azospirillum brasilense/genetics , Gene Expression Regulation, Bacterial , Indoleacetic Acids/metabolism , Plant Growth Regulators/biosynthesis , Azospirillum brasilense/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Culture Media/chemistry , Culture Media/metabolism , Tryptophan/metabolismABSTRACT
Bacterial metabolism of phytohormones includes several processes such as biosynthesis, catabolism, conjugation, hydrolysis and homeostatic regulation. However, only biosynthesis and occasionally catabolism are studied in depth in microorganisms. In this work, we evaluated and reconsidered IAA metabolism in Bradyrhizobiumjaponicum E109, one of the most widely used strains for soybean inoculation around the world. The genomic analysis of the strain showed the presence of several genes responsible for IAA biosynthesis, mainly via indole-3-acetonitrile (IAN), indole-3-acetamide (IAM) and tryptamine (TAM) pathways. However; in vitro experiments showed that IAA is not accumulated in the culture medium in significant amounts. On the contrary, a strong degradation activity was observed after exogenous addition of 0.1 mM of IAA, IBA or NAA to the medium. B. japonicum E109 was not able to grow in culture medium containing IAA as a sole carbon source. In YEM medium, the bacteria degraded IAA and hydrolyzed amino acid auxin conjugates with alanine (IAAla), phenylalanine (IAPhe), and leucine (IAPhe), releasing IAA which was quickly degraded. Finally, the presence of exogenous IAA induced physiological changes in the bacteria such as increased biomass and exopolysaccharide production, as well as infection effectiveness and symbiotic behavior in soybean plants.
Subject(s)
Bradyrhizobium/metabolism , Glycine max/microbiology , Indoleacetic Acids/metabolism , Polysaccharides, Bacterial/biosynthesis , Seeds/microbiology , Alanine/metabolism , Bradyrhizobium/genetics , Leucine/metabolism , Phenylalanine/metabolism , Plant Root Nodulation/physiology , Symbiosis/physiologyABSTRACT
Resumen En México la interculturalidad en salud se plantea como una política ideal para la atención sanitaria de la población indígena; sin embargo, esta implica la convergencia de dos sistemas de conocimiento, lo cual permite interrogar su implementación. Desde una perspectiva antropológica, se analizó la pertinencia de la interculturalidad en salud en una zona de cobertura médica indígena. Mediante un abordaje etnográfico mixto se aplicaron 35 cuestionarios al personal médico del Hospital General de Ciudad Valles entre agosto del 2012 y enero del 2013. Los datos se analizaron con estadística descriptiva y se complementaron con entrevistas a profundidad y observación participante. Se encontró que existe una valoración del conocimiento tradicional indígena (77%) y las plantas medicinales (80%) dentro de la práctica médica alópata, porque la mayoría de médicos (89%) recibió pacientes que los habían utilizado, así que consideran pertinente la implementación de una política sanitaria que integre el conocimiento tradicional indígena a la práctica médica alópata.
Abstract In Mexico the interculturalism in health appears as an ideal policy for the indigenous health care, nevertheless this one implies the convergence of two systems of knowledge and it allows to examine his implementation. From an anthropologic perspective, the relevancy of the interculturalism in health was analyzed in one area of indigenous medical coverage. Through one mixed ethnographic approach 35 questionnaires were applied to the medical personnel of General Hospital of Ciudad Valles from August 2012 to January 2013. The data was analyzed by descriptive statistics, complementing them with interviews and participant observation. It was found that an important recognition exists about the traditional indigenous knowledge (77%) and the medicinal plants (80%) inside medical practice because the majority of physicians (89%) received patients who used them, consequently they consider pertinent the implementation of health care policy that integrates the indigenous traditional knowledge to the medical practicetion of the institutions, where they appear on scene and negotiate different regulation logics.
Resumo No México a interculturalidade em saúde coloca-se como política ideal para o atendimento sanitário da população indígena; no entanto, aquela implica a convergência de dois sistemas de conhecimento, o qual permite questionar sua implementação. Desde uma perspectiva antropológica, foi analisada a pertinência da interculturalidade em saúde em una zona de cobertura médica indígena. Mediante abordagem etnográfico misto aplicaram-se 35 questionários ao pessoal médico do Hospital General de Ciudad Valles entre agosto de 2012 e janeiro de 2013. Os dados foram analisados com estatística descritiva e complementados com entrevistas a profundidade e observação participante. Encontrou-se que existe uma valoração do conhecimento tradicional indígena (77%) e as plantas medicinais (80%) dentro da prática médica alópata, porque a maioria de médicos (89%) recebeu pacientes que haviam utilizado, assim que acham pertinente a implementação de uma política sanitária que integre o conhecimento tradicional indígena na prática médica alópata.
ABSTRACT
Fluorescent Pseudomonas spp., isolated from rhizosphere soil of tomato and pepper plants, were evaluated in vitro as potential antagonists of fungal pathogens. Strains were characterized using the API 20NE biochemical system, and tested against the causal agents of stem canker and leaf blight (Alternaria alternata f. sp. lycopersici), southern blight (Sclerotium rolfsii Sacc.), and root rot (Fusarium solani). To this end, dual culture antagonism assays were carried out on 25% Tryptic Soy Agar, King B medium, and Potato Dextrose Agar to determine the effect of the strains on mycelial growth of the pathogens. The effect of two concentrations of FeCl(3) on antagonism against Alternaria alternata f. sp. lycopersici was also tested. In addition, strains were screened for ability to produce exoenzymes and siderophores. Finally, the selected Pseudomonas strain, PCI2, was evaluated for effect on tomato seedling development and as a potential candidate for controlling tomato damping-off caused by Sclerotium rolfsii Sacc., under growth chamber conditions. All strains significantly inhibited Alternaria alternata f. sp. lycopersici, particularly in 25% TSA medium. Antagonistic effect on Sclerotium rolfsii Sacc. and Fusarium solani was greater on King B medium. Protease was produced by 30% of the strains, but no strains produced cellulase or chitinase. Growth chamber studies resulted in significant increases in plant stand as well as in root dry weight. PCI2 was able to establish and survive in tomato plants rhizosphere after 40 days following planting of bacterized seeds.
