Azospirillum brasilense Az39, a model rhizobacterium with AHL quorum quenching capacity

AimsThe aim of this research was to analyze the Quorum sensing (QS) and Quorum quenching (QQ) mechanisms based on N‐acyl‐L‐homoserine lactones (AHLs) in A. brasilense Az39, a strain with remarkable capacity to benefit a wide range of crops under agronomic conditions. Methods and ResultsWe performed an in silico and in vitro analysis of the quorum mechanisms in A. brasilense Az39. The results obtained in vitro using the reporter strains C. violaceum and A. tumefaciens and Liquid Chromatography coupled to Mass‐Mass Spectrometry (LC‐MS/MS) analysis showed that although Az39 does not produce AHL molecules, it is capable of degrading them by at least two hypothetical enzymes identified by bioinformatics approach, associated to the bacterial cell. In Az39 cultures supplemented with 500 nmol l−1 of the C3 unsubstituted AHLs (C4, C6, C8, C10, C12, C14), AHL levels were lower than in non‐inoculated LB media controls. Similar results were observed upon addition of AHLs with hydroxy (OH‐) and keto (oxo‐) substitutions in carbon 3. These results not only demonstrate the ability of Az39 to degrade AHLs. They also show the wide spectrum of molecules that can be degraded by this bacterium. ConclusionsAlthough A.brasilense Az39 is a silent bacterium unable to produce AHL signals, it is able to interrupt the communications between other bacteria and/or plants by a quorum quenching activity

Guess the cheese flavour by the size of its holes: A cosmological test using the abundance of Popcorn voids

We present a new definition of cosmic void and a publicly available code with the algorithm that implements it. Underdense regions are defined as free-form objects, called popcorn voids, made from the union of spheres of maximum volume with a given joint integrated underdensity contrast.The method is inspired by the excursion-set theory and consequently no rescaling processing is needed, the removal of overlapping voids and objects with sizes below the shot noise threshold is inherent in the algorithm. The abundance of popcorn voids in the matter field can be fitted using the excursion-set theory provided the relationship between the linear density contrast of the barrier and the threshold used in void identification is modified relative to the spherical evolution model. We also analysed the abundance of voids in biased tracer samples in redshift space. We show how the void abundance can be used to measure the geometric distortions due to the assumed fiducial cosmology, in a test similar to an Alcock-Paczy\'nski test. Using the formalism derived from previous works, we show how to correct the abundance of popcorn voids for redshift-space distortion effects. Using this treatment, in combination with the excursion-set theory, we demonstrate the feasibility of void abundance measurements as cosmological probes. We obtain unbiased estimates of the target parameters, albeit with large degeneracies in the parameter space. Therefore, we conclude that the proposed test in combination with other cosmological probes has potential to improve current cosmological parameter constraints.Comment: Updated manuscript sent to the MNRAS after referee report: 16 pages, 8 figures. Corrections were made to Fig. 4, some related conclusions were modified. The main conclusions remain unchange

Análisis y diseño del sistema administrativo para el colegio Miguel Moreno Ordóñez

Se analiza como se maneja la información en el colegio Miguel Moreno; además las labores que desempeñan las personas implicadas en el manejo de información de dicha institución. Al llevar a cabo este análisis, nos permitirá examinar los resultados de este proceso, para esto debemos disponer de todos los datos, los mismos que nos permitirán realizar el sistema de esta institución. Los ordenadores pueden también ayudar a que las organizaciones que no buscan un beneficio, funcionen de forma más eficazAnálista y Diseño de SistemasCuenc

Azospirillum brasilense Az39, a model rhizobacterium with AHL quorum-quenching capacity

The aim of this research was to analyse the quorum-sensing (QS) and quorum-quenching (QQ) mechanisms based on N-acyl-L-homoserine lactones (AHLs) in Azospirillum brasilense Az39, a strain with remarkable capacity to benefit a wide range of crops under agronomic conditions. We performed an in silico and in vitro analysis of thequorum mechanisms in A. brasilense Az39. The results obtained in vitro using the reporter strains Chromobacterium violaceum and Agrobacterium tumefaciens and liquid chromatography coupled with mass-mass spectrometry analysis showed that although Az39 does not produce AHL molecules, it is capable of degrading them by at least two hypothetical enzymes identified by bioinformatics approach, associated with the bacterial cell. In Az39 cultures supplemented with 500 nmol l-1 of the C3 unsubstituted AHLs (C4, C6, C8, C10, C12, C14), AHL levels were lower than in noninoculated LB media controls. Similar results were observed upon the addition of AHLs with hydroxy (OH-) and keto (oxo-) substitutions in C3. These results not only demonstrate the ability of Az39 to degrade AHLs. They also show the wide spectrum of molecules that can be degraded by this bacterium. Although A. brasilense Az39 is a silent bacterium unable toproduce AHL signals, it is able to interrupt the communications between other bacteria and/or plants by a QQ activity.Significance and Impact of the Study: This is the first report confirming byunequivocal methodology the ability of A. brasilense, one of the most agriculturally used benefic bacteria around the world, to degrade AHLs by a QQ mechanism.Fil: Gualpa, J.. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Investigaciones Agrobiotecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones Agrobiotecnologicas.; ArgentinaFil: Lopez, Gaston Alberto. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Investigaciones Agrobiotecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones Agrobiotecnologicas.; ArgentinaFil: Nievas, Sofia Mariela. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Investigaciones Agrobiotecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones Agrobiotecnologicas.; ArgentinaFil: Coniglio, Nayla Anahí. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Investigaciones Agrobiotecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones Agrobiotecnologicas.; ArgentinaFil: Halliday, N.. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Cámara, M.. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Cassán, F.. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Investigaciones Agrobiotecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones Agrobiotecnologicas.; Argentin

Analysis of the denitrification pathway and greenhouse gases emissions in Bradyrhizobium sp. strains used as biofertilizers in South America

Aims: Greenhouse gases are considered as potential atmospheric pollutants, with agriculture being one of the main emission sources. The practice of inoculating soybean seeds with Bradyrhizobium sp. might contribute to nitrous oxide (NO) emissions. We analysed this capacity in five of the most used strains of Bradyrhizobium sp. in South America. Methods and Results: We analysed the denitrification pathway and NO production by Bradyrhizobium japonicum E109 and CPAC15, Bradyrhizobium diazoefficiens CPAC7 and B. elkanii SEMIA 587 and SEMIA 5019, both in free-living conditions and in symbiosis with soybean. The in silico analysis indicated the absence of nosZ genes in B. japonicum and the presence of all denitrification genes in B. diazoefficiens strains, as well as the absence of nirK, norC and nosZ genes in B. elkanii. The in planta analysis confirmed NO production under saprophytic conditions or symbiosis with soybean root nodules. In the case of symbiosis, up to 26.1 and 18.4 times higher in plants inoculated with SEMIA5019 and E109, respectively, than in those inoculated with USDA110. Conclusions: The strains E109, SEMIA 5019, CPAC15 and SEMIA 587 showed the highest NO production both as free-living cells and in symbiotic conditions in comparison with USDA110 and CPAC7, which do have the nosZ gene. Although norC and nosZ could not be identified in silico or in vitro in SEMIA 587 and SEMIA 5019, these strains showed the capacity to produce NO in our experimental conditions. Significance and Impact of the Study: This is the first report to analyse and confirm the incomplete denitrification capacity and NO production in four of the five most used strains of Bradyrhizobium sp. for soybean inoculation in South America.Financial support was obtained from the Universidad Nacional de Río Cuarto and Consejo Nacional de Investigación Científico‐Tecnológica (CONICET) from Argentina, the FEDER‐cofinanced Project AGR2012‐1968 from Consejería de Economía, Innovación y Ciencia (Junta de Andalucía, Spain) and from the CSIC‐sponsored I‐COOP2014 project COOPA20069. We thank J. Chacón for technical assistance. M.O. and J.G. are PhD students at the UNRC granted by CONICET.Peer Reviewe