Heterologous expression of nifA or nodD genes improves chickpea-Mesorhizobium symbiotic performance

Aims The aim of this study was to investigate whether the overexpression of NifA and NodD regulators contribute to the symbiotic improvement of chickpea mesorhizobia. Methods The native strains V-15b, ST-2, and PMI-6 were transformed with extra copies of nifA or nodD genes and several plants trial were performed. Results Plant growth assays showed that nifA overexpression was able to improve the symbiotic effectiveness of V-15b, while nodD overexpression lead to the improvement of ST-2 and PMI-6. Hydroponic assays showed that plants inoculated with V15bnifA+ and PMI6nodD+ started developing nodules earlier than those inoculated with the corresponding control strains. In addition, the number of nodules was always higher in plants inoculated with the strains overexpressing the symbiotic genes. Analysis of histological sections of nodules formed by V15bnifA+ showed a more developed fixation zone when compared with control. On the other hand, nodules induced by PMI6nodD+ did not show a senescent zone, which was observed in nodules from plants inoculated with the control strain. Plants inoculated with PMI6nodD+ and ST2nodD+ showed a higher number of infection threads than the corresponding control inoculations. Conclusion These results indicate that overexpressing nifA and nodD may be an important tool to achieve the improvement of the symbiotic performance of mesorhizobia.The authors thank Dr Alvaro Peix (IRNASA-CSIC) for providing pMP4661 plasmid. Moreover, the authors thank G. Mariano for technical assistance. This work was financed by FEDER Funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT (Fundação para a Ciência e a Tecnologia), under the Strategic Project UID/AGR/00115/2013, Project nº FCOMP-01-0124-FEDER-028316 (PTDC/BIA-EVF/4158/2012), project POCI-01-0145-FEDER-016810 (PTDC/AGR-PRO/2978/2014) and InAlentejo ALENT-07-0262-FEDER-001871. J. Rodrigo da-Silva acknowledges a PhD fellowship (1254-13-8) from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior)

Morphology and Photoluminescence of HfO2Obtained by Microwave-Hydrothermal

In this letter, we report on the obtention of hafnium oxide (HfO2) nanostructures by the microwave-hydrothermal method. These nanostructures were analyzed by X-ray diffraction (XRD), field-emission gum scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDXS), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. XRD patterns confirmed that this material crystallizes in a monoclinic structure. FEG-SEM and TEM micrographs indicated that the rice-like morphologies were formed due to an increase in the effective collisions between the nanoparticles during the MH processing. The EDXS spectrum was used to verify the chemical compositional of this oxide. UV–vis spectrum revealed that this material have an indirect optical band gap. When excited with 488 nm wavelength at room temperature, the HfO2nanostructures exhibited only one broad PL band with a maximum at around 548 nm (green emission)

traG Gene Is Conserved across Mesorhizobium spp. Able to Nodulate the Same Host Plant and Expressed in Response to Root Exudates

Evidences for an involvement of the bacterial type IV secretion system (T4SS) in the symbiotic relationship between rhizobia and legumes have been pointed out by several recent studies. However, information regarding this secretion system in Mesorhizobium is still very scarce. The aim of the present study was to investigate the phylogeny and expression of the traG gene, which encodes a substrate receptor of the T4SS. In addition, the occurrence and genomic context of this and other T4SS genes, namely, genes from tra/trb and virB/virD4 complexes, were also analyzed in order to unveil the structural and functional organization of T4SS in mesorhizobia. The location of the T4SS genes in the symbiotic region of the analyzed rhizobial genomes, along with the traG phylogeny, suggests that T4SS genes could be horizontally transferred together with the symbiosis genes. Regarding the T4SS structural organization in Mesorhizobium, the virB/virD4 genes were absent in all chickpea (Cicer arietinum L.) microsymbionts and in the Lotus symbiont Mesorhizobium japonicum MAFF303099T. Interestingly, the presence of genes belonging to another secretion system (T3SS) was restricted to these strains lacking the virB/virD4 genes. The traG gene expression was detected in M. mediterraneum Ca36T and M. ciceri LMS-1 strains when exposed to chickpea root exudates and also in the early nodules formed by M. mediterraneum Ca36T, but not in older nodules. This study contributes to a better understanding of the importance of T4SS in mutualistic symbiotic bacteria

Síntese in situ pelo método hidrotérmico de heteroestruturas de titanato-ferritas e sua atividade fotocatalítica

Resumo A aplicação de fotocatalisadores na forma de heteroestruturas tem se destacado através da propriedade de degradação de diversos compostos orgânicos no tratamento de efluentes. Neste contexto, o objetivo deste trabalho foi sintetizar compostos heteroestruturados à base de titanato-ferritas pelo método hidrotérmico in situ para aplicação em processo foto-Fenton. Os materiais sintetizados in situ foram caracterizados por difratometria de raios X, espectroscopia de infravermelho, espectroscopia de reflectância difusa, área específica superficial por BET e microscopia eletrônica de transmissão. A síntese in situ de SrTiO3-CoFe2O4 e SrTiO3-NiFe2O4 foi desenvolvida de forma inédita neste trabalho, resultando com sucesso em sistemas heteroestruturados sem presença de fases secundárias, distribuição altamente homogênea das fases constituintes com tamanho médio de partículas nanométrico e garantia de reprodutibilidade do método. A atividade fotocatalítica dos compostos sintetizados foi investigada por meio da degradação do corante Rodamina B, utilizando luz visível, onde o sistema SrTiO3-CoFe2O4 apresentou a melhor atividade fotocatalítica degradando 82% do corante

Empirical Studies on Biomass Briquette Production: A Literature Review

The densification of raw material into fuel briquettes is one of the routes to convert biomass into energy. This method provides uniformity to the solid fuel, better physical and energy properties, facilitating its storage and transport, in addition to more homogeneous combustion. Given the importance of these characteristics, this work presents a literature review, emphasizing the experimental levels of the variables of the briquetting process, as well as on the most relevant quality parameters for obtaining briquettes. We also carry out a survey of the main technologies used in the production of briquettes, as well as the experimental methodologies and statistical analysis used in the planning and validation of processes. It was observed among the studies that the raw material granulometry, followed by pressure, initial moisture, compaction time and binder are the most used process variables for the production of briquettes. Other factors, such as the proportion of biomass, process temperature and thermal pre-treatments are used to obtain greater energetic and physical responses. Among the works, divergences were observed regarding the relevance and interaction of some process variables on the quality variables of the briquettes, indicating the need for the experiments to be mathematically modeled

Empirical Studies on Biomass Briquette Production: A Literature Review

The densification of raw material into fuel briquettes is one of the routes to convert biomass into energy. This method provides uniformity to the solid fuel, better physical and energy properties, facilitating its storage and transport, in addition to more homogeneous combustion. Given the importance of these characteristics, this work presents a literature review, emphasizing the experimental levels of the variables of the briquetting process, as well as on the most relevant quality parameters for obtaining briquettes. We also carry out a survey of the main technologies used in the production of briquettes, as well as the experimental methodologies and statistical analysis used in the planning and validation of processes. It was observed among the studies that the raw material granulometry, followed by pressure, initial moisture, compaction time and binder are the most used process variables for the production of briquettes. Other factors, such as the proportion of biomass, process temperature and thermal pre-treatments are used to obtain greater energetic and physical responses. Among the works, divergences were observed regarding the relevance and interaction of some process variables on the quality variables of the briquettes, indicating the need for the experiments to be mathematically modeled