Endophytic microorganisms live inside plants for at least part of their life cycle. According to their life strategies, bacterial endophytes can be classified as “obligate” or “facultative”. Reports that members of the genus Micromonospora, Gram-positive Actinobacteria, are normal occupants of nitrogen-fixing nodules has opened up a question as to what is the ecological role of these bacteria in interactions with nitrogen-fixing plants and whether it is in a process of adaptation from a terrestrial to a facultative endophytic life. The aim of this work was to analyse the genome sequence of Micromonospora lupini Lupac 08 isolated from a nitrogen fixing nodule of the legume Lupinus angustifolius and to identify genomic traits that provide information on this new plant-microbe interaction. The genome of M. lupini contains a diverse array of genes that may help its survival in soil or in plant tissues, while the high number of putative plant degrading enzyme genes identified is quite surprising since this bacterium is not considered a plant-pathogen. Functionality of several of these genes was demonstrated in vitro, showing that Lupac 08 degraded carboxymethylcellulose, starch and xylan. In addition, the production of chitinases detected in vitro, indicates that strain Lupac 08 may also confer protection to the plant. Micromonospora species appears as new candidates in plant-microbe interactions with an important potential in agriculture and biotechnology. The current data strongly suggests that a beneficial effect is produced on the host-plant.
For a long time, it was believed that a healthy plant did not harbor any microorganisms within its tissues, as these were often considered detrimental for the plant. In the last three decades, the numbers of studies on plant microbe-interactions has led to a change in our view and we now know that many of these invisible partners are essential for the overall welfare of the plant. The application of Next Generation Sequencing techniques is a powerful tool that has permitted the detection and identification of microbial communities in healthy plants. Among the new plant microbe interactions recently reported several actinobacteria such as Micromonospora are included. Micromonospora is a Gram-positive bacterium with a wide geographical distribution; it can be found in the soil, mangrove sediments, and freshwater and marine ecosistems. In the last years our group has focused on the isolation of Micromonospora strains from nitrogen fixing nodules of both leguminous and actinorhizal plants and reported for the first time its wide distribution in nitrogen fixing nodules of both types of plants. These studies have shown how this microoganism had been largely overlooked in this niche due to its slow growth. Surprisingly, the genetic diversity of Micromonospora strains isolated from nodules is very high and several new species have been described. The current data indicate that Micromonospora saelicesensis is the most frequently isolated species from the nodular tissues of both leguminous and actinorhizal plants. Further studies have also been carried out to confirm the presence of Micromonospora inside the nodule tissues, mainly by specific in situ hybridization. The information derived from the genome of the model strain, Micromonospora lupini, Lupac 08, has provided useful information as to how this bacterium may relate with its host plant. Several strategies potentially necessary for Micromonospora to thrive in the soil, a highly competitive, and rough environment, and as an endophytic bacterium with the capacity to colonize the internal plant tissues which are protected from the invasion of other soil microbes were identified. The genome data also revealed the potential of M. lupini Lupac 08 as a plant growth promoting bacterium. Several loci involved in plant growth promotion features such as the production of siderophores, phytohormones, and the degradation of chitin (biocontrol) were also located on the genome and the functionality of these genes was confirmed in the laboratory. In addition, when several host plants species were inoculated with Micromonospora strains, the plant growth enhancing effect was evident under greenhouse conditions. Unexpectedly, a high number of plant-cell wall degrading enzymes were also detected, a trait usually found only in pathogenic bacteria. Thus, Micromonospora can be added to the list of new plant-microbe interactions. The current data indicate that this microorganism may have an important application in agriculture and other biotechnological processes. The available information...
Small size, monodispersed hexagonal particles of Mg,Al-CO 3 hydrotalcite-like compounds have been synthesized in short periods of time by the microwave-hydrothermal method. An in-depth study of the influence of the irradiation time and the process temperature has been carried out. Well-crystalized materials with relatively high specific surface area values have been prepared in 30 min at 150 °C.
The electrocatalytic conversion of 5‐hydroxymethylfurfural (HMF), a biomass platform molecule, to 2,5‐bis(hydroxymethyl)furan (BHMF), a polymer precursor, is a fully sustainable route that operates at room temperature and pressure, using water as source of hydrogen, and avoids high H2 pressures. In this work, we investigate the use of 3D electrocatalysts, made by Ag0 electrodeposited on Cu open‐cell foams (Ag/Cu), to improve the efficiency in the electrochemical conversion of HMF to BHMF in basic media at different HMF concentrations. For comparison purposes, Ag and Cu bulk foams as well as Ag, Cu and Ag/Cu foil counterparts are investigated. For diluted 0.02 M HMF solutions, BHMF is selectively produced at high HMF conversion and FE over Ag/Cu foams. The large surface area of 3D Ag/Cu foams, compared to their 2D counterparts, does not affect selectivity, but increases the rate of conversion and in turn the productivity. However, it would appear that the increase in the surface area is not enough to increase the efficiency in the conversion of more concentrated HMF electrolytes (0.05–0.50 M). The productivity of Ag/Cu is modified with electrocatalytic cycles.
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