Search

In this work, for the first time, a set of two-and three-dimensional (3D) analysis techniques are combined to clarify the nature of resistive switching (RS) in state-of-the-art TiO2-based vacancy modulated conductive oxide (VMCO) memory. (1) A non-filamentary switching mechanism is observed. (2) The role of oxygen incorporation and motion in the TiO2 is demonstrated. (3) The oxygen profile inside scaled cells is measured and a RS-model based on the modulation of oxygen inside the stack is proposed. In addition, we perform the tomographic analysis of fully-fabricated devices with Scalpel SPM, thus probing in 3D the entire stack and the contribution of TiO2 grain boundaries (GBs) to the switching operations. Finally, devices failed by breakdown (BD) during cycling are characterized, identifying the formation of parasitic filaments as root-cause of the failure.

Polycyclic Aromatic Hydrocarbons (PAHs) are among the most widespread organic pollutants in the environment. PAHs are of great concern because some of them show strong mutagenicity and carcinogenity. Bioremediation, which involves the use of microorganisms to reduce the concentration of various chemical pollutants, has become nowadays one of the most promising approach for environmental clean-up. Unfortunately, the presence of heavy metals in environments contaminated by organic compounds often hamper the environmental restoration. Several species of bacteria have been isolated from polluted environments able to degrade recalcitrant compounds. We have recently characterized a novel Sphingomonadales, Novosphingobium sp. PP1Y, isolated from surface seawater samples collected inside the harbour of Pozzuoli (Naples, Italy). The strain PP1Y not only uses a surprisingly large number of mono and polycyclic aromatic compounds as the sole carbon and energy sources but it shows a very interesting and effective adaptation to grow on complex mixtures of aromatic compounds dissolved in oil phases like diesel-oil and gasoline. Novosphingobium sp. PP1Y showed the ability to form “biofilm” on several types of hydrophobic surfaces and, in water/oil systems. It is well known that biofilm formation make bacteria able to adhere to growing substrates and to confer the resistance towards heavy metals and organic pollutants. We investigated the biodegradation abilities of Novosphingobium sp. PP1Y in natural soil and compost, artificially contaminated by PAHs and heavy metals such as nickel, copper and zinc, in small-scale experiments. N. sp. PP1Y showed the ability to quickly remove phenanthrene from the compost after addition of the organic compound in crystal form or dissolved in oil phase. The bacterium was also able to metabolize phenanthrene in the presence of heavy metals, showing the most significant delay in phenanthrene removal only at high nickel concentration. When a mixture of PAHs in paraffin containing naphthalene, phenanthrene and pyrene, was added to the compost, the bacterium was able to remove all the three compounds, although with different rates. Furthermore, the addition of N. sp. PP1Y to a natural soil contaminated by heavy metals and PAHs, already endowed with a microbial community adapted to use PAHs in the presence of heavy metals, halved the time of natural self-purifying of the soil, thus suggesting the ability of N. sp. PP1Y to compete with the adapted endogenous microbial community.In conclusion Novosphingobium sp. PP1Y is a good candidate for the bioremediation of organic compound contaminated soils in the presence of heavy metals.

The MariaBox project, funded by the European Commission (Contract 614088), is developing an autonomous, analytical device, based on novel biosensors, for monitoring chemical and biological pollutants in sea water. The device, currently at first prototype level, is suitable for installation in free floating devices, buoys or ships. The main, high-level user requirements for the system are for the device to be of high-sensitivity, portable and capable of repeating measurements over a long time, allowing long-term deployment at sea. The first phase of the project, “user requirements collection”, was dedicated to understanding the current needs of water monitoring through institutions in different areas of Europe, at different location types. The locations in which the research was focused are also the ones in which the field validation of MariaBox will take place: a sea water lagoon in Spain with different characteristics of water salinity and natural environment, currently exploited for shellfish farming; a natural site in Ireland (Galway bay); the Skagerrak, a sea arm between Norway, Denmark and Sweden; and a harbour area close to industrial facilities in Cyprus. The analytes of interest for the monitoring institutions are coherent to the list of pollutants to be monitored by the European Commission. A first trade-off between end-user requirements and engineering feasibility, available time and final system cost had to be made. On one hand, the MariaBox device is intended to be portable and its size must be such as to allow permanent positioning inside sea buoys. Several modules are required to achieve the aim of monitoring, in an autonomous and unattended way, all selected target analytes for a period of several months. Energy expenditure is a relevant constraint. Nevertheless, being a device deployed at sea, energy scavenging is a real option to guarantee the system autonomy or, at least, to keep the system operating at a minimum level, that is, to maintain the biosensors and the biochemical reactants in a controlled and safe environment. This controlled environment is managed by the analytical core unit of MariaBox, that acts as a cooler or heater depending on the external temperatures (from −10°C up to +50°C). The system design has been confronted with all of these challenging requirements. The device is intended to provide not only scientific data but also early warnings in relation to both algal blooming and production of toxins, as well as to chemical, man-made pollutants (heavy metals, camphechlor, naphthalene, PFOS). This means that considering the European thresholds for pollutants is not enough. The MariaBox detection capacity has to be under the legal threshold, so as to enable early warnings and the possibility to prevent the pollution with adequate countermeasures. The first MariaBox prototype has been recently produced and is currently being tested and validated in the lab. Within 2017, the device will be replicated and 4 replicas will be installed in the 4 selected pilot locations.

Gram-negative bacteria release Outer Membrane Vesicles (OMVs) into the extracellular environment. Recent studies recognized these vesicles as vectors to horizontal gene transfer, however, the parameters that mediate OMVs transfer within bacterial communities remain unclear. The present study highlights for the first time the transfer of plasmids containing resistance genes via OMVs derived from Klebsiella pneumoniae (K. pneumoniae). This mechanism confers DNA protection, it is plasmid copy number dependent with a ratio of 3.6 times among high copy number plasmid (pGR) versus low copy number plasmid (PRM), and the transformation efficiency was 3.6 times greater. Therefore, the DNA amount in the vesicular lumen and the efficacy of horizontal gene transfer was strictly dependent on the identity of the plasmid. Moreover, the role of K. pneumoniae-OMVs in interspecies transfer was described. The transfer ability was not related to the phylogenetic characteristics between the donor and the recipient species. K. pneumoniae-OMVs transferred plasmid to Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa and Burkholderia cepacia. These findings address the pivotal role of K. pneumoniae-OMVs as vectors for antimicrobial resistance genes spread, contributing to the development of antibiotic resistance in the microbial communities.

In recent decades, intensive crop management has involved excessive use of pesticides or fertilizers, compromising environmental integrity and public health. Accordingly, there has been worldwide pressure to find an eco-friendly and safe strategy to ensure agricultural productivity. Among alternative approaches, Plant Growth-Promoting (PGP) rhizobacteria are receiving increasing attention as suitable biocontrol agents against agricultural pests. In the present study, 22 spore-forming bacteria were selected among a salt-pan rhizobacteria collection for their PGP traits and their antagonistic activity against the plant pathogen fungus Macrophomina phaseolina. Based on the higher antifungal activity, strain RHFS10, identified as Bacillus vallismortis, was further examined and cell-free supernatant assays, column purification, and tandem mass spectrometry were employed to purify and preliminarily identify the antifungal metabolites. Interestingly, the minimum inhibitory concentration assessed for the fractions active against M. phaseolina was 10 times lower and more stable than the one estimated for the commercial fungicide pentachloronitrobenzene. These results suggest the use of B. vallismortis strain RHFS10 as a potential plant growth-promoting rhizobacteria as an alternative to chemical pesticides to efficiently control the phytopathogenic fungus M. phaseolina.

Il saggio esamina la questione dell'assegno di divorzio nella prospettiva della solidarietà post-coniugale, analizzando criticamente l'esito di cripto-indissolubilità del matrimonio che emerge dalla consolidata lettura della relativa obbligazione come tendenzialmente priva di termine finale. The essay examines the issue of the divorce allowance from the perspective of post-marital solidarity, critically analyzing the outcome of the crypto-indissolubility of marriage that emerges from the consolidated reading of the relative obligation as tendentially without a final term.

Background Bacterial spores displaying heterologous antigens or enzymes have long been proposed as mucosal vaccines, functionalized probiotics or biocatalysts. Two main strategies have been developed to display heterologous molecules on the surface of Bacillus subtilis spores: (i) a recombinant approach, based on the construction of a gene fusion between a gene coding for a coat protein (carrier) and DNA coding for the protein to be displayed, and (ii) a non-recombinant approach, based on the spontaneous and stable adsorption of heterologous molecules on the spore surface. Both systems have advantages and drawbacks and the selection of one or the other depends on the protein to be displayed and on the final use of the activated spore. It has been recently shown that B. subtilis builds structurally and functionally different spores when grown at different temperatures; based on this finding B. subtilis spores prepared at 25, 37 or 42 °C were compared for their efficiency in displaying various model proteins by either the recombinant or the non-recombinant approach. Results Immune- and fluorescence-based assays were used to analyze the display of several model proteins on spores prepared at 25, 37 or 42 °C. Recombinant spores displayed different amounts of the same fusion protein in response to the temperature of spore production. In spores simultaneously displaying two fusion proteins, each of them was differentially displayed at the various temperatures. The display by the non-recombinant approach was only modestly affected by the temperature of spore production, with spores prepared at 37 or 42 °C slightly more efficient than 25 °C spores in adsorbing at least some of the model proteins tested. Conclusion Our results indicate that the temperature of spore production allows control of the display of heterologous proteins on spores and, therefore, that the spore-display strategy can be optimized for the specific final use of the activated spores by selecting the display approach, the carrier protein and the temperature of spore production.

Klebsiella pneumoniae is an opportunistic pathogen that causes nosocomial and community-acquired infections. The spread of resistant strains of K. pneumoniae represents a growing threat to human health, due to the exhaustion of effective treatments. K. pneumoniae releases outer membrane vesicles (OMVs). OMVs are a vehicle for the transport of virulence factors to host cells, causing cell injury. Previous studies have shown changes of gene expression in human bronchial epithelial cells after treatment with K. pneumoniae OMVs. These variations in gene expression could be regulated through microRNAs (miRNAs), which participate in several biological mechanisms. Thereafter, miRNA expression profiles in human bronchial epithelial cells were evaluated during infection with standard and clinical K. pneumoniae strains. Microarray analysis and RT-qPCR identified the dysregulation of miR-223, hsa-miR-21, hsa-miR-25 and hsa-let-7g miRNA sequences. Target gene prediction revealed the essential role of these miRNAs in the regulation of host immune responses involving NF-ĸB (miR-223), TLR4 (hsa-miR-21), cytokine (hsa-miR-25) and IL-6 (hsa-let-7g miRNA) signalling pathways. The current study provides the first large scale expression profile of miRNAs from lung cells and predicted gene targets, following exposure to K. pneumoniae OMVs. Our results suggest the importance of OMVs in the inflammatory response.

Endogenous reactive oxygen species (ROS) are by-products of the aerobic metabolism of cells and have an important signalling role as secondary messengers in various physiological processes, including cell growth and development. However, the excessive production of ROS, as well as the exposure to exogenous ROS, can cause protein oxidation, lipid peroxidation and DNA damages leading to cell injuries. ROS accumulation has been associated to the development of health disorders such as neurodegenerative and cardiovascular diseases, inflammatory bowel disease and cancer. We report that spores of strain SF185, a human isolate of Bacillus megaterium, have antioxidant activity on Caco-2 cells exposed to hydrogen peroxide and on a murine model of dextran sodium sulfate-induced oxidative stress. In both model systems spores exert a protective state due to their scavenging action: on cells, spores reduce the amount of intracellular ROS, while in vivo the pre-treatment with spores protects mice from the chemically-induced damages. Overall, our results suggest that treatment with SF185 spores prevents or reduces the damages caused by oxidative stress. The human origin of SF185, its strong antioxidant activity, and its protective effects led to propose the spore of this strain as a new probiotic for gut health.