Emulsion Polymerase Chain Reaction Coupled with Denaturing Gradient Gel Electrophoresis for Microbial Diversity Studies.

Emulsion PCR-DGGE is a molecular biology technique used to amplify and analyze DNA fragments. This technique combines two processes, emulsion PCR and denaturing gradient gel electrophoresis (DGGE), to enhance the specificity and yield of the amplification process and to separate the amplified fragments based on their melting behavior. In the emulsion PCR step, a high-quality DNA template is mixed with the PCR reagents and droplet generator oil to create an oil-in-water emulsion. The emulsion is then subjected to thermal cycling to amplify the target DNA fragments. The amplified fragments are recovered from the droplets and purified to remove any impurities that may interfere with downstream applications. In the DGGE step, the purified amplicon is loaded onto a DGGE apparatus, where the DNA fragments are separated and visualized based on their melting behavior. This method allows for the concurrent amplification and separation of multiple DNA fragments, thereby enhancing the resolution and sensitivity of the analysis. It is widely used in environmental and medical microbiology research, as well as in other fields that require the identification and characterization of microorganisms, such as the study of microbial diversity in soil, water, and other natural environments, as well as in the human gut microbiome and other medical samples.

Hepatitis A and E in the Mediterranean: A systematic review.

Hepatitis A (HAV) and Hepatitis E (HEV) considered to be major public health threats worldwide. Although, both infections are more common in developing countries, an increased number of HAV and HEV cases have been reported in developed countries. This systematic review analyzes epidemiological profiles of HAV and HEV in the Mediterranean countries. By using PRISMA guideline, we searched for articles from 2010 to 2020 referring HAV and HEV outbreaks from online databases: Scopus, PubMed and Springerlink. From 33265 unique publications initially captured, data was extracted from 101 articles investigating country and year of outbreak, transmission mode, vehicle of infection, mean age and sex of patients, symptoms reported, vaccination applied and diagnostic method. Our results indicate that occurrence of HAV and HEV in Mediterranean countries had increased with main transmission vehicle reported as food or water and transmission point as refugee camps. More results (countries, differences, other characteristics). Thus, public health authorities should give a priority to face up challenges regarding the prevalence of both viruses and control strategies to prevent upcoming outbreaks.

Improved PCR-DGGE analysis by emulsion-PCR for the determination of food geographical origin: A case study on Greek PDO "avgotaracho Mesolonghiou".

Greek avgotaracho Mesolonghiou (fish eggs from Flathead Mullet) is a highly valuable food product which holds Protected Destination of Origin status. The aim of this work was to use PCR-DGGE technique to examine whether there is a correlation between bacteria population in fish eggs and geographical origin. Cluster analysis of fish eggs from three geographical locations (Mesolonghi, Australia and Mauritania) discriminated samples according to their provenance. Moreover, we utilized emulsion-PCR amplification in DGGE analysis in order to investigate whether we could obtain further information about food products' bacteria communities. PCR-DGGE proved to be a suitable method for fish eggs traceability, moreover emulsion PCR-DGGE provides better results. Emulsion-PCR can face up the existing limitations of conventional PCR and thus can be demonstrated as alternative molecular technique for complex and processed matrices, regarding food traceability and authentication.

Nontargeted 1 H NMR fingerprinting and multivariate statistical analysis for traceability of Greek PDO Vostizza currants.

In this study, non-targeted 1 H NMR fingerprinting was used in combination with multivariate statistical analyses for the classification of Greek currants based on their geographical origins (Aeghion, Nemea, Kalamata, Zante, and Amaliada). As classification techniques, Principal Component Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) were carried out. To elucidate different components according to PDO (Protected Designation of Origin), products from Aeghion (Vostizza) were statistically compared with each one of the four other regions. PLS-DA plots ensure that currants from Kalamata, Nemea, Zante, and Amaliada are well classified with respect to the PDO currants, according to differences observed in metabolites. Results suggest that composition differences in carbohydrates, amino, and organic acids of currants are sufficient to discriminate them in correlation to their geographical origin. In conclusion, currants metabolites which mostly contribute to classification performance of such discriminant analysis model present a suitable alternative technique for currants traceability. The study results contribute information to the currants' metabolite fingerprinting by NMR spectroscopy and their geographical origin. PRACTICAL APPLICATION: This study presents an analytical approach for a high nutritional value Greek PDO product, Vostizza currant. A further research and implementation of this method in food industry, can be the key to food fraud incidents. Thus, application of this work opens up posibilities to "farm to table" mission.

Atomic-Scale Observation of the Metal-Promoter Interaction in Rh-Based Syngas-Upgrading Catalysts.

The direct conversion of syngas to ethanol, typically using promoted Rh catalysts, is a cornerstone reaction in CO2 utilization and hydrogen storage technologies. A rational catalyst development requires a detailed structural understanding of the activated catalyst and the role of promoters in driving chemoselectivity. Herein, we report a comprehensive atomic-scale study of metal-promoter interactions in silica-supported Rh, Rh-Mn, and Rh-Mn-Fe catalysts by aberration-corrected (AC) TEM. While the catalytic reaction leads to the formation of a Rh carbide phase in the Rh-Mn/SiO2 catalyst, the addition of Fe results in the formation of bimetallic Rh-Fe alloys, which further improves the selectivity and prevents the carbide formation. In all promoted catalysts, Mn is present as an oxide decorating the metal particles. Based on the atomic insight obtained, structural and electronic modifications induced by promoters are revealed and a basis for refined theoretical models is provided.

Insights into structure and dynamics of (Mn,Fe)Ox-promoted Rh nanoparticles.

The mutual interaction between Rh nanoparticles and manganese/iron oxide promoters in silica-supported Rh catalysts for the hydrogenation of CO to higher alcohols was analyzed by applying a combination of integral techniques including temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and Fourier transform infrared (FTIR) spectroscopy with local analysis by using high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) in combination with energy dispersive X-ray spectroscopy (EDX). The promoted catalysts show reduced CO adsorption capacity as evidenced through FTIR spectroscopy, which is attributed to a perforated core-shell structure of the Rh nano-particles in accordance with the microstructural analysis from electron microscopy. Iron and manganese occur in low formal oxidation states between 2+ and zero in the reduced catalysts as shown by using TPR and XAS. Infrared spectroscopy measured in diffuse reflectance at reaction temperature and pressure indicates that partial coverage of the Rh particles is maintained at reaction temperature under operation and that the remaining accessible metal adsorption sites might be catalytically less relevant because the hydrogenation of adsorbed carbonyl species at 523 K and 30 bar hydrogen essentially failed. It is concluded that Rh0 is poisoned due to the adsorption of CO under the reaction conditions of CO hydrogenation. The active sites are associated either with a (Mn,Fe)Ox (x < 0.25) phase or species at the interface between Rh and its co-catalyst (Mn,Fe)Ox.

Understanding the growth of amorphous SiO2 nanofibers and crystalline binary nanoparticles produced by laser ablation.

The pulsed-laser evaporation synthesis of silica nanofibers and crystalline binary nanoparticles is investigated in detail. By careful adjustment of the synthesis parameters one can tailor the product to form high yield nanofibers or binary nanoparticles. Some control on their diameters is also possible through the synthesis parameters. Oxidation of the nanofibers occurs upon exposure to air after the reaction.

In situ observations of fullerene fusion and ejection in carbon nanotubes.

We present in situ experimental observations of fullerenes seamlessly fusing to single-walled carbon nanotubes. The morphing-entry of a fullerene to the interior of a nanotube is also captured. The confined (1D) motion of the newly-encapsulated fullerene within its host attests to the actual change from the exterior to interior.