Broadening The Substrate Scope of Aldolases Through Metagenomic Enzyme Discovery.

Bio-processes based on enzymatic catalysis play a major role in the development of green, sustainable processes, and the discovery of new enzymes is key to this approach. In this work, we analysed ten metagenomes and retrieved 48 genes coding for deoxyribose-5-phosphate aldolases (DERAs, EC 4.1.2.4) using a sequence-based approach. These sequences were recombinantly expressed in Escherichia coli and screened for activity towards a range of aldol additions. Among these, one enzyme, DERA-61, proved to be particularly interesting and catalysed the aldol addition of furfural or benzaldehyde with acetone, butanone and cyclobutanone with unprecedented activity. The product of these reactions, aldols, can find applications as building blocks in the synthesis of biologically active compounds. Screening was carried out to identify optimized reaction conditions targeting temperature, pH, and salt concentrations. Lastly, the kinetics and the stereochemistry of the products were investigated, revealing that DERA-61 and other metagenomic DERAs have superior activity and stereoselectivity when they are provided with non-natural substrates, compared to well-known DERAs.

Application of an integrated pyrolysis and chemical leaching process for pulper waste conversion into coal, hydrogen and chemical flocculating agent.

This work aims to investigate the potentials of integrating slow pyrolysis and chemical leaching to recycle pulper waste (PW), the waste generated by paper mills, and consists of plastics, metallic films, and biobased polymers. The concentration of chlorine and metals is a barrier against PW valorisation by combustion or high temperature thermochemical processes. In this study, PW was tested by slow pyrolysis at 400 °C and 500 °C. Chemical leaching tests were performed by processing both chars in a 1.4 M HCl solution, at 80 °C for 2 h, to remove inorganic compounds and upgrade the char to a coal-like material. Then, precipitation by NaOH was conducted on the leachate. Slow pyrolysis led to a char mass yield around 30 %. Due to the high inorganic matter concentration (almost 36 %, mainly including chlorine, calcium, and aluminium), the char retained only 25 % of the feedstock's chemical energy, while the remaining 75 % was recovered in the pyrogas. Leaching of the 500 °C pyrolysis char led to extract 93 % of aluminium, and almost 100 % of calcium and chlorine, resulting in an upgraded char containing 15.5 % ash, comparable to a fossil coal. By char leaching, the oxidation reaction of aluminium could produce 8 kg hydrogen per dry ton PW. The effectiveness of the precipitated compounds as flocculating agents was demonstrated, enabling a closed-loop recycling in the same paper mill. In conclusion, the proposed process demonstrated to be an effective solution to convert PW into high quality products.

Spatially resolved CO2 carbon stable isotope analyses at the microscale using Raman spectroscopy.

Measuring the carbon stable isotope ratio (13C/12C, expressed as δ13CCO2) in geogenic CO2 fluids is a crucial geochemical tool for studying Earth's degassing. Carbon stable isotope analysis is traditionally performed by bulk mass spectrometry. Although Raman spectroscopy distinguishes 12CO2 and 13CO2 isotopologue bands in spectra, using this technique to determine CO2 isotopic signature has been challenging. Here, we report on in-situ non-destructive analyses of the C stable isotopic composition of CO2, applying a novel high-resolution Raman configuration on 42 high-density CO2 fluid inclusions in mantle rocks from the Lake Tana region (Ethiopia) and El Hierro (Canary Islands). We collected two sets of three spectra with different acquisition times at high spectral resolution in each fluid inclusion. Among the 84 sets of spectra, 58 were characterised by integrated 13CO2/12CO2 band area ratios with reproducibility better than 4‰. Our results demonstrate the determination of δ13CCO2 by Raman spectroscopy in individual fluid inclusions with an error better than 2.5 ‰, which satisfactorily matches bulk mass spectrometry analyses in the same rock samples, supporting the accuracy of the measurements. We thus show that Raman Spectroscopy can provide a fundamental methodology for non-destructive, site-specific, and spatially resolved carbon isotope labelling at the microscale.

Trace elements in sediments and plankton from two high-altitude lakes in a volcanic area from North Patagonia, Argentina.

This study analyzes the distribution of nine potentially toxic trace elements (arsenic, antimony, bromine, cobalt, chromium, mercury, rubidium, selenium, and zinc) in sediments and plankton from two small mesotrophic lakes in a non-industrialized area impacted by the Caviahue-Copahue volcanic complex (CCVC). The two lakes have different plankton community structures and received different amounts of pyroclastic material after the last CCVC eruption. Trace element concentrations of surface sediments differed between lakes, according to the composition of the volcanic ashes deposited in the lakes. The size of organisms was the principal factor influencing the accumulation of most trace elements in plankton within each lake, being trace element concentrations generally higher in the microplankton than in the mesozooplankton. The planktonic biomass in the shallower lake was dominated by small algae and copepods, while mixotrophic ciliates and different-sized cladocerans dominated the deeper lake. These differences in the community structure and species composition influenced the trace element bioaccumulation, especially in microplankton, while habitat use and feeding strategies seem more relevant in mesozooplankton bioaccumulation. This work contributes to the scarce records of trace elements and their dynamics in plankton from freshwater ecosystems impacted by volcanic activity.

Tracking carbon from subduction to outgassing along the Aleutian-Alaska Volcanic Arc.

Subduction transports volatiles between Earth's mantle, crust, and atmosphere, ultimately creating a habitable Earth. We use isotopes to track carbon from subduction to outgassing along the Aleutian-Alaska Arc. We find substantial along-strike variations in the isotopic composition of volcanic gases, explained by different recycling efficiencies of subducting carbon to the atmosphere via arc volcanism and modulated by subduction character. Fast and cool subduction facilitates recycling of ~43 to 61% sediment-derived organic carbon to the atmosphere through degassing of central Aleutian volcanoes, while slow and warm subduction favors forearc sediment removal, leading to recycling of ~6 to 9% altered oceanic crust carbon to the atmosphere through degassing of western Aleutian volcanoes. These results indicate that less carbon is returned to the deep mantle than previously thought and that subducting organic carbon is not a reliable atmospheric carbon sink over subduction time scales.

Natural iron fertilization by shallow hydrothermal sources fuels diazotroph blooms in the ocean.

Iron is an essential nutrient that regulates productivity in ~30% of the ocean. Compared with deep (>2000 meter) hydrothermal activity at mid-ocean ridges that provide iron to the ocean's interior, shallow (<500 meter) hydrothermal fluids are likely to influence the surface's ecosystem. However, their effect is unknown. In this work, we show that fluids emitted along the Tonga volcanic arc (South Pacific) have a substantial impact on iron concentrations in the photic layer through vertical diffusion. This enrichment stimulates biological activity, resulting in an extensive patch of chlorophyll (360,000 square kilometers). Diazotroph activity is two to eight times higher and carbon export fluxes are two to three times higher in iron-enriched waters than in adjacent unfertilized waters. Such findings reveal a previously undescribed mechanism of natural iron fertilization in the ocean that fuels regional hotspot sinks for atmospheric CO2.

Assessment of the Use of Common Juniper (Juniperus communis L.) Foliage following the Cascade Principle.

Juniperus communis L. is a species commonly grown in regions of the Northern Hemisphere, and is a good candidate to be cultivated in marginal lands. Plants coming from a pruning performed in a natural population located in Spain were used to assess the yield and quality of different products obtained following the cascade principle. A total of 1050 kg of foliage biomass were crushed, steam-distilled, and separated into fractions to produce biochar and absorbents for the pet industry using pilot plants. The obtained products were analysed. The essential oil, with a yield of 0.45% dry basis and a qualitative chemical composition similar to that described for the berries in international standards or monographs, showed antioxidant activity with promising CAA results (inhibition of 89% of the cell's oxidation). However, regarding antibacterial and antifungal activities, it only inhibited the growth of microorganisms at the maximum concentration tested, 2.5%. Concerning the hydrolate, it did not show bioactivity. Regarding the biochar, whose yield was 28.79% dry basis, interesting results were obtained for its characterisation as a possible soil improver for agronomic purposes (PFC 3(A)). Finally, promising results were obtained regarding the use of common juniper as absorbent, taking into account the physical characterisation and odour control capacity.

Recovery of Terephthalic Acid from Densified Post-consumer Plastic Mix by HTL Process.

In this study, we investigate the hydrothermal liquefaction (HTL) of PET separated from a densified postconsumer plastic mix, with the aim of recovering its monomer. This second raw material is made up of 90% polyolefin, while the remaining 10% is made up of PET, traces of metals, paper, and glass. After preliminary separation by density in water, two batch experiments were performed on the sunken fraction (composed mainly of PET) in a stainless steel autoclave at 345 °C for 30 and 20 min. Both trials resulted in similar yields of the three phases. In particular, the solid yield is around 76% by weight. After a purification step, this phase was analyzed by UV-Vis, 1H-NMR, and FTIR spectroscopy and resulted to be constituted by terephthalic acid (TPA), a product of considerable industrial interest. The study proved that the hydrothermal liquefaction process coupled with density separation in water is effective for obtaining TPA from a densified postconsumer plastic mix, which can be used for new PET synthesis.

Impairment of RAD17 Functions by miR-506-3p as a Novel Synthetic Lethal Approach Targeting DNA Repair Pathways in Ovarian Cancer.

Epithelial ovarian cancer (EOC) remains the most lethal gynecological cancer and development of chemo-resistance is a major factor in disease relapse. Homologous recombination (HR) is a critical pathway for DNA double strand break repair and its deficiency is associated to a better response to DNA damage-inducing agents. Strategies to inhibit HR-mediated DNA repair is a clinical need to improve patients' outcome. MicroRNA (miRNAs) affect most of cellular processes including response to cancer treatment. We previously showed that miR-506-3p targets RAD51, an essential HR component. In this study we demonstrated that: i) another HR component, RAD17, is also a direct target of miR-506-3p and that it is involved in mediating miR-506-3p phenotypic effects; ii) the impairment of miR-506-3p binding to RAD17 3' UTR reverted the miR-506-3p induced platinum sensitization; iii) miR-506-3p/RAD17 axis reduces the ability of EOC cell to sense DNA damage, abrogates the G2/M cell cycle checkpoint thus delaying the G2/M cell cycle arrest likely allowing the entry into mitosis of heavily DNA-damaged cells with a consequent mitotic catastrophe; iv) RAD17 expression, regulated by miR-506-3p, is synthetically lethal with inhibitors of cell cycle checkpoint kinases Chk1 and Wee1 in platinum resistant cell line. Overall miR-506-3p expression may recapitulate a BRCAness phenotype sensitizing EOC cells to chemotherapy and helping in selecting patients susceptible to DNA damaging drugs in combination with new small molecules targeting DNA-damage repair pathway.

Effects of biochar on berseem clover (Trifolium alexandrinum, L.) growth and heavy metal (Cd, Cr, Cu, Ni, Pb, and Zn) accumulation.

Urban soil pollution by heavy metals (HMs) is a pressing problem in the development of urban agriculture (UA). In this context, the use of amendments, such as biochar, and phytoremediation are considered potentially cost-effective alternatives to conventional methods, and can be also combined to improve the remediation of soils from HMs. A pot experiment was performed to investigate the combined effect of berseem clover (Trifolium alexandrinum, L.) and biochar amendment in remediating a sandy soil collected near a shooting range area co-contaminated with Cd, Cr, Cu, Ni, Pb, and Zn. The biochar, obtained from a wood-chip gasifier fed with a mix of Douglas (Pseudotsuga menziesii, Mirb.) and Black Pine (Pinus nigra, J.F.Arnold) wood, was applied at two rates (0.8% and 1.6%, w/w). Eighteen weeks after sowing, all plants were harvested. The roots and aboveground tissues of the crops were separately collected and analyzed. The tested biochar effectively adsorbed the HMs (Cd, Cr, Cu, Ni, Pb, and Zn) from the soil. Biochar increased DW production of aboveground and root tissues. Moreover, biochar significantly reduced the concentration of Cr, Cu, Ni, and Pb in the aboveground tissues of berseem clover, although a significant reduction was not detected for Cd and Zn. Results indicated that berseem clover was a Cr, Ni and Pb excluder. However, this species can be considered suitable for Cu phytoextraction and Cd and Zn phytostabilization of slightly polluted urban soil. Only the Cu levels in the aerial biomass were below the acceptable limit for use as fodder.