Multi-catalysis reactions: new prospects and challenges of biotechnology to valorize lignin

Considerable effort has been dedicated to the chemical depolymerization of lignin, a biopolymer constituting a possible renewable source for aromatic value-added chemicals. However, these efforts yielded limited success up until now. Efficient lignin conversion might necessitate novel catalysts enabling new types of reactions. The use of multiple catalysts, including a combination of biocatalysts, might be necessary. New perspectives for the combination of bio- and inorganic catalysts in one-pot reactions are emerging, thanks to green chemistry-driven advances in enzyme engineering and immobilization and new chemical catalyst design. Such combinations could offer several advantages, especially by reducing time and yield losses associated with the isolation and purification of the reaction products, but also represent a big challenge since the optimal reaction conditions of bio- and chemical catalysis reactions are often different. This mini-review gives an overview of bio- and inorganic catalysts having the potential to be used in combination for lignin depolymerization. We also discuss key aspects to consider when combining these catalysts in one-pot reaction

Sorption-assisted surface conjugation: a way to stabilize laccase enzyme

Enyzme immobilization on solid surfaces is one of the most relevant methods to improve enzyme activity and stability under harsh conditions over extended periods. A typically interesting application is the immobilization of laccases, multicopper enzymes oxidizing aromatic compounds, to solid surfaces in order to develop valuable tools for the elimination of micropollutants in wastewater. Laccase of the white-rot fungus Coriolopsis polyzona has been successfully immobilized on fumed silica nanoparticles using a novel method. It consists in the sorption of the enzyme to amino-modified silica nanoparticles and the subsequent covalent cross-linking using glutaraldehyde as a homobifunctional linker. The so-produced nanoparticulate material has been characterized by means of scanning electron microscopy and Brunauer-Emmett-Teller surface area analysis revealing modifications of the surface structure and area during the coupling procedure. Laccase immobilization on spherical nanoparticles produced according to the method of Stöber has been shown to be much less efficient than on fumed silica nanoparticles. Long-term stability assays revealed that the novel developed method allows a drastic stabilization of the enzyme. In real wastewater, 77% of the laccase activity remained on the nanoparticles over 1month, whereas the activity of free laccase dropped to 2.5%. The activity loss on the nanoparticles resulted from partial inactivation of the immobilized enzymes and additional release into the surrounding solution with subsequent fast inactivation of the free enzymes, since almost no activity was found in the supernatant

Radio (14C)- and fluorescent-doubly labeled silica nanoparticles for biological and environmental toxicity assessment

A new and efficient synthetic route to fluorescent and 14C-double-labeled silica-based nanoparticles (NPs) is described. The synthesis has been carried out using the "oil-in-water” micro-emulsion technique. Fluorescent and radioactive labeling have been achieved entrapping labeled poly(ethylene glycol) (PEG) molecules in the NPs. The produced particles have been analyzed by means of scanning electron microscopy, photon correlation spectroscopy, confocal microscopy, scintillation counting and oxidation/combustion experiments. Fluorescence quenching experiments confirm that the label is entrapped in the particles. The results presented suggest that the silica matrix does not block the β-radiations emitted from the labeled PEG molecules entrapped in the NP

Impact of bio-augmentation with Sphingomonas sp. strain TTNP3 in membrane bioreactors degrading nonylphenol

This study evaluates the potential of bio-augmentation to improve the degradation of recalcitrant nonylphenol during the wastewater treatment in membrane bioreactors (MBR). One MBR containing activated sludge was bio-augmented using multistep inoculation with freeze dried Sphingomonas sp. strain TTNP3, whereas a second control reactor contained activated sludge solely. The 14C-labeled-nonylphenol isomer (4-[1-ethyl-1,3-dimethylpentyl]phenol) was applied as a single pulse. Bio-augmentation resulted in an immediate increase of dissolved radioactivity in the effluent in comparison to the control reactor (13% and 2% of initially applied radioactivity after 1day, respectively). After 5days of operation, the retentate of the bio-augmented reactor contained only 7% of the initial radioactivity in contrast to 50% in the control reactor. The radioactivity associated to the mixed liquor suspended solids, i.e., the suspension of biomass and other solids on the retentate side of the membrane, was mainly found as non-extractable residues that were increasingly formed during prolonged reactor operation, especially for the control MBR. HPLC-LSC and GC-MSn analyses revealed that the bio-augmented reactor produced more polar hydroquinone as main degradation intermediate, whereas the control reactor effluent contained a complex mixture of apolar compounds with shortened oxidized alkyl chains. Thus, the apparent differences in the behavior of nonylphenol between the reactors were due to the catabolism of nonylphenol conferred by bio-augmentation with Sphingomonas sp. strain TTNP

Self-cleaning stainless steel surfaces induced by laser processing and chemical engineering

Nanostructured surfaces show a variety of beneficial macroscopic effects. The combination of hierarchic nanostructures with a suitable chemical surface composition allows for the fabrication of surfaces with interesting fluidic properties beyond such effects. This approach enables the specification of nano/microstructure and chemical composition independent of each other. Various hierarchical micro- and nanostructures can be realized by laser texturing of stainless steel surfaces with infrared picosecond laser. Simultaneously, the surface is activated for chemical processing. The surface can now be tuned by bonding of a self-assembled monolayer on the laser-treated surface by chemical treatment. This two-step functionalization process allows the for separated adjusting of the surface topography and chemical composition and thus for the well-defined setting of the surface properties. The fabrication of superhydrophobic surfaces with self-cleaning properties are performed that can be functionalized further by subsequent laser-irradiation. Furthermore, the long-time stability of the surface functionalization in relation to the impact chemicals or radiation was investigated

Immobilization of defined laccase combinations for enhanced oxidation of phenolic contaminants

Immobilization is an important method to increase enzyme stability and allow enzyme reuse. One interesting application in the field of environmental biotechnology is the immobilization of laccase to eliminate phenolic contaminants via oxidation. Fumed silica nanoparticles have interesting potential as support material for laccase immobilization via sorption-assisted immobilization in the perspective of applications such as the elimination of micropollutants in aqueous phases. Based on these facts, the present work aimed to formulate laccase-nanoparticle conjugates with defined laccase combinations in order to obtain nanobiocatalysts, which are active over a broad range of pH values and possess a large substrate spectrum to suitably address pollution by multiple contaminants. A multi-enzymatic approach was investigated by immobilizing five different types of laccases originating from a Thielavia genus, Coriolopsis polyzona, Cerrena unicolor, Pleurotus ostreatus, and Trametes versicolor onto fumed silica nanoparticles, separately and in combinations. The laccases differed concerning their pH optima and substrate affinity. Exploiting their differences allowed the formulation of tailor-made nanobiocatalysts. In particular, the production of a nanobiocatalyst could be achieved that retained a higher percentage of its relative activity over the tested pH range (3-7) compared to the dissolved or separately immobilized enzymes. Furthermore, a nanobiocatalyst could be formulated able to oxidize a broader substrate range than the dissolved or separately immobilized enzymes. Thereby, the potential of the nanobiocatalyst for application in biochemical oxidation applications such as the elimination of multiple target pollutants in biologically treated wastewater has been illustrated

Технологические решения для строительства разведочной вертикальной скважины глубиной 2950 метров на нефтяном месторождении (Тюменская область)

Цель работы – проектирование вертикальной разведочной скважины глубиной 2950 метров. В процессе работы был составлен проект на строительство вертикальной разведочной скважины на нефть глубиной 2950 м (по вертикали). Разработаны мероприятия по организации строительству, охране труда и окружающей среды. В работе рассмотрен вопрос технология установки клино-отклонителя.The purpose of the work is to design a vertical exploration well with a depth of 2,950 meters. In the process, a project was drawn up for the construction of a vertical exploration well for oil of 2950 m depth (vertical). Developed measures for the organization of construction, labor and environmental protection. The paper considers the issue of installation technology wedge-diverter

Leaf wall area related dose within the framework of the authorisation for plant protection products in grape vine uses

Mit Pflanzenschutzmittel zu behandelnde Kulturpflanzen werden im Spritz- oder Sprühverfahren in der Regel durch eine waagerecht oder senkrecht zur Erdoberfläche geführte Einrichtung behandelt, je nachdem ob es sich um eine Flächenkultur – wie z.B. Getreide oder Kartoffel – bzw. um eine Raumkultur – wie z.B. Weinrebe oder Apfel – handelt. Da die Zielfläche bei Raumkulturen in aller Regel nicht wie bei Flächenkulturen identisch mit der Grundfläche ist, soll auch bei der Zulassung von Pflanzenschutzmitteln die Aufwandmenge auf die tatsächlich zu behandelnde Fläche bezogen werden, nämlich auf die Laubwandfläche.Bei der Zulassung von Indikationen in Weinrebe, Kern­obst und hochwachsende Gemüsekulturen soll die Wirksamkeitsbewertung laubwandflächenbasiert erfolgen. Entsprechend wird die Beschreibung der Anwendungen zusätzlich mit der Angabe einer laubwandflächenbasierten Aufwandmenge ergänzt. Die Konsequenzen für die Zulassung und die weinbauliche Praxis werden dargestellt.Plant protection products are usually applied as a spray application with the help of a boom sprayer. Depending on whether it is a field crop – such as cereal or potato – or a high growing crop – such as grapevine or apple – the boom sprayer is horizontally or vertically guided parallel in relation to the target surface.In the case of high growing crops the target area is generally not identical to the ground area as it is the case of field crops. Within the authorisation the dosage of plant protection products in high growing crops should also be related to the real treated area, namely the leaf wall area.The efficacy assessment should be based on the leaf wall area when approving uses of vine grape, pome fruits or high growing vegetable crops. In future the efficacy assess­ment should be based on the leaf wall area when approving vine grape uses. Accordingly, the description of the uses is adapted with an additional information of a leaf wall area based application rate. The consequences for the registration and the viticulture practice are presented

Advanced enzymatic elimination of phenolic contaminants in wastewater: a nano approach at field scale

The removal of recalcitrant chemicals in wastewater treatment systems is an increasingly relevant issue in industrialized countries. The elimination of persistent xenobiotics such as endocrine-disrupting chemicals (EDCs) emitted by municipal and industrial sewage treatment plants remains an unsolved challenge. The existing efficacious physico-chemical methods, such as advanced oxidation processes, are resource-intensive technologies. In this work, we investigated the possibility to remove phenolic EDCs [i.e., bisphenol A (BPA)] by means of a less energy and chemical consuming technology. To that end, cheap and resistant oxidative enzymes, i.e., laccases, were immobilized onto silica nanoparticles. The resulting nanobiocatalyst produced at kilogram scale was demonstrated to possess a broad substrate spectrum regarding the degradation of recalcitrant pollutants. This nanobiocatalyst was applied in a membrane reactor at technical scale for tertiary wastewater treatment. The system efficiently removed BPA and the results of long-term field tests illustrated the potential of fumed silica nanoparticles/laccase composites for advanced biological wastewater treatment