This review aims to present current knowledge of the fungi involved in lignocellulose degradation with an overview of the various classes of lignocellulose‐acting enzymes engaged in the pretreatment ...and saccharification step. Fungi have numerous applications and biotechnological potential for various industries including chemicals, fuel, pulp, and paper. The capability of fungi to degrade lignocellulose containing raw materials is due to their highly effective enzymatic system. Along with the hydrolytic enzymes consisting of cellulases and hemicellulases, responsible for polysaccharide degradation, they have a unique nonenzymatic oxidative system which together with ligninolytic enzymes is responsible for lignin modification and degradation. An overview of the enzymes classification is given by the Carbohydrate‐Active enZymes (CAZy) database as the major database for the identification of the lignocellulolytic enzymes by their amino acid sequence similarity. Finally, the recently discovered novel class of recalcitrant polysaccharide degraders‐lytic polysaccharide monooxygenases (LPMOs) are presented, because of these enzymes importance in the cellulose degradation process.
The importance of the lytic polysaccharide monooxygenase (LPMO) enzyme in the preparation of lignocellulosic raw materials for production in biorefineries has been confirmed in numerous ...investigations. Therefore, LPMO enzymes were investigated to explore the enzyme-substrate interaction with the aim of successful biomass conversion in biorefinery processes. After reductive activation of LPMOs active site, they cleave the substrate and prepare it for biomass degradation by hydrolytic enzymes. In this paper, the role of LPMO in lignocellulosic biomass conversion is described based on the recent studies of: LPMO enzyme structure, LPMO substrate preferences, and the LPMO reaction mechanism. These findings are important for the selection of suitable bioprocess conditions with the aim of LPMO activation/stabilisation in biorefinery production processes.
The underutilized biomass and different organic waste streams are nowadays in the focus of research for renewable energy production due to the effusive use of fossil fuels and greenhouse gas ...emission. In addition, one of the major environmental problems is also a constant increase of the number of organic waste streams. In a lot of countries, sustainable waste management, including waste prevention and reduction, has become a priority as a means to reduce pollution and greenhouse gas emission. Application of biogas technology is one of the promising methods to provide solutions for both actual energy-related and environmental problems. This review aims to present conventional and novel biogas production systems, as well as purification and upgrading technologies, nowadays applicable on a large scale, with a special focus on the CO
and H
S removal. It also gives an overview of feedstock and the parameters important for biogas production, together with digestate utilization and application of molecular biology in order to improve the biogas production.
The effect of different hydrodistillation pretreatments, namely, reflux extraction, reflux extraction with the addition of cell wall-degrading enzymes, and ultrasound, on the yield and chemical ...composition of essential oils of sage, bay laurel, and rosemary was examined. All pretreatments improved essential oil yield compared to no-pretreatment control (40–64% yield increase), while the oil quality remained mostly unchanged (as shown by statistical analysis of GC-MS results). However, enzyme-assisted reflux extraction pretreatment did not significantly outperform reflux extraction (no-enzyme control), suggesting that the observed yield increase was mostly a consequence of reflux extraction and enzymatic activity had only a minute effect. Thus, we show that ultrasound and reflux extraction pretreatments are beneficial in the production of essential oils of selected Mediterranean plants, but the application of enzymes has to be carefully re-evaluated.
This work investigates the methodology of producing a 3D-printed microreactor from the acrylic resin by PolyJet Matrix process. The PolyJet Matrix technology employs different materials or their ...combinations to generate 3D-printed structures, from small ones to complex geometries, with different material properties. Experimental and numerical methods served for the evaluation of the geometry and production of the microreactor and its hydrodynamic characterization. The operational limits of the single-phase flow in the microchannels, further improvements and possible applications of the microreactor were assessed based on the hydrodynamic characterization.
A three-step process consisting of biomass hydrolysis, fermentation and in-situ gas stripping by a vacuum assisted recovery system, was optimized to increase the ethanol production from sugar beet ...pulp. The process combines the advantages of stripping and vacuum separation and enhances the fermentation productivity through in-situ ethanol removal. Using the design of experiment and response surface methodology, the effect of major factors in the process, such as pressure, recycling ratio and solids concentration, was tested to efficiently remove ethanol after the combined hydrolysis and fermentation step. Statistical analysis indicates that a decreased pressure rate and an increased liquid phase recycling ratio enhance the productivity and the yield of the strip-vacuum fermentation process. The results also highlight further possibilities of this process to improve integrated bioethanol production processes. According to the statistical analysis, ethanol production is strongly influenced by recycling ratio and vacuum ratio. Mathematical models that were established for description of investigated processes can be used for the optimization of the ethanol production.
In this work the green synthesis of gold nanoparticles (Au-NPs) using the oxidoreductive enzymes
Myriococcum thermophilum
cellobiose dehydrogenase (
Mt
CDH),
Glomerella cingulata
glucose ...dehydrogenase (
Gc
GDH), and
Aspergillus niger
glucose oxidase (
An
GOX)) as bioreductants was investigated. The influence of reaction conditions on the synthesis of Au-NPs was examined and optimised. The reaction kinetics and the influence of Au ions on the reaction rate were determined. Based on the kinetic study, the mechanism of Au-NP synthesis was proposed. The Au-NPs were characterized by UV–Vis spectroscopy and transmission electron microscopy (TEM). The surface plasmon resonance (SPR) absorption peaks of the Au-NPs synthesised with
Mt
CDH and
Gc
GDH were observed at 535 nm, indicating an average size of around 50 nm. According to the image analysis performed on a TEM micrograph, the Au-NPs synthesized with
Gc
GDH have a spherical shape with an average size of 2.83 and 6.63 nm after 24 and 48 h of the reaction, respectively.
Key points
• The Au NPs were synthesised by the action of enzymes CDH and GDH.
• The synthesis of Au-NPs by CDH is related to the oxidation of cellobiose.
• The synthesis of Au-NPs by GDH was not driven by the reaction kinetic.
Graphical Abstract
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•NADESs were screened for valorisation of orange peel waste.•The use of NADESs enhances enantioselectivity of orange peel-catalysed synthesis.•NADESs serve as excellent solvents for ...extraction of biologically active compounds.•Stabilisation of hydrolytic enzymes (including PME) in NADESs was confirmed.•ChEg50 can serve as a unique solvent for orange peel waste integrated biorefinery.
This research investigates the use of seven natural deep eutectic solvents (NADESs) for valorisation of orange peel waste, with the final goal to propose a unique NADES for integrated biorefinery. Initial screening of NADESs revealed the excellent ability of cholinium-based NADES with ethylene glycol as hydrogen bond donor (ChEg50) to serve as a medium for orange peel-catalysed kinetic resolution (hydrolysis) of (R,S)-1-phenylethyl acetate with high enantioselectivity (ee = 83.2%, X = 35%), as well as it’s stabilizing effect on the hydrolytic enzymes (hydrolytic enzymes within ChEg50 peel extract were stabile during 20 days at 4 °C). The ChEg50 also showed a satisfactory capacity to extract D-limonene (0.5 mg gFW−1), and excellent capacity to extract polyphenols (45.7 mg gFW−1), and proteins (7.7 mg gFW−1) from the peel. Based on the obtained results, the integrated biorefinery of orange peel waste using ChEg50 in a multistep process was performed. Firstly, enantioselective kinetic resolution was performed (step I; ee = 83.2%, X = 35%), followed by isolation of the product 1-phenylethanol (step II; h = 82.2%) and extraction of polyphenols (step III; h = 86.8%) from impoverished medium. Finally, the residual orange peel was analysed for sugar and lignin content, and results revealed the potential of waste peel for the anaerobic co-digestion process. The main bottlenecks and futures perspective of NADES-assisted integrated biorefinery of orange peel waste were outlined through SWOT analysis.
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