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The demand for cheap, healthy, and sustainable alternative protein sources has turned research interest into microbial proteins. Mycoproteins prevail due to their quite balanced amino acid profile, low carbon footprint and high sustainability potential. The goal of this research was to investigate the capability of Pleurotus ostreatus to metabolize the main sugars of agro-industrial side streams, such as aspen wood chips hydrolysate, to produce high-value protein with low cost. Our results indicate that P. ostreatus LGAM 1123 could be cultivated both in a C-6 (glucose)- and C-5(xylose)-sugar-containing medium for mycoprotein production. A mixture of glucose and xylose was found to be ideal for biomass production with high protein content and rich amino acid profile. P. ostreatus LGAM 1123 cultivation in a 4 L stirred-tank bioreactor using aspen hydrolysate was achieved with 25.0 ± 3.4 g L−1 biomass production, 1.8 ± 0.4 d−1 specific growth rate and a protein yield of 54.5 ± 0.5% (g/100 g sugars). PCA analysis of the amino acids revealed a strong correlation between the amino acid composition of the protein produced and the ratios of glucose and xylose in the culture medium. The production of high-nutrient mycoprotein by submerged fermentation of the edible fungus P. ostreatus using agro-industrial hydrolysates is a promising bioprocess in the food and feed industry.

Esterases are among the most studied enzymes with applications expanding in several branches of industrial biotechnology. Yet, besides the fact that information on substrate specificity is crucial for selecting or designing the best fitted biocatalyst for the desired application, it cannot be predicted from the amino acid sequence. In the present work, we study the substrate scope of the newly discovered hydrolytic enzyme, EstDZ3, an extremozyme, against a library ofesters with variable carbon chain lengths, in an effort to unveil the amino acids for the substrate selectivity of this enzyme. EstDZ3 appears to be active against a wide range of esters with high selectivity towards medium to long carbon chain vinyl esters. In silico studies revealed that the selectivity may arise from the mainly hydrophobic nature of the active site's environment.

Multi-enzymatic assemblies offer the opportunity of bringing in proximity several enzymes that are enabled to work together for the catalysis of multi-step reactions. Especially, the development of robust nanobiocatalytic systems comprising of several enzymes has gained considerable attention over the last few years for the catalysis of complex reactions and the production of high added-value products. In the present chapter, we describe the methodology for the development of a bi-enzymatic nanobiocatalyst consisting of the enzymes β-glucosidase from Thermotoga maritima and lipase A from Candida antarctica (CalA) co-immobilized on chitosan-coated magnetic nanoparticles. This nanobiocatalyst can be efficiently applied for the biotransformation of oleuropein to hydroxytyrosol, a reaction of increased biotechnological interest. Several techniques, as well as methodologies that are required for the characterization of the structure and the activity of such systems are also comprehensively described.

Germanane (GeH), a graphane analogue, has attracted significant interest because of its optoelectronic properties; however, the environmental and biological effects of GeH have scarcely been investigated so far. Here we report a facile approach based on the Langmuir-Schaefer deposition to produce homogeneous and dense GeH monolayer films on various substrates. In view of possible applications and to extend the use of GeH to unexplored fields, we investigated its antibacterial activity for the first time and found that this promising 2D structure exhibits remarkable antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

As olive leaves constitute the main by-product of the olive oil industry with important environmental and economic impact, there is an increasing demand for its valorization. In the present work, we report the development and application of immobilized enzyme batch bioreactors for the chemo-enzymatic treatment of an aqueous Olea europaea leaf extract rich in oleuropein to produce an extract enriched in hydroxytyrosol and other oleuropein hydrolysis products. To this end, a robust biocatalyst was developed through the immobilization of β-glucosidase on chitosan-coated magnetic beads which exhibited high hydrolytic stability after 240 h of incubation at 37 °C. The biocatalyst was successfully used in both a rotating bed-reactor and a stir-tank reactor for the modification of the olive leaf extract leading to high conversion yields of oleuropein (exceeding 90%), while an up to 2.5 times enrichment in hydroxytyrosol was achieved. Over 20 phenolic compounds (from different classes of phytochemicals such as flavonoids, secoiridoids, and their derivatives) were identified, in the extract before and after its modification through various chromatographic and spectroscopic techniques. Finally, the biological activity of both extracts was evaluated. Compared to the non-modified extract, the modified one demonstrated 20% higher antioxidant activity, seven-fold higher antibacterial activity, and enhanced cytotoxicity against leiomyosarcoma cells.

In this work, hybrid zinc oxide–iron oxide (ZnOFe) magnetic nanoparticles were synthesized employing Olea europaea leaf aqueous extract as a reducing/chelating and capping medium. The resulting magnetic nanoparticles were characterized by basic spectroscopic and microscopic techniques, namely, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared (FTIR) and atomic force microscopy (AFM), exhibiting a spherical shape, average size of 15–17 nm, and a functionalized surface. Lipase from Thermomyces lanuginosus (TLL) was efficiently immobilized on the surface of ZnOFe nanoparticles through physical absorption. The activity of immobilized lipase was found to directly depend on the enzyme to support the mass ratio, and also demonstrated improved pH and temperature activity range compared to free lipase. Furthermore, the novel magnetic nanobiocatalyst (ZnOFe-TLL) was applied to the preparation of hydroxytyrosyl fatty acid esters, including derivatives with omega-3 fatty acids, in non-aqueous media. Conversion yields up to 90% were observed in non-polar solvents, including hydrophobic ionic liquids. Different factors affecting the biocatalyst performance were studied. ZnOFe-TLL was reutilized for eight subsequent cycles, exhibiting 90% remaining esterification activity (720 h of total operation at 50 °C). The green synthesized magnetic nanoparticles, reported here for the first time, are excellent candidates as nanosupports for the immobilization of enzymes with industrial interest, giving rise to nanobiocatalysts with elevated features.

Enzymes are pliable systems and core cellular components allowing the performance of several processes. They can also be utilized as "green" synthetic factories to generate bioactive therapeutic, diagnostic or theranostic compounds. Methods to enable the mapping of enzyme substrates as well as the understanding of the interactions of the formed products with target proteins could be of importance. This chapter describes the utilization of the "NMR tube bioreactor" method. This method, carried out inside an NMR tube, can allow for the prediction of compounds that are able to serve as potential enzyme substrates, and also exploit the regioselectivity of the enzymatic reactions. Furthermore, it enables the real time monitoring of multiple-biotransformation products in the NMR tube without the need of fractionation or isolation of each individual component. Finally, it allows for the screening of the resulting biotransformation products as ligands for protein targets.

Enzymes are pliable systems and core cellular components allowing the performance of several processes. They can also be utilized as "green" synthetic factories to generate bioactive therapeutic, diagnostic or theranostic compounds. Methods to enable the mapping of enzyme substrates as well as the understanding of the interactions of the formed products with target proteins could be of importance. This chapter describes the utilization of the "NMR tube bioreactor" method. This method, carried out inside an NMR tube, can allow for the prediction of compounds that are able to serve as potential enzyme substrates, and also exploit the regioselectivity of the enzymatic reactions. Furthermore, it enables the real time monitoring of multiple-biotransformation products in the NMR tube without the need of fractionation or isolation of each individual component. Finally, it allows for the screening of the resulting biotransformation products as ligands for protein targets.

The ever-growing demand for cost-effective and innocuous biocatalytic transformations has prompted the rational design and development of robust biocatalytic tools. Enzyme immobilization technology lies in the formation of cooperative interactions between the tailored surface of the support and the enzyme of choice, which result in the fabrication of tremendous biocatalytic tools with desirable properties, complying with the current demands even on an industrial level. Different nanoscale materials (organic, inorganic, and green) have attracted great attention as immobilization matrices for single or multi-enzymatic systems. Aiming to unveil the potentialities of nanobiocatalytic systems, we present distinct immobilization strategies and give a thorough insight into the effect of nanosupports specific properties on the biocatalysts' structure and catalytic performance. We also highlight the development of nanobiocatalysts for their incorporation in cascade enzymatic processes and various types of batch and continuous-flow reactor systems. Remarkable emphasis is given on the application of such nanobiocatalytic tools in several biocatalytic transformations including bioremediation processes, biofuel production, and synthesis of bioactive compounds and fine chemicals for the food and pharmaceutical industry.

Lipase A from Candida antarctica (CalA) and β-glucosidase from Thermotoga maritima (bgl) were covalently co-immobilized onto the surface of chitosan-coated magnetic nanoparticles (CS-MNPs). Several parameters regarding the co-immobilization procedure (glutaraldehyde concentration, incubation time, CS-MNPs to enzyme mass ratio and bgl to CalA mass ratio) were evaluated and optimized. The developed nanobiocatalyst was characterized by various spectroscopic techniques. Biochemical parameters such as kinetic constants and thermal stability were also evaluated. The nanobiocatalytic system revealed an increase in the Km constant followed by a decrease in Vmax value compared with the native enzymes, while a significant increase (&gt, 5-fold higher) of the thermal stability of the immobilized CalA, both in individual and in co-immobilized form, was observed after 24 h incubation at 60 °C. Finally, the nanobiocatalyst was efficiently applied for the bioconversion of oleuropein to hydroxytyrosol, one of the most powerful naturally derived antioxidants, and it could be recycled for up to 10 reaction cycles (240 h of constant operation) at 60 °C, retaining more than 50% of its initial activity.

Enantiomeric ratios for the esterification reaction of 2-phenylpropionic acid with 1-octanol catalyzed by immobilized Candida antarctica lipase B in sixteen organic solvents have been measured. Correlation equations that relate the enzyme enantioselectivity with the van der Waals volume (Vw), the van der Waals area (Aw), and the Hildebrand solubility parameters (δ2) of the solvents were obtained, and they were compared with linear solvation energy relationship (LSER) correlation equations, which relates the enzyme enantioselectivity with polarity, acidity, basicity, and Hildebrand solubility parameters of the solvents. Statistical analysis of the experimental data for the esterification reaction investigated here as well as for seven other reactions taken from the literature showed that the pure solvent Vw, Aw and δ2 parameters, sufficiently describe the dependence of enzyme enantioselectivity on the properties of the solvent, yielding better results than the LSER equations that use one more parameter. Furthermore, the enzyme enantioselectivity has been related to the infinite dilution activity coefficients of substrates in the solvent, which are predicted by the COSMO-RS model. It is shown that the predicted by COSMO-RS ratios of infinite dilution activity coefficients of the two enantiomers can be used to correlate satisfactorily the enantiomeric ratios.

In the present study, we developed novel &beta, glucosidase-based nano-biocatalysts for the bioconversion of oleuropein to hydroxytyrosol. Using non-covalent or covalent immobilization approaches, &beta, glucosidases from almonds and Thermotoga maritima were attached for the first time on oxidized and non-oxidized porous carbon cuboids (PCC). Various methods were used for the characterization of the bio-nanoconjugates, such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and fluorescence spectroscopy. The oxidation state of the nan&omicron, support and the immobilization procedure play a key role for the immobilization efficiency or the catalytic activity of the immobilized &beta, glucosidases. The nano-biocatalysts were successfully used for the hydrolysis of oleuropein, which leads to the formation of its bioactive derivative, hydroxytyrosol (up to 2.4 g L&minus, 1), which is a phenolic compound with numerous health benefits. The bio-nanoconjugates exhibited high thermal and operational stability (up to 240 hours of repeated use), which indicated that they are efficient tools for various bio-transformations.

Natural products have served as a rich source for drug discovery and development. In the last decade their fruitful integration in the drug discovery pipeline declined due to their reduced bioavailability, mainly attributed to their poor aqueous solubility. We synthesized a quercetin (QUE)-(2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) complex that enabled amplification of its solubility and in the same time retained its bioactivity in T24 human bladder cancer cell line. The stability of the complex and the molecular basis of the interactions developed in this host-guest complex were assayed by incorporating an array of analytical techniques and Molecular Dynamics (MD) experiments. 2D DOSY NMR experiment revealed that the diffusion coefficient of free HP-β-CD was 3.55×10(-10)m(2)s(-1) while that of QUE-HP-β-CD inclusion complex 3.09×10(-10)m(2)s(-1), indicating the formation of a complex. Solid and liquid high resolution NMR spectroscopy data showed that the most pronounced differences in chemical shifts at carbons and protons correspondingly during complexation occur in the aromatic ring Α (bearing the two phenolic hydroxyl groups meta to each other). The chemical shift differences in the aromatic ring Β (bearing the two phenolic hydroxyl groups ortho to each other) were less pronounced. The MD results confirmed the experimental data.

The preparation, characterization and application of a novel robust nanobiocatalyst, developed through the covalent binding of lipase B from Pseudozyma antarctica on magnetic hierarchically porous carbon materials (HPCFe), is reported. The nanobiocatalyst was characterized by combination of spectroscopic and microscopic techniques. Structural and catalytic characterization indicates that HPCFe nanostructures create a microenvironment which stabilizes the structure of the immobilized enzyme, resulting in enhanced activity and stability in non-aqueous media over other forms of the biocatalyst. The nanobiocatalyst was effectively applied for the selective deacetylation of peracetylated quercetin towards the synthesis of 3,5,7-triacetoxy-3′,4′-dihydroxyflavone, a compound with high antiproliferative activity. At the optimum bioprocess conditions, the produced amount of the bioactive quercetin derivative in a single-step process reached values up to 3.48 g L−1 which is 13 times higher than that reported to date. The immobilized enzyme retains ~100% of its catalytic activity after 10 repeated reaction cycles.

This chapter deals with the use of functionalized derivatives of graphene oxide as nanoscaffolds for the immobilization and stabilization of laccase from Trametes versicolor. Covalent and noncovalent immobilization approaches are described, while a novel method for the development of laccase-based multilayer nanoassemblies is also presented. Various biochemical, spectroscopic, and microscopic techniques were applied to characterize the nanobiocatalytic systems in respect to their microstructure and catalytic performance. Laccase-GO nanosystems were characterized with FTIR spectroscopy in order to confirm the functionalization of the nanomaterials, as well as to interpret the nanomaterial-enzyme interactions, while the multilayer structure of laccase-based multilayer nanoassemblies was confirmed by atomic force microscopy. The nanobiocatalytic systems presented here demonstrated exceptional stability and reusability compared with the free enzyme form, leading to robust biocatalytic systems appropriate for various applications of industrial interest.

This chapter deals with the use of functionalized derivatives of graphene oxide as nanoscaffolds for the immobilization and stabilization of laccase from Trametes versicolor. Covalent and noncovalent immobilization approaches are described, while a novel method for the development of laccase-based multilayer nanoassemblies is also presented. Various biochemical, spectroscopic, and microscopic techniques were applied to characterize the nanobiocatalytic systems in respect to their microstructure and catalytic performance. Laccase-GO nanosystems were characterized with FTIR spectroscopy in order to confirm the functionalization of the nanomaterials, as well as to interpret the nanomaterial-enzyme interactions, while the multilayer structure of laccase-based multilayer nanoassemblies was confirmed by atomic force microscopy. The nanobiocatalytic systems presented here demonstrated exceptional stability and reusability compared with the free enzyme form, leading to robust biocatalytic systems appropriate for various applications of industrial interest.

Cyclodextrins (CDs) are a well-known class of supermolecules that have been widely used to protect drugs against conjugation and metabolic inactivation as well as to enhance the aqueous solubility and hence to ameliorate the oral bioavailability of sparingly soluble drug molecules. The hepatoprotectant drug silibinin can be incorporated into CDs, and here we elucidate the interaction between the drug and the host at the molecular level. The complexation product of silibinin with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) is characterized by Differential Scanning Calorimetry, mass spectrometry, solid and liquid high-resolution NMR spectroscopy. The chemical shift changes using (13)C CP/MAS on the complexing of the guest with the host provided significant information on the molecular interactions, and they were in agreement with the 2D NOESY results. These results point out that in both solid and liquid forms, the drug is engulfed and interacts with HP-β-CD in identical manner. Molecular dynamics calculations have been performed to examine the thermodynamic characteristics associated with the silibinin-HP-β-CD interactions and to study the stability of the complex. To approximate the physiological conditions, the aqueous solubility and dissolution characteristics of the complex at pH states simulating those of the upper gastrointestinal tract have been applied. To evaluate the antiproliferative activity of silibinin-HP-β-CD complex comparatively to silibinin in MCF-7 human cancer cells, MTT assays have been performed.

Recent science evidenced the interlinkage of oxidative stress and cancer. Due to the inherent complexity of cancer and its accompanying effect of oxidative stress, novel molecules, containing combinatorial functionalities should be targeted. Herein, we synthesized gemcitabine-5'-O-lipoate derived from a regioselective coupling of the chemotherapeutic drug gemcitabine (GEM), a first-line agent for cancer therapy and α-lipoic acid (LA), a potent antioxidant. gemcitabine-5'-O-lipoate was obtained in 4 chemical steps. To avoid the tedious and laborious chemical steps we also utilized biocatalysis using immobilized Candida antarctica lipase B (CALB), and the optimum conditions for the regioselective and one-pot synthesis of gemcitabine-5'-O-lipoate were established by exploiting different solvents (organic solvents and ionic liquids) and enzyme immobilization (acrylic resin and carbon nanotubes). Cytotoxic activity of co-administrating GEM and LA was proven to be synergistic against non-small cell lung cancer cells whereas antagonistic for bladder cancer cells. In contrast, the gemcitabine-5'-O-lipoate hybrid was found to be superior to the parent compounds against both non-small cell lung cancer and bladder cancer cells as also was found to preserve the redox activity of the parent compound LA. The regioselective biotransformation mediated synthesis of the anticancer-antioxidant hybrid illustrates the capacity of biocatalysis to act as an asset in molecular hybridization techniques.

The lipase-catalyzed molecular hybridization of α-lipoic acid (LA) with bioactive compounds pyridoxine, tyrosol and tyramine was performed in ionic solvents and deep eutectic solvents. The biocatalytic reactions were catalyzed by Candida antarctica lipase B immobilized onto various functionalized multi-walled carbon nanotubes (f-CNTs-CaLB), as well as by commercial Novozym 435. The use of f-CNTs-CaLB leads, in most cases, to higher conversion yields as compared to Novozym 435. The nature and ion composition of ionic solvents affect the performance of the biocatalytic process. The highest conversion yield was observed in (mtoa)NTf2. The high enzyme stability and the relatively low solubility of substrates in specific media account for the improved biocatalytic synthesis of molecular hybrids of LA. Principal component analysis was used to screen for potential lipoxygenase inhibitors. In vitro studies showed that the synthesized compounds exhibit up to 10-fold increased inhibitory activity on lipoxygenase mediated lipid peroxidation as compared to parent molecules.