Simple Substrates Research Articles

Bioactive Compounds from and against Yeasts in the One Health Context: A Comprehensive Review

Yeasts are the most used microorganisms for biotechnological purposes. Although they have been mainly recognized for their application in the beverage and bioethanol industries, these microorganisms can be efficiently employed in pharmaceutical and food production companies. In these industrial sectors, yeasts are highly desirable for their capacity to produce bioactive compounds from simple substrates, including wastes. In this review, we present the state of the art of bioactive compound production in microbial cell factories and analyze the avenues to increase the productivity of these molecules, which benefit human and environmental health. The article addresses their vast biological activities, from preventing to treating human diseases and from pre to postharvest control on agroindustrial streams. Furthermore, different yeast species, genetically engineered or not, are herein presented not only as biofactories of the referred to compounds but also as their targets. This comprehensive analysis of the literature points out the significant roles of biodiversity, bioprospection, and genome editing tools on the microbial production of bioactive compounds and reveals the value of these approaches from the one health perspective.

Cu-Co Dual-Atom Catalysts Supported on Hierarchical USY Zeolites for an Efficient Cross-Dehydrogenative C(sp2)-N Coupling Reaction.

A cross-coupling reaction via the dehydrogenative route over heterogeneous solid atomic catalysts offers practical solutions toward an economical and sustainable elaboration of simple organic substrates. The current utilization of this technology is, however, hampered by limited molecular definition of many solid catalysts. Here, we report the development of Cu-M dual-atom catalysts (where M = Co, Ni, Cu, and Zn) supported on a hierarchical USY zeolite to mediate efficient dehydrogenative cross-coupling of unprotected phenols with amine partners. Over 80% isolated yields have been attained over Cu-Co-USY, which shows much superior reactivity when compared with our Cu1 and other Cu-M analogues. This amination reaction has hence involved simple and non-forceful reaction condition requirements. The superior reactivity can be attributed to (1) the specifically designed bimetallic Cu-Co active sites within the micropore for "co-adsorption-co-activation" of the reaction substrates and (2) the facile intracrystalline (meso/micropore) diffusion of the heterocyclic organic substrates. This study offers critical insights into the engineering of next-generation solid atomic catalysts with complex reaction steps.

Synthesis of Chiral 1,1,1-Trifluoro-α,α-disubstituted 2,4-Diketones via Palladium-Catalyzed Asymmetric Allylation

Trifluoromethyl ketones are important enzyme inhibitors and versatile synthons for the preparation of trifluoromethylated heterocycles and complex molecules. An efficient methodology for the synthesis of chiral 1,1,1-trifluoro-α,α-disubstituted 2,4-diketones via palladium-catalyzed allylation with allyl methyl carbonates under mild conditions has been developed. This method surmounts the major obstacle of detrifluoroacetylation, and a chiral trifluoromethyl ketone library could be rapidly built up from simple substrates in good yields and enantioselectivities, thereby offering a new choice for scientists in pharmaceutical and material industries.

A flow-through strategy using supported ionic liquids for L-asparaginase purification

L-asparaginase (ASNase) is an amidohydrolase enzyme widely distributed in nature, e.g., microorganisms, plants and tissues of several animals. Nevertheless, microorganisms are the preferential source of ASNase since they usually grow in simple substrates and culture conditions. However, a high level of enzyme purity is required by the pharmaceutical industry, in which the applied downstream process may account for up to 80% of the total ASNase production costs. Silica-based supported ionic liquid-like phase (SSILLP) materials are here proposed as alternative immobilization/capture or processing supports for the ASNase purification. SSILLP materials with different alkyl chain lengths at the cation source and Cl− as the counterion were investigated to purify ASNase by the flow-through like mode. Silica functionalized with dimethylbutylpropylammonium chloride ([Si][N3114]Cl) was selected as the most promising material since it displayed the highest purification factor (1.65) and specific activity of ASNase (0.026 U mg−1) achieved. The ASNase purification operating conditions were then optimized through Response Surface Methodology, using pH (range in which enzyme is active) and solid/liquid ratio (S/L ratio) as factors, achieving a maximum purification factor of 3.36. Semi-continuous purification of ASNase was finally performed under the optimized purification conditions (pH 3 and S/L ratio of 15), enabling a purification factor of 5.15. This corresponds to a 3.12- and a 1.53-fold increase in the purification factor obtained compared with the initial screening and batch assays under optimized purification conditions. These findings demonstrate that SSILLP materials can act as simple semi-continuous ASNase purification supports with potential in flow-through downstream processing.

Preparation of Wear-Resistant Superhydrophobic Coatings Based on a Discrete-Phase Adhesive

Among the many methods to prepare superhydrophobic coatings, the liquid spraying method has the advantages of simple operation, low equipment and substrate requirements, and a low cost to achieve large-scale industrialization. However, superhydrophobic coatings prepared using the existing one-step and two-step spraying methods are not wear resistant, and the failure mechanism is also not clear. After preparing coatings using existing methods and conducting wear tests, we show that the reason for their lack of wear resistance is the excessive bonding caused by the nanoparticles embedded in the continuous-phase adhesive, or the low bonding caused by adhesion to the adhesive surface. Based on the above conclusion, we propose a method to transform a continuous-phase adhesive into a discrete-phase adhesive via phase separation, after which it is mixed with nanoparticles for spraying. This new method allows the nanoparticles to bond to the adhesive while avoiding embedding, which avoids the shortcomings of existing methods. Consequently, coatings fabricated using the new method have better wear resistance properties and important significance for practical applications.

L-ergothioneine reduces nitration of lactoferrin and loss of antibacterial activity associated with nitrosative stress

Lactoferrin (LF) is a multifunctional antimicrobial, anti-inflammatory, and antioxidant protein that occurs naturally in mammals, most notably in exocrine gland tissues and fluids, such as in the eye. Nitrosative stress can promote changes to tyrosine and other amino acid residues of the protein, which also reduces the activity of LF. l-ergothioneine (ET) is a potent anti-inflammatory antioxidant present in the eye and other tissues through nutrition or supplementation and that may play a role in the prevention or treatment of a variety of diseases. Here we investigated the ability of ET to reduce 3-nitrotyrosine (NTyr) formation using two separate substrates, with the goal of determining whether ET can protect the antibacterial function of LF and other proteins when exposed separately to peroxynitrite and tetranitromethane as nitrating reagents. Native human LF was used as a simple protein substrate, and lamb corneal lysate was chosen as one example of mammalian tissue with a more complex mixture of proteins and other biomolecules. Nitration was monitored by absorbance and fluorescence spectroscopy as well as sandwich (nitrated LF) and direct NTyr (corneal lysate) enzyme-linked immunosorbent assays (ELISAs). We found that pretreatment with ET reduced chemical modification of both native LF and corneal lysate samples and loss of antibacterial LF function due to exposure to the nitrating reagents. These initial results suggest that ET, raised to sufficiently elevated levels, could be tailored as a therapeutic agent to reduce effects of nitrosative stress on LF and in turn sustain the protein activity.

In-line Multidimensional NMR Monitoring of Photochemical Flow Reactions.

This work demonstrates the in-line monitoring of a flow photochemical reaction using 1D and ultrafast 2D NMR methods at high magnetic field. The reaction mixture exiting the flow reactor is flown through the NMR spectrometer and directly analyzed. In the case of simple substrates, suitable information can be obtained through 1D 1 H spectra, but for molecules of higher complexity the use of 2D experiments is key to address signal overlaps and assignment issues. Here we show the usefulness of ultrafast 2D COSY experiments acquired in 70 s or less, for the in-line monitoring of photochemical reactions, and the possibility to obtain reliable quantitative information. This is a powerful framework to, for example, efficiently screen reaction conditions.

Iron-Catalyzed Coupling of Alkenes and Enones: Sakurai-Michael-type Conjugate Addition of Catalytic Allyliron Nucleophiles.

The iron-catalyzed coupling of alkenes and enones through allylic C(sp3)-H functionalization is reported. This redox-neutral process employs a cyclopentadienyliron(II) dicarbonyl catalyst and simple alkene substrates to generate catalytic allyliron intermediates for 1,4-addition to chalcones and other conjugated enones. The use of 2,4,6-collidine as the base and a combination of triisopropylsilyl triflate and LiNTf2 as Lewis acids was found to facilitate this transformation under mild, functional group-tolerant conditions. Both electronically unactivated alkenes as well as allylbenzene derivatives could be employed as pronucleophilic coupling partners, as could a range of enones bearing electronically varied substituents.

Rotational dive into the water clusters on a simple sugar substrate

Most biomolecular activity takes place in aqueous environments, and it is strongly influenced by the surrounding water molecules. The hydrogen bond networks that these water molecules form are likewise influenced by their interactions with the solutes, and thus, it is crucial to understand this reciprocal process. Glycoaldehyde (Gly), often considered the smallest sugar, represents a good template to explore the steps of solvation and determine how the organic molecule shapes the structure and hydrogen bond network of the solvating water cluster. Here, we report a broadband rotational spectroscopy study on the stepwise hydration of Gly with up to six water molecules. We reveal the preferred hydrogen bond networks formed when water molecules start to form three-dimensional (3D) topologies around an organic molecule. We observe that water self-aggregation prevails even in these early stages of microsolvation. These hydrogen bond networks manifest themselves through the insertion of the small sugar monomer in the pure water cluster in a way in which the oxygen atom framework and hydrogen bond network resemble those of the smallest three-dimensional pure water clusters. Of particular interest is the identification, in both the pentahydrate and hexahydrate, of the previously observed prismatic pure water heptamer motif. Our results show that some specific hydrogen bond networks are preferred and survive the solvation of a small organic molecule, mimicking those of pure water clusters. A many-body decomposition analysis of the interaction energy is also performed to rationalize the strength of a particular hydrogen bond, and it successfully confirms the experimental findings.

A Novel Compact Filtering Antenna for 5.0-GHz WLAN Communication System

The proposed antenna presents a microstrip filter antenna with both filter out-of-band rejection characteristics and antenna radiation characteristics for WLAN communication system. The antenna consists of four U-shaped microstrip resonators, one Γ-shaped antenna, and one parallel coupling line. The Γ-shaped antenna has the filtering function as the last order resonator, and the parallel coupling line integrates the filter and antenna as the conductance converter. After simulation and test, the results show that the center frequency of the filter antenna is 5.25 GHz, the fractional bandwidthis 8.0% (5.0 − 5.42 GHz), the in-band gain changes smoothly, the maximum in-band gain is 3.059 dBi, the gain at 150 MHz outside the passband rapidly decreases to 10.0 dBi, and the overall out-of-band gain drops to below −24 dBi. The filter antenna has a simple structure and thin substrate, which optimizes the overall size of the filter and antenna, reduces the transmission loss between them, and is applicable to the RF front-end of wireless communication systems.

Anaerobic co-metabolic degradation of ceftriaxone sodium: Performance and mechanism

Ceftriaxone sodium (CTX) is a typical β-lactam antibiotic in pharmaceutical wastewater. Although traditional biological treatments are low-cost and eco-friendly, antibiotics usually inhibit microorganisms, resulting in limited treatment performance. The biological co-metabolism process provides carbon sources and energy for microorganisms through co-substrate addition, thereby producing enzymes or cofactors to enhance the degradation of refractory pollutants. Therefore, the present study aimed to investigate the degradation performance of CTX through anaerobic biological co-metabolism. A simple co-metabolic substrate (i.e., glucose, 80 mg L−1) was added into an anaerobic-activated sludge system, and its mechanism was explored in terms of the variations in extracellular polymeric substances, microbial structure, and resistance genes. Additionally, the possible degradation pathways of CTX were described. The results showed that the degradation efficiency of CTX (200 mg L−1) was only about 35% within 8 h in the control group, while it increased to 67.6% in the experimental group with glucose. Chloroflexi, Actinobacteria, Bacteroidetes ADurb.Bin123, and Bacteroidales were the predominant bacterial species in the system. Additionally, the types of enzymes and the relative abundance of β-lactam resistance genes in the co-metabolic system significantly increased by 7 and 0.77%, respectively. Furthermore, nine primary anaerobic CTX biodegradation products were detected, indicating the existence of three possible degradation pathways. Overall, the study results provide a novel approach to treating CTX-containing wastewater.

Substrate-Controlled Product Divergence in Iron(III)-Catalyzed Reactions of Propargylic Alcohols: Easy Access to Spiro-indenyl 1,4-Benzoxazines and 2-(2,2-Diarylvinyl)quinoxalines.

We report herein unprecedented cascade reactions of O-propargyl-N-tosyl-amino phenols with 10 mol% FeCl3 in DCE at room temperature for 0.67-3 h to form spiro-indenyl 1,4-benzoxazines with 38-89 % yield. Replacing the substrates' oxygen atom by a N-tosylimine group followed by treatment with the same catalyst and solvent at 80 °C produced 2-(2,2-diarylvinyl)quinoxalines in 12-20 h with up to 62 % yield. Mechanistic understanding provided an insight into the transformations. The use of simple substrates and an environmentally benign low-cost catalyst, broad substrate scope and tolerance of diverse functional groups makes the methodology inherently attractive.

Synthesis of Arynes via Formal Dehydrogenation of Arenes

Arynes offer immense potential for diversification of benzenoid rings, which occur in pharmaceuticals, agrochemicals, and liquid crystals. However, accessing these high-energy intermediates requires synthetic precursors, which involve either harsh conditions or multistep syntheses. The development of alternative methods to access arynes using simpler substrates and milder conditions is necessary for a more streamlined approach. Here, we describe a two-step formal dehydrogenation of simple arenes to generate arynes at a remote position relative to traditionally reactive groups, e.g., halides. This approach is enabled by regioselective installation and ejection of an "onium" leaving group, and we demonstrate the compatibility of simple arenes (20 examples) and arynophiles (8 examples). Moreover, through direct comparison, we show that our formal dehydrogenation method is both more functional group tolerant and efficient in generating arynes than the current state-of-the-art aryne precursors. Finally, we show that aryne intermediates offer opportunities for regioselective C-H amination that are distinct from other methods.

Start-up strategies of electromethanogenic reactors for methane production from cattle manure

This study qualitatively assessed the impacts of different start-up strategies on the performance of methane (CH4) production from cattle manure (CM) in electromethanogenic reactors. Single chamber MECs were operated with an applied voltage of 0.7 V and the impact of electrode acclimatization with a simple substrate, acetate (ACE) vs a complex waste, CM, was compared. Upon biofilm formation on the sole carbon source (ACE or CM), several MECs (ACE_CM and CM_ACE) were subjected to cross-feeding (switching substrate to CM or ACE) during the test period to evaluate the impact of the primary substrate. Even though there was twice as much peak current density via feeding ACE during biofilm formation, this did not translate into higher CH4 production during the test period, when reactors were fed with CM. Higher or similar CH4 production was recorded in CM_CM reactors compared to ACE_CM at various soluble chemical oxygen demand (sCOD) concentrations. Additionally, feeding ACE as primary substrate did not significantly impact either COD removals or coulombic efficiencies. On the other hand, the use of anaerobic digester (AD) seed as an inoculum in CM-fed MECs (CM_CM), relative to no inoculum added MECs (Blank), increased the initial CH4 production rate by 45% and reduced the start-up time by 20%. In CM-fed MECs, Geobacter dominated bacterial communities of bioanodes and hydrogenotrophic methanogen Methanoculleus dominated archaeal communities of biocathodes. Community cluster analysis revealed the significance of primary substrate in shaping electrode biofilm; thus, it should be carefully selected for successful start-up of electromethanogenic reactors treating wastes.

Electronic Structure Calculations on Endohedral Complexes of Fullerenes: Reminiscences and Prospects.

The history of electronic structure calculations on the endohedral complexes of fullerenes is reviewed. First, the long road to the isolation of new allotropes of carbon that commenced with the seminal organic syntheses involving simple inorganic substrates is discussed. Next, the focus is switched to author's involvement with fullerene research that has led to the in silico discovery of endohedral complexes. The predictions of these pioneering theoretical studies are juxtaposed against the data afforded by subsequent experimental developments. The successes and failures of the old and modern quantum-chemical calculations on endohedral complexes are summarized and their remaining deficiencies requiring further attention are identified.

Effect of granular activated carbon and chloroform on chain elongation with simple substrate ethanol and acetate

Chain elongation is a promising technology for production of medium-chain fatty acids (MCFAs). Granular activated carbon (GAC) is commonly used in anaerobic fermentation. Low level CHCl3 can inhibit methanogenesis and homoacetogenesis at the same time. However, the effect of them on chain elongation performance with highly enriched consortia and simple substrate (i.e., ethanol and acetate) was still unclear. Hence, the effects of CHCl3 and on MCFAs production and the microbial community was studied here. CHCl3 displayed fatal effect on chain elongation system when its concentration was higher than 0.1% v/v. 0.05% v/v CHCl3 was enough to inhibit homoacetogens and further decreased the caproate production efficiency without altering the core bacteria tremendously. GAC was found to be adverse for chain elongation with simple substrate (i.e., ethanol and acetate) and highly enriched microbial consortia dominated by Clostridium sensu stricto, less than 20% electrons were finally distributed in caproate. It might be attributed to other electron consuming activities induced by GAC.

Low-cost and flexible paper-based plasmonic nanostructure for a highly sensitive SERS substrate.

The application of a noble-metal-based plasmon-enhanced substrate to detect low-concentration analytes has attracted extensive attention. Most of the substrates used in recently reported researches are based on two-dimensional structures. Hence, we prepared a higher efficiency Raman activity substrate with a filter paper structure, which not only provides more plasmonic "hot spots," but also facilitates analyte extraction and detection due to the flexibility of the paper. The preparation of the plasmonic paper substrate adopted centrifugation to deposit the alloy nanoparticles onto the paper base. The optimal particle deposition condition was found by adjusting the centrifugal force and centrifugation time. Then, the surface-enhanced Raman spectroscopy (SERS) performance of the substrate was enhanced by altering the plasmon resonance peak on the surface of the nanoparticles. The enhancement factor of this paper-based substrate was 1.55×107, with high detection uniformity (10-6 M, rhodamine 6G) and a low detection limit (10-11 M, rhodamine 6G). Then, we applied the SERS substrate to pesticide detection; the detection limit of the thiram reached 10-6 M. As a result, the simple and cost-effective paper-based SERS substrate obtained in this way has high detection performance for pesticides and can be used for rapid detection in the field, which is beneficial to food safety and environmental safety.

Synthesis of Ultralong Carbon Nanotubes with Ultrahigh Yields.

Ultralong carbon nanotubes (CNTs) are in huge demand in many cutting-edge fields due to their macroscale lengths, perfect structures, and extraordinary properties, while their practical application is limited by the difficulties in their mass production. Herein, we report the synthesis of ultralong CNTs with a dramatically increased yield by a simple but efficient substrate interception and direction strategy (SIDS), which couples the advantages of floating-catalyst chemical vapor deposition with the flying-kite-like growth mechanism of ultralong CNTs. The SIDS-assisted approach prominently improves the catalyst utilization and significantly increases the yield. The areal density of the ultralong CNT arrays with length of over 1 cm reached a record-breaking value of ∼6700 CNTs mm-1, which is 2-3 orders of magnitude higher than the previously reported values obtained by traditional methods. The SIDS provides a solution for synthesizing high-quality ultralong CNTs with high yields, laying the foundation for their mass production.

Copper removal from wastewater and electricity generation using dual-chamber microbial fuel cells with shrimp shell as the substrate

High-content solid waste (HCSWs) contains numerous polysaccharides and is widely recognized as an energy-generating substance. However, detailed studies on the use of HCSWs as substrates in microbial fuel cells (MFCs) to generate electricity and remove heavy metals from wastewater are scarce. In this study, the effects of shrimp shell (SS) and sodium acetate (SA), which are complex and simple substrates, respectively, as anodic carbon sources on the electricity generation performance of dual-chamber MFCs and the removal of Cu at the cathode were investigated. The structural characteristics of the anodic microbial communities of the MFCs were analyzed in terms of substrate type and concentration. The results demonstrated that the maximum voltage (206 mV) and maximum power density (28.82 mW/m2) of the MFC-SA were higher than those of the MFC-SS groups. The operating time and maximum power density increased with increasing SS concentration, and the maximum power density reached 24.75 mW/m2 at an SS concentration of 16 g/L. The Cu2+ ions in the catholyte were primarily reduced to elemental Cu and small amounts of Cu2O or CuO. The higher the concentration of SS, the higher the Cu removal rate, the greater the total amount of Cu removed, and the higher the MFC removal capacity. Pseudomonas was the only electroactive microorganism in the raw sludge, whereas Geobacter, Corynebacterium, Clostridium, Desulfovibrio, and Desulfosporosinus were detected in the MFCs at the end of the experiment. The relative abundance of the electroactive microorganisms increased from 19.4% to 36.0% as the SS concentration increased from 2 to 16 g/L. These results suggest that SS can be used as substrate for HCSW degradation to provide the energy required for heavy-metal reduction.

One reaction - double stereoinduction: C-H activation as a privileged route towards complex atropisomeric molecules.

Expanding the importance of chirality and implementation of stereogenic information within complex molecular design has recently reached a new level: design of innovative enantiopure scaffolds bearing multiple chiral elements. In particular, regarding sustainability aspects and straightforward use of relatively simple substrates, the C-H activation strategy offers unique opportunities to assemble complex chiral molecules with unique topologies while controlling two stereoselective events in a single transformation. Herein, the emerging field of asymmetric C-H activation allowing rapid construction of atropisomeric molecules bearing a second chirality element, such as a stereogenic center, vicinal chiral axis or planar chirality, is described. Aiming at in-depth comprehension of such innovative systems, the emphasis is put on the nature of stereodiscriminant steps, allowing the simultaneous control of both chiral elements.