Microbial enzymes: industrial progress in 21st century

Hydrolytic enzyme production from açai palm (Euterpe precatoria) endophytic fungi and characterization of the amylolytic and cellulolytic extracts

Enzymes are biocatalysts that are widely used in different industries and generate billions of dollars annually. With the advancement of biotechnology, new enzymatic sources are being evaluated, especially microbial ones, in order to find efficient producers. Endophytic fungi are promising sources of biomolecules; however, Amazonian species are still poorly studied as to their enzymatic production potential. In this sense, the production of hydrolases (amylases, lipases, cellulases and pectinases) was evaluated in endophytic fungi isolated from the leaves, roots and stems of açai palms (Euterpe precatoria). A qualitative test was carried out to detect the enzymatic synthesis in each isolate, and the most promising ones were cultivated using submerged fermentation. The enzyme extracts were quantified to determine those with the greatest activity. Cellulolytic and amylolytic extracts showed the highest enzymatic activities and were partially characterized. Among 50 isolates, 82.9% produced pectinase, 58.5% produced cellulase, 31.7% produced amylase, and 12.2% produced lipase. Penicillium sp. L3 was the best producer of amylase and Colletotrichum sp. S1 was the best producer of cellulase in liquid medium cultivation. The amylolytic extract showed the highest enzymatic activity at pH 8.0 and 45 °C, and the cellulolytic extract at pH 5.0 and 35 °C. The cellulase and amylase produced by the endophytes had their molecular masses estimated between 38 and 76 kDa. These results indicate that endophytic fungi from the açai palm can be used as a new source of hydrolytic enzymes, which can be applied in numerous biotechnological processes.

Identification of industrial detergent enzymes by SDS-PAGE and MALDI-TOF mass spectrometry

An efficient method was proposed for routine analysis of the most widely used detergent enzymes.

Two-Tiered Selection and Screening Strategy to Increase Functional Enzyme Production in E. coli

Development of recombinant enzymes as industrial biocatalysts or metabolic pathway elements requires soluble expression of active protein. Here we present a two-step strategy, combining a directed evolution selection with an enzyme activity screen, to increase the soluble production of enzymes in the cytoplasm of E. coli. The directed evolution component relies on the innate quality control of the twin-arginine translocation pathway coupled with antibiotic selection to isolate point mutations that promote intracellular solubility. A secondary screen is applied to ensure the solubility enhancement has not compromised enzyme activity. This strategy has been successfully applied to increase the soluble production of a fungal endocellulase by 30-fold in E. coli without change in enzyme specific activity through two rounds of directed evolution.

OUP accepted manuscript

Droplet-based microfluidics has emerged as a powerful tool for single-cell screening with ultrahigh throughput, but its widespread application remains limited by the accessibility of a droplet microfluidic high-throughput screening (HTS) platform, especially to common laboratories having no background in microfluidics. Here, we first developed a microfluidic HTS platform based on fluorescence-activated droplet sorting technology. This platform allowed (i) encapsulation of single cells in monodisperse water-in-oil droplets; (ii) cell growth and protein production in droplets; and (iii) sorting of droplets based on their fluorescence intensities. To validate the platform, a model selection experiment of a binary mixture of Bacillus strains was performed, and a 45.6-fold enrichment was achieved at a sorting rate of 300 droplets per second. Furthermore, we used the platform for the selection of higher α-amylase-producing Bacillus licheniformis strains from a mutant library generated by atmospheric and room temperature plasma mutagenesis, and clones displaying over 50% improvement in α-amylase productivity were isolated. This droplet screening system could be applied to the engineering of other industrially valuable strains.

Creation of a recombinant Komagataella phaffii strain, a producer of proteinase K from Tritirachium album

The objects of the study were recombinant clones of Komagataella phaffii K51 carrying the heterologous proteinase K (PK-w) gene from Tritirachium album integrated into their genome as well as samples of recombinant proteinase K isolated from these clones. The aims of this work were i) to determine whether it is possible to create recombinant K. phaffii K51 clones overexpressing functionally active proteinase K from T. album and ii) to analyze the enzymatic activity of the resulting recombinant enzyme. The following methods were used: computational analysis of primary structure of the proteinase K gene, molecular biological methods (PCR, electrophoresis of DNA in an agarose gel, electrophoresis of proteins in an SDS polyacrylamide gel under denaturing conditions, spectrophotometry, and quantitative assays of protease activity), and genetic engineering techniques (cloning and selection of genes in bacterial cells Escherichia coli TOP10 and in the methylotrophic yeast K. phaffii K51). The gene encoding natural proteinase K (PK-w) was designed and optimized for expression in K. phaffii K51. The proteinase K gene was synthesized and cloned within the plasmid pPICZα-A vector in E. coli TOP10 cells. The proteinase K gene was inserted into pPICZα-A in such a way that – at a subsequent stage of transfection into yeast cells – it was efficiently expressed under the control of the promoter and terminator of the AOX1 gene, and the product of the exogenous gene contained the signal peptide of the Saccharomyces cerevisiae a-factor to ensure the protein’s secretion into the culture medium. The resultant recombinant plasmid (pPICZα-A/PK-w) was transfected into K. phaffii K51 cells. A recombinant K. phaffii K51 clone was obtained that carried the synthetic proteinase K gene and ensured its effective expression and secretion into the culture medium. An approximate productivity of the yeast recombinant clones for recombinant proteinase K was 25 μg/ mL after 4 days of cultivation. The resulting recombinant protease has a high specific proteolytic activity: ~5000 U/mg.

Bioprospecting Kluyveromyces marxianus as a Robust Host for Industrial Biotechnology

Kluyveromyces marxianus is an emerging non-conventional food-grade yeast that is generally isolated from diverse habitats, like kefir grain, fermented dairy products, sugar industry sewage, plants, and sisal leaves. A unique set of beneficial traits, such as fastest growth, thermotolerance, and broad substrate spectrum (i.e., hemi-cellulose hydrolysates, xylose, l-arabinose, d-mannose, galactose, maltose, sugar syrup molasses, cellobiose, and dairy industry) makes this yeast a particularly attractive host for applications in a variety of food and biotechnology industries. In contrast to Saccharomyces cerevisiae, most of the K. marxianus strains are apparently Crabtree-negative or having aerobic-respiring characteristics, and unlikely to endure aerobic alcoholic fermentation. This is a desirable phenotype for the large-scale biosynthesis of products associated with biomass formation because the formation of ethanol as an undesirable byproduct can be evaded under aerobic conditions. Herein, we discuss the current insight into the potential applications of K. marxianus as a robust yeast cell factory to produce various industrially pertinent enzymes, bioethanol, cell proteins, probiotic, fructose, and fructo-oligosaccharides, and vaccines, with excellent natural features. Moreover, the biotechnological improvement and development of new biotechnological tools, particularly CRISPR-Cas9-assisted precise genome editing in K. marxianus are delineated. Lastly, the ongoing challenges, concluding remarks, and future prospects for expanding the scope of K. marxianus utilization in modern biotechnology, food, feed, and pharmaceutical industries are also thoroughly vetted. In conclusion, it is critical to apprehend knowledge gaps around genes, metabolic pathways, key enzymes, and regulation for gaining a complete insight into the mechanism for producing relevant metabolites by K. marxianus.

Highly Stable, Cold-Active Aldehyde Dehydrogenase from the Marine Antarctic Flavobacterium sp. PL002

Stable aldehyde dehydrogenases (ALDH) from extremophilic microorganisms constitute efficient catalysts in biotechnologies. In search of active ALDHs at low temperatures and of these enzymes from cold-adapted microorganisms, we cloned and characterized a novel recombinant ALDH from the psychrotrophic Flavobacterium PL002 isolated from Antarctic seawater. The recombinant enzyme (F-ALDH) from this cold-adapted strain was obtained by cloning and expressing of the PL002 aldH gene (1506 bp) in Escherichia coli BL21(DE3). Phylogeny and structural analyses showed a high amino acid sequence identity (89%) with Flavobacterium frigidimaris ALDH and conservation of all active site residues. The purified F-ALDH by affinity chromatography was homotetrameric, preserving 80% activity at 4 °C for 18 days. F-ALDH used both NAD+ and NADP+ and a broad range of aliphatic and aromatic substrates, showing cofactor-dependent compensatory KM and kcat values and the highest catalytic efficiency (0.50 µM−1 s−1) for isovaleraldehyde. The enzyme was active in the 4–60 °C-temperature interval, with an optimal pH of 9.5, and a preference for NAD+-dependent reactions. Arrhenius plots of both NAD(P)+-dependent reactions indicated conformational changes occurring at 30 °C, with four(five)-fold lower activation energy at high temperatures. The high thermal stability and substrate-specific catalytic efficiency of this novel cold-active ALDH favoring aliphatic catalysis provided a promising catalyst for biotechnological and biosensing applications.

Enzymatic and Microwave Pretreatments and Supercritical CO2 Extraction for Improving Extraction Efficiency and Quality of Origanum vulgare L. spp. hirtum Extracts

The goal of the study was to establish a procedure for improving the efficiency of supercritical carbon dioxide (scCO2) extraction of Origanum vulgare L. spp. hirtum (Greek oregano) and enhancing the quality of obtained extracts. Microwave and enzymatic pretreatments of the plant material were applied prior to the scCO2 extraction. It was determined that the microwave pretreatment with irradiation power 360 W during 2 min accelerated the extraction of lipophilic compounds and provided a twofold higher extraction yield compared to the control. Moreover, this pretreatment also led to an increase in oxygenated monoterpenes content and the most dominant component carvacrol, as well as the extracts' antioxidant activity. The enzymatic pretreatment caused a significant increase in the extraction yield and the attainment of the extract with the most potent antioxidant properties. Coupling the pretreatments with scCO2 extraction improves the process of obtaining high value lipophilic products of oregano in terms of utilization of the plant material, acceleration of the extraction with the possibility to adjust its selectivity and quality of extracts, and enhancement of biological activity.

Microbial protein cell factories fight back?

The biopharmaceutical market is growing faster than ever, with two production systems competing for market dominance: mammalian cells and microorganisms. In recent years, based on the rise of antibody-based therapies, new biotherapeutic approvals have favored mammalian hosts. However, not only has extensive research elevated our understanding of microbes to new levels, but emerging therapeutic molecules also facilitate their use; thus, is it time for microbes to fight back? In this review, we answer this timely question by cross-comparing four microbial production hosts and examining the innovations made to both their secretion and post-translational modification (PTM) capabilities. Furthermore, we discuss the impact of tools, such as omics and systems biology, as well as alternative production systems and emerging biotherapeutics.

Biotechnology Applications of Cell-Free Expression Systems

Cell-free systems are a rapidly expanding platform technology with an important role in the engineering of biological systems. The key advantages that drive their broad adoption are increased efficiency, versatility, and low cost compared to in vivo systems. Traditionally, in vivo platforms have been used to synthesize novel and industrially relevant proteins and serve as a testbed for prototyping numerous biotechnologies such as genetic circuits and biosensors. Although in vivo platforms currently have many applications within biotechnology, they are hindered by time-constraining growth cycles, homeostatic considerations, and limited adaptability in production. Conversely, cell-free platforms are not hindered by constraints for supporting life and are therefore highly adaptable to a broad range of production and testing schemes. The advantages of cell-free platforms are being leveraged more commonly by the biotechnology community, and cell-free applications are expected to grow exponentially in the next decade. In this study, new and emerging applications of cell-free platforms, with a specific focus on cell-free protein synthesis (CFPS), will be examined. The current and near-future role of CFPS within metabolic engineering, prototyping, and biomanufacturing will be investigated as well as how the integration of machine learning is beneficial to these applications.

Virus-templated magnetic composite hydrogels for surface immobilization of mimic-free-lipase

Surface immobilization of enzymes on magnetic-recoverable carriers is of great interest and importance for the biocatalysis of relatively large molecules. In this work, the nanosized amino-rich filamentous M13 virus, a versatile biological scaffold, was applied as the unique soft backbone for lipase immobilization. Based on the structure and capsid proteins of M13 phages, the magnetic-recoverable mimic-free-lipases (MFLs) composed of the M13 hydrogels and magnetic particles were developed in two designs. In the first design, nanosized wild M13 phages were crosslinked into a phage hydrogel through the N-terminals of pVIII peptides while NH₂-Fe₃O₄ magnetic nanoparticles (MNPs) were attached to the M13 virus through glutaraldehyde, forming the M13-(NH₂-Fe₃O₄) magnetic phage hydrogel. In the second design, special M13 with Fe₃O₄ affinity pIII-peptide (FAP-M13) was biopanned for strongly binding towards bare Fe₃O₄ with the "hook"-like pIII-peptide (N-LPLSTQH-C). TEM observation confirmed the direct grasp of FAP-M13 on bare Fe₃O₄, forming the magnetic (FAP-M13)-Fe₃O₄ virus hydrogel. Lipases were uniformly anchored on the phage surface of nanoscale by crosslinking with the N-terminals of pVIII peptides, and then lipase@M13-(NH₂-Fe₃O₄) and lipase@(FAP-M13)-Fe₃O₄ MFLs were constructed. For both MFLs, high activity recovery yield (>95%) and efficient magnetic separation were characterized. Significantly reduced MNP-usage-amount and enhanced lipase-loading-amount both by about 40 folds were obtained, compared with the conventional NH₂-Fe₃O₄ carriers. The quantified K_m and V_max/K_m values were almost equal to those of the free lipases, verifying free-enzyme-mimicking features of the MFLs. High pH-tolerance, wide temperature adaptability, enhanced thermal stability and stable magnetic separation capability of both MFLs were also observed. In particular, the (FAP-M13)-Fe₃O₄ magnetic virus hydrogel simply using bare Fe₃O₄ MNPs would be more convenient and economical in the scaled-up biocatalysis.

Novel Enzymes From the Red Sea Brine Pools: Current State and Potential

The Red Sea is a marine environment with unique chemical characteristics and physical topographies. Among the various habitats offered by the Red Sea, the deep-sea brine pools are the most extreme in terms of salinity, temperature and metal contents. Nonetheless, the brine pools host rich polyextremophilic bacterial and archaeal communities. These microbial communities are promising sources for various classes of enzymes adapted to harsh environments - extremozymes. Extremozymes are emerging as novel biocatalysts for biotechnological applications due to their ability to perform catalytic reactions under harsh biophysical conditions, such as those used in many industrial processes. In this review, we provide an overview of the extremozymes from different Red Sea brine pools and discuss the overall biotechnological potential of the Red Sea proteome.

Outer membrane vesicles (OMVs) enabled bio-applications: A critical review

Outer membrane vesicles (OMVs) are nanoscale spherical vesicles released from Gram-negative bacteria. The lipid bilayer membrane structure of OMVs consists of similar components as bacterial membrane and thus has attracted more and more attention in exploiting OMVs' bio-applications. Although the endotoxic lipopolysaccharide on natural OMVs may impose potential limits on their clinical applications, genetic modification can reduce their endotoxicity and decorate OMVs with multiple functional proteins. These genetically engineered OMVs have been employed in various fields including vaccination, drug delivery, cancer therapy, bioimaging, biosensing, and enzyme carrier. This review will first briefly introduce the background of OMVs followed by recent advances in functionalization and various applications of engineered OMVs with an emphasis on the working principles and their performance, and then discuss about the future trends of OMVs in biomedical applications.

Exploring the Diversity and Biotechnological Potential of Cultured and Uncultured Coral-Associated Bacteria

Coral-associated microbes are crucial for the biology of their hosts, contributing to nutrient cycling, adaptation, mitigation of toxic compounds, and biological control of pathogens. Natural products from coral-associated micro-organisms (CAM) may possess unique traits. Despite this, the use of CAM for biotechnological purposes has not yet been adequately explored. Here, we investigated the production of commercially important enzymes by 37 strains of bacteria isolated from the coral species Mussismilia braziliensis, Millepora alcicornis, and Porites astreoides. In-vitro enzymatic assays showed that up to 56% of the isolates produced at least one of the seven enzymes screened (lipase, caseinase, keratinase, cellulase, chitinase, amylase, and gelatinase); one strain, identified as Bacillus amyloliquefaciens produced all these enzymes. Additionally, coral species-specific cultured and uncultured microbial communities were identified. The phylum Firmicutes predominated among the isolates, including the genera Exiguobacterium, Bacillus, and Halomonas, among others. Next-generation sequencing and bacteria culturing produced similar but also complementary data, with certain genera detected only by one or the other method. Our results demonstrate the importance of exploring different coral species as sources of specific micro-organisms of biotechnological and industrial interest, at the same time reinforcing the economic and ecological importance of coral reefs as reservoirs of such diversity.

Strategies to Improve the Potential Functionality of Fruit-Based Fermented Beverages

It is only recently that fermentation has been facing a dynamic revival in the food industry. Fermented fruit-based beverages are among the most ancient products consumed worldwide, while in recent years special research attention has been granted to assess their functionality. This review highlights the functional potential of alcoholic and non-alcoholic fermented fruit beverages in terms of chemical and nutritional profiles that impact on human health, considering the natural occurrence and enrichment of fermented fruit-based beverages in phenolic compounds, vitamins and minerals, and pro/prebiotics. The health benefits of fruit-based beverages that resulted from lactic, acetic, alcoholic, or symbiotic fermentation and specific daily recommended doses of each claimed bioactive compound were also highlighted. The latest trends on pre-fermentative methods used to optimize the extraction of bioactive compounds (maceration, decoction, and extraction assisted by supercritical fluids, microwave, ultrasound, pulsed electric fields, high pressure homogenization, or enzymes) are critically assessed. As such, optimized fermentation processes and post-fermentative operations, reviewed in an industrial scale-up, can prolong the shelf life and the quality of fermented fruit beverages.

Microbial proteases: ubiquitous enzymes with innumerable uses

Proteases are ubiquitous enzymes, having significant physiological roles in both synthesis and degradation. The use of microbial proteases in food fermentation is an age-old process, which is today being successfully employed in other industries with the advent of ‘omics’ era and innovations in genetic and protein engineering approaches. Proteases have found application in industries besides food, like leather, textiles, detergent, waste management, agriculture, animal husbandry, cosmetics, and pharmaceutics. With the rising demands and applications, researchers are exploring various approaches to discover, redesign, or artificially synthesize enzymes with better applicability in the industrial processes. These enzymes offer a sustainable and environmentally safer option, besides possessing economic and commercial value. Various bacterial and fungal proteases are already holding a commercially pivotal role in the industry. The current review summarizes the characteristics and types of proteases, microbial source, their current and prospective applications in various industries, and future challenges. Promoting these biocatalysts will prove significant in betterment of the modern world.

Hydrolytic Enzymes Producing Bacterial Endophytes of Some Poaceae Plants

Endophytic bacteria represent microorganisms that live during the whole life cycle within the tissues of healthy plants without causing any obvious signs of disease. In this study, the ability of 128 endophyte bacterial isolates from some cultivated and wild grain plants (Poaceae family) in Van, Turkey, were investigated in terms of producing several extracellular hydrolytic enzymes. It was demonstrated that lipases, proteases, amylases, cellulases, pectinases, and xylanases were produced by the bacteria with relative frequencies of 74.2%, 65.6%, 55.4%, 32%, 21.8%, and 7.8%, respectively. In addition, molecular identification of a certain number of isolates selected according to their enzyme-producing capabilities was performed by 16S rRNA gene sequencing using a next-generation sequencing platform. As a result of the analysis, the isolates yielded certain strains belonging to Pseudomonas, Micrococcus, Paenibacillus, Streptococcus, Curtobacterium, Chryseobacterium, and Bacillus genera. Also, the strain G117Y1T was evaluated as a member of potential novel species based on 16S rRNA sequencing results.

Purification, Identification, and Characterization of a Glycoside Hydrolase Family 11-Xylanase with High Activity from Aspergillus niger VTCC 017

Xylanases (EC 3.2.1.8) have been considered as a potential green solution for the sustainable development of a wide range of industries including pulp and paper, food and beverages, animal feed, pharmaceuticals, and biofuels because they are the key enzymes that degrade the xylosidic linkages of xylan, the major component of the second most abundant raw material worldwide. Therefore, there is a critical need for the industrialized xylanases which must have high specific activity, be tolerant to organic solvent or detergent and be active during a wide range of conditions, such as high temperature and pH. In this study, an extracellular xylanase was purified from the culture broth of Aspergillus niger VTCC 017 for primary structure determination and properties characterization. The successive steps of purification comprised centrifugation, Sephadex G-100 filtration, and DEAE-Sephadex chromatography. The purified xylanase (specific activity reached 6596.79 UI/mg protein) was a monomer with a molecular weight of 37 kDa estimating from SDS electrophoresis. The results of LC/MS suggested that the purified protein is indeed an endo-1,4-β-D-xylanase. The purified xylanase showed the optimal temperature of 55 °C, and pH 6.5 with a stable xylanolytic activity within the temperature range of 45-50 °C, and within the pH range of 5.0-8.0. Most divalent metal cations including Zn²⁺, Fe²⁺, Mg²⁺, Cu²⁺, Mn²⁺ showed some inhibition of xylanase activity while the monovalent metal cations such as K⁺ and Ag⁺ exhibited slight stimulating effects on the enzyme activity. The introduction of 10-30% different organic solvents (n-butanol, acetone, isopropanol) and several detergents (Triton X-100, Tween 20, and SDS) slightly reduced the enzyme activity. Moreover, the purified xylanase seemed to be tolerant to methanol and ethanol and was even stimulated by Tween 80. Overall, with these distinctive properties, the putative xylanase could be a successful candidate for numerous industrial uses.

Structure-Function and Industrial Relevance of Bacterial Aminopeptidase P

Aminopeptidase P (APPro, E.C 3.4.11.9) cleaves N-terminal amino acids from peptides and proteins where the penultimate residue is proline. This metal-ion-dependent enzyme shares a similar fold, catalytic mechanism, and substrate specificity with methionine aminopeptidase and prolidase. It adopts a canonical pita bread fold that serves as a structural basis for the metal-dependent catalysis and assembles as a tetramer in crystals. Similar to other metalloaminopeptidase, APPro requires metal ions for its maximal enzymatic activity, with manganese being the most preferred cation. Microbial aminopeptidase possesses unique characteristics compared with aminopeptidase from other sources, making it a great industrial enzyme for various applications. This review provides a summary of recent progress in the study of the structure and function of aminopeptidase P and describes its various applications in different industries as well as its significance in the environment.

Microbial Transglutaminase Is a Very Frequently Used Food Additive and Is a Potential Inducer of Autoimmune/Neurodegenerative Diseases

Microbial transglutaminase (mTG) is a heavily used food additive and its industrial transamidated complexes usage is rising rapidly. It was classified as a processing aid and was granted the GRAS (generally recognized as safe) definition, thus escaping full and thorough toxic and safety evaluations. Despite the manufacturers claims, mTG or its cross-linked compounds are immunogenic, pathogenic, proinflammatory, allergenic and toxic, and pose a risk to public health. The enzyme is a member of the transglutaminase family and imitates the posttranslational modification of gluten, by the tissue transglutaminase, which is the autoantigen of celiac disease. The deamidated and transamidated gliadin peptides lose their tolerance and induce the gluten enteropathy. Microbial transglutaminase and its complexes increase intestinal permeability, suppresses enteric protective pathways, enhances microbial growth and gliadin peptide's epithelial uptake and can transcytose intra-enterocytically to face the sub-epithelial immune cells. The present review updates on the potentially detrimental side effects of mTG, aiming to interest the scientific community, induce food regulatory authorities' debates on its safety, and protect the public from the mTG unwanted effects.

Experimental and computational investigation of enzyme functional annotations uncovers misannotation in the EC 1.1.3.15 enzyme class

Only a small fraction of genes deposited to databases have been experimentally characterised. The majority of proteins have their function assigned automatically, which can result in erroneous annotations. The reliability of current annotations in public databases is largely unknown; experimental attempts to validate the accuracy within individual enzyme classes are lacking. In this study we performed an overview of functional annotations to the BRENDA enzyme database. We first applied a high-throughput experimental platform to verify functional annotations to an enzyme class of S-2-hydroxyacid oxidases (EC 1.1.3.15). We chose 122 representative sequences of the class and screened them for their predicted function. Based on the experimental results, predicted domain architecture and similarity to previously characterised S-2-hydroxyacid oxidases, we inferred that at least 78% of sequences in the enzyme class are misannotated. We experimentally confirmed four alternative activities among the misannotated sequences and showed that misannotation in the enzyme class increased over time. Finally, we performed a computational analysis of annotations to all enzyme classes in the BRENDA database, and showed that nearly 18% of all sequences are annotated to an enzyme class while sharing no similarity or domain architecture to experimentally characterised representatives. We showed that even well-studied enzyme classes of industrial relevance are affected by the problem of functional misannotation.

Correct annotation of genomes is crucial for our understanding and utilization of functional gene diversity, yet the reliability of current protein annotations in public databases is largely unknown. In our work we validated annotations to an S-2-hydroxyacid oxidase enzyme class (EC 1.1.3.15) by assessing activity of 122 representative sequences in a high-throughput screening experiment. From this dataset we inferred that at least 78% of the sequences in the enzyme class are misannotated, and confirmed four alternative activities among the misannotated sequences. We showed that the misannotation is widespread throughout enzyme classes, affecting even well-studied classes of industrial relevance. Overall, our study highlights the value of experimental and computational validation of predicted functions within individual enzyme classes.

Bioproduced Proteins On Demand (Bio-POD) in hydrogels using Pichia pastoris

Traditional production of industrial and therapeutic proteins by eukaryotic cells typically requires large-scale fermentation capacity. As a result, these systems are not easily portable or reusable for on-demand protein production applications. In this study, we employ Bioproduced Proteins On Demand (Bio-POD), a F127-bisurethane methacrylate hydrogel-based technique that immobilizes engineered Pichia pastoris for preservable, on-demand production and secretion of medium- and high-molecular weight proteins (in this case, SEAP, α-amylase, and anti-HER2). The gel samples containing encapsulated-yeast demonstrated sustained protein production and exhibited productivity immediately after lyophilization and rehydration. The hydrogel platform described here is the first hydrogel immobilization using a P. pastoris system to produce recombinant proteins of this breadth. These results highlight the potential of this formulation to establish a cost-effective bioprocessing strategy for on-demand protein production.

Optimization of an organic solvent-tolerant lipase production by Staphylococcus capitis SH6. Immobilization for biodiesel production and biodegradation of waste greases

Using the statistical approach, this work seeks to optimize the process parameters to boost the generation of an organic solvent-tolerant lipase by Staphylococcus capitis SH6. The main parameters influencing the enzyme production were identified by using Plackett-Burman's screening design. Among the test variables, only tryptone (25 g/L), malt extract (2.5 g/L), NaCl (10 g/L) and pH (7.0) contributed positively to enzyme production. Then, the crude lipase was immobilized by adsorption on CaCO₃ at pH 10. A maximum immobilization efficiency of 82% was obtained by incubating 280 mg of enzyme with CaCO₃ (1 g) during 30 min. The immobilized lipase was more stable toward organic solvents than the free enzyme. It retained about 90% of its original activity in the presence of ethanol and methanol. After that, the immobilized enzyme was used for biodiesel production by transesterification process between waste oil and methanol or ethanol during 24 h at 30 °C. Our results show that the lipase can be utilized efficiently in biodiesel industry. Likewise, we have demonstrated that the immobilized enzyme may be implicated in the biodegradability of waste grease; the maximum conversion yield into fatty acids obtained after 12 h at 30 °C, was 57%.

Residual biomass from surfactin production is a source of arginase and adsorbed surfactin that is useful for environmental remediation

Lipopeptides are important secondary metabolites produced by microbes. They find applications in environmental decontamination and in the chemical, pharmaceutical and food industries. However, their production is expensive. In the present work we propose three strategies to lower the production costs of surfactin. First, the coproduction of surfactin and arginase in a single growth. Second, extract the fraction of surfactin that adsorbs to the biomass and is removed from the growth medium through centrifugation. Third, use microbial biomass for the remediation of organic and inorganic contaminants. The coproduction of surfactin and arginase was evaluated by factorial design experiments using the LB medium supplemented with arginine. The best conditions for surfactin production were 22 h of growth at 37 °C using LB supplemented with arginine 7.3 g/L. Almost similar conditions were found to produce highest levels of arginase, 24 h and 6.45 g/L arginine. Decontamination of phenol and copper from artificial samples was attained by treatment with residues from lipopeptide production. Thus, cell suspensions and wash-waters used to extract surfactin from the biomass. Cell suspensions were used to successfully remove hydroquinone. Cell suspensions and wash-waters containing surfactin were successfully used to recover copper from solution. Specific monitoring methods were used for phenol and metal solutions, respectively a biosensor based on tyrosinase and either atomic absorption flame ionization spectrometry or absorbance coupled to the Arduino™ platform. Therefore, we report three alternative strategies to lower the production costs in lipopeptide production, which include the effective recovery of copper and phenol from contaminated waters using residues from surfactin production. Sustainable and profitable production of surfactin can be achieved by a coproduction strategy of lipopeptides and enzymes. Lipopeptides are collected in the supernatant and enzymes in the biomass. In addition, lipopeptides that coprecipitate with biomass can be recovered by washing. Lipopeptide wash-waters find applications in remediation and cells can also be used for environmental decontamination.

Discovery of New Carbonyl Reductases Using Functional Metagenomics and Applications in Biocatalysis

Enzyme discovery for use in the manufacture of chemicals, requiring high stereoselectivities, continues to be an important avenue of research. Here, a sequence directed metagenomics approach is described to identify short chain carbonyl reductases. PCR from a metagenomic template generated 37 enzymes, with an average 25% sequence identity, twelve of which showed interesting activities in initial screens. Six of the most productive enzymes were then tested against a panel of 21 substrates, including bulkier substrates that have been noted as challenging in biocatalytic reductions. Two enzymes were selected for further studies with the Wieland Miescher ketone. Notably, enzyme SDR-17, when co-expressed with a co-factor recycling system produced the anti-(4aR,5S) isomer in excellent isolated yields of 89% and 99% e.e. These results demonstrate the viability of a sequence directed metagenomics approach for the identification of multiple homologous sequences with low similarity, that can yield highly stereoselective enzymes with applicability in industrial biocatalysis.

Isolation and characterization of a new cold-active protease from psychrotrophic bacteria of Western Himalayan glacial soil

As an approach to the exploration of cold-active enzymes, in this study, we isolated a cold-active protease produced by psychrotrophic bacteria from glacial soils of Thajwas Glacier, Himalayas. The isolated strain BO1, identified as Bacillus pumilus, grew well within a temperature range of 4-30 °C. After its qualitative and quantitative screening, the cold-active protease (Apr-BO1) was purified. The Apr-BO1 had a molecular mass of 38 kDa and showed maximum (37.02 U/mg) specific activity at 20 °C, with casein as substrate. It was stable and active between the temperature range of 5-35 °C and pH 6.0-12.0, with an optimum temperature of 20 °C at pH 9.0. The Apr-BO1 had low K_m value of 1.0 mg/ml and V_max 10.0 µmol/ml/min. Moreover, it displayed better tolerance to organic solvents, surfactants, metal ions and reducing agents than most alkaline proteases. The results exhibited that it effectively removed the stains even in a cold wash and could be considered a decent detergent additive. Furthermore, through protein modelling, the structure of this protease was generated from template, subtilisin E of Bacillus subtilis (PDB ID: 3WHI), and different methods checked its quality. For the first time, this study reported the protein sequence for psychrotrophic Apr-BO1 and brought forth its novelty among other cold-active proteases.

Additives in pet food: are they safe?

A good, nutritious diet is essential for the health and well-being of our domestic pets. Today, most pet dogs and cats are fed highly processed food bearing little resemblance to canine and feline ancestral diets. Additives are included in processed pet food to provide nutritional benefits, ensure food safety, and maintain the desirable features of colour, flavour, texture, stability and resistance to spoilage. This paper reviews the safety of various additives in processed pet food. Labelling, safety assessment, and ethical concerns regarding existing toxicity testing procedures are also considered. The adequacy of testing for many additives and the scientific basis for determining safety are questioned. Additives can be synthetic or 'natural' although the distinction can be blurred when naturally derived substances are synthesised in the laboratory, or extracted using a high level of physical and chemical processing. Although additives play important roles in processed food production, updated strategies and technologies may be required to establish their safety in the pet food industry.

New perspectives for evaluating relative risks of African swine fever virus contamination in global feed ingredient supply chains

There are no published reports indicating that the African swine fever virus (ASFV) has been detected in feed ingredients or complete feed. This is primarily because there are only a few laboratories in the world that have the biosecurity and analytical capabilities of detecting ASFV in feed. Several in vitro studies have been conducted to evaluate ASFV concentration, viability and inactivation when ASFV was added to various feed ingredients and complete feed. These inoculation studies have shown that some feed matrices support virus survival longer than others and the reasons for this are unknown. Current analytical methodologies have significant limitations in sensitivity, repeatability, ability to detect viable virus particles and association with infectivity. As a result, interpretation of findings using various measures may lead to misleading conclusions. Because of analytical and technical challenges, as well as the lack of ASFV contamination data in feed supply chains, quantitative risk assessments have not been conducted. A few qualitative risk assessments have been conducted, but they have not considered differences in potential scenarios for ASFV contamination between various types of feed ingredient supply chains. Therefore, the purpose of this review is to provide a more holistic understanding of the relative potential risks of ASFV contamination in various global feed ingredient supply chains and provide recommendations for addressing the challenges identified.

Cost-effective production of biocatalysts using inexpensive plant biomass: a review

Enzymes are the complex protein moieties, catalyze the rate of chemical reactions by transforming various substrates to specific products and play an integral part in multiple biochemical cycles. Advancement in enzyme research and its integration with industries have reformed the biotech industries. It provides a superior monetary and ecological exchange to traditional material measures in an efficient and environmentally sustainable manner. The cost-effective production of pure and highly active enzymes is still a challenge for the biocatalyst industries. The use of high purity substrates further raises the cost of a typical biocatalyst. The use of low-cost plant-based biomasses as an enticing and sustainable substrate for enzyme production is the most cost-effective approach to these problems. Given the relevance of biomass as a substrate for enzyme development, this review article focuses on the key source, composition and major enzyme generated using various biomass residues. Furthermore, the difficulties associated with the use of biomass as a substrate and technical developments in this area, are also addressed. The use of waste biomass as a substrate lowers the ultimate cost for the production of biocatalysts while simultaneously reduces the waste burden from the environment.

Pectin Degradation in Fruit Juices by Pectinase from Meyerozyma sp. VITPCT75 Isolated from Phyllanthus emblica

This study aimed to identify and characterize a pectinase-producing novel yeast from the fermented juice of Phyllanthus emblica and apply the enzyme for fruit juice clarification. Among the five pectinase-producing yeasts, isolate-1 exhibited the highest pectinase activity and was further used in this study. Based on morphological, physiological, and 18SrRNAanalyses, isolate-1 was recognized as a new strain sharing 99% sequence homology with other Meyerozyma strains and was thus designated as Meyerozyma sp. VITPCT75. The strain produced pectinase optimally at a temperature and pH of 25oC and 7, respectively. Maximum pectinase production was observed after 4-days incubation. The enzyme exhibited optimum activity at the temperature of 25 °C and pH 7.0. The enzyme was more stable at a temperature and pH of 20 °C and 7, respectively. Storage stability studies revealed that the enzyme was stable at -20 °C. The cell-free supernatant was partially purified using ammonium sulfate and solvent precipitation. Acetone at a concentration of 20% assured an adequate partial purification. The molecular weight of pectinase was determined as 6 kDa. The enzymatic metal ion preference-related studies revealed that Ca²z, Kz, Cu²z, Fe²z, and Ba²z ions enhanced, Ni²z ions moderately inhibited, and Mn²z ions intensely inhibited the enzymatic activity. Neither Na+ and Mg2+ ions nor EDTA affected the enzyme activity. When subjected to fruit juice clarification, the enzyme significantly reduced the viscosity of the juice.

Optimization of immobilization of Pseudomonas cepacia lipase on multiwalled carbon nanotubes functionalized with glycyrrhizin and Tween 80

In the present study, multiwalled carbon nanotubes (MWCNTs) were functionalized with glycyrrhizin and Tween 80 and applied for immobilization of Pseudomonas cepacia lipase (PcL). Characterization of f-MWCNTs was performed through Fourier-transform infrared spectroscopy, thermal gravimetric, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis. The optimum specific activity of immobilized PcL (studied by Plackett-Burman statistical design) occurred at 0.3 mg/mL of f-MWCNTs, 25 mM of phosphate buffer (pH 6.0), 15 min sonication time, 8 U/mL of enzyme concentration, and 24 h immobilization time at 4 °C in the absence of glutaraldehyde. In these conditions, the specific activity was 16.57 ± 0.71 U/mg, which was very close to the predicted amount (16.62 ± 0.64 U/mg). The results of thermal and pH stability showed that the stability of immobilized PcL was higher than that of the free PcL. The activity of immobilized PcL on f-MWCNTs held 93% after being incubated for 60 min at 70 °C. Moreover, the immobilized PcL on f-MWCNTs retained about 65% of its initial activity after 30 days of storage at 25 °C. In addition, about 50% of initial activity of immobilized PcL retained after 10 cycles of uses. Therefore, f-MWCNTs could be introduced as suitable support for enzymes immobilization.

Recombinant Bovine and Human Osteopontin Generated by Chlamydomonas reinhardtii Exhibit Bioactivities Similar to Bovine Milk Osteopontin When Assessed in Mouse Pups Fed Osteopontin-Deficient Milk

SCOPE

Osteopontin (OPN), a highly phosphorylated and glycosylated protein, is present in most body fluids, including milk. OPN appears at a high concentration in human milk (130-180 mg L^-1 ), but not bovine milk (≈18 mg mL^-1 ). It is previously shown that milk OPN is involved in various biological processes and therefore may be a valuable infant formula additive.

METHODS AND RESULTS

In the present study, recombinant bovine OPN (rbOPN) and recombinant human OPN (rhOPN) are generated in a Chlamydomonas reinhardtii (C. reinhardtii) algal expression system. The rbOPN and rhOPN are phosphorylated but not glycosylated. To assess the bioactivities of rbOPN and rhOPN and compare their bioactivities to those of bovine milk OPN (bmOPN), wild-type (WT) mouse pups nursed by OPN knock-out (KO) dams are orally fed bmOPN, rbOPN, and rhOPN daily from postnatal days 1-21 (P1-21). Effects of these OPNs on development of the brain, intestine, and immune function are evaluated. The results show that rbOPN and rhOPN exhibit effects similar to those of bmOPN as well as mouse milk OPN on stimulating proliferation of the small intestine, increasing brain myelination and cognitive development, and enhancing development of immune function.

CONCLUSION

rbOPN and rhOPN are likely to provide beneficial bioactivities when added to infant diets.

Yeasts isolated from a lotic continental environment in Brazil show potential to produce amylase, cellulase and protease

Yeasts have wide applicability in the industrial field, as in the production of enzymes used in biocatalysts. Biocatalysts are more efficient when compared to chemical catalysts, with emphasis on hydrolytic enzymes, such as amylase, cellulase and protease. Here we focused on prospecting yeasts, with a high capacity to synthesize hydrolytic enzymes, from a continental lotic ecosystem environment in Brazil. 75 yeasts were grown in Yeast Extract-Peptone-Dextrose (YPD) medium supplemented with antibacterial and their capacity for enzymatic production was tested in specific media. Accordingly, 64 yeasts showed enzyme production capacity. From those, six showed good enzyme indexes, 3 for amylase, 2 for cellulase and 1 for protease. All showed at least one hydrolytic enzyme activity for the tested enzymes (amylase, cellulase and protease), which suggested that the yeasts are metabolically active. By sequencing the 26S gene, we identified Naganishia diffluens and Apiotrichum mycotoxinivorans as the species with highest enzyme production activities. Those species showed potential for application as biological catalysts in the biotechnological scope, collaborating in a sustainable way for the development of industrial products.

Application of Co-Culture Technology to Enhance Protease Production by Two Halophilic Bacteria, Marinirhabdus sp. and Marinobacter hydrocarbonoclasticus

Although axenic microbial cultures form the basis of many large successful industrial biotechnologies, the production of single commercial microbial strains for use in large environmental biotechnologies such as wastewater treatment has proved less successful. This study aimed to evaluate the potential of the co-culture of two halophilic bacteria, Marinirhabdus sp. and Marinobacter hydrocarbonoclasticus for enhanced protease activity. The co-culture was significantly more productive than monoculture (1.6–2.0 times more growth), with Marinobacter hydrocarbonoclasticus being predominant (64%). In terms of protease activity, enhanced total activity (1.8–2.4 times) was observed in the co-culture. Importantly, protease activity in the co-culture was found to remain active over a much broader range of environmental conditions (temperature 25 °C to 60 °C, pH 4–12, and 10–30% salinity, respectively). This study confirms that the co-culturing of halophilic bacteria represents an economical approach as it resulted in both increased biomass and protease production, the latter which showed activity over arange of environmental conditions.

Diversity, Ecological Role and Biotechnological Potential of Antarctic Marine Fungi

The Antarctic Ocean is one of the most remote and inaccessible environments on our planet and hosts potentially high biodiversity, being largely unexplored and undescribed. Fungi have key functions and unique physiological and morphological adaptations even in extreme conditions, from shallow habitats to deep-sea sediments. Here, we summarized information on diversity, the ecological role, and biotechnological potential of marine fungi in the coldest biome on Earth. This review also discloses the importance of boosting research on Antarctic fungi as hidden treasures of biodiversity and bioactive molecules to better understand their role in marine ecosystem functioning and their applications in different biotechnological fields.

Superoxide dismutase: an updated review on its health benefits and industrial applications

Many short-lived and highly reactive oxygen species, such as superoxide anion (O₂^-) and hydrogen peroxide (H₂O₂), are toxic or can create oxidative stress in cells, a response involved in the pathogenesis of numerous diseases depending on their concentration, location, and cellular conditions. Superoxide dismutase (SOD) activities as an endogenous and exogenous cell defense mechanism include the potential use in treating various diseases, improving the potential use in treating various diseases, and improving food-stuffs preparation dietary supplements human nutrition. Published work indicates that SOD regulates oxidative stress, lipid metabolism, inflammation, and oxidation in cells. It can prevent lipid peroxidation, the oxidation of low-density lipoprotein in macrophages, lipid droplets' formation, and the adhesion of inflammatory cells into endothelial monolayers. It also expresses antioxidant effects in numerous cancer-related processes. Additionally, different forms of SOD may also augment food processing and pharmaceutical applications, exhibit anticancer, antioxidant, and anti-inflammatory effects, and prevent arterial problems by protecting the proliferation of vascular smooth muscle cells. Many investigations in this review have reported the therapeutic ability and physiological importance of SOD. Because of their antioxidative effects, SODs are of great potential in the medicinal, cosmetic, food, farming and chemical industries. This review discusses the findings of human and animal studies that support the advantages of SOD enzyme regulations to reduce the formation of oxidative stress in various ways.

Antioxidant Production in Dunaliella

Microalgae have become an attractive natural source of a diverse range of biomolecules, including enzymatic and non-enzymatic antioxidants; nevertheless, economically sustainable production of such compounds from microalgae biomass is still challenging. The main hurdles are: (a) increasing microalgae yield; (b) achieving optimal cultivation conditions; (c) energy-efficient and cost-effective downstream processing (extraction and purification); (d) optimal storage of post-processed antioxidant molecules. This review provides a detailed overview of enzymatic and non-enzymatic antioxidants in the cellular metabolism of the commercially important microalgae Dunaliella, industrial applications of antioxidant enzymes, strategies to enhanced antioxidant accumulation in cells, and the opportunities and limitations of current technologies for antioxidant enzymes production from microalgae biomass as an alternative to common microbial sources.

Potential Applications of Endo-β-N-Acetylglucosaminidases From Bifidobacterium longum Subspecies infantis in Designing Value-Added, Next-Generation Infant Formulas

Human milk is the optimal source of infant nutrition. Among many other health benefits, human milk can stimulate the development of a Bifidobacterium-rich microbiome through human milk oligosaccharides (HMOs). In recent years, the development of novel formulas has placed particular focus on incorporating some of the beneficial functional properties of human milk. These include adding specific glycans aimed to selectively stimulate the growth of Bifidobacterium. However, the bifidogenicity of human milk remains unparalleled. Dietary N-glycans are carbohydrate structures conjugated to a wide variety of glycoproteins. These glycans have a remarkable structural similarity to HMOs and, when released, show a strong bifidogenic effect. This review discusses the biocatalytic potential of the endo-β-N-acetylglucosaminidase enzyme (EndoBI-1) from Bifidobacterium longum subspecies infantis (B. infantis), in releasing N-glycans inherently present in infant formula as means to increase the bifidogenicity of infant formula. Finally, the potential implications for protein deglycosylation with EndoBI-1 in the development of value added, next-generation formulas are discussed from a technical perspective.

Valorization of Lignocellulosic Wastes to Produce Phytase and Cellulolytic Enzymes from a Thermophilic Fungus, Thermoascus aurantiacus SL16W, under Semi-Solid State Fermentation

Agricultural wastes are lignocellulosic biomasses that contain high mineral and nutrient contents. This waste can be used as a raw material in industrial enzyme production by microbial fermentation. Phytase is an important enzyme used in animal feed to enhance the amount of phosphorus available for the growth and overall health improvement of monogastric animals. Fungi offer high potential as an effective source in the production of various extracellular enzymes. In this study, the production of lignocellulolytic enzymes (endoglucanase and xylanase) and phytase by a thermophilic fungus, namely Thermoascus aurantiacus strain SL16W, was evaluated using sixteen different Thai agricultural forms of waste under conditions of high temperature (45 °C). Semi-solid state fermentation was used in the production experiments. The results of this study reveal that the highest phytase activity (58.6 U/g substrate) was found in rice bran, whereas the highest degrees of activity of endoglucanase and xylanase were observed in wheat bran and red tea leaves at 19 and 162 U/g substrate, respectively. Consequently, the optimal conditions for phytase production of this fungus using rice bran were investigated. The results indicate that the highest phytase yield (58.6 to 84.1 U/g substrate) was observed in rice bran containing 0.5% ammonium sulfate as a nitrogen source with 10 discs of inoculum size at a cultivation period of 9 days at 45 °C and moisture content of 95%. Notably, the phytase yield increased by 1.71-fold, while endoglucanase and xylanase were also increased by 1.69- and 1.12-fold, respectively. Furthermore, the crude enzyme obtained from the optimal condition was extracted. The crude enzyme extract was then separately added to red tea leaves, rice straw, corncobs, palm residue, and peanut husks. Subsequently, total reducing sugar and phosphorus contents were determined. The results indicate that the highest level of reducing sugar (122.6 mg/L) and phosphorus content (452.6 mg/L) (p < 0.05) were obtained in palm residue at 36 and 48 h, respectively, after the addition of the crude enzyme extract. This study has provided valuable information on a potentially eco-friendly way to valorize agricultural waste into value-added products as industrial enzymes.

Isolation of Bacillus spp. with High Fibrinolytic Activity and Performance Evaluation in Fermented Douchi

ABSTRACT

Fibrinolytic enzymes are effective and highly safe in treating cardiovascular and cerebrovascular diseases. Therefore, screening fibrinolytic enzyme-producing microbial strains with excellent fermentation performance is of great value to industrial applications. The fibrin plate method was used in screening strains with high yields of fibrinolytic enzymes from different fermented food products, and the screened strains were preliminarily identified using molecular biology. Then, the strains were used for solid-state fermentation of soybeans. Moreover, the fermentation product douchi was subjected to fibrinolytic activity measurement, sensory evaluation, and biogenic amine content determination. The fermentation performance of each strain was comprehensively evaluated through principal component analysis. Finally, the target strain was identified based on strain morphology, physiological and biochemical characteristics, 16S rDNA sequence, and phylogenetic analysis results. A total of 15 Bacillus species with high fibrinolysin activity were selected. Their fibrinolytic enzyme-producing activity levels were higher than 5,500 IU/g. Through molecular biology analysis, we found 4 strains of Bacillus subtilis, 10 strains of Bacillus amyloliquefaciens, and 1 strain of Bacillus velezensis. The principal component analysis results showed that SN-14 had the best fermentation performance and reduced the accumulation of histamine and total amine, the fibrinolytic activity of fermented douchi reached 5,920.5 ± 107.7 IU/g, and the sensory score was 4.6 ± 0.3 (out of 5 points). Finally, the combined results of physiological and biochemical analyses showed SN-14 was Bacillus velezensis. The high-yield fibrinolytic and excellent fermentation performance strain Bacillus velezensis SN-14 has potential industrial application.

HIGHLIGHTS

Hybrid chemoenzymatic heterogeneous catalyst prepared in one step from zeolite nanocrystals and enzyme-polyelectrolyte complexes

The combination of inorganic heterogeneous catalysts and enzymes, in so-called hybrid chemoenzymatic heterogeneous catalysts (HCEHCs), is an attractive strategy to effectively run chemoenzymatic reactions. Yet, the preparation of such bifunctional materials remains challenging because both the inorganic and the biological moieties must be integrated in the same solid, while preserving their intrinsic activity. Combining an enzyme and a zeolite, for example, is complicated because the pores of the zeolite are too small to accommodate the enzyme and a covalent anchorage on the surface is often ineffective. Herein, we developed a new pathway to prepare a nanostructured hybrid catalyst built from glucose oxidase and TS-1 zeolite. Such hybrid material can catalyse the in situ biocatalytic formation of H₂O₂, which is subsequently used by the zeolite to trigger the epoxidation of allylic alcohol. Starting from an enzymatic solution and a suspension of zeolite nanocrystals, the hybrid catalyst is obtained in one step, using a continuous spray drying method. While enzymes are expectedly unable to resist the conditions used in spray drying (temperature, shear stress, etc.), we leverage on the preparation of "enzyme-polyelectrolyte complexes" (EPCs) to increase the enzyme stability. Interestingly, the use of EPCs also prevents enzyme leaching and appears to stabilize the enzyme against pH changes. We show that the one-pot preparation by spray drying gives access to hybrid chemoenzymatic heterogeneous catalysts with unprecedented performance in the targeted chemoenzymatic reaction. The bifunctional catalyst performs much better than the two catalysts operating as separate entities. We anticipate that this strategy could be used as an adaptable method to prepare other types of multifunctional materials starting from a library of functional nanobuilding blocks and biomolecules.

Designing of Nanomaterials-Based Enzymatic Biosensors: Synthesis, Properties, and Applications

Among the many biological entities employed in the development of biosensors, enzymes have attracted the most attention. Nanotechnology has been fostering excellent prospects in the development of enzymatic biosensors, since enzyme immobilization onto conductive nanostructures can improve characteristics that are crucial in biosensor transduction, such as surface-to-volume ratio, signal response, selectivity, sensitivity, conductivity, and biocatalytic activity, among others. These and other advantages of nanomaterial-based enzymatic biosensors are discussed in this work via the compilation of several reports on their applications in different industrial segments. To provide detailed insights into the state of the art of this technology, all the relevant concepts around the topic are discussed, including the properties of enzymes, the mechanisms involved in their immobilization, and the application of different enzyme-derived biosensors and nanomaterials. Finally, there is a discussion around the pressing challenges in this technology, which will be useful for guiding the development of future research in the area.