Expression and Characterization of Glucose Oxidase from Aspergillus niger in Yarrowia lipolytica

Hypersecretory production of glucose oxidase in Pichia pastoris through combinatorial engineering of protein properties, synthesis, and secretion

Glucose oxidase (EC 1.1.3.4, GOD) is a widely used industrial enzyme. To construct a GOD-hyperproducing Pichia pastoris strain, combinatorial strategies have been applied to improve GOD activity, synthesis, and secretion. First, wild-type GOD was subjected to saturation mutagenesis to obtain an improved variant, MGOD1 (V20W/T30S), with 1.7-fold higher kcat /KM . Subsequently, efficient signal peptides were screened, and the copy number of MGOD1 was optimized to generate a high-producing strain, 8GM1, containing eight copies of AOX1 promoter-GAS1 signal peptide-MGOD1 expression cassette. Finally, the vesicle trafficking of 8GM1 was engineered to obtain the hyperproducing strain G1EeSe co-expressing the trafficking components EES and SEC. 22, and the EES gene (PAS_chr3_0685) was found to facilitate both protein secretion and production for the first time. Using these strategies, GOD secretion was enhanced 65.2-fold. In the 5-L bioreactor, conventional fed-batch fermentation without any process optimization resulted in up to 7223.0 U/mL extracellular GOD activity (3.3-fold higher than the highest level reported to date), with almost only GOD in the fermentation supernatant at a protein concentration of 30.7 g/L. Therefore, a GOD hyperproducing strain for industrial applications was developed, and this successful case can provide a valuable reference for the construction of high-producing strains for other industrial enzymes.

Regulation of different protonated states of two intimate histidine residues on the reductive half-reaction of glucose oxidase

Glucose oxidase (GOx) can catalyze the oxidation of β-D-glucose under mild conditions to directly convert biological energy into electrical energy, which has great potential for applications in the fields of enzyme biofuel cells and glucose biosensors. In enzymatic biofuel cells, GOx is often used as an anodic catalyst to improve the performance. The important role of two intimate histidine residues, His505 and His548 (PDB code 4YNU), in the GOx active center has been highlighted in the catalytic oxidation of β-D-glucose, but there is still a lack of systematic examination on the influence of different protonated states of His505 and His548 on the catalytic oxidation of β-D-glucose in GOx. Therefore, in the present work, the GOx active center under the possible protonated states of His548 and His505 is systematically examined by using ONIOM calculations, as well as the influence of remote Arg210 is considered. The calculations reveal that the intimate His505 and His548 can modulate the interaction of the β-D-glucose substrate with isoalloxazine and then control the deprotonization of the hydroxyl group bound to the anomeric carbon of β-D-glucose like controllers. The remote Arg210 provides the driving force for the transfer of two electrons from β-D-glucose to isoalloxazine of FAD via the long-range electrostatic attraction like a horse. Specially, the protonated His505 can serve as a good helper of Arg210 to promote the occurring of the two-proton-coupled two-electron transfer from β-D-glucose to isoalloxazine and His548 in the active center of GOx. These findings provide much insight into the catalytic reactions of GOx in a low pH environment, which may be beneficial to expand the applications of GOx.

Tumor Microenvironment-Adaptive Nanoplatform Synergistically Enhances Cascaded Chemodynamic Therapy

Chemodynamic therapy (CDT), a noninvasive strategy, has emerged as a promising alternative to conventional chemotherapy for treating tumors. However, its therapeutic effect is limited by the amount of H₂O₂, pH value, the hypoxic environment of tumors, and it has suboptimal tumor-targeting ability. In this study, tumor cell membrane-camouflaged mesoporous Fe₃O₄ nanoparticles loaded with perfluoropentane (PFP) and glucose oxidase (GOx) are used as a tumor microenvironment-adaptive nanoplatform (M-mFeP@O₂-G), which synergistically enhances the antitumor effect of CDT. Mesoporous Fe₃O₄ nanoparticles are selected as inducers for photothermal and Fenton reactions and as nanocarriers. GOx depletes glucose within tumor cells for starving the cells, while producing H₂O₂ for subsequent ·OH generation. Moreover, PFP, which can carry O₂, relieves hypoxia in tumor cells and provides O₂ for the cascade reaction. Finally, the nanoparticles are camouflaged with osteosarcoma cell membranes, endowing the nanoparticles with homologous targeting and immune escape abilities. Both in vivo and in vitro evaluations reveal high synergistic therapeutic efficacy of M-mFeP@O₂-G, with a desirable tumor-inhibition rate (90.50%), which indicates the great potential of this platform for clinical treating cancer.

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GOx and PFP were loaded in mFe₃O₄ to form a TME-adaptive nanoplatform and synergistically enhance the cascaded reactions.

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Tumor cell membranes, endowing the nanoparticles with homologous targeting and immune escape abilities.

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The nanoparticles had excellent combined chemodynamic therapy, starvation therapy and photothermal tumor therapy effect.

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Tumor cell membranes coated nanoparticles improved cell uptake and had a desirable tumor-inhibition rate.

Aspergillus welwitschiae: A Potential amylases Producer

Amylases, glycoside hydrolases widely used in several industrial processes, can be produced by many animals, plants, bacteria, and fungi. Fungal amylases from Aspergillus sp. hold remarkable importance in biotechnological applications for presenting a great catalysis efficiency in a wide range of pH and temperature. The production of amylases is mainly dependent on the genetic background of the species, i.e., Aspergillus strains, and abiotic factors. Among the major producers of amylases are the species of Aspergillus section Nigri, including Aspergillus welwitschiae. In this study, Aspergillus welwitschiae strains were evaluated for their ability to produce extracellular amylases. Among the 24 strains, wild Aspergillus welwitschiae UELAs 15.262 and mutant A. welwitschiae UELAs 15.262/35 strains showed greater potential for amylases production. The A. welwitschiae UELAs 15.262 produced more amylases (8645 U/mg) when compared to A. welwitschiae UELAs 15.262/35 (6666 U/mg). The amylases activity from partially purified crude enzymatic extract of A. welwitschiae UELAs 15.262 strain obtained at pH 5.5, 60 °C, resulted in 1.98-fold (3837 U/mg) increase in enzymatic activity. Likewise, the amylases activity from partially purified crude extract of A. welwitschiae UELAs 15.262/35 obtained at pH 5.0, 60 °C resulted in 2.2-fold (9077 U/mg) increase in amylases activity. The presence of metallic ions (Cu²⁺ and Fe³⁺) also provided an increase of amylases activity for both strains. To our knowledge, this is the first study reporting the ability of Aspergillus welwitschiae strains in order to produce amylases.

Insights into the Structures, Inhibitors, and Improvement Strategies of Glucose Oxidase

Glucose oxidase, which uses molecular oxygen as an electron acceptor to specifically catalyze the conversion of β-d-glucose to gluconic acid and hydrogen peroxide (H₂O₂), has been considered an important enzyme in increasing environmental sustainability and food security. However, achieving the high yield, low price and high activity required for commercial viability remains challenging. In this review, we first present a brief introduction, looking at the sources, characteristics, catalytic process, and applications of glucose oxidase. Then, the predictive structures of glucose oxidase from two different sources are comparatively discussed. We summarize the inhibitors of glucose oxidase. Finally, we highlight how the production of glucose oxidase can be improved by optimizing the culture conditions and microbial metabolic engineering.

Mussel-inspired multifunctional hydrogel dressing with hemostasis, hypoglycemic, photothermal antibacterial properties on diabetic wounds

To meticulously establish an efficient photothermal multifunctional hydrogel dressing is a prospective strategy for the treatment of diabetic chronic wounds. Herein, glucose oxidase (GOx) was added to polydopamine/acrylamide (PDA/AM) hydrogels to reduce hyperglycemia to a normal level (3.9-6.1 mmol L^-1) and enhance compressive properties (55 kPa) and adhesive properties (32.69 kPa), which are capable of hemostasis in the wound. Then, MnO₂ nanoparticles were encapsulated into a polydopamine/acrylamide (PDA/AM) hydrogel, endowing it with excellent antibacterial properties (E. coli and S. aureus were 97.87% and 99.99%) under the irradiation of 808 nm NIR; meanwhile, the biofilm was eliminated completely. Besides, O₂ was generated (18 mg mL^-1) by the decomposition of H₂O₂ under the catalysis of MnO₂, which could accelerate the formation of angiogenesis and promote the crawling and proliferation of cells. Furthermore, the diabetic wound in vivo treated with the PDA/AM/GOx/MnO₂ hydrogel had a less inflammatory response and faster healing speed, which was completely healed in 14 days. Therefore, the multifunctional hydrogels with the capability of high compressible, hemostasis, antibacterial, hyperglycemia manipulation, and O₂ generation, demonstrate promise in diabetic chronic wound dressing.

Molecular Cloning, Expression, and Enzyme Activity of Glucose Oxidase Gene from Soil Thermophilic Streptomyces

Background

Glucose oxidase is an oxidoreductase that depletes oxygen in food processing and is used in biosensors, glucose diagnostic kits, food processing, cosmetics, and chemical industries. This enzyme is often isolated from fungi, such as Penicillium and Aspergillus Niger.

Objectives

The objective of this study was to clone and express a full-length GOX gene from soil thermophilic streptomyces for bioinformatic and enzyme activity evaluations.

Materials and Methods

After collecting samples from the Gandom Beryan area of Kerman province, Iran, Streptomyces strains were identified with specific biochemical and molecular tests. Streptomyces strains with glucose oxidase gene were detected by PCR, and the amplified gene fragment was cloned into Escherichia coli host bacterium using TA cloning technique. The expression of the cloned GOX gene in the host bacterium was measured using real-time PCR, and the recombinant plasmids were sequenced. The enzymatic activity was measured in the extracts of E. coli cells carrying the plasmids.

Results

After screening the samples, 12 strains of Streptomyces were identified, 4 of which carried the GOX gene. The GOX open reading frame, obtained by PCR, was cloned into a vector and transformed into Escherichia coli origami to generate GOX-producing bacteria. Enzyme activity was confirmed and a phylogenetic tree showed the degree of kinship between Streptomyces species and other species, including Streptomyces SP MI02-7b. The expression levels of GOX genes mRNA were found to be approximately 4-fold higher in transformed E. coli than in soil thermophilic Streptomyces (P <0.001).

Conclusion

This study showed that natural thermostable streptomyces producing glucose oxidase enzyme could be found in Iran. The enzyme gene was successfully transformed into Escherichia coli generating a recombinant host with high yield capability that can be a major step towards the production of this enzyme from indigenous strains. It should be emphasized that the GOX enzyme produced by these strains is profitable due to high production levels correlated to the optimum condition in cheap culture media, short fermentation cycles, high expression capability, and ease of growth.

Expression of Aspergillus niger glucose oxidase in Pichia pastoris and its antimicrobial activity against Agrobacterium and Escherichia coli

The gene encoding glucose oxidase from Aspergillus niger ZM-8 was cloned and transferred to Pichia pastoris GS115, a transgenic strain P. pastoris GS115-His-GOD constructed. The growth curve of P. pastoris GS115-His-GOD was consistent with that of Pichia pastoris GS115-pPIC9K under non-induced culture conditions. Under methanol induction conditions, the growth of the GOD-transgenic strain was significantly lowered than P. pastoris GS115-pPIC9K with the induced-culture time increase, and the optical densities of GOD-transgenic strain reached one-third of that of the P. pastoris GS115-pPIC9K at 51 h. The activity of glucose oxidase in the cell-free supernatant, the supernatant of cell lysate, and the precipitation of cell lysate was 14.3 U/mL, 18.2 U/mL and 0.48 U/mL, respectively. The specific activity of glucose oxidase was 8.3 U/mg, 6.52 U/mg and 0.73 U/mg, respectively. The concentration of hydrogen peroxide formed by glucose oxidase from supernatant of the fermentation medium, the supernatant of the cell lysate, and the precipitation of cell lysate catalyzing 0.2 M glucose was 14.3 μg/mL, 18.2 μg/mL, 0.48 μg/mL, respectively. The combination of different concentrations of glucose oxidase and glucose could significantly inhibit the growth of Agrobacterium and Escherichia coli in logarithmic phase. The filter article containing supernatant of the fermentation medium, supernatant of the cell lysate, and precipitation of cell lysate had no inhibitory effect on Agrobacterium and E. coli. The minimum inhibitory concentration of hydrogen peroxide on the plate culture of Agrobacterium and E. coli was 5.6 × 10³ μg/mL and 6.0 × 10³ μg/mL, respectively.

The production and application of enzymes related to the quality of fruit wine

Grape wine is the most widely consumed fruit wine in the world. With the increasing diversification of consumers' needs, the variety of fruit wines in the market is becoming more and more abundant. Whether it is the production of grape wine or other fruit wines these processes are inseparable from the participation of enzymes. The quality of these wines is closely related to the application of enzymes in the winemaking process. Enzymes are involved in pretreatment, fermentation, filtration, flavoring, aging and storage of fruit wines. This review systematically illustrated the role of pectinase, β-glucanase, β-glucosidase, glucose oxidase, lysozyme, protease, tannase and urease in the production of wines and their current production status and also provided a theoretical basis for better application of various enzymes in the production of various fruit wines. This knowledge could be great significance to improve the quality of fruit wines and reduce the production costs in the fruit wine industry.

Enzyme production ofd-gluconic acid and glucose oxidase: successful tales of cascade reactions

This review mainly focuses on the use of glucose oxidase in the production ofd-gluconic acid, which is a reactant of undoubtable interest in different industrial areas. As example of diverse enzymatic cascade reactions.

Construction of Microreactors for Cascade Reaction and Their Potential Applications as Antibacterial Agents

Enzymatic cascade reactions in confined microenvironments play important roles in cellular chemical transformation. They also have important biotechnological and therapeutic applications. Here, enzymatic cascade microreactors (MRs) coupling glucose oxidase (GOx) and hemoglobin (Hb) (GOx-Hb MRs) were successfully fabricated by co-precipitation of GOx and Hb into a MnCO₃ template, followed by the assembly of a multilayer film on a template surface, slight cross-linking, and final removal of MnCO₃. In the presence of glucose with blood-relevant concentration, the GOx-Hb MRs exhibited a higher cascade reaction activity under mild acidic conditions than that under neutral conditions at physiological temperature. The GOx-Hb MRs effectively consumed glucose to generate HO^· at pH = 5, which significantly inhibited bacterial growth and biofilm formation. This kind of enzymatic cascade microreactors might be useful for applications in biomedical fields.

Production and structural modeling of a novel asparaginase in Yarrowia lipolytica

Asparaginase catalyzes the conversion of asparagine into aspartic acid and ammonia. The enzyme has various industrial applications and it is considered as an anticancer drug for treatment of certain leukemias. In the current study, production of asparaginase was investigated by Yarrowia lipolytica as well as optimized its production and determined its molecular characteristics by in silico analysis. Y. lipolytica DSM3286 produced 17.14 U/ml of asparaginase in flask culture. Optimization of asparaginase production was done by response surface methodology and the enzyme production increases up to 102.85 U/ml. The enzyme production reached 210 U/ml in a bioreactor which is 12-fold more than flask culture containing non-optimized medium. Asparaginase gene of Y. lipolytica was identified and isolated on the basis of comparison with asparaginase gene sequences of other microorganisms. The gene has 981 nucleotides and its protein has 326 amino acids. According to in silico analysis, the secondary structure of the enzyme is composed of 9 α-helixes and 11 β-sheets. Y. lipolytica produces type II asparaginase with high affinity for asparagine which is a suitable eukaryotic asparaginase for treatment of hematopoietic cancers. Hence, Y. lipolytica could be recommended as a new eukaryotic microbial source for the production of this important therapeutic enzyme.

In silico and in vivo analysis of signal peptides effect on recombinant glucose oxidase production in nonconventional yeast Yarrowia lipolytica

Signal peptide (SP) is an important factor and biobrick in the production and secretion of recombinant proteins. The aim of this study was in silico and in vivo analysis of SPs effect on the production of recombinant glucose oxidase (GOX) in Yarrowia lipolytica. Several in silico softwares, namely SignalP4, Signal-CF, Phobius, WolfPsort 0.2, SOLpro and ProtParam, were used to analyse the potential of 15 endogenous and exogenous SPs for the secretion of recombinant GOX in Y. lipolytica. According to in silico results, the SP of GOX was predicted as suitable in terms of high secretory potential and of protein solubility and stability which is chosen for in vivo analysis. The recombinant Y. lipolytica strain produced 280 U/L of extracellular GOX after 7 days in YPD medium. The results show that the SP of GOX can be applied to efficient production of extracellular heterologous proteins and metabolic engineering in Y. lipolytica.

Enzymes and Dairy Products

The use of enzymes in food production, including dairy products, is below expected due the high costs associated with their production and purification. Microbial enzymes have great potential for industrial applications since they can be produced via large-scale fermentation and they are easily expressed by cloning in well-known cultivated microorganisms. The combination of different procedures such as over-expression techniques and the use of low costs induction sources has resulted in the production of enzymes to be used in high added-value dairy products. The addition of glucose oxidase to probiotic yogurts has been indicated as an alternative to the maintenance of probiotic functionality. Bile salt hydrolase contributes to prevention of hypercholesterolemia which is interesting to produce new functional dairy products. This chapter discusses enzyme sources and their relevance in dairy products, the production of enzymes using cloning and super-expression techniques, as well as enzymes related to functional dairy products.

Biochemical and Thermodynamical Characterization of Glucose Oxidase, Invertase, and Alkaline Phosphatase Secreted by Antarctic Yeasts

The use of enzymes in diverse industries has increased substantially over past decades, creating a well-established and growing global market. Currently, the use of enzymes that work better at ambient or lower temperatures in order to decrease the temperatures of production processes is desirable. There is thus a continuous search for enzymes in cold environments, especially from microbial sources, with amylases, proteases, lipases and, cellulases being the most studied. Other enzymes, such as glucose oxidase (GOD), invertase (Inv), and alkaline phosphatase (ALP), also have a high potential for application, but have been much less studied in microorganisms living in cold-environments. In this work, secretion of these three enzymes by Antarctic yeast species was analyzed, and five, three, and five species were found to produce extracellular GOD, Inv, and ALP, respectively. The major producers of GOD, Inv, and ALP were Goffeauzyma gastrica, Wickerhamomyces anomalus, and Dioszegia sp., respectively, from which the enzymes were purified and characterized. Contrary to what was expected, the highest GOD and Inv activities were found at 64°C and 60°C, respectively, and at 47°C for ALP. However, the three enzymes maintained a significant percentage of activity at lower temperatures, especially ALP that kept a 67 and 43% of activity at 10°C and 4°C, respectively.