Production of catalase and glucose oxidase by Aspergillus niger using unconventional oxygenation of culture

Catalase from the Antarctic Fungus Aspergillus fumigatus I-9-Biosynthesis and Gene Characterization

Extremely cold habitats are a serious challenge for the existing there organisms. Inhabitants of these conditions are mostly microorganisms and lower mycetae. The mechanisms of microbial adaptation to extreme conditions are still unclear. Low temperatures cause significant physiological and biochemical changes in cells. Recently, there has been increasing interest in the relationship between low-temperature exposure and oxidative stress events, as well as the importance of antioxidant enzymes for survival in such conditions. The catalase is involved in the first line of the cells' antioxidant defense. Published information supports the concept of a key role for catalase in antioxidant defense against cold stress in a wide range of organisms isolated from the Antarctic. Data on representatives of microscopic fungi, however, are rarely found. There is scarce information on the characterization of catalase synthesized by adapted to cold stress organisms. Overall, this study aimed to observe the role of catalase in the survival strategy of filamentous fungi in extremely cold habitats and to identify the gene encoded catalase enzyme. Our results clearly showed that catalase is the main part of antioxidant enzyme defense in fungal cells against oxidative stress caused by low temperature exposure.

Enhanced In Vitro Cascade Catalysis of Glycerol into Pyruvate and Acetoin by Integration with Dihydroxy Acid Dehydratase from Paralcaligenes ureilyticus

Recently, an in vitro enzymatic cascade was constructed to transform glycerol into the high-value platform chemical pyruvate. However, the low activity of dihydroxy acid dehydratase from Sulfolobus solfataricus (SsDHAD) limited the efficiency. In this study, the enzymatic reduction of pyruvate catalyzed by d-lactate dehydrogenase from Pseudomonas aeruginosa PAO1 was used to assay the activities of dihydroxy acid dehydratases. Dihydroxy acid dehydratase from Paralcaligenes ureilyticus (PuDHT) was identified as the most efficient candidate for glycerate dehydration. After the optimization of the catalytic temperature for the enzymatic cascade, comprising alditol oxidase from Streptomyces coelicolor A3, PuDHT, and catalase from Aspergillus niger, 20.50 ± 0.27 mM of glycerol was consumed in 4 h to produce 18.95 ± 0.97 mM of pyruvate with a productivity 12.15-fold higher than the previous report using SsDHAD. The enzymatic cascade was further coupled with the pyruvate decarboxylase from Zymomonas mobile for the production of another platform compound, acetoin. Acetoin at a concentration of 8.52 ± 0.12 mM was produced from 21.62 ± 0.19 mM of glycerol with a productivity of 1.42 ± 0.02 mM h−1.

Cold-active catalase from the psychrotolerant fungus Penicillium griseofulvum

Cold-active catalase (CAT) elicits great interest because of its vast prospective at the medical, commercial, and biotechnological levels. The study paper reports the production of cold-active CAT by the strain Penicillium griseofulvum P29 isolated from Antarctic soil. Improved enzyme production was achieved by optimization of medium and culture conditions. Maximum CAT was demonstrated under low glucose content (2%), 10% inoculum size, temperature 20°C, and dissolved oxygen concentration (DO) 40%. An effective laboratory technology based on changing the oxidative stress level through an increase of DO in the bioreactor was developed. The used strategy resulted in a 1.7- and 1.4-fold enhanced total enzyme activity and maximum enzyme productivity. The enzyme was purified and characterized. P. griseofulvum P29 CAT was most active at approximately 20°C and pH 6.0. Its thermostability was in the range between 5°C and 40°C.

Effects of dietary glucose oxidase, catalase, or both supplementation on reproductive performance, oxidative stress, fecal microflora and apoptosis in multiparous sows

Objective

The objective of this experiment was to investigate the effect of dietary glucose oxidase (GOD), catalase (CAT), or both supplementation on reproductive performance, oxidative stress, and apoptosis in sows.

Methods

A total of 104 multiparous sows were randomly assigned to four groups (n = 26) with each group given a basal diet, basal diet plus GOD at 60 U/kg, basal diet plus CAT at 75 U/kg, and basal diet plus GOD at 60 U/kg and CAT at 75 U/kg. Sows were fed the experimental diets throughout gestation and lactation.

Results

Dietary GOD supplementation increased average daily feed intake of sows and litter weight at weaning (p<0.05). Dietary CAT supplementation reduced the duration of parturition, stillbirth, and piglet mortality and increased growth performance of weaned piglets (p<0.05). Dietary GOD and CAT supplementation enhanced antioxidant enzyme activities and lessened oxidative stress product levels in plasma of sows and elevated antioxidant capacity of 14-day milk and plasma in weaned piglets (p<0.05). Dietary GOD supplementation increased fecal Lactobacillus counts and reduced Escherichia coli counts of sows (p<0.05). Compared with the basal diet, the GOD diet reduced fecal Escherichia coli counts of sows, but the addition of CAT did not reduce Escherichia coli counts in the GOD diet. Dietary GOD and CAT supplementation reduced the apoptosis rate of the liver, endometrium, and ovarian granulosa cells in sows (p<0.05). In the liver, uterus, and ovary of sows, the mRNA expression of caspase-3 and caspase-9 was downregulated by dietary GOD and CAT supplementation (p<0.05).

Conclusion

Dietary GOD and CAT supplementation could improve the antioxidant capacity of sows and weaned piglets, and alleviate hepatic, ovarian and uterine apoptosis by weakening apoptosis-related gene expression. Glucose oxidase regulated fecal microflora of sows, but supplementation of CAT to GOD could weaken the inhibitory effect of GOD on fecal Escherichia coli.

Preparation of Pd–Ni Nanoparticles Supported on Activated Carbon for Efficient Removal of Basic Blue 3 from Water

Pd–Ni nanoparticles supported on activated carbon (Pd–Ni/AC) were prepared using a phase transfer method. The purpose of synthesizing ternary composites was to enhance the surface area of synthesized Pd–Ni nanoparticles, as they have a low surface area. The resulting composite was characterized by scanning electronic microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) for investigating its surface morphology, particle size, percentage of crystallinity and elemental composition, respectively. The XRD data and EDX analysis revealed the presence of Pd–Ni alloys impregnated on the AC. Pd–Ni/AC was used as an adsorbent for the removal of the azo dye basic blue 3 from an aqueous medium. Kinetic and isotherm models were used to calculate the adsorption parameters. The most suitable kinetic model amongst the applied models was the pseudo-second-order model, confirming the chemisorption characteristics of the process, and the most suitable isotherm model was the Langmuir model, with a maximum adsorption capacity of 333 mg/g at 333 K. Different experimental parameters, such as the adsorbent dosage, pH, temperature and contact time, were optimized. The optimum parameters reached were: a pH of 12, temperature of 333 K, adsorbent dosage of 0.01 g and optimum contact time of 30 min. Moreover, the thermodynamics parameters of adsorption, such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°), showed the adsorption processes being exothermic with values of ΔH° equal to −6.206 kJ/mol and being spontaneous with ΔG° values of −13.297, −13.780 and −14.264 kJ/mol, respectively at 293, 313 and 333 K. An increase in entropy change (ΔS°) with a value of 0.0242 kJ/mol K, indicated the enhanced disorder at a solid–solution interface during the adsorption process. Recycling the adsorbent for six cycles with sodium hydroxide and ethanol showed a decline in the efficiency of the selected azo dye basic blue 3 up to 79%. The prepared ternary composite was found effective in the removal of the selected dye. The removal of other pollutants represents one of the possible future uses of the prepared adsorbent, but further experiments are required.

A novel reactor combining anammox and Fenton-like reactions for the simultaneous removal of organic carbon and nitrogen at different organic carbon to nitrogen ratios

A Fenton-like reaction and anaerobic ammonium oxidation (anammox) were combined to construct a novel process named FenTaMox for removing nitrogen (N) and organic carbon (measured as chemical oxidation demand (COD)). Two columns were packed with iron-manganese-sepiolite, a catalyst that uses hydrogen peroxide (H₂O₂) to catalyze Fenton-like reactions, and inoculated with marine anammox bacteria. During the start-up, marine anammox medium was fed into both columns to acclimate the marine anammox bacteria to iron-manganese-sepiolite. Batch experiments revealed that the marine anammox bacteria were not affected by 60 mgL^-1 of H₂O₂. Next, medium containing glucose and H₂O₂ was fed into one column as the FenTaMox treatment, while medium containing glucose but no H₂O₂ was fed into the other column as the control. At a COD/N of 4, FenTaMox exhibited higher removal efficiencies of N and COD compared with that of the control, suggesting the application of FenTaMox for organic carbon- and N- removal.

A chemiluminescence-based catalase assay using H2O2-sensitive CdTe quantum dots

A method is described for the chemiluminescence based determination of the activity of catalase (CAT) using H₂O₂-sensitive CdTe quantum dots (QDs). It is based on the finding that the chemiluminescence (CL) of the CdTe/H₂O₂ system is reduced due to the consumption of H₂O₂ by the catalytic action of CAT. The Michaelis constant is calculated to be 519 ± 27 mM, showing the potential of the method to accurately measure the K_m compared to the standard method. The method does not require QDs to be conjugated to biological/organic molecules and therefore is considered to be a rapid and convenient method for determination of CAT in real samples. At an incubation time of 2 s, the LOD was calculated to be 4.5 unit/mL, with a linear range from 6 to 400 unit/mL. The assay is sensitive, simple, and suitable for practical applications. Graphical abstract Schematic representation of chemiluminescence-based catalase U(CAT) assay using the CdSe QD/H₂O₂ system. The reduction of H₂O₂ is reflected by the chemiluminescence of the QDs. A mechanism is put forward based on the changes in chemiluminescence intensity of the QDs by the consumption of H₂O₂ due to the catalytic action of CAT.

Self-cloning significantly enhances the production of catalase in Bacillus subtilis WSHDZ-01

The katA gene that encodes catalase (CAT) in Bacillus subtilis WSHDZ-01 was overexpressed in B. subtilis WB600 and B. subtilis WSHDZ-01. The CAT yield in both transformed strains was significantly improved compared to that in the wild-type WSHDZ-01 in shake flask culture. When cultured in a 3-L stirred tank reactor (STR), the recombinant CAT activity in B. subtilis WSHDZ-01 could be improved by 419 %, reaching up to 39,117 U/mL and was 8,149.4 U/mg dry cell weight, which is the highest activity reported in Bacillus sp. However, the recombinant CAT in B. subtilis WB600 cultured in a 3-L STR was not significantly improved by any of the common means for process optimization, and the highest CAT activity was 3,673.5 U/mg dry cell weight. The results suggest that self-cloning of the complete expression cassette in the original strain is a reasonable strategy to improve the yield of wild-type enzymes.

Glucose oxidase--an overview

Glucose oxidase (beta-D-glucose:oxygen 1-oxidoreductase; EC 1.1.2.3.4) catalyzes the oxidation of beta-D-glucose to gluconic acid, by utilizing molecular oxygen as an electron acceptor with simultaneous production of hydrogen peroxide. Microbial glucose oxidase is currently receiving much attention due to its wide applications in chemical, pharmaceutical, food, beverage, clinical chemistry, biotechnology and other industries. Novel applications of glucose oxidase in biosensors have increased the demand in recent years. Present review discusses the production, recovery, characterization, immobilization and applications of glucose oxidase. Production of glucose oxidase by fermentation is detailed, along with recombinant methods. Various purification techniques for higher recovery of glucose oxidase are described here. Issues of enzyme kinetics, stability studies and characterization are addressed. Immobilized preparations of glucose oxidase are also discussed. Applications of glucose oxidase in various industries and as analytical enzymes are having an increasing impact on bioprocessing.

Cell bound and extracellular glucose oxidases from Aspergillus niger BTL: evidence for a secondary glycosylation mechanism

Two glucose oxidase (GOX) isoforms where purified to electrophoretic homogeneity from the mycelium extract (GOXI) and the extracellular medium (GOXII) of Aspergillus niger BTL cultures. Both enzymes were found to be homodimers with nonreduced molecular masses of 148 and 159 kDa and pI values of 3.7 and 3.6 for GOXI and GOXII, respectively. The substrate specificity and the kinetic characteristics of the two GOX forms, as expressed through their apparent K m values on glucose, as well as pH and T activity optima, were almost identical. The only structural difference between the two enzymes was in their degrees of glycosylation, which were determined equal to 14.1 and 20.8% (w/w) of their molecular masses for GOXI and GOXII, respectively. The above difference in the carbohydrate content between the two enzymes seems to influence their pH and thermal stabilities. GOXII proved to be more stable than GOXI at pH values 2.5, 3.0, 8.0, and 9.0. Half-lives of GOXI at pH 3.0 and 8.0 were 8.9 and 17.5 h, respectively, whereas the corresponding values for GOXII were 13.5 and 28.1 h. As far as the thermal stability is concerned, GOXII was also more thermostable than GOXI as judged by the deactivation constants determined at various temperatures. More specifically, the half-lives of GOXI and GOXII, at 45 degrees C, were 12 and 49 h, respectively. These results suggest A. niger BTL probably possesses a secondary glycosylation mechanism that increases the stability of the excreted GOX.

Saeed M, Andaleeb F, I. Rajoka M, A. Sheikh M, A. Khan I, I. Khan A. Thermal Characterization of Purified Glucose Oxidase from A Newly Isolated Aspergillus Niger UAF-1

An intracellular glucose oxidase was isolated from the mycelium extract of a locally isolated strain of Aspergillus niger UAF-1. The enzyme was purified to a yield of 28.43% and specific activity of 135 U mg(-1) through ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The enzyme showed high affinity for D-glucose with a Km value of 2.56 mM. The enzyme exhibited optimum catalytic activity at pH 5.5. Temperature optimum for glucose oxidase, catalyzed D-glucose oxidation was 40 degrees C. The enzyme showed a high thermostability having a half-life 30 min, enthalpy of denaturation 99.66 kJ mol(-1) and free energy of denaturation 103.63 kJ mol(-1). These characteristics suggest the use of glucose oxidase from Aspergillus niger UAF-1 as an analytical reagent and in the design of biosensors for clinical, biochemical and diagnostic assays.

Involvement of Gluconic Acid and Glucose Oxidase in the Pathogenicity of Penicillium expansum in Apples

ABSTRACT The contribution of gluconic acid secretion to the colonization of apple tissue by Penicillium expansum was analyzed by modulation (increase or decrease) of gluconic acid accumulation at the infection court. P. expansum isolates that express the most gox2 transcripts and concomitant glucose oxidase (GOX) activity and that secrete the most gluconic acid cause disease of apple at the fastest rate. Cultures grown under reduced oxygen concentration generated fewer gox2 transcripts, produced less gluconic acid, and led to a 15% reduction in disease. Furthermore, the detection of significantly high levels of transcripts of gox2 and GOX activity at the edge of the decaying tissue emphasize the involvement of GOX in tissue acidification of the decaying tissue. Taken together, these results emphasize the importance of GOX in the production of the gluconic acid that leads, in turn, to host tissue acidification. This acidification enhanced the expression of pectolytic enzymes and the establishment of conditions for necrotrophic development of P. expansum.

Aspergillus hyphae in infected tissue: evidence of physiologic adaptation and effect on culture recovery

Microbiologic cultures of fungi are routinely incubated at ambient temperatures in room air, and the rate of recovery of Aspergillus species from clinical specimens is poor. Failure of current culture methods to mimic the physiologic temperature and low-oxygen environment found in hypha-laden infected tissue may underlie this poor recovery. Experiments were performed to compare the recovery of Aspergillus spp. incubated at 35 degrees C in 6% O(2)-10% CO(2) with that at 25 degrees C in room air. The samples tested included Aspergillus-infected tissue specimens from a dog model and human autopsies, experimental anaerobically stressed Aspergillus inocula, and 10,062 consecutive clinical specimens. Culture at 35 degrees C in 6% O(2)-10% CO(2) significantly enhanced the recovery of Aspergillus spp. from the infected autopsy tissue samples. Incubation at 35 degrees C alone resulted in approximately 10-fold-improved culture recovery from the experimentally stressed hyphae, and the 6% O(2)-10% CO(2) atmosphere independently favored growth under temperature-matched conditions. Finally, incubation at 35 degrees C (in room air) improved the overall recovery of Aspergillus spp. from clinical specimens by 31%. Culture at 35 degrees C in a microaerobic atmosphere significantly enhances the recovery of Aspergillus spp. from various sources. Aspergillus hyphae growing in infected tissue appear to be adapted to the physiologic temperature and hypoxic milieu.

Catalase activity in arctic microfungi grown at different temperatures

The total of 98 strains of moulds were isolated from soils collected in arctic tundra (Spitzbergen). Among these strains Penicillium cyclopium 1, the most effective for production of catalase, was selected by the method of test-tube microculture. The time course of growth and catalase production by this strain showed the intracellular activity of this enzyme to be about 3-fold higher than its extracellular level Some properties of crude catalase preparation, isolated from postculture liquids by lyophilization, were also examined. Catalase activity showed its maximum at 15 degrees C, indicating adaptation of the enzyme to lower temperatures of the arctic environment.