Purification, immobilization and characterization of tannase from Penicillium variable

Bioremoval of tannins and heavy metals using immobilized tannase and biomass of Aspergillus glaucus

BACKGROUND

The presence of inorganic pollutants and heavy metals in industrial effluents has become a serious threat and environmental issues. Fungi have a remarkable ability to exclude heavy metals from wastewater through biosorption in eco-friendly way. Tannase plays an important role in bioconversion of tannin, a major constituent of tannery effluent, to gallic acid which has great pharmaceutical applications. Therefore, the aim of the current study was to exploit the potential of tannase from Aspergillus glaucus and fungal biomass waste for the bioremediation of heavy metals and tannin.

RESULTS

Tannase from A. glaucus was partially purified 4.8-fold by ammonium sulfate precipitation (80%). The enzyme was optimally active at pH 5.0 and 40 °C and stable at this temperature for 1 h. Tannase showed high stability at different physiological conditions, displayed about 50% of its activity at 60 °C and pH range 5.0-6.0. Immobilization of tannase was carried out using methods such. as entrapment in Na-alginate and covalent binding to chitosan. The effects of Na-alginate concentrations on the beads formation and enzyme immobilization revealed that maximum immobilization efficiency (75%) was obtained with 3% Na-alginate. A potential reusability of the immobilized enzyme was showed through keeping 70% of its relative activity up to the fourth cycle. The best bioconversion efficiency of tannic acid to gallic acid by immobilized tannase was at 40 °C with tannic acid concentration up to 50 g/l. Moreover, bioremediation of heavy metal (Cr3+, Pb2+, Cu2+, Fe3+, and Mn2+) from aqueous solution using A. glaucus biomass waste was achieved with uptake percentage of (37.20, 60.30, 55.27, 79.03 and 21.13 respectively). The biomass was successfully used repeatedly for removing Cr3+ after using desorbing agent (0.1 N HCl) for three cycles.

CONCLUSION

These results shed the light on the potential use of tannase from locally isolated A. glaucus in the bioremediation of industrial tanneries contained heavy metals and tannin.

Purification and characterization of extracellular tannase from Aspergillus fumigatus MA using Syzigium cumini leaves under solid state fermentation

This study reports the tannase purification produced by a tannery effluent-originated fungal isolate i.e., Aspergillus fumigatus MA under solid state fermentation (SSF) condition. Purification of tannase from culture filtrate was attained using ammonium sulfate precipitation with subsequent diethylaminoethyl (DEAE)-cellulose mediated ion exchange chromatographic technique. Fractional precipitation of the culture filtrate with 60-80% ammonium sulfate yielded 80.9% recovery of tannase with 6.16-fold purification. The enzyme fractions were collected and eluted as a single peak using 0.5 M NaCl-gradient concentration. DEAE-cellulose column chromatography results in overall 23-fold purification with 27.6% recovery of the enzyme. SDS-PAGE analysis of purified tannase confirmed the presence of a single band of protein with a molecular mass equivalent to 66.2 kDa. The highest activity of tannase was observed at optimum pH ranged between 5.0-6.0 whereas, the tannase stability (>80%) was observed at 4.0 to 7.0 pH ranges. The purified tannase activity was found to be optimally active at 30 °C whereas stability (>90%) was accomplished between 30-50 °C temperature. The Km and Vmax were found to be 1.61 × 10-3 M and 1.04 mM respectively. These properties suggest the potential of the enzyme to be utilized in various food, feed, and pharmaceutical sectors.

Optimization of tannase production by Aspergillus glaucus in solid-state fermentation of black tea waste

Tannases are valuable industrial enzymes used in food, pharmaceutical, cosmetic, leather manufacture and in environmental biotechnology. In this study, 15 fungal isolates were obtained from Egyptian cultivated soil and marine samples. The isolated fungi were qualitatively and quantitatively screened for their abilities to produce tannase. The selected fungal isolate NRC8 giving highest tannase activity was identified by molecular technique (18S rRNA) as Aspergillus glaucus. Among different tannin-containing wastes tested, the black tea waste was the best substrate for tannase production by Aspergillus glaucus in solid-state fermentation (SSF). Optimization of the different process parameters required for maximum enzyme production was carried out to design a suitable SSF process. Maximal tannase production was achieved with moisture content of 75%, an inoculums size of 6 × 108 spore/ml and sodium nitrate 0.2% (pH of 5.0) at 30 °C after 5 days of incubation. Box-Behnken experiment was designed to get a quadratic model for further optimization studies. Four-factor response-surface method with 27 runs was prepared using independent parameters including (moisture content %, initial pH, substrate concentration (g) and sodium nitrate concentration (g) for tannase model. The F- and P-values of the model were 4.30 and 0.002, respectively, which implied that the model is significant. In addition, the lack-of-fit was 1040.37 which indicates the same significance relative to the pure error. A. glaucus tannase was evaluated by the efficiency of conversion of tannic acid to gallic acid. Moreover, production of gallic acid from SSF process of A. glaucus using black tea waste was found to be 38.27 mg/ml. The best bioconversion efficiency was achieved at 40 °C with tannic acid concentration up to 200 g/L.

Characterization and Secretory Expression of a Thermostable Tannase from Aureobasidium melanogenum T9: Potential Candidate for Food and Agricultural Industries

Being a key industrial enzyme, tannase is extensively applied in various fields. Despite the characterizations of a large number of tannases, there are hardly a few tannases with exceptional thermostability. In this detailed study, a tannase-encoding gene named tanA was identified from Aureobasidium melanogenum T9 and heterologously expressed in Yarrowia lipolytica host of food grade. The purified tannase TanA with a molecular weight of above 63.0 kDa displayed a specific activity of 941.4 U/mg. Moreover, TanA showed optimum activity at 60°C and pH 6.0. Interestingly, TanA exhibited up to 61.3% activity after incubation for 12 h at 55°C, signifying its thermophilic property and distinguished thermostability. Additionally, TanA was a multifunctional tannase with high specific activities to catalyze the degradation of various gallic acid esters. Therefore, this study presents a novel tannase, TanA, with remarkable properties, posing as a potential candidate for food and agricultural processing.

Heterologous expression and biophysical characterization of a mesophilic tannase following manganese nanoparticle immobilization

In the current study, we analyzed the efficacy of manganese oxide nanoparticle (MnNP)-water dispersion as an immobilization matrix for bacterial tannase. The tannase-secreting Bacillus subtilis strain NJKL.tan.2 obtained from tannery effluent soil was subsequently purified and cloned in pET20b vector. The activity of MnNP-tan (tannase activated by manganese nanoparticles) was 1.51- and 3.5-fold higher at 20 °C and 80 °C, respectively, compared with the free enzyme. MnNP-tan decreased K_m by 41.66 % and 3-fold, whereas free tannase showed two-fold and six-fold improvement in K_cat at 37 °C and 80 °C, respectively. MnNP-tan showed an increase in (half-life)t_1/2and E_d by 13-fold and 50.05 units, respectively, at 80 °C, in contrast to the native enzyme. MnNP-tan retained its residual activity by 78.2 % at 37 °C and 34.24 % at 80 °C after 180 min of incubation when compared with untreated set. MnNP-tan retained 51 % of its activity after 120 days with the native enzyme losing ∼50 % functionality following 40 days of incubation. The MnNP-mediated tannase immobilization technique is being reported for the first time. The technique has numerous advantages due to the use of MnNP as a potential matrix for biomolecule immobilization, which can be further extended to immobilize other biocatalysts used in agro-industrial and lab-based applications.

Synthesis of a precursor of D-fagomine by immobilized fructose-6-phosphate aldolase

Fructose-6-phosphate aldolase (FSA) is an important enzyme for the C-C bond-forming reactions in organic synthesis. The present work is focused on the synthesis of a precursor of D-fagomine catalyzed by a mutant FSA. The biocatalyst has been immobilized onto several supports: magnetic nanoparticle clusters (mNC), cobalt-chelated agarose (Co-IDA), amino-functionalized agarose (MANA-agarose) and glyoxal-agarose, obtaining a 29.0%, 93.8%, 89.7% and 53.9% of retained activity, respectively. Glyoxal-agarose FSA derivative stood up as the best option for the synthesis of the precursor of D-fagomine due to the high reaction rate, conversion, yield and operational stability achieved. FSA immobilized in glyoxal-agarose could be reused up to 6 reaction cycles reaching a 4-fold improvement in biocatalyst yield compared to the non-immobilized enzyme.

Characterization of Aspergillus fumigatus CAS-21 tannase with potential for propyl gallate synthesis and treatment of tannery effluent from leather industry

One of the tannase isoforms produced by the fungus Aspergillus fumigatus CAS-21 under submerged fermentation (SbmF) was purified 4.9-fold with a 10.2% recovery. The glycoprotein (39.1% carbohydrate content) showed an estimated molecular mass of 60 kDa. Optimum temperature and pH for its activity were 30-40 °C and 5.0, respectively. It showed a half-life (t50) of 60 min at 45 and 50 °C, and it was stable at pH 5.0 and 6.0 for 3 h. The tannase activity was insensitive to most salts used, but it reduced in the presence of Fe2(SO4)3 and FeCl3. On contrary, in presence of SDS, Triton-X100, and urea the enzyme activity increased. The Km value indicated high affinity for propyl gallate (3.61 mmol L-1) when compared with tannic acid (6.38 mmol L-1) and methyl gallate (6.28 mmol L-1), but the best Kcat (362.24 s-1) and Kcat/Km (56.78 s-1 mmol-1 L) were obtained for tannic acid. The purified tannase reduced 89 and 25% of tannin content of the leather tannery effluent generated by manual and mechanical processing, respectively, after 2-h treatment. The total phenolic content was also reduced. Additionally, the enzyme produced propyl gallate, indicating its ability to do the transesterification reaction. Thus, A. fumigatus CAS-21 tannase presents interesting properties, especially the ability to degrade tannery effluent, highlighting its potential in biotechnological applications.

Purification and characterization of a novel tannase produced by Kluyveromyces marxianus using olive pomace as solid support, and its promising role in gallic acid production

Tannase is considered one of the most important industrial enzymes that find great applications in various sectors. Production of tannases through solid state fermentation (SSF) using agro-industrial wastes is an eco-friendly and cheap technology. Tannase was produced by the yeast Kluyveromyces marxianus using olive pomace as a solid support under SSF. It was purified using ammonium sulfate fractional precipitation followed by Sephadex G-200 gel filtration resulting in 64.6% enzyme yield with 1026.12U/mg specific activity and 24.21 purification fold. Pure tannase had molecular weight of 65 KDa and 66.62 KDa by SDS-PAGE and gel filtration, respectively. It showed a maximal activity at 35°C having two different pH optima, one of which is acidic (4.5) and the other one is alkaline (8.5). The enzyme was stable in the acidic range of pH (4.0-5.5) for 30min, and thermostable within the temperature range 30-70°C. Using tannic acid, the enzyme had a Km value of 0.77mM and Vmax of 263.20μmolemin^-1ml^-1. The effect of different metal ions on enzymatic activity was evaluated. HPLC analysis data indicated that the purified enzyme could carry out 24.65% tannic acid conversion with 5.25 folds increase in gallic acid concentration within 30min only.

Structural characterization, catalytic, kinetic and thermodynamic properties of Aspergillus oryzae tannase

Tannase (EC.3.1.1.20) from Aspergillus oryzae was purified using ammonium sulphate precipitation (75%), gel filtration chromatography through Sephadex G-100, and G-200. The purified enzyme was monomeric protein with a molecular mass of 106kDa. The activation energy for tannic acid hydrolysis was 32.6kJmol^-1 and its temperature quotient (Q₁₀) was 1.0. The pK_a1 and pK_a2 values of acidic and basic limbs of the active site residues were 4.6 and 6.4. The calculated values of thermodynamic parameters for tannic acid hydrolysis, were as follows: ΔH*=30.02kJmol^-1, ΔG*=59.75kJmol^-1 ΔS*=-95.90Jmol^-1K^-1, (ΔG*_E-S)=3.66kJmol^-1 and ΔG*_E-T -12.61kJmol^-1. The pure enzyme exhibited K_m, V_max and k_cat of 4.13mM, 3507Umgprotein^-1 and 551.4s^-1_. The calculated half-life time at 40, 45, 50, 55, 60, and 70°C was 955.15, 142.0, 30.28, 17.88, 8.23 and 2.95min, respectively. The thermodynamic parameters for irreversible thermal inactivation at different temperatures (40-70°C) were determined. The enzyme was activated by Ca²⁺, and Mg²⁺ while Hg²⁺, Fe²⁺, and Cu²⁺ strongly inhibited it. Hydrolysis of tannic acid by the pure enzyme indicated that gallic acid was the end-product.

Preparation and characterization of tannase immobilized onto carboxyl-functionalized superparamagnetic ferroferric oxide nanoparticles

Tannase from Aspergillus tubingensis was immobilized onto carboxyl-functionalized Fe3O4 nanoparticles (CMNPs), and conditions affecting tannase immobilization were investigated. Successful binding between CMNPs and tannase was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Vibrating sample magnetometry and X-ray diffraction showed that the CMNPs and immobilized tannase exhibit distinct magnetic responses and superparamagnetic properties. Free and immobilized tannase exhibited identical optimal temperatures of 50°C and differing pH optima at 6 and 7, respectively. The thermal, pH, and storage stabilities of the immobilized tannase were superior to those of free tannase. After six cycles of catalytic hydrolysis of propyl gallate, the immobilized tannase maintained over 60% of its initial activity. The Michaelis constant (Km) of the immobilized enzyme indicated its higher affinity for substrate binding than the free enzyme.

Novel trends for use of microbial tannases

Tannases, mainly produced by microorganisms, are able to hydrolyze gallotannins, ellagitannins, complex tannins, and gallic acid esters into gallic acid, ellagic acid, glucose, or alcohols, and also synthesize gallic acid esters using tannic acid or gallic acid with a variety of alcohols in nonaqueous media. Microbial tannases have been widely applied especially in beverage processing, pharmaceutics, and brewing. However, many factors, especially high production costs, severely limit the use of microbial tannases at the industrial level. In this minireview, we aim to provide an overview of the advances in applications of microbial tannases during the last 15 years, mainly including the following respects: hydrolysis of tea cream, modification of green tea catechins, production of gallic acid, debittering of fruit juices, degradation of tannery effluents, and synthesis of propyl gallate, trying to know the trends and prospects for the future in applications of microbial tannases.

Biomedical potential of natural products derived through metagenomic approaches

Microbes are ubiquitous, irrespective of the environment they thrive in. Only 1% of these are culturable in laboratory. Metagenomics is useful in exploring biomedically important small molecules using culture independent approaches.

Production, characterization of tannase from Penicillium montanense URM 6286 under SSF using agroindustrial wastes, and application in the clarification of grape juice (Vitis vinifera L.)

Tannase is an enzyme that hydrolyzes esters and lateral bonds of tannins, such as tannic acid, releasing glucose and gallic acid and stands out in the clarification of wines and juices. Fungi of the genera Aspergillus and Penicillium are excellent producers of this enzyme. The search for fungi that produce high levels of tannase as well as new substrates for the enzyme production by the SSF is required. The objectives of this study were to evaluate the production of tannase by Aspergillus and Penicillium species through SSF using leaves and agroindustrial waste barbados cherry and mangaba fruit as substrate, select the best producer, optimize production, characterize the crude enzyme extract, and apply it the clarification of grape juice. Selecting the best producer was performed by planning Placket-Burman and RSM. P. montanense showed highest activity with 41.64 U/mL after 72 h of fermentation residue using barbados cherry, with 3.5% tannic acid and 70% moisture. The enzyme showed the highest activity at pH 9.0 and 50°C. The tannase of P. montanense was stable over a wide pH range and temperature and, when applied to grape juice, showed higher efficiency by reducing 46% of the tannin content after incubation 120 m.

Some factors affecting tannase production by Aspergillus niger Van Tieghem

One variable at a time procedure was used to evaluate the effect of qualitative variables on the production of tannase from Aspergillus niger Van Tieghem. These variables including: fermentation technique, agitation condition, tannins source, adding carbohydrates incorporation with tannic acid, nitrogen source type and divalent cations. Submerged fermentation under intermittent shaking gave the highest total tannase activity. Maximum extracellular tannase activity (305 units/50 mL) was attained in medium containing tannic acid as tannins source and sodium nitrate as nitrogen source at 30 °C for 96 h. All added carbohydrates showed significant adverse effects on the production of tannase. All tested divalent cations significantly decreased tannase production. Moreover, split plot design was carried out to study the effect of fermentation temperature and fermentation time on tannase production. The results indicated maximum tannase production (312.7 units/50 mL) at 35 °C for 96 h. In other words, increasing fermentation temperature from 30 °C to 35 °C resulted in increasing tannase production.

Interaction of tannase from Aspergillus niger with polycations applied to its primary recovery

The interaction of tannase (TAH) with chitosan, polyethyleneimine and Eudragit(®)E100 was studied. It was found that TAH selectively binds to these polycations (PC), probably due to the acid nature of the target protein. TAH could interact with these PC depending on the medium conditions. The effect of the interaction on the secondary and tertiary structure of TAH was assayed through circular dichroism and fluorescence spectroscopy. TAH was recovered from Aspergillus niger culture broth by means of precipitation and adsorption using chitosan.

Novel strategies for upstream and downstream processing of tannin acyl hydrolase

Tannin acyl hydrolase also referred as tannase is an enzyme with important applications in several science and technology fields. Due to its hydrolytic and synthetic properties, tannase could be used to reduce the negative effects of tannins in beverages, food, feed, and tannery effluents, for the production of gallic acid from tannin-rich materials, the elucidation of tannin structure, and the synthesis of gallic acid esters in nonaqueous media. However, industrial applications of tannase are still very limited due to its high production cost. Thus, there is a growing interest in the production, recovery, and purification of this enzyme. Recently, there have been published a number of papers on the improvement of upstream and downstream processing of the enzyme. These papers dealt with the search for new tannase producing microorganisms, the application of novel fermentation systems, optimization of culture conditions, the production of the enzyme by recombinant microorganism, and the design of efficient protocols for tannase recovery and purification. The present work reviews the state of the art of basic and biotechnological aspects of tannin acyl hydrolase, focusing on the recent advances in the upstream and downstream processing of the enzyme.

Catalytical Properties of Free and Immobilized Aspergillus niger Tannase

A fungal tannase was produced, recovered, and immobilized by entrapment in calcium alginate beads. Catalytical properties of the immobilized enzyme were compared with those of the free one. Tannase was produced intracellularly by the xerophilic fungus Aspergillus niger GH1 in a submerged fermentation system. Enzyme was recovered by cell disruption and the crude extract was partially purified. The catalytical properties of free and immobilized tannase were evaluated using tannic acid and methyl gallate as substrates. K_M and V_max values for free enzyme were very similar for both substrates. But, after immobilization, K_M and V_max values increased drastically using tannic acid as substrate. These results indicated that immobilized tannase is a better biocatalyst than free enzyme for applications on liquid systems with high tannin content, such as bioremediation of tannery or olive-mill wastewater.

Catalytic and thermodynamic properties of a tannase produced by Aspergillus niger GH1 grown on polyurethane foam

Tannase is an inducible enzyme with important applications in the food and pharmaceutical industries. This enzyme was produced by the fungus Aspergillus niger GH1 under solid-state fermentation using polyurethane foam as solid support and tannic acid as sole carbon source and tannase inducer. Physicochemical properties of A. niger tannase were characterized, and the kinetic and thermodynamics parameters on methyl gallate hydrolysis were evaluated. The enzyme was stable in a pH range of 2-8 and a functional temperature range of 25-65 °C. The highest k(cat) value was 2,611.10 s(-1) at 65 °C. Tannase had more affinity for methyl gallate at 45 °C with a K(M) value of 1.82 mM and an efficiency of hydrolysis (k(cat)/K(M)) of 330.01 s(-1) mM(-1). The lowest E(a) value was found to be 21.38 kJ/mol at 4.4 mM of methyl gallate. The lowest free energy of Gibbs (ΔG) and enthalpy (ΔH) were found to be 64.86 and 18.56 kJ/mol, respectively. Entropy (ΔS) was -0.22 kJ/mol K. Results suggest that the A. niger GH1 tannase is an attractive enzyme for industrial applications due its catalytic and thermodynamical properties.

Isolation and characterization of a novel tannase from a metagenomic library

A novel gene (designated as tan410) encoding tannase was isolated from a cotton field metagenomic library by functional screening. Sequence analysis revealed that tan410 encoded a protein of 521 amino acids. SDS-PAGE and gel filtration chromatography analysis of purified tannase suggested that Tan410 was a monomeric enzyme with a molecular mass of 55 kDa. The optimum temperature and pH of Tan410 were 30 °C and 6.4. The activity was enhanced by addition of Ca(2+), Mg(2+) and Cd(2+). In addition, Tan410 was stable in the presence of 4 M NaCl. Chlorogenic acid, rosmarinic acid, ethyl ferulate, tannic acid, epicatechin gallate and epigallocathchin gallate were efficiently hydrolyzed by recombinant tannase. All of these excellent properties make Tan410 an interesting enzyme for biotechnological application.

Purification and characterization of a novel NADH-dependent carbonyl reductase from Pichia stipitis involved in biosynthesis of optically pure ethyl (S)-4-chloro-3-hydroxybutanoate

A novel NADH-dependent dehydrogenases/reductases (SDRs) superfamily reductase (PsCRII) was isolated from Pichia stipitis. It produced ethyl (S)-4-chloro-3-hydroxybutanoate [(S)-CHBE] in greater than 99% enantiomeric excess. This enzyme was purified to homogeneity by ammonium sulfate precipitation followed by Q-Sepharose chromatography. Compared to similar known reductases producing (S)-CHBE, PsCR II was more suitable for production since the purified PsCRII preferred the inexpensive cofactor NADH to NADPH as the electron donor. Furthermore, the Km of PsCRII for ethyl 4-chloro-3-oxobutanoate (COBE) was 3.3 mM, and the corresponding Vmax was 224 μmol/mg protein/min. The catalytic efficiency is the highest value ever reported for NADH-dependent reductases from yeasts that produce CHBE with high enantioselectivity. In addition, this enzyme exhibited broad substrate specificity for several β-keto esters using NADH as the coenzyme. The properties of PsCRII with those of other carbonyl reductases from yeasts were also compared in this study.