Production of tannase from a newly isolated yeast, Geotrichum cucujoidarum using agro-residues

With an aim of producing commercially important tannase enzyme using cheap and readily available agro-residues, leaves of Indian Gooseberry (Phyllanthus emblica) and Jamun (Syzygium cumini), peels of Lemon (Citrus limon), and Pomegranate (Punica granatum) were screened. Newly isolated Geotrichum cucujoidarum was utilized for the study. Preliminary studies indicated that tannase titer obtained is not proportional to the tannin content of the agro-residues and solid state fermentation superior compared to submerged fermentation. Jamun mixed with lemon peel in equal proportion supplemented with minerals under solid-state fermentation gave a tannase titer of 15.46 U/g dry solids. Through successful implantation of Plackett-Burman design, yeast extract concentration, inoculum volume, and amount of substrate were found to be the most significant factors. Further optimization of these three factors through Response Surface Methodology resulted in the 1.7-fold increase in tannase titer. Validation experiments using 3.97 g of Jamun leaves + lemon peel powder mixed with a nutrient solution having (w/v) yeast extract - 1.1%, dextrose - 3%, Urea - 1.125%, potassium chloride - 0.1%, magnesium sulfate heptahydrate - 0.1% with the initial pH of 5, inoculated with 2.48 ml of inoculum gave a tannase titer of 26.43 U/g dry solids after 6 days of solid-state fermentation.

Reconnoitring the antioxidant and antibacterial potential of different fruits after tannin acyl hydrolase mediated biotransformation

Condensed and hydrolyzable tannins are secondary metabolites present in almost every plant part. Tannase enzyme acts on hydrolyzable tannins to produce gallic acid and tannase-mediated end-products with immense therapeutic potential. Seven different fruits with significant presence of hydrolyzable tannin content were selected to check for phenol, tannin, and hydrolyzable tannin contents. Prunus domestica had the maximum phenol content, that is, 85.4 ± 0.207, followed by Syzygium cumini, Fragaria ananassa, Rubus fruticosus, and Psidium guajava. Plum showed the maximum number of hydrolyzable tannins. Fruit extracts were subjected to tannase hydrolysis and their antimicrobial and antioxidant activities were determined. There was a significant increase in the antioxidant abilities of the fruits with Punica granatum extract, displaying the highest decline of 132 units of IC50 followed by F. ananassa hydrolyzable extract, showing a decrease from 224.75 to 119.98 μg/mL. The extracts also depicted a significant increase in antibacterial activity after hydrolysis against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus with Rubus idaeus aqueous extract observed to be most effective against E. coli. The increase in antioxidant and antibacterial activity can be attributed to the production of tannase-mediated products formed after the biotransformation of hydrolyzable tannins present in the aqueous extracts.

Structural diversity and substrate preferences of three tannase enzymes encoded by the anaerobic bacterium Clostridium butyricum

Tannins are secondary metabolites that are enriched in the bark, roots, and knots in trees and are known to hinder microbial attack. The biological degradation of water-soluble gallotannins, such as tannic acid, is initiated by tannase enzymes (EC 3.1.1.20), which are esterases able to liberate gallic acid from aromatic-sugar complexes. However, only few tannases have previously been studied in detail. Here, for the first time, we biochemically and structurally characterize three tannases from a single organism, the anaerobic bacterium Clostridium butyricum, which inhabits both soil and gut environments. The enzymes were named CbTan1-3, and we show that each one exhibits a unique substrate preference on a range of galloyl ester model substrates; CbTan1 and 3 demonstrated preference toward galloyl esters linked to glucose, while CbTan2 was more promiscuous. All enzymes were also active on oak bark extractives. Furthermore, we solved the crystal structure of CbTan2 and produced homology models for CbTan1 and 3. In each structure, the catalytic triad and gallate-binding regions in the core domain were found in very similar positions in the active site compared with other bacterial tannases, suggesting a similar mechanism of action among these enzymes, though large inserts in each enzyme showcase overall structural diversity. In conclusion, the varied structural features and substrate specificities of the C. butyricum tannases indicate that they have different biological roles and could further be used in development of new valorization strategies for renewable plant biomass.

Immobilization of the Tannase From Aspergillus fumigatus CAS21: Screening the Best Derivative for the Treatment of Tannery Effluent Using a Packed Bed Reactor

Enzyme immobilization is an important alternative to stabilize enzyme properties favoring the efficiency of derivatives (enzyme + support/matrix) for different purposes. According to this, the current study aimed to immobilize the Aspergillus fumigatus CAS21 tannase and the use of the derivatives in the treatment of the effluent produced by the tannery industry. The tannase was immobilized on sodium alginate, DEAE-Sephadex, amberlite, and glass pearls as supports. Calcium alginate was the most adequate support for tannase immobilization with 100% yield and 94.3% for both efficiency and activity. The best tannase activity for the calcium alginate derivative was obtained at 50°C–60°C and pH 5.0. Thermal and pH stabilities evaluated for 24 h at 30°C–60°C and pH 4–7, respectively, were improved if compared to the stability of the free enzyme. Considering the reuse of the calcium alginate derivative, 78% of the initial activity was preserved after 10 catalytic cycles, and after the 9-month storage at 4°C, the activity was maintained in 70%. This derivative was applied in a packed bed reactor (PBR) for the treatment of tannin-rich effluents from the tannery industry. The reduction of the tannin content was effective reaching degradation of 74–78% after 48 h of PBR operation. The concentration of total phenolic compounds was also reduced, and the color and clarity of the effluent improved. In conclusion, the calcium alginate derivative is an attractive alternative as biocatalyst for large-scale treatment of the effluents from the tannery industry.

Extracellular Tannase from Aspergillus ochraceus: Influence of the Culture Conditions on Biofilm Formation, Enzyme Production, and Application

Aspergillus ochraceus biofilm, developed on an inert support, can produce tannase in Khanna medium containing 1.5% (w/v) tannic acid as the carbon source, at an initial pH of 5.0, for 72 h at 28 °C. Addition of 0.1% yeast extract increased enzyme production. The enzyme in the crude filtrate exhibited the highest activity at 30 °C and pH 6.0. At 50 °C, the half-life was 60 min and 260 min at pH 6.0. In general, addition of detergents and surfactants did not affect tannase activity significantly. Tannase has potential applications in various biotechnological processes such as the production of propyl gallate and in the treatment of tannin-rich effluents. The content of tannins and total phenolic compounds in effluents from leather treatment was reduced by 56-83% and 47-64%, respectively, after 2 h of enzyme treatment. The content of tannins and total phenolic compounds in the sorghum flour treated for 120 h with tannase were reduced by 61% and 17%, respectively. Interestingly, the same A. ochraceus biofilm was able to produce tannase for three sequential fermentative process. In conclusion, fungal biofilm is an interesting alternative to produce high levels of tannase with biotechnological potential to be applied in different industrial sectors.

Application of aqueous biphasic systems as strategy to purify tannase from Aspergillus tamarii URM 7115

The aims of the current study are to assess the influence of polyethylene glycol (PEG) concentration, molar mass, pH, and citrate concentrations on aqueous biphasic systems based on 2⁴ factorial designs, as well as to check their capacity to purify tannase secreted by Aspergillus tamarii URM 7115. Tannase was produced through submerged fermentation at 26°C for 67 h in Czapeck-Dox modified broth and added with yeast extract and tannic acid. The factorial design was followed to assess the influence of PEG molar mass (M_PEG 600; 4,000 and 8,000 g/ mol), and PEG (C_PEG 20.0; 22.0 and 24.0% w/w) and citrate concentrations (C_CIT 15.0, 17.5, and 20.0%, w/w), as well as of pH (6.0, 7.0, and 8.0) on the response variables; moreover, partition coefficient (K), yield (Y), and purification factor (PF) were analyzed. The most suitable parameters to purify tannase secreted by A. tamarii URM 7115 through a biphasic system were 600 (g/mol) M_PEG, 24% (w/w) C_PEG, 15% (w/w) C_CIT at pH 6.0 and they resulted in 6.33 enzyme partition, 131.25% yield, 19.80 purification factor and 195.08 selectivity. Tannase secreted by A. tamarii URM 7115 purified through aqueous biphasic systems composed of PEG/citrate can be used for industrial purposes, since it presents suitable purification factor and yield.

Kinetic and thermodynamic parameters, and partial characterization of the crude extract of tannase produced by Saccharomyces cerevisiae CCMB 520

Tannase can be used in different industrial sectors such as in food (juices and wine) and pharmaceutical production (trimethoprim) because it catalyses the hydrolysis of hydrolysable tannins. The aim of the current study is to assess the tannase found in the crude extract of Saccharomyces cerevisiae CCMB 520, and to set its catalytic and thermodynamic properties. The enzyme was optimally active at pH 6.0 and temperature 30 °C. Tannase was activated by Na⁺, Ca²⁺, K⁺ at 5 × 10^-3 mol/L. The half-life at 30 °C was 3465.7 min. The activation energy was 40.32 kJ/mol. The Gibbs free energy, enthalpy and entropy at 30 °C were 85.40, 48.10 and -0.12 kJ/mol K, respectively. Our results suggest that the tannase found in the crude extract of S. cerevisiae is an attractive enzyme for industrial applications, such as for beverage manufacturing and gallic acid production, due its catalytic and thermodynamic properties (heat-stable and resistant to metal ions).