Microbial Production of Tannase: State of the Art

Optimization of production conditions, isolation, purification, and characterization of tannase from filamentous fungi

Tannase-producing filamentous fungi residing alongside tannin-rich ambient in the Northwest Himalayas were isolated at laboratory conditions and further identified by 18S ribosomal RNA gene sequencing. Five most potent tannase producing strains (EI ≥ 2.0), designated Aspergillus fumigatus AN1, Fusarium redolens AN2, Penicillium crustosum AN3, Penicillium restrictum AN4, and Penicillium commune AN5, were characterized. The strain Penicillium crustosum AN3 exhibited a maximum zone dia (25.66 mm ± 0.38). During solid-state fermentation, a maximal amount of tannase was attained with Penicillium crustosum AN3 using pine needles (substrate) by adopting response surface methodology for culture parameter optimization. Gel filtration chromatography yielded 46.48% of the partially purified enzyme with 3.94-fold of tannase purification. We found two subunits in enzyme-117.76 KDa and 88.51 KDa, respectively, in the SDS-PAGE. Furthermore, the characterization of partially purified tannase revealed a maximum enzyme activity of 8.36 U/mL at 30 °C using a substrate concentration (methyl gallate) of 10 mM. To broaden the knowledge of crude enzyme application, dye degradation studies were subjected to extracellular crude tannase from Penicillium crustosum AN3 where the maximum degradation achieved at a low enzyme concentration (5 ppm).

K. M, Preethi T.C., B. S. G. Tamarindus indica seed induced tannase production from Aspergillus niger

Introduction and Aim: Tannase an inducible extracellular microbial enzyme is extensively produced by different fermentation techniques and finds wide applications in food, pharmaceutical and textile industries. The present investigation focused on tannase production from Aspergillus niger through submerged (SmF) and solid-substrate fermentation (SSF) using different media. The enzyme was also induced using tamarind seeds.  Methods and Materials: Aspergillus niger was grown in various submerged media such as Tannase screening broth (TSB), Czapek Dox broth (CDB), Sabouraud’s Dextrose broth (SDB) and Potato Dextrose broth (PDB). Among solid substrates wheat bran, ground nut cake, coconut cake and tamarind seed powder used individually and in mixed form. Results: In SmF, the highest tannase activity of 713.6 U/ml was found in TSB, followed by CDB (590.6 U/ml), SDB (465.6 U/ml) and PDB (424.8 U/ml).  In all media highest activity was on 4th day while in SDB on 6th day of incubation. Tannase production was also carried out in CDB supplemented with 2% processed tamarind seeds to test for its induction, where the highest (936 U/ml) activity was in raw seeds than in processed seeds. SSF in mixed substrates showed highest activity of 1708.6 U/gds followed by 1278.0, 986.5, 826.3 and 723.6 U/gds in tamarind seeds, wheat bran, ground nut cake and coconut cake, respectively. Conclusion: Tannase enzyme is found to be induced by raw tamarind seed supplemented submerged medium than with processed seeds. In SSF with tamarind seed showed the highest tannase activity indicating that the tannic acid present in raw seeds serve to induce Aspergillus niger for increased production of tannase enzyme.

Kinetics and antimicrobial activity of gallic acid by novel bacterial co-culture system using Taguchi's method and submerged fermentation

A tannase-positive Bacillus gottheilii M2S2 and Bacillus cereus M1GT were co-cultivated for the production of gallic acid using tannic acid as the sole carbon source through submerged fermentation. Taguchi orthogonal array of design of experimental methodology was used to estimate the influence and significance of tannic acid concentration, glucose concentration, agitation speed, and inoculum size on the gallic acid production in a shake flask. Among all the factors, agitation speed contributed the highest for gallic acid production (28.28%), followed by glucose concentration (21.59%), inoculum size (19.6%), tannic acid concentration (19.54%), and pH (11.09%). Validation experiments were executed at the found optimized conditions which resulted in a 6.36-fold increase in gallic acid yield compared to unoptimized conditions. Further, the kinetics of growth, tannic acid degradation, and gallic acid yield were evaluated at the optimized conditions. The kinetic parameters Y _x/s, Y _p/s, and Y _p/x were determined as 0.292 mg of cells/mg of tannic acid, 22.2 µg of gallic acid/mg of tannic acid, and 70.76 µg of gallic acid/mg of cells with a growth rate of 0.273 h ⁻¹ after 24 h of fermentation. Finally, the antimicrobial activity of the product gallic acid was investigated against food-borne pathogenic E. coli, S. aureus, and Serriatia marcescens and showed a zone of inhibition of 2 cm, 1.6 cm, and 1.3 cm, respectively, using the agar disc diffusion technique. Thus, the cost-effective bioproduct gallic acid proved to be potentially effective to control food poisoning diseases and preserve foodstuff.

Profiling of contemporary beer styles using liquid chromatography quadrupole time-of-flight mass spectrometry, multivariate analysis, and machine learning techniques

Although all beer is brewed using the same four classes of ingredients, contemporary beer styles show wide variation in flavor and color, suggesting differences in their chemical profiles. A selection of 32 beers covering five styles (India pale ale, blonde, stout, wheat, and sour) were investigated to determine chemical features, which discriminate between popular beer styles. The beers were analyzed in an untargeted fashion using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). The separation and detection method were tuned to include compounds from important beer components, namely iso-α-acids and phenolic compounds. Due to the sheer number of unknown compounds in beer, multivariate analysis and machine learning techniques were used to pinpoint some of the compounds most influential in distinguishing beer styles. It was determined that while many phenols and iso-α-acids were present in the beers, they were not the compounds most responsible for the variations between styles. However, it was possible to discriminate each beer style using multivariate analysis. Principal component analysis (PCA) was able to separate and cluster the individual beer samples by style. A combination of statistical tools were used to predict formulas for some of the most influential metabolites from each style. Machine learning models accurately classified patterns in the five beer styles, indicating that they can be precisely distinguished by their nonvolatile chemical profile.

Inter-trophic Interaction of Gut Microbiota in a Tripartite System

Gut microbiota can be transmitted either environmentally or socially and vertically at intraspecific level; however, whether gut microbiota interact along trophic levels has been largely overlooked. Here, we characterized the gut bacterial communities of weevil larvae of Curculio arakawai that infest acorns of Mongolian oak (Quercus mongolica) as well as acorn-eating mammals, Siberian chipmunk (Tamias sibiricus), to test whether consumption of seed-borne larvae remodels the gut bacterial communities of T. sibiricus. Ingestion of weevil larvae of C. arakawai significantly altered the gut bacterial communities of T. sibiricus. Consequently, T. sibiricus fed larvae of C. arakawai showed higher capability to counter the negative effects of tannins, in terms of body weight maintenance, acorn consumption, N content in feces, urine pH, and blood ALT activity. Our results may first show that seed-borne insects as hidden players have a potential to alter the gut microbiota of seed predators in the tripartite system.

Grapevine as a Rich Source of Polyphenolic Compounds

Grapes are rich in primary and secondary metabolites. Among the secondary metabolites, polyphenolic compounds are the most abundant in grape berries. Besides their important impacts on grape and wine quality, this class of compounds has beneficial effects on human health. Due to their antioxidant activity, polyphenols and phenolic acids can act as anti-inflammatory and anticancerogenic agents, and can modulate the immune system. In grape berries, polyphenols and phenolic acids can be located in the pericarp and seeds, but distribution differs considerably among these tissues. Although some classes of polyphenols and phenolic acids are under strict genetic control, the final content is highly influenced by environmental factors, such as climate, soil, vineyard, and management. This review aims to present the main classes of polyphenolic compounds and phenolic acids in different berry tissues and grape varieties and special emphasis on their beneficial effect on human health.

Contributions of protein microenvironment in tannase industrial applicability: An in-silico comparative study of pathogenic and non-pathogenic bacterial tannase

Tannase is an inducible industrially important enzyme, produced by several microorganisms. A large number of bacteria have reported as tannase producers; however, some of them are pathogenic in nature. Therefore, it is quite uncertain whether the application of these tannase enzymes from such pathogenic bacteria is suitable for industries and human welfare. Till date, there is no clear evidence regarding which group of bacteria (non-pathogenic or pathogenic) is better suited for their application in the edge of industries with particular reference to the food industry. The present study is following the findings of the above queries. In this study, a large number of tannase protein sequences have been retrieved from the databases, including both non-pathogenic and pathogenic bacterial species. Physiochemical and evolutionary properties of those sequences have been evaluated. Results have shown that non-pathogenic bacterial tannase possesses a high number of acidic and basic amino acid residues as compared to their pathogenic counterparts. The acidic and basic amino acid residues of tannase provide unique microenvironment to it. In the other hand, the numbers of disorder forming residues are higher in tannase sequences of pathogenic bacteria. The study of tannase microenvironment leads in the formation of salt bridges, which finally favoring the stability and proper functioning of tannase. This is the first report of such observation on tannase enzyme using in silico approach. Study of the microenvironment concept will be helpful in protein engineering.

The role of cosubstrate and mixing on fungal biofilm efficiency in the removal of tannins

Tannins are polyphenolic compounds produced by plants and they are used in industrial vegetable tanning of leather. Tannins represent one of the low biodegradability substances in tannery wastewaters with high recalcitrant soluble chemical oxygen demand, furthermore high concentration of tannins can inhibit biological treatment. In the present study, four novel rotating submerged packed bed reactors were inoculated with a selected fungal strain to reach a biological degradation of tannins in non-sterile conditions. The selected fungal strain, Aspergillus tubingensis MUT 990, was immobilised in polyurethane foam cubes carriers and inserted inside a submerged rotating cage reactors. The reactors were feed with a solution composed of four tannins: Quebracho (Schinopsis spp.), Wattle (Mimosa spp.), Chestnut (Castanea spp.) and Tara (Caesalpinia spp.). Four reactors with a volume of 4 L each were used, the co-substrate was pure malt extract, the hydraulic retention time was 24 h and the pH setpoint was 5.5. The reactors configuration was chosen to allow the study of the effect of rotation and the co-substrate addition on tannins removal. The experiment lasted two months and it was achieved 80% of chemical oxygen demand and up to 90% dissolved organic carbon removal, furthermore it was detected an important tannase activity.

Cytoproliferative and Anti-Oxidant Effects Induced by Tannic Acid in Human Embryonic Kidney (Hek-293) Cells

Tannic acid (TA) portrays a myriad of beneficial properties and has forthwith achieved incessant significance for its cytoprotective qualities in traditional and modern-day medicine. However, TA displays an ambiguous nature demonstrating anti-oxidant and pro-oxidant traits, beckoning further research. Although vast literature on the anti-proliferative effects of TA on cancer cell lines exist, the effects on normal cells remain unchartered. Herein, the cytoproliferative and anti-oxidant effects induced by TA in human embryonic kidney (Hek-293) cells were investigated. Data obtained from the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay demonstrated that TA increased the cell viability and cellular proliferation rate at higher concentrations. Hoechst assay, examining proliferation marker Ki67 supported these findings. DNA fragmentation and oxidative stress-inducers were specifically noted at IC25 and IC50 treatments via biochemical assays. This alluded to TA's pro-oxidant characteristics. However, the countervailing anti-oxidant defence mechanisms as the endogenous anti-oxidants and phase2 detoxification enzymes were significantly upregulated. Luminometry fortified the anti-oxidant capacity of TA, whereby executioner caspase-3/7 were not activated subservient to the activation of initiator caspases-8 and -9. Thus, proving that TA has anti-apoptotic traits, inter alia. Therefore, TA proved to harbour anti-oxidant, anti-apoptotic, and proliferative effects in Hek-293 cells with its partial cytotoxic responses being outweighed by its cytoprotective mechanisms.

Recovery of phenolic antioxidants from Syrah grape pomace through the optimization of an enzymatic extraction process

Phenolic compounds are highly valuable products that remain trapped in grape pomace, an abundant winery by-product. Therefore, efficient extraction procedures of these compounds represent a route for grape pomace valorisation. Here we performed a screening of the factors affecting the aqueous enzymatic extraction of phenolic compounds from Syrah grape pomace, including the following independent variables: temperature, pH, pectinase, cellulase and tannase; and a subsequent optimization through response surface methodology. At the optimal region, the enzymatic treatment enhanced the extraction yield of phenolics by up to 66% and its antioxidant capacity by up to 80%, reducing the incubation time and enzyme doses in respect to previous studies. We found that tannase raises the antioxidant capacity of the extract by the liberation of gallic acid, while cellulose favours the liberation of p-coumaric acid and malvidin-3-O-glucoside. We also tested the procedure in different grape pomace varieties, verifying its wide applicability.

Bacterial tannases: classification and biochemical properties

Tannin acyl hydrolases, also known as tannases, are a group of enzymes critical for the transformation of tannins. The study of these enzymes, which initially evolved in different organisms to detoxify and/or use these plant metabolites, has nowadays become relevant in microbial enzymology research due to their relevant role in food tannin transformation. Microorganisms, particularly bacteria, are major sources of tannase. Cloning and heterologous expression of bacterial tannase genes and structural studies have been performed in the last few years. However, a systematic compilation of the information related to all recombinant tannases, their classification, and characteristics is missing. In this review, we explore the diversity of heterologously produced bacterial tannases, describing their substrate specificity and biochemical characterization. Moreover, a new classification based on sequence similarity analysis is proposed. Finally, putative tannases have been identified in silico for each group of tannases taking advantage of the use of the "tannase" distinctive features previously proposed.

Solid state fermentation of Bacillus gottheilii M2S2 in laboratory-scale packed bed reactor for tannase production

Production of tannase was performed in packed bed reactor filled with an inert support polyurethane foam (PUF) using Bacillus gottheilii M2S2. The influence of process parameters such as fermentation time (24-72 h), tannic acid concentration (0.5-2.5% w/v), inoculum size (7-12% v/v), and aeration rate (0-0.2 L/min) on tannase production with PUF were analyzed using one variable at a time (OVAT) approach. The outcome of OVAT was optimized by central composite design. Based on the statistical investigation, the proposed mathematical model recommends 1% (w/v) of tannic acid, 10% (v/v) of inoculum size and 0.13 L/min of aeration rate for maximum production (76.57 ± 1.25 U/L). The crude enzyme was purified using ammonium sulfate salt precipitation method followed by dialysis. The biochemical properties of partially purified tannase were analyzed and found the optimum pH (4.0), temperature (40 °C) for activity, and K_m (1.077 mM) and V_max (1.11 µM/min) with methyl gallate as a substrate. Based on the SDS-PAGE analysis, tannase exhibited two bands with molecular weights of 57.5 and 42.3 kDa. Briefly, the partially purified tannase showed 4.2 fold increase (63 ± 1.60 U/L) in comparison to the submerged fermentation and the production of tannase was validated by using NMR spectrometer.

Evaluation of model parameters for growth, tannic acid utilization and tannase production in Bacillus gottheilii M2S2 using polyurethane foam blocks as support

Production of tannase from B. gottheilii M2S2 was studied under solid-state fermentation with an optimized medium consisting of polyurethane foam matrix of dimension 40 × 40 × 5 mm, impregnated with a liquid medium comprising (w/v): 4% tannic acid; 2% NH₄NO₃; 0.1% KH₂PO₄; 0.2% MgSO₄; 0.1% NaCl and 0.05% CaCl₂·2H₂O in distilled water, having a pH of 4.7. Maximum tannase production of 56.87 U/L was obtained after 32 h of fermentation at 32 °C in static condition. This study deals with the evaluation of unstructured kinetic models to understand the behavior of biomass, tannase production and tannic acid degradation, with the fermentation time. The growth rate of B. gottheilii M2S2 was 0.0703 h^-1 at 32 h of fermentation. Product (Y_x/s) and biomass yield (Y_p/s) coefficients were estimated as 1.77 U/g of tannic acid and 0.276 g of biomass/g of tannic acid. All the kinetic constants µ, α, β, m and n were evaluated using MATLAB 2015Rb program. The experimental and model-generated data showed a good correlation, which indicated that these models will describe tannase production and fermentation process.

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.

Evaluation of the Combined Effects of Stilbenoid from Shorea gibbosa and Vancomycin against Methicillin-Resistant Staphylococcus aureus (MRSA)

The aim of this study is to determine the combined effects of stilbenoids from Shorea gibbosa and vancomycin against methicillin-resistant Staphylococcus aureus (MRSA). A total of nine pure compounds, five stilbenoid dimers ε-viniferin, ampelopsin A, balanocarpol, laevifonol and diptoindonesin G and four stilbenoid trimers α-viniferin, johorenol A, ampelopsin E and vaticanol G were evaluated for their antibacterial activities against ATCC 33591 and a HUKM clinical isolate. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each active compound were determined using the serial microdilution and plate-streak techniques. The combined effect of stilbenoids with vancomycin against MRSA was evaluated using the checkerboard assay to determine their fractional inhibitory concentration (FIC) index values. The MIC value of α-viniferin on both MRSA strains was 100 μg/mL, whereas those of johorenol A on ATCC 33591 and HUKM strain were 100 μg/mL and 200 μg/mL, respectively. The MIC values of ampelopsin E and vaticanol G were higher than 400 μg/mL. Out of the five stilbenoid dimers, only ε-viniferin was capable of inhibiting the growth of both MRSA strains at MIC 400 μg/mL. The MBC value of ε-viniferin, α-viniferin and johorenol A showed bacteriostatic action against MRSA. The FIC index value of ε-viniferin and α-viniferin in combination with vancomycin showed an additive effect (0.5 < FIC ≤ 2.0) against both MRSA strains. Johorenol A-vancomycin combination was also additive against HUKM strain, but it showed synergistic interaction with vancomycin against ATCC 33591 (FIC < 0.5). Stilbenoid compounds from Shorea gibbosa have anti-MRSA activity and huge potential as an alternative phytotherapy in combating MRSA infections.

Genome sequence of the naturally plasmid-free Lactobacillus plantarum strain NC8 (CCUG 61730)

Lactobacillus plantarum is a highly versatile lactic acid bacterium found in various ecological niches, such as fermented vegetable, meat, and dairy products and the gastrointestinal tract. We sequenced the genome of L. plantarum NC8, a naturally plasmid-free strain, which has been used as a model strain in many laboratories worldwide.

Bio-processing of agro-byproducts to animal feed

Agricultural and food-industry residues constitute a major proportion (almost 30%) of worldwide agricultural production. These wastes mainly comprise lignocellulosic materials, fruit and vegetable wastes, sugar-industry wastes as well as animal and fisheries refuse and byproducts. Agro-residues are rich in many bioactive and nutraceutical compounds, such as polyphenolics, carotenoids and dietary fiber among others. Agro residues are a major valuable biomass and present potential solutions to problems of animal nutrition and the worldwide supply of protein and calories, if appropriate technologies can be used for their valorization by nutrient enrichment. Technologies available for protein enrichment of these wastes include solid substrate fermentation, ensiling, and high solid or slurry processes. Technologies to be developed for the reprocessing of these wastes need to take account of the peculiarities of individual wastes and the environment in which they are generated, reprocessed, and used. In particular, such technologies need to deliver products that are safe, not just for animal feed use, but also from the perspective of human feeding. This review focuses on the major current applications of solid-state fermentation in relation to the feed sector.

Two-phase olive mill waste composting: community dynamics and functional role of the resident microbiota

In this study, physico-chemical modifications and community dynamics and functional role of the resident microbiota during composting of humid husk from a two-phase extraction system (TPOMW) were investigated. High mineralization and humification of carbon, low loss of nitrogen and complete degradation of polyphenols led to the waste biotransformation into a high-quality compost. Viable cell counts and denaturing gradient gel electrophoresis (DGGE) profiling of the 16S rRNA genes showed that the thermophilic phase was characterized by the strongest variations of cell number, the highest biodiversity and the most variable community profiles. The isolation of tannin-degrading bacteria (e.g. Lysinibacillus fusiformis, Kocuria palustris, Tetrathiobacter kashmirensis and Rhodococcus rhodochrous) suggested a role of this enzymatic activity during the process. Taken together, the results indicated that the composting process, particularly the thermophilic phase, was characterized by a rapid succession of specialized bacterial populations with key roles in the organic matter biotransformation.

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.