Some factors affecting tannase production by Aspergillus niger Van Tieghem

Evaluation of wool protein hydrolysate as peptone for production of microbial enzymes

Peptones are one of the most expensive components of microbial culture media. The present study was conducted to test the usability of low-cost sheep wool peptone (SWP) as an organic nitrogen source in the production of six industrially important enzymes (lipase, amylase, tannase, pectinase, cellulase and invertase). SWP was prepared by alkaline hydrolysis and acid neutralization. Bacillus licheniformis and Aspergillus niger were selected as test microorganisms for enzyme production. To evaluate the efficacy of SWP in enzyme production, it was compared with commercial tryptone peptone (TP) in the shaking flask cultures of the test microorganisms. The optimum concentration of both SWP and TP was determined to be 8 g/L for the production of B. licheniformis-derived enzymes, but 6 g/L for the production of A. niger-derived enzymes. It was determined that SWP was superior to TP in the production of four enzymes (lipase, amylase, tannase and pectinase) of both B. licheniformis and A. niger. This is the first study about the usage of sheep wool protein hydrolysate (SWP) as an organic nitrogen source or a peptone in fermentative production of microbial enzymes.

Biochemical and Structural Characterization of a Novel Bacterial Tannase From Lachnospiraceae bacterium in Ruminant Gastrointestinal Tract

Tannases are a family of esterases that catalyze the hydrolysis of ester and depside bonds present in hydrolyzable tannins to release gallic acid. Here, a novel tannase from Lachnospiraceae bacterium (TanA_Lb) was characterized. The recombinant TanA_Lb exhibited maximal activity at pH 7.0 and 50°C, and it maintained more than 70% relative activity from 30°C to 55°C. The activity of TanA_Lb was enhanced by Mg²⁺ and Ca²⁺, and was dramatically reduced by Cu²⁺ and Mn²⁺. TanA_Lb is capable of degrading esters of phenolic acids with long-chain alcohols, such as lauryl gallate as well as tannic acid. The Km value and catalytic efficiency (k_cat /Km) of TanA_Lb toward five substrates showed that tannic acid (TA) was the favorite substrate. Homology modeling and structural analysis indicated that TanA_Lb contains an insertion loop (residues 341–450). Based on the moleculer docking and molecular dynamics (MD) simulation, this loop was observed as a flap-like lid to interact with bulk substrates such as tannic acid. TanA_Lb is a novel bacterial tannase, and the characteristics of this enzyme make it potentially interesting for industrial use.

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.

Stability of fungal biomass continuously fed with tannic acid in a non-sterile moving-packed bed reactor

A number of bacteria and fungi are known to degrade tannins. In this study, the efficiency of the white-rot fungus, Bjerkandera adusta MUT 2295, was evaluated for the treatment of a synthetic solution prepared with tannic acid. Tests were performed in continuously fed, bench-scale, packed-bed reactors, operated under non-sterile conditions with biomass immobilized within PolyUrethane Foam cubes (PUFs). The main parameters monitored to evaluate the process efficiency were: soluble Chemical Oxygen Demand (sCOD), Total Organic Carbon (TOC) removal, and activities. of Tannase and Lignin Peroxidase. At the end of the process, additional parameters were evaluated, including the increase of fungal dry weight and the presence of ergosterol. The reactor was operative for 210 days, with maximum sCOD and TOC removal of 81% and 73%, respectively. The reduction of sCOD and TOC were positively correlated with the detection of Tannase and Lignin Peroxidase (LiP) activities. Increases in biomass within the PUF cubes was associated with increases in ergosterol concentrations. This study proved that the fungal-based system tested was efficient for the degradation of tannic acid over a period of time, and under non-sterile conditions.

Co-production of tannase and gallic acid by a novel Penicillium rolfsii (CCMB 714)

A novel tannase and gallic acid-producing Penicillium rolfsii (CCMB 714) was isolated from cocoa leaves from the South of Bahia. The influence of nutritional sources and the simultaneous effect of parameters involved in the fermentation process were available. Tannase (9.97 U mL^-1) and gallic acid (9 mg mL^-1) production were obtained in 48 h by submerged fermentation in non-optimized conditions. Among the carbon sources, tested gallic acid and tannic acid showed the highest tannase production (p<.05) when compared with methyl gallate and glucose. After optimization using the temperature and tannic acid concentration as variables with the Central Compound Rotational Design (CCRD), the maximal tannase production (25.6 U mL^-1) was obtained at 29.8 °C and 12.7%, respectively, which represents an increase of 2.56 times in relation to the initial activity. The parameters optimized for the maximum production of gallic acid (21.51 mg mL^-1) were 30 °C and 10% tannic acid. P. rolfsii CCMB 714 is a new strain with a high tannase and gallic acid production and the gallic acid produced is very important, mainly for its applications in the food and pharmaceutical industry.