Treatment of wheat straw using tannase and white-rot fungus to improve feed utilization by ruminants

Background： Current research to enrich cattle feed has primarily focused on treatment using white rot fungi, while there are scarce reports using the enzyme tannase, which is discussed only in reviews or in the form of a hypothesis. In this context, the aim of the present study was to evaluate the effect of tannase on wheat straw （WS） and also the effect of lyophilized tannase at concentrations of 0.1%, 0.2%, and 0.3% （w/w） on WS followed by fermentation with Ganodermo sp. for 10 d and compared in relation to biochemical parameters, crude protein （CP） content, and nutritional value by calculating the C/N ratio in order to improve the nutritional value of cattle feed. Results： Penicillium charlesii, a tannase-producing microorganism, produced 61.4 IU/mL of tannase in 54 h when 2% （w/v） tannic acid （TA） was initially used as a substrate in medium containing （% w/v） sucrose （1.0）, NaNO3 （1.0）, and MgSO4 （0.08 pH, 5.0） in a 300-L fermentor （working volume 220 L）, and concomitantly fed with 1.0% （w/v） TA after 24 h. The yield of partially purified and lyophilized tannase was 5.8 IU/mg. The tannin-free myco-straw at 0.1% （w/w） tannase showed 37.8% （w/w） lignin degradation with only a 20.4% （w/w） decrease in cellulose content and the in vitro feed digestibility was 32.2%. An increase in CP content （up to 1.28-fold） along with a lower C/N ratio of 25.0%, as compared to myco-straw, was obtained. Conclusions： The use of tannin-free myco-straw has potential to improve the nutritional content of cattle feed. This biological treatment process was safe, eco-friendly, easy to perform, and was less expensive as compared to other treatment methods.

Science Letters:Effects of polyurethane matrices on fungal tannase and gallic acid production under solid state culture

The influence of the physical structure of polyurethane matrix as a support in a solid state culture in tannase production and gallic acid accumulation by Aspergillus niger Aa-20 was evaluated. Three different polyurethane matrices were used as the support: continuous, semi-discontinuous and discontinuous. The highest tannase production at 2479.59 U/L during the first 12 h of culture was obtained using the discontinuous matrix. The gallic acid was accumulated at 7.64 g/L at the discontinuous matrix. The results show that the discontinuous matrix of polyurethane is better for tannase production and gallic acid accumulation in a solid state culture bioprocess than the continuous and semi-discontinuous matrices.

Diversity of Filamentous Fungi of Area from Brazilian Caatinga and High-Level Tannase Production Using Mango (<i>Mangifera indica</i>L.) and Surinam Cherry (<i>Eugenia uniflora</i>L.) Leaves under SSF

Tannase is a biotechnologically important enzyme that can be produced during fungal fermentation of organic matter. The Caatinga is an exclusive Brazilian ecosystem that has been largely unexplored by science, particularly its filamentous fungal diversity. This study evaluated the diversity of filamentous fungi in the Caatinga soils of Pernambuco, Brazil, and their potential for tannase production by solid-state fermentation (SSF) of mango (Mangifera indica L.) and Surinam cherry (Eugenia uniflora L.) leaves. A total of 4711 isolates were obtained, 2090 during the rainy seasonand 2621 during the dry season. The isolates belonged to 18 genera and 66 species, with Aspergillus and Penicillium having the highest species richness. The dry season had a higher diversity index. Aspergillus was the dominant genus, and A. flavus, A. sclerotiorum, and A. ochraceus the most abundant species. A representative of each species was tested for tannase production using dried mango and Surinam cherry leaves as substrates;the leaves contained 14.28 and 7.0 g/L tannin, respectively. Most fungal species produced tannase, but the highest yields were obtained when mango leaves were used as substrate for Penicillium restrictum (accession URM 6044), Aspergillus flavofurcatus (URM 6142), and A. stromatoides (URM 6609), which produced 104.16, 87.51, and 81.83 U/mL tannase, respectively. These yields exceeded previously published reports. Filamentous fungi from Caatinga soils have great potential for producing tannase by SSF, and low-cost mango leaves make excellent substrate.

The Optimization of Aspergillus sp.GM4 Tannase Production under Submerged Fermentation

Tannase is a hydrolytic enzyme that is involved in the biodegradation of tannins and it has biotechnological potential in the pharmaceutical, chemical, food and beverage industries. Microorganisms, especially filamentous fungi, are important tannase producers. The aims of this work were to find a potential tannase producer and to improve the cultivation conditions. Three Aspergillus species (A. japonicus 246A, A. tamarii 3 and Aspergillus sp. GM4) were investigated in different culture media (Adams, Czapeck, Khanna, M5 and Vogel) and inducers (1% and 2% tannic acid;1% green tea;1% methyl gallate;1% gallic acid). Aspergillus sp. GM4 and Adams medium were selected. The tannase production by Aspergillus sp. GM4 in Adams medium was induced in the presence of 2% (w/v) tannic acid and gallic acid as carbon sources, while green tea was not able to induce tannase production. The Plackett-Burman screening design was performed with the variables MgSO4, KH2PO4, yeast extract, tannic acid, agitation rate and salt solution. The variables MgSO4 and agitation rate were selected for the optimization of tannase production using a Central Composite Rotatable Design. Under optimized conditions, a 2.66-fold increase in the enzyme production was observed with small modifications in the medium composition.

Sequence identification, structure prediction and validation of tannase from Aspergillusniger N5-5

Tannases produced by filamentous fungi are in a family of important hydrolases of gallotannins and have broad industry applications.But until now,the 3-D structures of fungi tannases have not been reported.The protein sequence deduced from the cDNA sequence obtained using RT-PCR amplification was identified as tannase through sequence alignment and phylogenetic analysis.Structure models based on the tannase sequence were collected using I-TASSER,and the model with the best match to the surface charge density-pH titration profile was selected as the final structure for tannase from Aspergillusniger N5-5.This work provides an effective method for protein structure research.The structure constructed in this work should be very important to understand the enzyme bioactivities and further developments of fungi tannases.

Biodegradation of Toxic Compounds in Olive Mill Wastewater by a Newly Isolated Potent Strain: <i>Aspergillus niger</i>van Tieghem

Thirty-two strains isolated from olive oil production plants were screened for their tolerance to the polyphenols and their ability to grow in olive oil mill wastewaters (OMW). An Ascomycete isolate that grew best on OMW was selected for further study to evaluate its effect on removal of organic pollutants, phenolic compounds and OMW toxicity. This strain was identified by DSMZ as Aspergillus niger van Tieghem. The growth of Aspergillus niger van Tieghem on stored OMW decreased pH and led to the reduction of phenolic compounds with a resultant discoloration of OMW and significant reduction of chemical oxygen demand (COD), in proportion to the dilution of OMW. The reduction of the COD, phenolics and color exceeded 50%. Tannase, the enzyme detected in the growth medium of Aspergillus niger van Tieghem was produced during primary metabolic growth. The maximal enzyme activity attaining 0.68 EU/ml was achieved in 3rd days of cultivation. The phytotoxicity of the stored OMW was reduced to about 40% after 4 days’ incubation with Aspergillus niger van Tieghem.