Purification and Characterization of a Thermostable Hypothetical Xylanase from Aspergillus oryzae HML366

Purification and enzymatic properties of a new thermostable endoglucanase from Aspergillus oryzae HML366

Aspergillus oryzae HML366 is a newly screened cellulase-producing strain. The endoglucanase HML ED1 from A. oryzae HML366 was quickly purified by a two-step method that combines ammonium sulfate precipitation and strong anion exchange column. SDS-PAGE electrophoresis indicated that the molecular weight of the enzyme was 68 kDa. The optimum temperature of the purified endoglucanase was 60 ℃ and the enzyme activity was stable below 70 ℃. The optimum pH was 6.5, and the enzyme activity was stable at pH between 4.5 and 9.0. The analysis indicated that additional Na⁺, K⁺, Ca²⁺, and Zn²⁺ reduced the catalytic ability of enzyme to the substrate, but Mn²⁺ enhanced its catalytic ability to the substrate.The Km and Vmax of the purified endoglucanase were 8.75 mg/mL and 60.24 μmol/min·mg, respectively. In this study, we report for the first time that A. oryzae HML366 can produce a heat-resistant and wide pH tolerant endoglucanase HML ED1, which has potential industrial application value in bioethanol, paper, food, textile, detergent, and pharmaceutical industries.

Heterologous Expression of Xylanase xAor from Aspergillus oryzae in Komagataella phaffii T07

Xylanases (EC 3.2.1.8) hydrolyze the hemicellulose of plant cell walls. Xylanases are used in the food and paper industries and for bioconversion of lignocellulose to biofuel. In this work, the producer-strain with four copies of the xAor xylanase gene was organized in two tandem copies for optimal expression in Komagataella phaffii T07 yeast. The secreted 35 kDa xylanase was purified from culture medium by gel filtration on Sephadex G-25 and anion exchange chromatography on DEAE-Sepharose 6HF. Tryptic peptides of the recombinant enzyme were analyzed by liquid chromatography-tandem mass spectrometry where the amino acid sequence corresponded to Protein Accession # O94163 for Endo-1,4-beta-xylanase from Aspergillus oryzae RIB40. The recombinant xylanase was produced in a bioreactor where the secreted enzyme hydrolyzed oat xylane with an activity of 258240 IU/mL. High activity in the culture medium suggested xylanase could be used for industrial applications without being purified or concentrated. The pH optimum for xylanase xAor was 7.5, though the enzyme was active from pH 2.5 to pH 10. Xylanase was active at temperatures from 35 °C to 85 °C with a maximum at 60 °C. In conclusion, this protocol yields soluble, secreted xylanase suitable for industrial scale production.

Purification, Identification, and Characterization of a Glycoside Hydrolase Family 11-Xylanase with High Activity from Aspergillus niger VTCC 017

Xylanases (EC 3.2.1.8) have been considered as a potential green solution for the sustainable development of a wide range of industries including pulp and paper, food and beverages, animal feed, pharmaceuticals, and biofuels because they are the key enzymes that degrade the xylosidic linkages of xylan, the major component of the second most abundant raw material worldwide. Therefore, there is a critical need for the industrialized xylanases which must have high specific activity, be tolerant to organic solvent or detergent and be active during a wide range of conditions, such as high temperature and pH. In this study, an extracellular xylanase was purified from the culture broth of Aspergillus niger VTCC 017 for primary structure determination and properties characterization. The successive steps of purification comprised centrifugation, Sephadex G-100 filtration, and DEAE-Sephadex chromatography. The purified xylanase (specific activity reached 6596.79 UI/mg protein) was a monomer with a molecular weight of 37 kDa estimating from SDS electrophoresis. The results of LC/MS suggested that the purified protein is indeed an endo-1,4-β-D-xylanase. The purified xylanase showed the optimal temperature of 55 °C, and pH 6.5 with a stable xylanolytic activity within the temperature range of 45-50 °C, and within the pH range of 5.0-8.0. Most divalent metal cations including Zn²⁺, Fe²⁺, Mg²⁺, Cu²⁺, Mn²⁺ showed some inhibition of xylanase activity while the monovalent metal cations such as K⁺ and Ag⁺ exhibited slight stimulating effects on the enzyme activity. The introduction of 10-30% different organic solvents (n-butanol, acetone, isopropanol) and several detergents (Triton X-100, Tween 20, and SDS) slightly reduced the enzyme activity. Moreover, the purified xylanase seemed to be tolerant to methanol and ethanol and was even stimulated by Tween 80. Overall, with these distinctive properties, the putative xylanase could be a successful candidate for numerous industrial uses.

Purification and Enzymatic Properties of a Difunctional Glycoside Hydrolase from Aspergillus oryzae HML366

In the study, an extracellular enzyme HML CBH1 was purified from the fermentation solution of Aspergillus oryzae HML366, and characterized by biological and molecular analysis. Following the culturing of A. oryzae HML366 under the optimized conditions for enzyme production, an enzyme named HML CBH1 with a molecular weight of 48 kDa was purified using 3000 Da cellulose ultrafiltration column and anion exchange chromatography. The specific activity of the purified enzyme was 9.65 U/mg, and the optimum temperature and pH for the enzyme were 50 and 5.0 °C, respectively. The enzyme was stable at temperatures below 60 °C and pH ranging from 3.0 to 10.0. The partial amino acid sequence of HML CBH1 was analyzed by time-of-flight mass spectrometry, and Mascot and Blast analysis showed that the HML CBH1 sequence was identical to the protein gi:22138643, belonging to the glycoside hydrolase family 7, and had exoglucanase and endoglucanase activity.

Inhibition kinetics of acetosyringone on xylanase in hydrolysis of hemicellulose

Many phenolic compounds, derived from lignin during the pretreatment of lignocellulosic biomass, could obviously inhibit the activity of cellulolytic and hemicellulolytic enzymes. Acetosyringone (AS) is one of the phenolic compounds produced from lignin degradation. In this study, we investigated the inhibitory effects of AS on xylanase activity through kinetic experiments. The results showed that AS could obviously inhibit the activity of xylanase in a reversible and noncompetitive binding manner (up to 50% activity loss). Inhibitory kinetics and constants of xylanase on AS were conducted by the HCH-1 model (β = 0.0090 ± 0.0009 mM^-1). Furthermore, intrinsic and 8-anilino-1-naphthalenesulfonic (ANS)-binding fluorescence results showed that the tertiary structure of AS-mediated xylanase was altered. These findings provide new insights into the role of AS in xylanase activity. Our results also suggest that AS was an inhibitor of xylanase and targeting AS was a potential strategy to increase xylose production.

Effect of Endoxylanase and Iron Oxide Nanoparticles on Performance and Histopathological Features in Broilers

Endoxylanase enzyme is used as poultry feed additive to degrade anti-nutritional factors like non-starch polysaccharides. Moreover, iron is one of the most important trace elements, and its deficiency can lead to various pathological conditions and stunted growth. In the current study, a combination of xylanase and iron nanoparticles is used to assess the overall effect on poultry growth. Endoxylanase enzyme was obtained from Aspergillus awamori SAIB-17 (identified on the basis of internal transcribed spacer (ITS) sequence analysis). The characterization of purified endoxylanase revealed that the K_m and V_max were 0.25 g/ml and 833.33 nkat/ml/s, respectively. Effect of pH and temperature showed that pH 4.5 and temperature 45 °C was best for enzyme activity. Iron nanoparticles were synthesized by co-precipitation of ferric chloride and ferrous chloride. Characterization of nanoparticles using X-ray diffraction (XRD) and SEM revealed that the mean diameter of synthesized iron nanoparticles was around 50 nm. These nanoparticles have no inhibitory effect on endoxylanase up to concentration of 20 ppm. Iron oxide nanoparticles along with endoxylanase were used as additives in different concentrations and were fed to the groups of broiler chicks. It was observed that the group fed with 40 nkat of endoxylanase and 15 ppm of iron nanoparticles showed 54.5% (2010 ± 103.58) more weight gain by the fifth week as compared with the control group. The iron analysis in the muscles showed no increase in iron concentration while histopathology slides showed no morphological changes in liver cells. The combination of iron oxide nanoparticles and xylanase proved to have great potential to be used in poultry feed for large-scale meat production without any toxicological effects.

Production, characteristics, and biotechnological applications of microbial xylanases

Microbial xylanases have gathered great attention due to their biotechnological potential at industrial scale for many processes. A variety of lignocellulosic materials, such as sugarcane bagasse, rice straw, rice bran, wheat straw, wheat bran, corn cob, and ragi bran, are used for xylanase production which also solved the great issue of solid waste management. Both solid-state and submerged fermentation have been used for xylanase production controlled by various physical and nutritional parameters. Majority of xylanases have optimum pH in the range of 4.0-9.0 with optimum temperature at 30-60 °C. For biochemical, molecular studies and also for successful application in industries, purification and characterization of xylanase have been carried out using various appropriate techniques. Cloning and genetic engineering are used for commercial-level production of xylanase, to meet specific economic viability and industrial needs. Microbial xylanases are used in various biotechnological applications like biofuel production, pulp and paper industry, baking and brewing industry, food and feed industry, and deinking of waste paper. This review describes production, characteristics, and biotechnological applications of microbial xylanases.