Sylfation of Birch Wood Xylan with Sulfamic Acid in 1,4-dioxane

Sulfation of birch wood xylan in 1,4-dioxane by sulfamic acid in the presence of urea at 90 and 100 °C was studied for the first time. The effect of the duration of xylan sulfation on the yield of xylan sulfates and the sulfur content in them was studied. It was found that the sulfur content in the obtained xylan sulfates increases from 12.5 to 17.5 wt% with an increase in the duration of sulfation from 2 to 4 hours. The structure of initial and sulfated xylan was studied by FTIR and NMR spectroscopy. The ease of purification of the obtained xylan sulfates from 1,4-dioxane in comparison with the purification of xylan sulfates obtained by sulfation in pyridine and N, N‑dimethylformamide is an advantage of the proposed method of xylan sulfation

MATHEMATICAL OPTIMIZATION OF THE PROCESS OF BIRCH WOOD XYLAN SULFATION BY SULFAMIC ACID IN N, N-DIMETHYLFORMAMIDE MEDIUM

The effect of temperature and duration of sulfation of birch wood xylan by sulfamic acid in N, N-dimethylformamide (DMF) medium in the presence of urea on the yield of sulfated xylan and on the sulphur content was studied. By mathematical optimization, the sulfation conditions have been established allowing to achieve a high yield of the obtained xylan sulfates with a high sulphur content. Under optimal sulfation conditions: temperature 100±3 °C, duration 1.5 hours, the yield of sulfated xylan reaches to 63% mas. and the content of sulfur – 17.6% mas. The presence of sulfate groups in sulfated xylan samples obtained under optimal conditions was confirmed by elemental analysis and FTIR and 13C NMR spectroscopy.

Purification and evaluation for effects of temperature on extracellular xylanase activity from Aspergillus oryzae DSM 1863

Xylanase was purified from the crude culture of Aspergillus oryzae DSM1863 by sephadex G200 and DEAE – cellulose ion exchange chromatography. The molecular mass of the purified xylanase determined by SDS–PAGE was 21 kDa with a specific activity of 6768 U/mg towards 1% (w/v) of birch wood xylan. The optimum temperature was observed at 60°C. The enzyme was thermostable in the temperature range of 37-50°C with a high residual activity of 62-74% (650.6-775.9 U/mg protein). Enzyme xylanase được tinh sạch từ dịch lên men của chủng Aspergillus oryzae DSM1863 sau khi qua cột sắc ký lọc gel sephadex G200 và sắc ký trao đổi ion DEAE – cellulose. Khối lượng phân tử của enzyme xylanase tinh sạch được xác định bằng điên di đồ SDS- PAGE. Xylanase tinh sạch có kích thước là 21 kDa với hoạt tính đặc hiệu đạt 6768 U/mg sau khi được xác định với nồng độ cơ chất là 1% birch wood xylan. Nhiệt độ tối ưu để enzyme hoạt động mạnh nhất là 60C. Enzyme xylanase khá bền nhiệt. Hoạt tính của enzyme vẫn còn duy trì 62-74% (hoạt tính đặc hiệu đạt 650.6-775.9 U/mg protein) sau khi 8 giờ ủ ở 37-50°C.

Isolation, Production, and Characterization of Thermotolerant Xylanase from Solvent TolerantBacillus vallismortisRSPP-15

Sixty bacterial strains isolated from the soils sample in the presence of organic solvent were screened for xylanase production. Among them, strain RSPP-15 showed the highest xylanase activity which was identified asBacillus vallismortis. The isolate showed maximum xylanase production (3768 U/mL) in the presence of birch wood xylan and beef extract at 55°C pH 7.0 within 48 h of incubation. The enzyme activity and stability were increased 181.5, 153.7, 147.2, 133.6, and 127.9% and 138.2, 119.3, 113.9, 109, and 104.5% in the presence of Co2+, Ca2+, Mg+2, Zn+2, and Fe+3ions (10 mM). Xylanase activity and stability were strongly inhibited in the presence of Hg and Cu ions. The enzyme was also stable in the presence of 30% ofn-dodecane, isooctane,n-decane, xylene, toluene,n-hexane,n-butanol, and cyclohexane, respectively. The presence of benzene, methanol, and ethanol marginally reduced the xylanase stability, respectively. This isolate may be useful in several industrial applications owing to its thermotolerant and organic solvent resistance characteristics.

Identification and characterization of diverse xylanases from thermophilic and thermotolerant fungi

Thirteen fungal isolates included in this study expressed multiple xylanase isoforms as observed by xylan zymograms of polyacrylamide gel electrophoresis (PAGE) and isoelectrofocussing (IEF) fractionated proteins. Eighty-three xylanases produced by these thermophilic and thermotolerant strains were detected using the IEF profiling technique. Xylanases identified on the basis of their isoelectric points (pI) were functionally diverse and exhibited differential catalytic activities against various xylan types (birch wood xylan, larch wood xylan, oat spelt xylan, rye arabino xylan and wheat arabino xylan) as well as debranched arabinan. Thermophilic isolates, Chaetomium thermophilum , Humicola insolens , Melanocarpus sp., Malbranchea sp. and Thermoascus aurantiacus , were found to produce alkaline active xylanases that showed a bleach boosting effect on Decker pulp resulting in increased brightness (1.60-2.04 ISO units).