Xylanase is an enzyme in high demand for various industrial applications, such as those in the biofuel and pulp and paper fields. In this study, xylanase-producing microbes were isolated from the gut of the wood-feeding termite at 50°C. The isolated microbe produced thermostable xylanase that was active over a broad range of temperatures (40-90°C) and pH (3.5-9.5), with optimum activity (4,170 ± 23.5 U mg⁻¹) at 60°C and pH 4.5. The enzyme was purified using a strong cation exchanger and gel filtration chromatography, revealing that the protein has a molecular mass of 205 kDa and calculated pI of 5.38. The half-life of xylanase was 6 h at 60°C and 2 h at 90°C. The isolated thermostable xylanase differed from other xylanases reported to date in terms of size, structure, and mode of action. The novelty of this enzyme lies in its high specific activity and stability at broad ranges of temperature and pH. These properties suggest that this enzyme could be utilized in bioethanol production as well as in the paper and pulp industry.

A newly isolated Geobacillus sp. IIPTN (MTCC 5319) from the hot spring of Uttarakhand's Himalayan region produced a hyperthermostable alpha-amylase. The microorganism was characterized by biochemical tests and 16S rRNA gene sequencing. The optimal temperature and pH were 60 degrees C and 6.5, respectively, for growth and enzyme production. Although it was able to grow in temperature ranges from 50 to 80 degrees C and pH 5.5-8.5. Maximum enzyme production was in exponential phase with activity 135 U ml(-1) at 60 degrees C. Assayed with cassava as substrate, the enzyme displayed optimal activity 192 U ml(-1) at pH 5.0 and 80 degrees C. The enzyme was purified to homogeneity with purification fold 82 and specific activity 1,200 U mg(-1) protein. The molecular mass of the purified enzyme was 97 KDa. The values of K(m) and V(max) were 36 mg ml(-1) and 222 micromol mg(-1) protein min(-1), respectively. The amylase was stable over a broad range of temperature from 40 degrees C to 120 degrees C and pH ranges from 5 to 10. The enzyme was stimulated with Mn(2+), whereas it was inhibited by Hg(2+), Cu(2+), Zn(2+), Mg(2+), and EDTA, suggesting that it is a metalloenzyme. Besides hyperthermostability, the novelty of this enzyme is resistance against protease.

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a b s t r a c tThe present paper reports the two-stage hydrolysis of sugarcane bagasse to produce monomer sugars by using dilute and concentrated sulphuric acid. About 88% of the sugars present in bagasse could be recovered with a little formation of toxic compounds such as furfural/HMF. The sugar concentration in the first-stage of hydrolysis was obtained as xylose-rich solution of 49.7 g l À1 using 8% acid concentration at 100 C and a solid to liquid ratio of 1:4, whereas, with the same solid to liquid ratio of 1:4, 73.4 g l À1 glucose-rich solution was obtained in the second-stage of hydrolysis by using 40% acid concentration at 80 C. The acid hydrolysis of bagasse could be described by a first-order, two-step consecutive reaction model, where the polysaccharides first decompose into monomers through hydrolysis, and thereafter, decompose into various products in the second step. The proposed kinetic model correlates the experimental data satisfactorily.