S.Q. Yang

A xylose-tolerant β-xylosidase from Paecilomyces thermophila: Characterization and its co-action with the endogenous xylanase

An extracellular beta-xylosidase from the thermophilic fungus Paecilomyces thermophila J18 was purified 31.9-fold to homogeneity with a recovery yield of 2.27% from the cell-free culture supernatant. It appeared as a single protein band on SDS-PAGE with a molecular mass of approx 53.5 kDa. The molecular mass of beta-xylosidase was 51.8 kDa determined by Superdex 75 gel filtration. The enzyme was a glycoprotein with a carbohydrate content of 61.5%. It exhibited an optimal activity at 55 degrees C and pH 6.5, respectively. The enzyme was stable in the range of pH 6.0-9.0 and at 55 degrees C. The purified enzyme hydrolyzed xylobiose and higher xylooligosaccharides but was inactive against xylan substrates. It released xylose from xylooligosaccharides with a degree of polymerization ranging between 2 and 5. The rate of xylose released from xylooligosaccharides by the purified enzyme increased with increasing chain length. It had a K(m) of 4.3mM for p-nitrophenol-beta-d-xylopyranoside and was competitively inhibited by xylose with a K(i) value of 139 mM. Release of reducing sugars from xylans by a purified xylanase produced by the same organism increased markedly in the presence of beta-xylosidase. During 24-hour hydrolysis, the amounts of reducing sugar released in the presence of added beta-xylosidase were about 1.5-1.73 times that of the reaction employing the xylanase alone. This is the first report on the purification and characterization of a beta-xylosidase from Paecilomyces thermophila.

Characterization of a xylanase from the newly isolated thermophilic Thermomyces lanuginosus CAU44 and its application in bread making

Aims:  A xylanase from the newly isolated thermophilic fungus, Thermomyces lanuginosus CAU44, was characterized and evaluated for its suitability in bread making.

High‐level production of β‐1,3‐1,4‐glucanase by Rhizomucor miehei under solid‐state fermentation and its potential application in the brewing industry

To improve the β‐1,3‐1,4‐glucanase production by Rhizomucor miehei under solid‐state fermentation (SSF) for industrial application.