Extracellular enzyme production byThermomonospora curvata grown on bagasse

A detailed overview of xylanases: an emerging biomolecule for current and future prospective

Xylan is the second most abundant naturally occurring renewable polysaccharide available on earth. It is a complex heteropolysaccharide consisting of different monosaccharides such as l-arabinose, d-galactose, d-mannoses and organic acids such as acetic acid, ferulic acid, glucuronic acid interwoven together with help of glycosidic and ester bonds. The breakdown of xylan is restricted due to its heterogeneous nature and it can be overcome by xylanases which are capable of cleaving the heterogeneous β-1,4-glycoside linkage. Xylanases are abundantly present in nature (e.g., molluscs, insects and microorganisms) and several microorganisms such as bacteria, fungi, yeast, and algae are used extensively for its production. Microbial xylanases show varying substrate specificities and biochemical properties which makes it suitable for various applications in industrial and biotechnological sectors. The suitability of xylanases for its application in food and feed, paper and pulp, textile, pharmaceuticals, and lignocellulosic biorefinery has led to an increase in demand of xylanases globally. The present review gives an insight of using microbial xylanases as an “Emerging Green Tool” along with its current status and future prospective.

Purification and characterization of the major beta-1,4-endoglucanase from Thermomonospora curvata

The major beta-1,4-endoglucanase (EG) of the thermophilic actinomycete, Thermomonospora curvata, contributed over 80% of the total EG activity recovered from cell-free culture fluid after growth on cellulose. The enzyme was purified to electrophoretic homogeneity by ammonium sulphate precipitation, ion-exchange chromatography and size exclusion HPLC. This monomeric enzyme had a specific activity of 750 IU mg(-1) when assayed with 2.5% (w/v) carboxymethyl cellulose (CMC) at 70 degrees C, pH 6.0. Highest activity was observed on CMC with a degree of polymerization of 3200. The EG was stable for 48 h at 60 degrees C, pH 6.0 and had a half-life of 30 min at 80 degrees C; temperature and pH optima were 70-73 degrees C and 6.0-6.5, respectively. The mol. wt was 100,000 and the pI was 4.0. The Km and Vmax values were 7.33 mg/ml(-1) and 833 microns min(-1), respectively. EG activity was inhibited by Fe(2+), Hg(2+), Ag(+) and Pb(2+), and enhanced by dithiothreitol and Zn(2+). The first 12 amino acid residues at the N-terminus were: Asp-Glu-Val-Asp-Glu-Ile-Arg-Asn-Gly-Asp-Phe-Ser. Glutamic and aspartic acid constituted 24% of the total amino acid composition; no amino sugar was found.