Xylanase Synthesis

isolating the gluten from the starch in the wheat flour. This enzyme is also used in coffee-bean mucilage (Wong and Saddler, 1993). The main desirable properties for xylanases for use in the food industry are high stability and optimum activity at an acid pH. With the advances in the techniques of molecular biology, other uses of xylanases are being discovered. Recently, a recombinant yeast of wine was constructed with the gene for xylanase of Aspergillus nidulans, xlnA, resulting in a wine with a more pronounced aroma than is conventional (Ganga et al., 1999). During the manufacture of beer, the cellular wall of the barley is hydrolyzed re- leasing long chains of arabinoxylans which increase the beer’s viscosity rendering it “muddy” in appearance.

Pharmaceutical and chemical applications xylan and Xylanase have little used in the pharmaceutical industry. Xylanases are sometimes used as a dietary supplement or to treat poor digestion when added in combination with a complex of enzymes (hemicellulases, proteases and others), but few medicinal products can be found with this formulation. Hydrolytic products of xylan, such as β-D-xylopyranosyl residues, can be used as combustible liquids (ethanol), solvents and artificial low-calorie

Xylanases enzymes start to be used in this sector in the last two decades, ever since peroxidases were applied to the degradation of lignin as reported by Sandrim et al., (2004). At present, in many countries, including Brazil, the chemical process, rather than enzymatic hydrolysis, is employed in paper manufacture. The usual method is known as the Kraft process, the name signifying strength or force in German. The method starts firstly with the pretreatment of wood shavings with a combination of two reagents, sodium sulphide and sodium hydroxide, Under 8 kgf/cm2 and at 165°C, in a digestor. The two reagents in the cooking liquor serve to accelerate the delignification, with recovery of the cellulose fibres. At this step, the cellulose pulp is known as brown mass, appearing dark in colour because of the black liquor. It can be assumed that 90–95% of the hemicellulose and lignin are dissolved and partially degraded during this process. The main advantage of the Kraft process is the possibility of recovering the chemical products from the black liquor. However, not all industries recover the sodium hydroxide and other organic materials present in the black liquor. On the other hand, the disadvantages are the high initial costs, the strong smell of gases emitted by the process, low yield (40–50%) and the high cost of bleaching. It can be seen that in the Kraft process polluting reagents