Pretreatment processing of fabrics by alkalothermophilic xylanase from Bacillus stearothermophilus SDX

A highly active alkalothermophilic cellulase free xylanase (3446 U/g of dry substrate) has been produced from newly isolated strain of Bacillus stearothermophilus under solid-state fermentation using wheat bran (2.5%, w/v) pH 7.0 and at 37 °C. The xylanase was stable over broad range of pH (6.0–12.5) and temperature (37–85 °C) and hence was used in the bioprocessing of fabrics as an alternative to conventional chemical method. The desizing and bioscouring treatments were most efficient at 70 °C after 90 and 180 min of incubation respectively using 5 g/l of xylanase dose in the medium of pH 9.5. Enzymatically desized fabrics when subjected to bioscouring resulted in 0.91%, 0.88% weight loss for micropoly and 0.83%, 0.80% for cotton respectively under agitated (50 ± 2 rpm) and non-agitated conditions. Consequently Whiteness index for cotton (11.81%) and micropoly (52.15%) fabrics was increased. Induction in the release of reducing sugars was also observed for cotton (8.37%) and micropoly (16.79%) fabric over conventional method. Enzymatically processed fabric samples possessed 1.12% and 1.95% more tensile strength than reference. Tearness value also increased for bio-treated cotton (1.57%) and micropoly (2.37%) fabric samples as compared to control.