Thermo-alkali-stable xylanase of a novel polyextremophilic Bacillus halodurans TSEV1 and its application in biobleaching

Abstract

The production of thermo-alkali-stable and cellulase-free xylanase of polyextremophilic novel Bacillus halodurans TSEV1 (MTCC 10962) was optimized in batch fermentation using statistical approaches. Plackett–Burman (PB) design identified temperature, inoculum size, KH2PO4 and wheat bran (WB) as the significant variables that affect xylanase production, and therefore, these variables have been optimized by Central composite design (CCD) matrix of response surface methodology (RSM). A 7.35-fold enhancement in xylanase production was attained due to optimization. The UV absorption spectrum of the compounds released by the enzyme action on unbleached pulp showed a characteristic peak at 280 nm indicating the presence of lignin related compounds in the filtrate. The materials released after biobleaching also displayed strong absorption at 237 and 465 nm. The enzyme dose 40 Ug−1, pH 10.0, and treatment time of 3 h are optimal for enzymatic pre-bleaching of wheat pulp that caused 14.6% reduction in kappa number and 5.6% enhancement in brightness of hand sheets without noticeable change in viscosity. This is the first report on xylanase production by a wild type polyextremophilic B. halodurans in submerged fermentation and its application in pre-bleaching of paper pulps.