Xylanase production by Bacillus pumilus AB-1 under solid-state fermentation and its application

Abstract

Recently, xylanases have expanded their use in many processing industries, such as pulp and paper, food and textile. The production of xylanase by the bacteria Bacillus pumilus AB-1 under solid state and submerged fermentation was investigated. Screenings of various agro-industrial materials such as wheat straw, wheat bran, rice bran, banana stem, soybean flour and mustard oil cake were done and wheat bran was found to be the best carbon source for the enzyme yield under solid-state fermentation. Maximum production of xylanase (1324.64 U/g) was observed when bran moistened with mineral salt solution (MA III) at a substrate-to-moistening agent ratio of 1:1.5 (w/v) at 30°C for 72h at pH 7.0. A 1% (v/w) inoculum was most suitable to attain high production of xylanase. Yeast extract at 2.5% (w/v) concentration were used as nitrogen source enhances xylanase production. Crude xylanase was used for enzymatic saccharification of agro residues like wheat straw, wheat bran and rice bran. 10% (w/v) NaOH pretreated wheat straw is found to be beneficial for the efficient enzymatic hydrolysis and releases reducing sugar (328.15 mg/g). Xylose was found to be the major end product with traces of glucose in the enzymatic hydrolyzate of wheat straw by HPTLC. Saccharomyces cere Visiae NCIM 3570 and Pichia stipitis NCIM 3498 were investigated for ethanol production. Pichia stipitis NCIM 3498 found to be produced higher ethanol (0.345 g %) and also showed highest yield 0.045 g ethanol/g of lignocellulose.