Screening Of An Alkaline Xylanase-Producing Strain, Optimization Of Xylanase Production Conditions And Characterization Of Xylanase

According to RBB-xylan-hydrolyzed halos method , A bacterial strain which can produce extra-cellular alkaline xylanase, was isolated from alkaline soil near the drain ditch of a paper-producing factory .The strain was named as HNX01.The activity of xylanase produced by HNX01 was 89.39 IU/ml. According to its morphological characterization, physiological and biochemical experiments, HNX01 should belong to Bacillus.sp.After single factor tests and orthogonal array ,the optimal medium consisted of 4% corn power, 2% wheat bran, 0.6% NH4Cl, 0.2% NaNO3, 1% K2HPO4, 0.2% tween-80, 2mmol/L FeCl3.The initial pH of medium was 8.0.The percent of inoculation was 3%.The volume was 50ml in 250ml flask.After shaken at 220rpm and cultured in this optimal medium for about 24 hours at 37℃ , the xylanase activity is 198.41 IU/ml, which is 2.5 times of original medium.The xylanase from HNX01 displayed an optimal temperature at 50℃ and optimal pH at 8.0,a pH stability range from 5.0 to 10.6 and thermal stability up to 50℃.After incubated for 60 minute at 50℃,it still had 70% activity. In the metal ions investigated, only Zn2+ promoted effects on Xylanase, other ions all inhabited its activity more or less. Especially, Cu2+ inhabited almost all the activity. Fe3+ inhabited 50% activity in the enzyme reaction.