Isolation And Fermentation Conditions Of Xylanase-producing Strain

Xylan is the main component of hemicellulose in the plant, and it is the second only to cellulose in natural amylose. Xylanase is a kind of pentosanase which can degrade the xylan to XyLo-oligosaccharides and xylose. It's mainly applied in paper making, foodstuff, medicine energy sources, and textile industry and so on. Both commerce value and application foreground are considerable. All bacteria in our study were collected from soil covered by lots of wood and leaves for long time in different area,the districts contain Qing Cheng mountain, Jjiuzhaigou valley in Si chuan Province, Lhasa, Linqi city in Shandong Province and else. The bacteria were first screened by RBB-xylan culture medium according to whether appear hydrolyzed holecircle or not. And the bacteria with clarity circle were cultivated in ferment medium for the next screening. We obtained four excellent xylanase enzyme producing strains through the anterior process. Finally we choose the high enzyme activity strain No. X-18 to carry out ferment condition optimization experiment. The Gram stain and spore stain are both Positive Rod toward the bacteria. The result of classification and characterization indicate the No. X-18 belongs to Bacillus sp. The result of single factor experiment show the most appropriate carbon sources are mannose and cane sugar corresponding to the enzyme activity is 17.24 IU/mL 16.68 IU/mL respectively, the most appropriate nitrogen sources is peptone corresponding to the enzyme activity is 18.5 IU/mLon the other hand, the result of double factors reveal the most high activity 19.86 IU/mL is made up of the compound of xylan and arabinose refer to the carbon source, When use the compound of peptone and ammonium oxalate as nitrogen source the enzyme is considerable up to 19.71 IU/mL.The optimal medium composition as 1.5% sucrose, 1% arabinose,0.37% NH₄Cl, 0.37% yeast extract, 0.5% K₂HPO₄, 0.02%MgSO₄·7H₂O, pH 8.0 after a series of the single factor experiment, double factors experiment and medium component optimization experiment. Furthermore, the optimal culture condition described below: 50mL initial PH 8.0 ferment medium in 250ml flask at 32℃for 72h. The enzyme activity can reach 74.21IU/mL at the optimal condition.We investigate part zymological property about the Bacillus sp.No X-18 xylanase, find the optimum temperature is50℃,And its heat stability is fine, it keep 100% activity after incubating at 50℃for 1 hour. Its pH range also is wide.the activity can keep high from pH5.0to pH8.0,and the optimum pH is 5.0,tolerance of the enzyme is much beffer than it reported already.