Screening Of Xylanase Producing Strains And Study Of Its Characteristics

One xylanase producing strain 2107 were selected from the strains collection in the laboratory. After Single-factor test and Response Surface Methodology, the optimum fermentation conditions of A. niger 2107 were obtained, which was as followed:concentration of the major carbon resource 4%, ratio between bran and corncob 5:5, concentration of glucose 0.161%, concentration of ammonium oxalate as supplemental nitrogen resource 1.27%, the initial pH of liquid medium 5.0,50mL/250mL flask. After shaken at 220rpm and cultured in this optimal medium for about 84 hours at 33℃, the xylanase activity was 596 IU/mL, which was 1.89 times of original medium.Result revealed that there were two differert kinds of xylanasea:X-Ⅰand X-Ⅱ. After research the enzymic properties of them,finding that X-Ⅰand X-Ⅱhad their optimum activity at 50℃and their better stability in the rang 30℃-50℃.X-Ⅰ’s temperature for loss half activity in 30 min was between 50℃-55℃,and X-Ⅱ’s was between 55℃-60℃.The two xylanases had maximal activity at pH5.0 and pH4.0 or so,respectively.X-Ⅰhad better stability between pH4-10 and X-Ⅱwas between pH2-5。They could be inhibited by different metallic ions in differert degree.