Production Of Xylanase From Aspergillus Niger JY021 And Its Application On Lignocellulosic Material Hydrolysis

As one of the most important enzymes, xylanase has wide applications in feed, food, textile, and paper industries.Xylanase production by Aspergillus niger JY021, enzymatic characteristic of the xylanase, xylooligosaccharides production from corncobs by xylanase hydrolysis and xylanase hydrolysis of cellulosic materials coordinated with cellulose were studied in the thesis.Xylanase production by Aspergillus niger JY021 was carried out under liquid fermentation process. The culture medium and the cultivation conditions were optimized as follows: liquid concentration of corn cobs 2%, glucode 0.3%, corn starch 1%, wheat bran 0.2%, Mandels nutrient 20%, Mandels microelement 0.2%, 1M citrate buffer 5%, Tween 80 0.3%, pH 4.8, shaking flask speed 200rpm.Under optimized conditions, xylanase activity reached 452IU/ml after 3 days at 30℃.Xylanase production by Aspergillus niger JY021 was carried out under solid-state fermentation process. The culture medium and the cultivation conditions were optimized as follows: concorb 60%,wheat bran 40%,surcose 0.4%,NH₄NO₃ 2%, carbamide 0.5%, KH₂PO₄0.5%, MgSO₄-7H₂O 0.2%, initial moisture content 70%, natural pH value, inoculum level of 6%( V/W) ,The high xylanase activity (7510IU/g dry koji) was attained after 3 days at 30℃.The optimal temperature and pH value for Aspergillus niger xylanase reaction were 50℃ and 4.8, respectively.Xylooligosaccharides production was carried out by enzymatic hydrolysis of xylan, the process conditions for xylooligosaccharides production were optimized as follows: reaction temperature, 50℃;pH value, 4.8;xylan substrate, 3.0%;xylanase dosage, 50IU/g substrate;hydrolysis time, 0.5 hours. The average degree of polymerization (DP) of the product was 3.61 and the total yield of xylooligosaccharides reached 91.2%.Xylanase and cellulase were used in coordinated enzymatic hydrolysis of cornstalks.The process conditions for enzymolysis were optimized as follows: reaction temperature, 50°C;pH value, 4.8;substrate concentration, 12%;enzyme dosage, xylanase 50IU/g substrate, cellulose 18FPIU/g substrate,cellobiase 8IU/g substrate;hydrolysis time, 48 hours.The yield of coordinated enzymatic hydrolysis was 85.3%. Some disadvantageous matter to fermentation like furfural, phenol sort compound were not found in the enzymatic hydrolysate.Production of xylanase from Aspergillus niger JY021 and its application on lignocellulosic material hydrolysis was studied, using inexpensive agricultural wastes as raw material. The results showed that the potential application of renewed cellulosic resource.