Study On Solid-State Fermentation Conditions And Enlargement Of Xylanase Production By Aspergillus Niger Lys2369

Aspergillus niger is a safe strain and has a good ability to produce xylanase.Bran and corncob are not only raw materials for fermentation,but also potential xylan hydrolysis substrates.The cultivation of Aspergillus niger with bran and corn cob as raw materials has profound significance for the deep resource utilization of agricultural waste resources and the reduction of environmental pollution caused by incineration.In this paper,the conditions of solid fermentation of Aspergillus niger Lys2369 to produce xylanase,the conditions of enzymatic hydrolysis,the products of enzymatic hydrolysis and the technology of produce xylanase by shallow plate scale-up fermentation of Aspergillus niger to produce xylanase were studied,it not only provides a research basis for large-scale production of xylanase,but also extends the processing chain of crops,and provides an efficient way for the utilization of agricultural wastes such as bran and corncob,which has a certain social significance and considerable economic value.The experimental results are as follows: 1.Optimization of solid fermentation conditions for xylanase production by Aspergillus nigerThe carbon source ratio,fermentation period,feed-water ratio,culture temperature,nitrogen source and nitrogen source content for xylanase production by Aspergillus niger solid fermentation were optimized by single factor test.According to the results of single factor test,three factors including carbon source recipes,material/water ratio and culture temperature were selected for response surface optimization test.The results showed that the best solid-state fermentation conditions for xylanase production by Aspergillus niger were as follows: bran,corncob for 6 g:4 g,fermentation period for 48 h,beef extract 2%,material /water ratio of 1:1.5,the culture temperature of 30?,and the enzyme activity of xylanase was 151.74 IU/g.2.Optimization of xylanase hydrolysis conditions and analysis of enzymatic hydrolysis productsThe optimum temperature,optimum pH,the stability of temperature and pH were studied.The results showed that the optimal conditions for xylanase hydrolysis were pH 4.0,temperature 50~55?;Xylanase had a good stability between pH 3.4~4.0,and the relative residual enzyme activity could still be maintained above 80% after 24 hours of treatment.Xylanase could maintain a good activity below 40? and residual enzyme activity could be kept at more than 89%,However,when the temperature is above 40?,the xylanase residual enzyme activity decreased rapidly,and suffered severe losses.Thin layer chromatography(TLC)analysis of xylanase hydrolysates showed that the hydrolysis products of xylanase were mainly xylose,xylobiose and a little xylotriose.3.Study on the technology of shallow plate scale-up fermentationThe scale-up fermentation of Aspergillus niger in shallow plate was studied.Aspergillus niger cultured under this technology condition was grew well,and no contamination was found.After fermentation for 4 days,most of the medium surface was completely covered by white mycelia,accompanied by evenly distributed black spores.and the middle and bottom of the shallow plate had been completely blackened.And the xylanase activity in fermentation products was up to 141.53 IU/g on average,indicating that the process conditions were feasible,but there was still exist optimizing space of the fermentation process.