Aspergillus Niger Synthesis Of ¦Â-mannanase Enzyme And Produce Functional Mos

It has been proved Aspergillus niger is capable of producing P-D-mannase, but studies on the course and control of its producing P-D-mannase were seldom done, and the study on enzymatic hydrolysis of refined konjac powder was even rare. These problems are studied in this dissertation which includes two parts . The first part studies on the optimum conditions of producing P-D-mannase such as carbon source density, nitrogen source, ratio of carbon to nitrogen, and so on. The second part is about the optimum conditions of enzymatic hydrolysis of refined konjac powder and it aims to obtain more glucoman-oligosaccarides and less monosacchatides. The main results are as follows:(1) The optimum conditions for Aspergillus niger to produce P-D-mannase are: refined konjac powder density 40g/L, peptone and sulphate of ammonia as nitrogen source with ratio of 2:1, ratio of carbon to nitrogen 7:1, beginning pH value of culture medium 6.0 around, seed volume 10%, fermentation temperature 36癈, time 3 days, P-D-mannase activity up to 75IU/mL.(2) The enzyme system of P-D-mannase from Aspergillus niger at least includes P-D-mannase, p-mannosidase and p-glucosidase. a cooperative action is taken on konjac glucomannan by these enzymes during the course of hydrolysis. That is to say, endo-p-D-mannase takes action inside the long chain of glucomannan to obtain glucoman-oligosaccharides which are then hydrolysed to monosaccharides by P-mannosidase and P-glucosidase.(3) Analyzed by HPLC, enzymatic hydrolysate mainly consists of glucose, mannose, biose, trisacharose and tetrose. Commonly, yield of monosaccharides is higher than that of oligosaccharides.(4) The optimum conditions of enzymatic hydrolysis are: enzyme dosage 75IU/g substrate, time 4 hours, pH value 6.0. Under these conditions, yield of oligosaccharides 19.32%, yield of monosaccharides only 9.58%, the ratio of the former to the latter 2.02. This result proves higher yield of oligosaccharides and lower yield of monosaccharideswill be obtained if enzymatic hydrolysis parameters are in control.