The Research Of Potato Pectin Degradation And Optimum Conditions Of Enzyme Producing By Aspergillus Niger

China is a big potato producing country,and has been committed to the potato starch production industry for many years.With the acceleration of the industrialization process,it brings economic benefits,but also brought us a lot of trouble.With the production of potato starch,it also products waste of potato residue and juice.That's difficult to store and transport,causing great pollution.And the waste is rich in a variety of macromolecule nutrients.Most of the studies have focused on microbial fermentation of cellulose residues in potato starch waste to produce single cell protein to feed animals.The study found that potato residue contains not only cellulose,amino acids,but also contains a large number of pectin polysaccharides.In recent years,many scholars are committed to the pectin and pectinase research.So in this project,I intend to select Aspergillus niger,Saccharomyces cerevisiae,Bacillus subtilis,Bacillus licheniformis as experimental strains to ferment,with the pectin as the only carbon source.The results showed that the activity of pectinase of Aspergillus niger was significantly better than that of other strains.It can reach 2198U/m L,so I determined to use the strains of Aspergillus niger as experimental strains.The potato residue was used as the experimental object,and 1% Aspergillus niger was added to start the microbial fermentation.The activity of pectinase was 435 U/m L and the degradation rate of pectin was 39.90%.In order to improve the enzymatic activity and the degradation rate of pectin,seven factors which affect the activity of pectinase were selected to carry out the PB experiment.And then I select three significant factors,fermentation time,fermentation temperature and pH to carry out the central combination of experimental design.The fermentation conditions were as follows: fermentation time was 52 h,fermentation temperature was 32.15 ?,fermentation pH was 5.09.Microbial fermentation experiment was carried out under that condition.The result showed the pectinase activity was 747 U/m L,it's very close to the theoretical value of 760 U/m L.Under the conditions of the original fermentation,mixed with 1% aspergillus niger,the activity of pectinase was 442 U/m L and the degradation rate of pectin was 39.90%.At optimized fermentation conditions,mixed with 1% aspergillus niger,the results showed that the activity of pectinase was 747 U/mL,it was improved by 69.00%;the degradation rate of pectin was 59.91%,it was improved by 50.15%.The total amount of reducing sugar in the fermentation broth of potato residue before and after fermentation was determined by DNS reducing sugar method.It was found that under the conditions of the original fermentation,the total amount of reducing sugar was 0.53 mg/m L.And under the optimized conditions,it was 0.98 mg/ mL,it was improved by 84.91%.The COD of the fermentation broth was 12158 mg/L,and the removal rate was 63.89% compared with the original potato residue COD 33666 mg/L.