Study On The Optimization Of Submerged Fermentation Of Nattokinase

Natto is a kind of traditional food of soybean fermented in Japan. 1t is manufacturedby mixing steam soybean under the certain condition of temperature and humidity. Itis considered the secret of longevity by Japanese. Natto have a quite large value inthe aspect of nutrition and health. Every one hundred gram of Natto consist of theprotein 31.2g, fat 19.9g, carbohydrates 22.8g, Ca 331mg, P 503mg;Fe 13.7mg.There is enough requisite amino acid by the body of person in the protein of nattowhich can be compared with beef. There is upwards of 50% is water-solubilityprotein and a great deal of unsaturated fatty acid, lipid, lecithin, vitamin B, especiallythe vitamin Bl2, etc. Eating natto frequently will have many kinds of functions, suchas antioxidant, antidoat, dissolving thrombustic, antitumour, depressing bloodpressure, preventing osteoporosis, and improving a rate of digest, and so on.Nattokinase (NK) is a fibrinolytic enzyme that is extracted from natto (a traditionalfermented food in Japan). In fact it has enzymatic property of protease. Comparedwith the thrombolytic agents such as urokinase and streptokinase, NK is safer andeasier to be absorbed by body because of its low molecular weight, and has moredirect and more persistent effect on thrombosis. It is more important that NK can befermented by bacteria, which will lower the production cost. So NK can bedeveloped as a new fibrinolytic medicine.This paper investigated the liquid fermentation of NK. The main results were asfollows from the Bacillus stored in lab, which can produce NK, the liquidfermentation condition was optimized: The best nitrogen source is the defattedsoybean, the best carbon source is maize powder, C:N=1:1 was the best choice, Ca2+was the positive ion of 0.02% which had the greatest effect on NK's synthesis, whilewhether Mg2+was added or not was not very important, 0.2% of Na2HPO4: 0.1 % ofNaH2PO4 were the optimal conditions for NK's yield;Mn2+ inhibit the biosynthesisof NK, Surface-activity agents could not effect the secretion of NK. The bacteriagrew the fast in 37℃,but 30℃ was the most suitable temperature for theproduction of NK. It is the best fit PH of the growing of the bacteria and the productof NK under PH7. This strain was oxybiotic, So less volume benefit the fermentationand growth of bacteria. Because the quick volatilization of water hasdisadvantageous raise in the production of the NK, It was the best choosen for the100m1/500m1. The best production of inoculating was 2%and the best time ofinoculating was 24h. In the above optimization conditions, the number of theproduction of the liquid fermentation was 1280IU/ml. It was the 3 times comparedwith the first production.This paper had the related study of theory and practice for the production of theNatto and Nattokinase, and provided a technical basis for its market development andapplication plan. Through the paper, it is hoped to draw on the experience ofproposition for the transformation of the Northeast soybean resources, and enhancethe added value of soybean products.